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In situ analysis of major and trace elements of anhydrous minerals by LA–ICP–MSLA–ICP–MS without applying an internal standard
Abstract
Here we describe an internal standard-independent calibration strategy for LA-ICP-MS analysis of anhydrous minerals and glasses. Based on the normalization of the sum of all metal oxides to 100 wt.%, the ablation yield correction factor (AYCF) was used to correct the matrix-dependent absolute amount of materials ablated during each run., where cpssamj and cpsrmj are net count rates of analyte element j of the sample and reference material for calibration, Crmj is concentration of element j in the reference material, N is the number of elements that can be determined by LA-ICP-MS. When multiple reference materials were used for calibration, l value can be calculated with regression statistics according to the used reference materials.Applying an AYCF and using the USGS reference glasses BCR-2G, BHVO-2G and BIR-1G as reference materials for external calibration, analyses of MPI-DING reference glasses generally agree with recommended values within 5% for major elements (relative standard deviation (RSD) = 0.3–3.9% except for P2O5, n = 11), and 5–10% for trace elements. Analyses of anhydrous silicate minerals (clinopyroxene, orthopyroxene, olivine, plagioclase and garnet) and spinel generally agree with the results of electron microprobe analysis within 0.2–7% for SiO2, Fe2O3, MgO and CaO. RSD are generally < 5% for elements with concentrations > 0.1 wt.%. The results indicate that, by applying an AYCF and using USGS reference glasses as multiple reference materials for calibration, elements of these anhydrous minerals can be precisely analyzed in situ by LA-ICP-MS without applying internal standardization. The different element fractionations between the NIST glasses and those glasses with natural compositions indicate that NIST SRM 610 is a less than ideal reference material for external calibration of analyses of natural silicates.
... Detailed operating conditions for the laser ablation system and the ICP-MS instrument and data reduction are the same as description by Liu et al. 28 . Laser sampling was performed using a GeoLas 2005. ...
... A SRM 610 was used as a quality control specimen to monitor and correct for instrument sensitivity drift. Multiple ISMs (BHVO-2G, BCR-2G, and BIR-1G) were used for multiple external standard corrections (Liu et al.) 28 . The preferred values of element concentrations for the USGS reference glasses are from the GeoReM database (http://georem.mpchmainz.gwdg.de/). ...
... The preferred values of element concentrations for the USGS reference glasses are from the GeoReM database (http://georem.mpchmainz.gwdg.de/). Off-line selection and integration of background and analyte signals, and time-drift correction and quantitative calibration were performed by ICPMSDataCal (Liu et al. 28 ; Liu et al.) 28,30 . ...
The origin of raw materials is a key area of study in jade archaeology, with significant implications for understanding the interactions and exchanges between ancient cultures. The Guojiamiao Cemetery, located in Zaoyang City, Hubei Province, China, has been the subject of two protective excavations, one in 2004 and another in 2014. These excavations revealed a large aristocratic cemetery from the Zeng State, dating from the late Western Zhou Dynasty to the early Spring and Autumn periods. The jade artifacts found at the site are diverse in type and exquisite in craftsmanship, serving as important burial items. This study applied gemological, spectroscopic, and geochemical methods to analyze 30 jade artifacts in detail. We examined the types of minerals, shape characteristics, and chemical composition of the materials. In particular, we focused on determining the origin of the tremolite jade artifacts found at the cemetery. Using a classification method based on combinations of trace and rare earth elements associated with different regions, we were able to identify the sources of the jade. Our findings suggest that the raw materials for the Guojiamiao Cemetery jade artifacts unearthed were transported over long distances, from northwestern China to the middle reaches of the Yangtze River. This research is important for understanding the jade use system of the Zeng State from the early Western Zhou to the mid-Warring States periods. It also provides insights into the sources of jade materials in different historical periods of the Zeng State and its connections with the Chu State. Ultimately, this study contributes to a broader understanding of the evolution of civilization in the middle Yangtze River region.
... The laser spot size and frequency were set to 32 µm and 5 Hz, respectively. The trace element compositions of amphibole were calibrated against the reference materials NIST610, BHVO-2G, BCR-2G, and BIR-1G without employing an internal standard, using the ICPMS-DataCal software (Liu et al., 2008). Although this calibration method was originally designed for anhydrous minerals, the calculated H2O content of the amphibole is extremely low (<1 wt %; App. ...
... Table A3), resulting in negligible bias in the trace element data (less than 1%). Using this method, the uncertainty in the trace element concentrations is expected to have been below 5 to 11% (e.g., Liu et al., 2008). The results and detection limits are provided in Appendix Table A5. ...
Fluoride-silicate melt immiscibility has been proposed as an important control on light rare earth element (LREE) and Y enrichment in a peralkaline granite (e.g., the Strange Lake pluton in Canada). It remains uncertain, however, whether this immiscibility is a requirement for ore formation in mineralized peralkaline granites globally. In this contribution, we present an integrated mineralogical and chemical study of the REE-Zr-Nb-Be–mineralized Baerzhe peralkaline granite pluton, northeast China. We focus on the mineralogy and chemistry of amphibole and the bulk-rock geochemistry to investigate whether the metal enrichment at Baerzhe was facilitated by fluoride-silicate melt immiscibility or simply resulted from fractional crystallization.
The Baerzhe pluton comprises, from early to late, a fine-grained hypersolvus granite, a porphyritic hypersolvus granite, and a transsolvus granite that evolved to pegmatite and a comb-textured amphibole unit. Hypersolvus granite enclave(s) can also be found within the transsolvus granite. The amphibole in these granitic units is arfvedsonite, providing evidence of fractional crystallization, magma mingling, fluoride melt immiscibility, fluid exsolution, and degassing. The presence of fluoride melt inclusions in arfvedsonite indicates that fluoride-silicate melt immiscibility took place in all units of the pluton except for the transsolvus granite, where rare metal mineralization occurs, and in pegmatite. The immiscibility was particularly intense in the porphyritic hypersolvus granite but very weak in other rock units, as evidenced by the abundance of fluoride melt inclusions in the former and lack of them in the latter. Most fluoride melt inclusions are rich in Ca and are enriched in LREEs, middle REEs (MREEs), and Y relative to heavy REEs (HREEs). The estimated volume of fluoride melt in the porphyritic hypersolvus granite was less than 1 wt %, storing about 2 to 6 wt % LREEs and up to 8 to 15 wt % MREEs and Y. The exsolution of fluoride melt, however, does not appear to have affected the trends of increasing concentrations of REEs and high field strength elements (HFSEs) in the coexisting silicate melt, which were driven by intense fractional crystallization of alkali feldspar, quartz, and arfvedsonite. Furthermore, the absence of fluoride melt inclusions in the transsolvus granite and pegmatite, together with their scarcity in the comb arfvedsonite unit, suggests that the early formed immiscible fluoride melt did not accumulate in the residual silicate melt. Fluoride melts appear to have played a limited role in the concentration of LREEs and Y to form the Baerzhe deposit. Instead, fractional crystallization of silicate minerals exerted a dominant control on the enrichment of REEs and HFSEs by factors of five to 20.
... Two spots of the cassiterite standard samples BB7 were added to every 5 sample points as monitoring samples. The U-Pb ages of cassiterite are determined via ICPMSDataCal and VizualAge DRS (Liu et al., 2008;Chew et al., 2014). Calculations of weighted mean ages and concordia diagrams were performed via IsoplotR online (Vermeesch, 2018). ...
... The trace element contents of cassiterite and skarn minerals were calibrated separately using 118 Sn and 29 Si. The ICPMSDataCal software was employed to process the original data, following the methodology described by Liu et al. (2008). ...
Discovery of the Jinshui skarn-type tin deposit marked the first instance of a tin deposit to be uncovered in the central segment of the East Kunlun Orogenic Belt (EKOB) in northwestern China. To determine the timing of tin mineralization and elucidate the progression of the ore-forming hydrothermal system, we conducted geochronology of cassiterite and trace element analysis on various minerals hosted in skarn ores. The U–Pb dating results of the cassiterite indicate that tin mineralization took place at 392.9 ± 5.8 Ma, which closely aligns with the syenogranite emplacement at 396.1 ± 2.1 Ma in the Jinshui deposit. This correlation suggests a temporal link between tin mineralization and granitic magmatism. The deposit is characterized by two generations of cassiterite, with trace element analyses consistently showing that the dark cathodoluminescent cores have relatively high W and U concentrations, whereas the bright rims are enriched in Sc, Ti, V, Zr, In, and Hf. Additionally, the Zr/Hf ratios confirm that the syenogranite was the source of the ore-forming fluids. During the prograde skarn stage, the ore-forming fluids maintained an equilibrium closed system. Initially, the ore-forming fluid experienced reducing conditions, characterized by a low water-to-rock (W/R) ratio and a neutral to slightly alkaline pH. This fluid subsequently evolved into an oxidizing fluid with an elevated W/R ratio and an acidic pH. During the retrograde skarn stage, the fluid continued to exhibit high levels of oxygen fugacity. As the mineralization process progressed from the oxide stage to the quartz-cassiterite-sulfide stage, the presence of cassiterite indicates that the ore-forming fluid experienced two increases in oxygen fugacity, and this fluctuation may be attributed to the mixing of external fluids. The post-collisional extensional environment provided the tectonic background for the formation of the Jinshui tin deposit. Magmas derived from mantle sources ascended, and partial melting of the felsic crustal materials led to the formation of the Jinshui syenogranite after differentiation. Skarn-type tin deposits formed at the favorable locations of the contact between the granite body and the Sn-rich Jinshuikou Group.
... The sample was ablated and sampled by the NWR-193UC excimer laser, and then the ion signal intensity was measured accurately by the Agilent 7900 quadrupole inductively coupled plasma spectrometer. The data processing stage is completed with the help of ICPMSDataCal [13,14] software, which supports offline data processing and greatly improves the efficiency and accuracy of analysis. The specific operating conditions and data processing methods of the experiment refer to the comprehensive method proposed by Liu et al. ...
... The specific operating conditions and data processing methods of the experiment refer to the comprehensive method proposed by Liu et al. In addition [13][14][15], the isochronal map is drawn by using Ex_ver3 [16] software, which is specially used for visual analysis of geochronological data and effectively assists researchers in interpreting complex isotopic age data. ...
Large‐scale Cenozoic magmatic rocks in the southern Qinghai‐Tibet Plateau show a key chapter of geological evolution, especially the northward subduction and gradual melting in the Neo‐Tethys Sea plate during the collision between the Asian continent and the Indian plate, which reveals its geological importance. Although some progress has been made in the study of the Linzizong volcanic rocks in southern Lhasa during the India‐Asia collision, the closure time of the Neo‐Tethys Sea and the exact timing of the first India‐Asia collision are still controversial in the geological community. This study focuses on the formation age, geochemical characteristics, and tectonic environment of the granitic diorite in the Duodigou area, central southern Lhasa. LA‐ICP‐MS U–Pb dating of zircons reveals that the diorite was formed in the Paleogene, with a specific age of 57.20 ± 0.56 Ma. Geochemical analysis indicates that the granite was formed in an island‐arc magmatic environment and belongs to peraluminous I‐type granite. Under the background of the continuous northward subduction in the Neo‐Tethys plate, the interaction of marine sediment dehydration and melting led to the intrusion of basaltic magma into the crust, which led to the remelting of the lower crust and the formation of granitic magma. Through this study, we have further improved the chronological framework of Cenozoic magmatism in southern Lhasa and provided new geological constraints for the analysis of the Neo‐Tethys Sea's evolution during the period. image
... The laser operational settings were adjusted to 44 μm spot size, 80 mJ energy, and 5 Hz frequency. A range of reference materials (BCR-2G, BHVO-2G, BIR-1G, and GSE-1G) were employed to calibrate trace element concentrations 58 . Analysis of each spot included a background acquisition of approximately 20-30 s followed by 50 s of data acquisition of the sample. ...
... Analysis of each spot included a background acquisition of approximately 20-30 s followed by 50 s of data acquisition of the sample. ICPMSDataCal, an Excel-based software, was used off-line for selection and integration of background and analyzed signals, time-drift correction, and quantitative calibration 58 . ...
There is ongoing debate about whether lunar magnesian suite (Mg-suite) magmatism was a global, nearly synchronous event with a genetic link to potassium, rare-earth element and phosphorus components (KREEP). Arguin 002, the first whole-rock meteorite classified as a lunar norite, offers a unique opportunity to explore the genesis and timing of Mg-suite rocks. Here we investigated the petrology, mineralogy, geochemistry, and chronology of Arguin 002, revealing it to be an evolved, KREEP-free Mg-suite rock with chemical similarities to atypical Apollo-15 Fe-norites. It likely formed through plutonic magmatism originating from low-degree partial melting of a deep, KREEP-free mantle source and has a ²⁰⁷Pb/²⁰⁶Pb age of 4341.5 ± 9.3 Ma. The potential source of Arguin 002 is within the South Pole-Aitken basin, near the Chang’e-6 landing site. These findings indicate that Mg-suite magmatism was a global and nearly synchronous event, potentially driven by rapid global mantle overturn.
... The instrument setup included a Prodigy-type ICP from Leeman Labs (Leeman labs INC., New Hampshire, USA) and a UP266Macro-type laser with a 515 nm beam diameter from New-Wave (New-Wave Research , Fremont, California, USA). The instrumental conditions and data processing methods followed those described by Liu et al. [33]. ...
... The instrument setup included a Prodigy-type ICP from Leeman Labs (Leeman labs Inc., NeH, USA) and a UP266Macro-type laser with a 515 nm beam diameter from New-Wave (New-Wave Research, Fremont, CA, USA). The instrumental conditions and data processing methods followed those described by Liu et al. [33]. ...
This study sheds light on the origin and trade routes of early red coral artifacts found in Xinjiang, primarily dating to the Han and Jin dynasties. The red coral relics examined, excavated from the Shengjindian cemetery of the Western Han Dynasty in Turpan, offer critical insights into the material’s provenance and its introduction to this pivotal region along the ancient Silk Road. Advanced gemological, mineralogical, and geochemical analyses—utilizing computed tomography (CT), laser Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)—has revealed distinctive features. These include red coloration, a waxy luster, concentric ring structures in cross-section, and calcareous composition, identifying the coral as Sardinian (Corallium rubrum), likely originating from the western Mediterranean region. The findings carry significant archaeological implications. Red coral first appears in the archaeological record in Xinjiang during the Western Han period, facilitated by the thriving Silk Road trade and the expanding influence of Buddhist culture. This study not only confirms the Mediterranean origin of these artifacts but also highlights their integration into the cultural and economic networks of ancient Xinjiang, underscoring the significance of early long-distance trade and cultural exchange.
... The analysis times for the measured elements were as follows: 204 Pb (8 ms), 206 Pb and 208 Pb (15 ms), and 207 Pb, 232 Th, and 238 U (20 ms). The data reduction was performed using the ZSkits and ICPMSDataCal programs [79,80], and the age of the cassiterite was calculated from the lower intercept of the U-Pb Tera-Wasserburg concordia plot. The U-Pb age calculations and the creation of the Tera-Wasserburg plot were conducted using the IsoplotR (v.3.3) ...
... The U-Pb isotope dating analysis was conducted using ZTA01 (isotope dilution (ID)-TIMS age of 263.67 ± 1.71 Ma; [85]) as an external standard for isotope fractionation correction, Coltan139 (from the Rubicon pegmatite in Namibia, ID-TIMS age of 506.2 ± 5.0 Ma; [86,87]) as a quality-control standard, and NIST610 as an external standard. The data processing was carried out using the ICPMSDataCal 10.1 software [79,80], and the creation of the concordia plot and weighted average age calculation were performed using the IsoplotR software [84]. ...
Rare metals such as lithium and beryllium are strategic mineral resources that play a highly significant role in the national aerospace, defense, and new energy industries. The western Kunlun–Songpan–Ganzi metallogenic belt is an important rare metal metallogenic belt in China that mainly consists of granite–pegmatite-type lithium–beryllium deposits with uncommon beryllium-only deposits. In the Jiulong area on the southeastern edge of this metallogenic belt, several deposits, including the Daqianggou lithium–beryllium, Luomo beryllium, Baitai beryllium, and Shangjigong beryllium deposits, have been identified. Unlike the northern areas of Jiajika, Ke’eryin, Zawulong, and the western regions of Dahongliutan and Bailongshan, this area contains beryllium-only deposits. In this paper, we examine representative beryllium deposits in the Jiulong area, including detailed petrographic observations and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb isotope dating of cassiterite and columbite–tantalite, to define the metallogenic age and summarize the spatiotemporal characteristics of the beryllium mineralization in this area. The research results show that the Daqianggou lithium–beryllium deposit is dominated by spodumene and beryl mineralization, while the Luomo and Baitai beryllium deposits primarily feature beryl mineralization. The dating results indicate that the U-Pb ages of the cassiterite and columbite–tantalite in the Daqianggou lithium–beryllium deposit are 157.3 ± 1.7 Ma and 164.1 ± 0.8 Ma, respectively. For the Luomo beryllium deposit, the U-Pb ages of the cassiterite and columbite–tantalite are 156.1 ± 1.5 Ma and 163.3 ± 0.8 Ma, respectively. For the Baitai beryllium deposit, the U-Pb age of the columbite–tantalite is 188.8 ± 1.1 Ma. Therefore, the Jiulong area experienced two pegmatite-type rare metal metallogenic events: a beryllium–niobium–tantalum–molybdenum event at 197~189 Ma and a lithium–beryllium–niobium–tantalum–rubidium event at 164~156 Ma. Based on the reported metallogenic ages, we suggest that the western Kunlun–Songpan–Ganzi rare metal metallogenic belt experienced three rare metal metallogenic events at 210~200 Ma, 200~180 Ma, and 170~150 Ma. Regarding exploration directions, early Yanshanian beryllium mineralization predominates in the Jiulong area along the southeastern edge of the belt, and deep exploration of the early Yanshanian rare metal mineralization within this belt should be strengthened to facilitate new breakthroughs.
... Each analysis incorporated a 20-30 s background acquisition (with no laser ablation) followed by 50 s data acquisition from the sample (during this time, the laser ablates the sample at a single spot). ICPMSDataCal software (Liu et al., 2008) was used for data processing, which included quantitative calibration and time-drift correction (Liu et al., 2008(Liu et al., , 2010.Concordia diagrams and weighted mean calculations were generated using Isoplot/Ex_ver3 (Ludwig, 2003). ...
... Each analysis incorporated a 20-30 s background acquisition (with no laser ablation) followed by 50 s data acquisition from the sample (during this time, the laser ablates the sample at a single spot). ICPMSDataCal software (Liu et al., 2008) was used for data processing, which included quantitative calibration and time-drift correction (Liu et al., 2008(Liu et al., , 2010.Concordia diagrams and weighted mean calculations were generated using Isoplot/Ex_ver3 (Ludwig, 2003). ...
... Mineral trace element analysis was conducted at Guilin University of Technology using a 193 nm ArF excimer laser coupled with an Agilent 7500a ICP-MS. The detailed analytical procedures and instrument parameters are described in Scheibner et al. (2007) and Liu et al. (2008). A laser spot size of 24 μm was used for the analyses. ...
... A method employing multiple external standards and a single internal standard was used for quantitative analysis, with the SiO 2 (wt%) content of the minerals as the internal standard. Offline data processing was performed by ICPMSDataCal software (Liu et al., 2008). The analytical error for mineral trace element analysis was better than ±10%. ...
The arc-type characteristics of subducted crustal material incorporated into the mantle are closely related to metasomatism by melts and fluids derived from subducted oceanic crust. However, the specific compositions and proportions of melts and fluids from different end members of oceanic crust that metasomatize the mantle, as well as the subsequent processes of magma ascent, emplacement, and the evolution of mineral crystallization, remain inadequately understood. We conducted a detailed investigation of the major and trace element compositions of clinopyroxene, amphibole, and plagioclase in gabbro and gabbroic diorite from the North Qilian orogen in Northwest China to quantify the mechanisms of melt-fluid metasomatism, reveal the nature of the mafic magmatic arc source, and elucidate the processes of recharge and mixing of cognate magmas. Zircon U-Pb dating results indicate that the mafic intrusions in Zhamashi have emplacement ages of 505−481 Ma. The Sr-Nd isotopic compositions are relatively depleted, with (87Sr/86Sr)i ratios ranging from 0.7047 to 0.7086, and εNd(t) values ranging from 0.62 to 2.63. Trace elements display arc-related characteristics that are closely associated with the subduction of oceanic slab, which suggests that the Zhamashi mafic magmatic rocks originated from a mantle source metasomatized by aqueous fluids and hydrous melts derived from subducted North Qilian oceanic basaltic crust and sediments. Amphibole thermobarometer results indicate that the temperature for magma crystallization ranged from 940 °C to 994 °C, with pressure ranging from 417 MPa to 774 MPa, which corresponds to depths of 17.4 km to 29.5 km. The oxygen fugacity ranged from +1.3 to +1.9. The water content for melt varied from 5.3 wt% to 8.0 wt%, which is indicative of the typical heating and hydrous melting processes associated with contributions from subducting slab-derived fluids and melts. Complex mineral zoning structures and compositional variations record multiple episodes of cognate magma recharge and mixing during magma evolution, providing new insights into the dynamic processes that occur in subduction zone environments. Simulation results suggest that 5%−12% of oceanic crust-derived fluid and 0.5%−1.3% of sediment-derived melt reacted with garnet-phase lherzolite in the mantle wedge to form the metasomatized mantle, followed by 21% partial melting of the mantle source. These findings underscore the significance of melt-fluid metasomatism and multiple episodes of cognate magma recharge for understanding the genesis and diversity of arc magmatic rocks in subduction zones.
... The international glass standard substances (BCR-2G, BHVO-2G) and glass standard NIST610 were used as the external calibration standards. The element content was quantitatively determined using the multi-external standard method without an internal standard [54], while NIST610 was utilized to correct for any mass drift in the instrument. All data processing was conducted using ICPMSDataCal software 12.2 [54,55]. ...
... The element content was quantitatively determined using the multi-external standard method without an internal standard [54], while NIST610 was utilized to correct for any mass drift in the instrument. All data processing was conducted using ICPMSDataCal software 12.2 [54,55]. ...
The trapiche garnet, a gemstone of unparalleled beauty, boasts a rare structure comprising one core, six radiating arms, and a main body. The occurrence of garnet within the trapiche structure elevates it beyond the species, granting it significant scientific and gemological value. In this study, we conducted the first systematic investigation of trapiche garnets from the Chun’an area, Zhejiang Province, China. These samples were proven grossular through the analysis of spectroscopy and major elements. The trace element features are consistent with the distribution patterns of garnet in hydrothermal metasomatic skarn. Microscopic observation and Raman spectroscopy revealed that dark inclusions within the core and arms consist predominantly of amorphous carbon. The in situ U-Pb dating of the trapiche garnets revealed a crystallization age of 120.7 ± 4.7 Ma, corresponding to the late Yanshanian movement. It is speculated that the contact metasomatism between magma enriched in Al and surrounding rock led to the formation of calcareous skarn. This study provides insights into gemological, geochemical, and chronological characteristics, broadening the research on trapiche structures, and enhancing the understanding of gemstone mineralization timing and local tectonic activity.
... Each analysis was performed using a background acquisition of approximately 20-30 s, followed by 50 s, of data acquisition. The offline processing of analysis data was completed by ICP-MS-DataCal software, including selection of background and analysis signal, instrument sensitivity drift correction, trace element analysis, U-Pb isotope ratio and age calculation, etc., (Liu et al., 2008a;Liu et al., 2010). The calculation of zircon U-Pb age weighted mean value and the Concordia diagrams were completed by Isoplot software (Ludwig, 2003). ...
... Whole-rock Sr-Nd isotopic compositions were measured using a Triton thermal ionization mass spectrometer (TIMS) at Sample Solution Analytical Technology Co., Ltd. The Sr-Nd isotopic analytical techniques are described in detail by Liu et al. (2008a). ...
The detailed study of HP/UHP metamorphic rocks and intermediate-acid rocks has revealed the complete tectonic evolution of the North Qaidam Orogenic Belt (NQOB), from oceanic to continental subduction and subsequent exhumation. However, less comprehensive studies of Paleozoic mafic rocks have led to a limited understanding of the subcontinental lithospheric mantle, geodynamic settings, and tectonic transitions. In this paper, a comprehensive study of mafic-intermediate rocks from the Yuka Terrane in the NQOB suggests that zircon U-Pb dating yielded ages of 471 ± 3 Ma and 438 ± 3 Ma, respectively. Both rocks exhibit arc-like trace element patterns, characterized by enrichment in REEs and LILEs (e.g., Cs, Rb, Ba, Th), depletion in HFSEs (e.g., Nb, Ta), moderate (⁸⁷Sr/⁸⁶Sr) i values (ranging from 0.70473 to 0.70811 and 0.70599 to 0.70685, respectively), and εNd(t) values ranging from positive to negative (−2.7 to +0.3 and −1.0 to +1.5, respectively), indicating derivation from the partial melting of enriched subcontinental lithospheric mantle. The current trace element compositions and previous studies on post-collisional mafic rocks suggest that the enriched material added to the subcontinental lithospheric mantle beneath the Qilian Block is primarily derived from fluids released by the subducting oceanic crust, with a smaller contribution from melts of overlying sediments. A comparison with previous studies, including mafic geochronological data and the period of UHP metamorphism, reveals that Paleozoic magmatism in the NQOB can be divided into three stages, while the NQOB experienced four distinct stages of geodynamic processes. These findings suggest a model of tectonic evolution and geodynamic transition: (1) 535–445 Ma: Slab retreat and associated back-arc extension; (2) 445–420 Ma: Slab rollback; (3) 420–395 Ma: Slab breakoff; (4) 395–360 Ma: Orogenic lithospheric collapse and extension. Overall, this study provides new insights into the nature of the subcontinental lithospheric mantle beneath the Qilian Block, as well as the tectonic evolution and geodynamic processes within the NQOB.
... The operational parameters of the instrument included an ablation duration of 50 s and a laser spot diameter of 32 μm, with a repetition rate of 5 Hz. The trace element compositions of tourmalines were determined by calibration against different reference materials (BHVO-2G, BIR-1G, and BCR-2G) without the use of an internal standard (Liu et al., 2008). To analyze the data acquired, an Excelbased software program, ICPMSDataCal, was employed for off-line selection and to integrate background and analyzed signals, correct timedrift, and conduct quantitative calibration (Liu et al., 2008). ...
... The trace element compositions of tourmalines were determined by calibration against different reference materials (BHVO-2G, BIR-1G, and BCR-2G) without the use of an internal standard (Liu et al., 2008). To analyze the data acquired, an Excelbased software program, ICPMSDataCal, was employed for off-line selection and to integrate background and analyzed signals, correct timedrift, and conduct quantitative calibration (Liu et al., 2008). The precision, ascertained through repeated analysis of the standards, exceeded 5%. ...
The magmatic-hydrothermal transition in LCT-type pegmatites, which are enriched in lithium (Li), cesium (Cs), and tantalum (Ta), has received international attention because rare metal (e.g., Li) minerals reach saturation at this stage. However, deciphering the details of the melt-fluid evolution and Li distribution behavior remains difficult. We conducted studies of in situ major and trace elements and B isotopes of tourmalines from the Dangba Li-rich and Li-poor pegmatites in the Songpan-Ganze terrane of the Eastern Tibetan Plateau to unravel the magmatic-hydrothermal transition processes that may have contributed to Li mineralization. Tourmalines range in composition from magmatic dravite and schorl to hydrothermal elbaite in the Li-rich pegmatite, while those from the Li-poor pegmatite primarily consist of magmatic schorl. Tourmalines from the Li-rich pegmatite show dominantly Fe3+Al3+−1 substitution, which indicates that they formed in an oxidizing and high-salinity magmatic-hydrothermal environment. Tourmalines from the Li-poor pegmatite, however, show the dominant substitution of Fe2+Mg2+−1, which suggests they formed in a reducing and low-salinity environment with limited aqueous fluid. Three types of tourmaline were identified in the Li-rich pegmatites: (1) tourmalines that formed earlier from primary melt in the border zone, (2) tourmalines in the intermediate zone that crystallized from fluid-rich melts during the magmatic-hydrothermal transition, and (3) the overgrowth rims that crystallized from hydrothermal fluids. The tourmalines from the intermediate zone (with spodumene mineralization) typically exhibit heavy and varied B isotopic compositions (δ11B = −12.3‰ to −6.0‰) with higher δ11B in the overgrowth rims, which was probably caused by massive fluid activities, as is also supported by the high Mn, Pb, and Li abundances in these tourmalines. By contrast, tourmalines from the Li-poor pegmatite show homogeneous and relatively light B isotopes (−12.3‰ to −11.0‰), which suggests weak fluid activity (consistent with their relatively low Mn, Pb, and Li). Modeling suggests that ∼29 wt% and ∼10 wt% of B is removed by fluid exsolution in the Li-rich and Li-poor pegmatites, respectively. We suggest that the occurrence of large amounts of hydrothermal fluids with high Cl contents is crucial to pegmatite Li mineralization. Aqueous fluids may be separated from the pegmatite-forming magma when water oversaturation is reached. As a result, Li could be continuously concentrated into the fluid-rich part of such a coexisting fluid-melt system. Eventually, this would lead to spodumene mineralization. This study highlights the potential of tourmaline as a tracer of the magmatic-hydrothermal transition and Li mineralization process in LCT-type pegmatite.
... Keywords：Pyrite; Trace element in situ; In-situ sulfur isotope; Xiquheqiao copper-gold deposit; Xizang 西渠河桥铜金矿床位于西南"三江"多金属成矿域金沙江构造带中段 [ 用玻璃标准物质NIST SRM610和MASS-1进行多外标无内标校正 [14] ，对分析数据的离线处理(包括 对样品和空白信号的选择、仪器灵敏度漂移校正以及元素含量计算)采用软件IOLITE [15] 的3D Trace ...
... Isotopic fractionation was corrected using Plešovice zircon as an external standard. ICPMSDataCal (Liu et al., 2008) was used to calculate trace element contents and U-Pb isotopic ratios. Concordia ages and diagrams were obtained using Isoplot/Ex (Ludwig, 2003). ...
Paleozoic intrusive rocks are exposed in the Longshoushan area in NW China, in the Northern Qilian Block and on the southern edge of the Alxa Block. Understanding the petrogenesis and tectonic setting of these intrusive rocks is crucial for reconstructing the tectonic evolution and tectonomagmatic processes that occurred along the North Qilian Orogenic Belt between the Alxa and Central Qilian blocks. This study presents an integrated analysis of petrology, zircon U-Pb geochronology, whole-rock geochemistry, along with Sr–Nd–Pb isotopic data and zircon Hf–O isotopic analyses for these intrusive rocks. The Shandan intrusive rocks consist primarily of calc-alkaline quartz diorite (∼430 Ma) and diorite (∼403 Ma). These diorites are enriched in large-ion lithophile elements (e.g., Ba and U) and depleted in high field strength elements (e.g., Nb, Ta, and Ti), similar to subduction-related magmas. The Shandan diorites have enriched Sr and Nd isotopic compositions, with high initial ⁸⁷ Sr/ ⁸⁶ Sr ratios (0.705247–0.70618), variable ε Nd (t) values (−1.58 to −3.53), positive zircon ε Hf (t) values (+0.08 to +3.55) and low zircon δ ¹⁸ O values (5.75‰–6.38‰). The older zircon grains (430 Ma) yield ε Hf (t) values of +0.14 to +6.58 and the younger grains (403 Ma) yield negative ε Hf (t) values (+2.24 to −11.0). The geochemical and isotopic data suggest that the diorites were derived through low-degree partial melting of enriched subcontinental lithospheric mantle with the addition of crustal material and subduction-related sediment-derived melts. We suggest that the formation of the Shandan diorites was dominated by slab breakoff at ∼430 Ma, which created a window that enabled the upwelling of asthenospheric material and induced partial melting of the subcontinental lithospheric mantle and crust. At ∼403 Ma, slab breakoff was nearing end, leading to weaker asthenospheric upwelling.
... In IOLITE, user-defined time intervals are established for the baseline correction procedure in order to calculate session-wide baseline-corrected values for each isotope. Details of the used analytical techniques were previously provided by Liu et al. [11] and Chu et al. [12]. ...
The Qingshan lead–zinc deposit is one of the typical deposits in the Weining–Shuicheng metallogenic belt in the northwest Guizhou mining area. This deposit is strictly controlled by tectonics, making it highly distinctive. This study used the REE, Fe, and Mn typological characteristics of calcite in the NE mineralization fault zone of the Qingshan lead–zinc deposit in Guizhou to trace the source of ore-forming materials and the local structural stress field characteristics of the fault. Through comprehensively applying structural analysis and LA-ICP-MS technology, the mechanical properties of the fault were analyzed and the REE characteristics of calcite, as well as the variation laws of Fe and Mn, were studied. The results of this study reveal that NE-trending mineralization faults controlled the production of gently inclined ore bodies; the distribution patterns of REEs in the three types of calcite are all “negative Eu-weak negative Ce-right skewed”, with the REE content in calcite near the ore body being significantly increased; furthermore, the variation pattern of Fe and Mn elemental contents in calcite indicate the local stress field characteristics of the ore-forming fault zone. The local opening space of NE-trending compressional and torsional ore-forming faults (where the dip angle slows down) is favorable for the nucleation of mineralized veins. With this study, we therefore improve knowledge regarding the relationships between tectonic stress fields and mineral exploration, serving as a potential source for the prediction of sites that are suitable for the exploitation of tectonic stress fields for mineral exploration, and show that mineral prediction is conducive to achieving the sustainable development of mines.
... NIST SRM 610 and NIST SRM 612 (Wu et al., 2018b;Wu et al., 2019) were used as calibration reference material for every ten analyses to correct the time-dependent drift of sensitivity and mass discrimination. Data reduction was carried out with the software ICPMSDataCal 10.8, and specific analytical procedures and calibration methods were described in Liu et al. (2008). ...
... The Ca and Si contents determined by EPMA were used as internal standards for silicate and carbonatitic melts, respectively. The offline data processing was performed by using a program called ICPMSDataCal (Liu et al., 2008). The estimated analytical uncertainties arising from the internal and external standardization procedures were ∼5% for major elements and 10%-15% for trace elements. ...
The occurrence of sulfate and fluoride minerals in carbonatite-hosted rare earth element (REE) deposits suggests that sulfur and fluorine play important roles in REE mineralization. However, their influence on the partitioning behavior of REEs during the immiscibility process remains poorly understood. This study performed partitioning experiments to explore the impact of sulfur and fluorine on the liquid immiscibility between carbonatitic melt and alkaline silicate melt at 1000‒1200 °C and 0.5‒2.2 GPa. Surprisingly, the experimental results indicate that the addition of sulfur and fluorine does not significantly change the partition coefficients of trace elements between carbonatitic melt and silicate melt. The key factor determining REE partitioning is the structural difference between the two immiscible melts, which can be characterized by the non-bridging oxygen per tetrahedrally coordinated cation of the silicate melt (NBO/T). Partition coefficients tend to decrease as NBO/T increases. Importantly, REE, SO3, and F exhibit similar behaviors, making sulfate and fluoride minerals useful indicators for exploring carbonatite-hosted REE deposits. Additionally, we used rhyolite-MELTS software to simulate crystallization differentiation and liquid immiscibility in alkaline silicate melts. Modeling results show that the initial CO2 content of silicate melt determines the degree of crystallization at which liquid immiscibility occurs. Lower initial CO2 content enhances the enrichment of REEs in the immiscible carbonatitic melt.
... Each analysis consisted of a background acquisition of approximately 20-30 s, followed by 50 s of data acquisition from the sample. To perform off-line selection and integration of background and analyzed signals, time-drift correction, and quantitative calibration for trace element analysis and U-Pb dating, the Excel-based software ICPMSDataCal (Liu et al., 2008;Liu et al., 2010). Concordia diagrams and weighted mean calculations were conducted using Isoplot/Ex_ver3 (Ludwig, 2003). ...
... NIST SRM610, SRM612, and SRM1412 (National Institute of Standards and Technology, Gaithersburg, MD, USA) were used as external standards. Data reduction was performed using the ICPMSDataCal software package (Liu et al., 2008). Results are given in Supplementary Material. ...
The Marmor Iassense (Iasos marble, Marmor Carium) banded marbles, produced from Kızılağaç formation near Kıyıkışlacık village, have been favorite marbles from ancient times to the present day with their colours and patterns. During the Roman and Byzantine periods, it was preferred as a decorative stone in many important buildings (ie. Hagia Sophia, Holy Apostles, Chora Monastery (Kariye Mosque) in Istanbul, and San Vitale in Ravenna) around the Mediterranean and was used in wall coverings, flooring, columns and mosaics. These marbles contain red and grey-white alternating folded layers of different thicknesses. They consist of calcite, quartz, feldspar (albite±orthoclase), chlorite, muscovite, graphite and hematite minerals and are fine-medium grained (MGS: 0.2-2 mm). The tone of the red colour varies depending on the amount of hematite. Geochemical properties and Sr- C-O isotope characteristics show that the parent rock of Kıyıkışlacık marbles are formed from carbonate rocks precipitated in the open sea environment. Marmor Iassense banded marbles are easily distinguished from most red marbles used in ancient times with their textural features. The new petrography, XRD, EPR, isotope and geochemistry analysis results produced in this study will be a data set that can be used in provenance studies by those who will study these marbles in the future.
... Data quality was assessed using repeated analyses of standard reference samples (Table S1). Offline processing of the analytical data, including selection of sample and blank signals, correction of instrument sensitivity drift, and calculation of element concentrations, was carried out using the software ICPMSDataCal 21,22 . ...
This study analyzes 25 natron glass samples from four Early Iron Age sites in Xinjiang using LA-ICP-AES, LA-ICP-MS, and SR-μCT techniques. The analysis results indicate that these natron glass beads probably originate from the Levant, and their similar decoration and chemical compositions suggest a common provenance. This study further discusses that early natron glass entered China through routes via Xinjiang and Gansu and that natron glass beads from Chu tombs in Hubei might have diverse origins. Additionally, the research highlights differences in the manufacturing techniques and distribution of natron glass in Xinjiang between the Western Han and earlier periods, illustrating changes in East-West cultural exchanges before and after the opening of the Silk Road.
Quartz trace elements are extensively employed in studying magmatic evolution, fluid evolution, and metal enrichment. The Bianjiadayuan Ag-Pb-Zn-Sn deposit is a typical magmatic-hydrothermal system in northeastern China, however, studies on its complex magmatic-hydrothermal evolution are limited. This study investigates the quartz from the Bianjiadayuan deposit to gain insight into the physicochemical evolution of mineralization using cathodoluminescence (CL) textures and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of quartz. Five types quartz (Q1 to Q5) were identified. From Q1 in quartz porphyry to Q5 in Ag-Pb-Zn veins, the CL intensity and Ti content gradually decreases, and Ge, Ge/Ti, and Al/Ti ratios increase, indicating a temperature decline from magmatic to hydrothermal stages. The Sb content shows an opposite trend to Ti content, correlating positively with Ge content in quartz, suggesting that Sb content could also be temperature-dependent. These trace elements in quartz indicate cooling is critical for Ag mineralization. Furthermore, quartz phenocryst (Q1) from the quartz porphyry shows low Al/Ti (mostly < 4) and Ge/Ti ratios (< 0.04), suggesting a low degree of magmatic evolution. The Sb content in Q5 from Ag-Pb-Zn-quartz veins (> 1 ppm, mostly tens of ppm) is notably higher compared to quartz in other lithologies including Sn-bearing quartz veins (< 1 ppm), suggesting that Sb contents can serve as an effective indicator of Ag mineralization.
The Jiepailing deposit in southern Hunan is a typical large to super-large polymetallic tin deposit enriched in beryllium and other rare metals. To enhance the understanding of the mineralization processes of the Jiepailing deposit, detailed mineralogical, in situ geochemical, and sulfur isotopic analyses were conducted on pyrite closely associated with tin–polymetallic mineralization. Five types of pyrite have been identified in the deposit: (1) euhedral to subhedral medium- to coarse-grained pyrite (PyI) in tungsten–tin ore; anhedral fine-grained pyrite (PyII) in tin polymetallic–fluorite ore; anhedral fine-grained or aggregate pyrite (PyIII) in lead–zinc ore; euhedral to subhedral coarse-grained pyrite (PyIV) in beryllium–fluorite mineralization; and subhedral to anhedral fine-grained pyrite (PyV) in carbonate veinlets developed in the wall rock. Backscattered electron imaging indicates consistent structural features across the five types of pyrite. In situ trace element analysis reveals differences in trace element concentrations among the pyrite types. PyI is relatively enriched in Sn, Cu, and Co. In contrast, PyIII is enriched in Pb, Zn, Sn, and Ti, while PyIV and PyV are enriched in Ag and Sb. PyI has a Co/Ni ratio more than 1, while the Co/Ni ratios in the other four types of pyrite are less than 1. LA-MC-ICP-MS in situ sulfur isotope analysis shows δ34S values ranging from 2.5‰ to 5.8‰ (average 4.3‰, PyI), 2.5‰ to 5.8‰ (average 4.3‰, PyII), −7.6‰ to 9.5‰ (average 3.9‰, PyIII), −3.7‰ to 10.6‰ (average 3.6‰, PyIV), and 6.8‰ to 14.1‰ (average 9.2‰, PyV). Based on previous studies, regional geological background, deposit characteristics, and the in situ trace element and sulfur isotope compositions of pyrite, it is inferred that the various ore bodies in the Jiepailing deposit are products of Late Cretaceous magmatic–hydrothermal activity. The early ore-forming fluid originated from magmatic sources and during the migration into the wall rock and shallow formations, mixed with fluids primarily derived from atmospheric precipitation. Temperature, pressure, and composition changed of the ore-forming fluid which carried a large amount of substances, leading to tungsten–tin, tin polymetallic–fluorite, lead–zinc, and beryllium–fluorite mineralization, followed by carbonation during the late-stage mineralization.
Numerous skarn-type Sn and hydrothermal vein-type Pb–Zn–Ag deposits occur in the northern Yidun Terrane, China. The Gongjuelong skarn Sn polymetallic deposit, adjacent to the Haizishan granite, is situated in the central region of Yidun Terrane. The genesis of the Gongjuelong Sn deposit and its relationship with the adjacent Pb–Zn–Ag deposits remains controversial. The ore-forming process can be divided into three stages: the prograde stage (I), marked by the formation of garnet and pyroxene; the retrograde stage (II), which includes the epidote–actinolite sub-stage (II-1) and the quartz-cassiterite sub-stage (II-2); and the sulfide stage (III), consisting of the chalcopyrite–pyrrhotite sub-stage (III-1) and the arsenopyrite–sphalerite sub-stage (III-2). Two types of garnet (Grt-I and Grt-II) have been identified in stage I and both belong to the grossular–andradite solid solution. Grt-II (Gro52-73And25-45Spe+Pyr+Alm2-3) contains slightly more Fe than Grt-I (Gro64-76And20-28Spe+Pyr+Alm2-10). Grt-I is enriched in heavy rare-earth elements (HREEs) and depleted in light rare-earth elements (LREEs), whereas Grt-II is enriched in LREEs and depleted in HREEs. Grt-I has higher U contents and lower Th/U ratios than those of Grt II, indicating a lower oxygen fugacity for the earlier skarn alteration. In contrast to Grt-I, Grt-II shows a more significant negative Eu anomaly along with lower LREEs/HREEs. Therefore, Grt-I and Grt-II likely formed under mildly acidic and near-neutral conditions, respectively. The W (350–3015 ppm) and Fe (235–3740 ppm) contents and Zr/Hf ratios (18.7–49.4) of cassiterite from Gongjuelong are similar to those of cassiterite from the granite-related Sn deposits, as well as the Xiasai hydrothermal vein-type Pb–Zn–Ag deposit in the northern Yidun Terrane. The Ti/Ge ratio (0.06–1.13) and P contents (13.9–173 ppm) of quartz are also similar to those from the Xiasai Pb–Zn–Ag deposit, both of which resemble those of skarn-type deposits and Sn-associated quartz. Furthermore, the Ti/Zr ratio (average 33.2) of cassiterite at Gongjuelong are much higher than that of cassiterite at Xiasai (average 3.7), indicating that the Pb–Zn–Ag veins could represent the distal product of the “parent” granite. On the basis of combined evidence from geology, geochemistry, and published geochronology data, we propose that the proximal skarn-type Sn deposits and distal hydrothermal vein-type Pb–Zn–Ag±Sn deposits in the northern Yidun Terrane constitute an integrated ore system, which is genetically related to the late Cretaceous highly fractionated granites. This proposed hypothesis highlights the potential prospecting of Sn mineralization beneath the hydrothermal Pb–Zn–Ag veins, as well as the hydrothermal Pb–Zn–Ag veins controlled by faults/fractures within the strata around the Sn deposits and highly fractionated granites.
The Qushi rhyolites, situated in the eastern sector of the Tengchong terrane, are critical to understanding the Early Cretaceous tectono-magmatic evolution of the Eastern Tethyan Tectonic Domain. Zircon LA-ICP-MS U-Pb geochronology indicates crystallization ages of 118.3–120.5 Ma, with Ti-in-zircon temperatures of 641–816 °C (mean = 716 °C), representing the Early Cretaceous magmatic activity in the Tengchong terrane. Inherited zircons within the rhyolites yield a zircon age of ca. 198.5 Ma, with corresponding Ti-in-zircon temperatures of 615–699 °C (mean = 657 °C), implying the potential presence of an Early Jurassic igneous basement beneath the Qushi region. Geochemically, the rhyolites are classified as calc-alkaline and weakly to moderately peraluminous (A/CNK = 1.07–2.86). These rocks display signatures typical of acidic magmas, marked by significant enrichments in light rare earth elements (LREE: La and Ce) and large ion lithophile elements (LILE: Rb, K, Th and U) while simultaneously exhibiting depletions in high-field-strength elements (HFSE: Nb, Ta, Ti, and P) and heavy rare earth elements (HREE). Trace element signatures further reveal marked depletions in Sr (12.4–244.7 ppm) and Ba while displaying enrichments in Zr and Hf. These geochemical features, including the huge range of the Sr content and A/CNK ratios, suggest both I-type and S-type granite affinities. The Early Cretaceous volcanism of the Qushi rhyolites is likely attributed to the combined effects of subduction and the closure of the Meso-Tethyan Ocean (MTO). This volcanic activity is interpreted to result from subduction-related processes associated with the MTO, potentially involving slab rollback, slab break-off, and subsequent asthenospheric upwelling. The formation of these rhyolites may also be linked to the final closure of the MTO, characterized by the Late Cretaceous collision and amalgamation of the Burma and Tengchong terranes.
A rapid, minimally destructive method for in situ determination of Sr isotope ratios ( ⁸⁷ Sr/ ⁸⁶ Sr) using short‐pulse laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (LA‐MC‐ICP‐MS) coupled with linear regression calibration is presented. The ablation lasts only one second, causing minimal surface damage (~ 7 μm depth, 60 μm diameter). A carbonate matrix reference material for Sr isotope measurement (GIC‐P, containing approximately 470 μg g ⁻¹ Sr), fabricated from pressed pearl nanopowder, has been developed for data quality control and validation. Analysis of GIC‐P using the proposed short‐pulse LA‐MC‐ICP‐MS method yielded results consistent with thermal ionisation mass spectrometry values. This method is ideal for analysis of valuable jewellery samples, as it ensures minimal destruction, high throughput, and cost efficiency while maintaining accuracy and precision, with intermediate precision quantified at better than 0.0004 (2 s ). When applied to market samples originating from China, Japan, French Polynesia and the South Pacific, the method confirms that saltwater pearls exhibit ⁸⁷ Sr/ ⁸⁶ Sr ratios consistent with modern seawater (~ 0.7092), whereas freshwater pearls show higher and more variable ratios (0.7102–0.7135 in this study), reflecting their growth environments in the freshwater of the middle and downstream regions of the Yangtze River, China. This distinct isotopic difference provides a reliable geochemical tool for differentiating between saltwater and freshwater pearls.
The Kongco area of Nima in the northern part of the Lhasa terrane has a suite of alkaline granitic porphyry dykes associated with Early Cretaceous granites and accompanied by Cu/Mo mineralization. LA-ICP-MS 206Pb/238U zircon geochronology performed on the dykes produced an age of 104.15 ± 0.94 Ma (MSWD = 0.98), indicating the Early Cretaceous emplacement of the dykes. The dykes exhibit high silica (SiO2 = 76.22~77.90 wt.%), high potassium (K2O = 4.97~6.21 wt.%), high alkalinity (K2O + Na2O = 8.07~8.98 wt.%), low calcium (CaO = 0.24~0.83 wt.%), low magnesium (MgO = 0.06~0.20 wt.%), and moderate aluminum content (Al2O3 = 11.93~12.45 wt.%). The Rieterman index (σ) ranges from 1.93 to 2.34. A/NK (molar ratio Al2O3/(Na2O + K2O)) and A/CNK (molar ratio Al2O3/(CaO + Na2O + K2O)) values of the dykes range from 1.06 to 1.18 and 0.98 to 1.09, respectively. The dykes are relatively enriched in Rb, Th, U, K, Ta, Ce, Nd, Zr, Hf, Sm, Y, Yb, and Lu, and they show a noticeable relative depletion in Ba, Nb, Sr, P, Eu, and Ti, as well as an average differentiation index (DI) of 96.42. The dykes also exhibit high FeOT/MgO ratios (3.60~10.41), Ga/Al ratios (2.22 × 10−4~3.01 × 10−4), Y/Nb ratios (1.75~2.40), and Rb/Nb ratios (8.36~20.76). Additionally, they have high whole-rock Zr saturation temperatures (884~914 °C), a pronounced Eu negative anomaly (δEu = 0.04~0.23), and a rightward-sloping “V-shaped” rare earth element pattern. These characteristics suggest that the granitic porphyry dykes can be classified as A2-type granites formed in a post-collisional tectonic environment and that they are weakly peraluminous, high-potassium, and Calc-alkaline basaltic rocks. Positive εHf(t) values = 0.43~3.63 and a relatively young Hf crustal model age (TDM2 = 826~1005 Ma, 87Sr/86Sr ratios = 0.7043~0.7064, and εNd(t) = −8.60~−2.95 all indicate lower crust and mantle mixing. The lower crust and mantle mixing model is also supported by (206Pb/204Pb)t = 18.627~18.788, (207Pb/204Pb)t = 15.707~15.719, (208Pb/204Pb)t = 39.038~39.110). Together, the Hf, Sr and Pb isotopic ratios indicate that the Kongco granitic porphyry dykes where derived from juvenile crust formed by the addition of mantle material to the lower crust. From this, we infer that the Kongco granitic porphyry dykes are related to a partial melting of the lower crust induced by subduction slab break-off and asthenospheric upwelling during the collision between the Qiangtang and Lhasa terranes and that they experienced significant fractional crystallization dominated by potassium feldspar and amphibole. These dykes are also accompanied by significant copper mineralization (five samples, copper content 0.2%), suggesting a close relationship between the magmatism associated with these dykes and regional metallogenesis, indicating a high potential for mineral exploration.
The olivine fabric is commonly used to infer mantle flow directions from seismic anisotropy. Despite this, the response of olivine fabric to variations in high pressure, stress, olivinewater content—and its subsequent impact on the seismic anisotropy — remains ambiguous. Here we studied 27 peridotite xenoliths from the adjacent Jericho and Muskox kimberlite pipes in the northern Slave craton (Canada) to correlate the olivine fabric with the seismic architecture of the lithospheric mantle. The xenoliths from depths of 70–190 km were analyzed for water content of olivine, and a subset of these samples were examined for the crystallographic preferred orientation of olivine and pyroxenes, major element compositions of minerals, and trace element compositions of garnet and clinopyroxene. Water content of olivine increases with depth, correlating with a decrease in the olivine Mg# (molar Mg/(Mg+Fe)) and increasing clinopyroxene modes. The dominant axial [010] olivine fabric coexists with two distinct fabrics above and below 120 km. These auxiliary fabrics transition from the A-type to the B-type, a change likely driven by increased pressure and the metasomatically-controlled high water content. This offers an explanation for an anisotropic seismic discontinuity observed at 120 km in the Northern Slave. The upper layer is defined by the preferred alignment of the fast [100] olivine axes along the N-S direction of the subhorizontal foliation plane, whereas in the lower layer the olivine [100] axes align parallel to the NE-SW direction. The discontinuity reflects the long, incremental formation process of the cratonic lithosphere that juxtaposes segments with distinct fossil flow directions, as evidenced by distinct fabric orientations. The upper layer may represent the older, depleted peridotites formed during the Mesoarchean craton stabilization, concurrently with the overlying crust. The deeper Proterozoic layer may have been added through accretion, subduction, plume-related melting, and modified by metasomatic events.
The Late Triassic to Early Jurassic (ca. 220 to 190 Ma) Dahongliutan pegmatite belt, located in the Western Kunlun orogenic belt, NW China, is a newly discovered, large Li-Be ore district comprising > 320 individual rare-metal pegmatites. The pegmatite belt was emplaced in a post-orogenic setting in relation with a ductile shear zone related to the Dahongliutan detachment fault, which is spatially and temporally related to post-orogenic exhumation. Deformed spodumene pegmatites, mostly striking NW with dip angle of 50 ~ 80°, occur within or adjacent to the NW-striking detachment fault. We present new field observations, mineralogical, geochemical and geochronological results from the Dahongliutan pegmatite belt, which lead to the following conclusions: 1) High-medium temperature/middle-to-low pressure metamorphic rocks and granitoids were intruded by ductile-deformed spodumene-bearing pegmatites during development of the gneissic domes; 2) Spodumene pegmatites from the Aktas, Kalaka, Bailongshan and Longmenshan deposits record two age groups, a first one during the Upper Triassic at ca. 212–205 Ma, and a second one during the Lower Jurassic at ca. 195–193 Ma, as revealed by in-situ Rb–Sr dating of micas and U–Pb dating of columbite-group minerals; 3) Textural observations and geochemical analyses of coexisting quartz and spodumene further indicate that ductile deformation provided favorable conditions for enrichment of Li and Be in pegmatites. The Western Kunlun-Songpan Ganzi rare-metal pegmatite belt shows a close spatial and genetic relationship with ductile shear zones induced by detachment faulting, making it a potential proxy for exploration targeting of Li-Be-mineralized occurrences at the regional scale as well as in other metallogenic provinces worldwide.
The Late Jurassic to Early Cretaceous was a critical transformative period for the North China Craton (NCC), marked by a tectonic shift from compression to extension and the formation of numerous Yanshanian magmatic intrusions across Shanxi Province. This article presents zircon U–Pb geochronology and Hf isotope, whole‐rock geochemistry and Sr–Nd isotopic compositions of Late Jurassic to Early Cretaceous intrusive rocks from the Hunyuan area in northern Shanxi Province. The Chakou, Liulengshan and Zhongzhuangpu intrusions yield zircon U–Pb ages of 150.9 ± 1.7 Ma, 137.9 ± 2.0 Ma and 115.4 ± 0.6 Ma, respectively. The Chakou monzogranites exhibit typical features of high‐K calc‐alkaline I‐type granites, and they are enriched in Rb, Ba, K and U, and depleted in Nb and Ta. The Sr and Nd isotopes of these samples show ( ⁸⁷ Sr/ ⁸⁶ Sr) i values ranging from 0.7062 to 0.7103 and ε Nd ( t ) values between −8.8 and −8.7. Additionally, zircon rims show highly variable ε Hf ( t ) values, spanning from −12.7 to −8.1. Geochemistry and isotopes suggest that the Chakou monzogranites originated primarily from the partial melting of the lower crust. The Liulengshan quartz syenites exhibit low SiO 2 and high K 2 O contents, classifying them as shoshonitic I‐type quartz syenites. They are enriched in LREE and LILE, depleted in HFSE with a weak negative Eu anomaly, and display moderate ε Nd ( t ) values between −17.1 and −17.0. Zircon Hf isotope composition is relatively uniform, with ε Hf ( t ) values ranging from −22.6 to −20.4. We propose that the quartz syenites from Liulengshan were formed by mixed products of mantle‐derived and crust‐derived magmas, with the latter being dominant. The Zhongzhuangpu biotite monzogranites are petrologically and geochemically uniform, showing enrichment in Pb and Ta, and strong depletion in Sr, Ba and Eu. We consider that they originated from the partial melting of crustal materials. Collectively, our data indicate that continuous crustal extension, thinning and asthenospheric upwelling facilitated partial melting of both lithospheric mantle and crustal materials. These processes were the primary drivers behind the formation of intrusions in the NCC during the Late Jurassic to Early Cretaceous.
A number of Cenozoic carbonatite-related deposits of rare earth elements (REEs), distributed along the western margin of the Yangtze block, southwest China, define the world-class Mianning-Dechang metallogenic belt. Numerous studies of this belt are available, but the potential role of fluids in the development of diverse REE mineralization styles in specific deposits is still poorly understood, particularly for the ~28 Ma Muluozhai deposit, which is distinctly rich in anhydrite. We investigated the evolution of fluids and genesis of diverse REE ores in the Muluozhai deposit, with emphasis on its mineralogical variations and trace element and Sr-Nd-O isotope compositions of calcite and dolomite formed at different evolutionary stages. The REE orebodies in this deposit are lenticular, generally characterized by REE-rich veins or veinlets ranging from <1 cm to several meters in width. On the basis of micro- and macrotextural relationships, we established a paragenetic sequence that includes three main evolutionary stages. Stage I involved fenitization that pervasively overprinted wall-rock syenites. It is characterized by the formation of Na-rich pyroxene (aegirine-augite) and amphibole (magnesio-arfvedsonite) with variable amounts of albite, phlogopite, calcite, celestine, fluorite, apatite, and monazite. The early mineralization stage (stage II) comprises a mineral assemblage of bastnäsite, celestine, calcite, and fluorite, broadly similar to that at other REE deposits in the Mianning-Dechang belt. The late mineralization stage (stage III) is distinguishable from stage II by the occurrence of abundant anhydrite and dolomite in addition to bastnäsite, parisite, monazite, celestine, and fluorite. The stage III mineralization is unique to Muluozhai relative to the other deposits in the Mianning-Dechang belt.
Our geochronological data for bastnäsite samples from stages II and III show that both stages have a similar U-Th-Pb age of ca. 28 Ma, indicating that they are products of the same mineralization event. Calcite and dolomite from stages I to III have indistinguishable Sr-Nd isotope compositions that are broadly similar to those of the coeval carbonatites in the Mianning-Dechang belt, strongly indicating that the two stages of mineralization in the Muluozhai deposit were genetically related to a common carbonatitic source. Stage I fluids have calculated δ18OVienna-standard mean ocean water (V-SMOW) values (4.7–8.5‰) comparable to those of typical carbonatites, indicating a dominantly magmatic fluid exsolved from carbonatitic magma. Subsequent stage II fluids have significantly lower δ18OV-SMOW values (–1.9 to 4.1‰), indicating a significant contribution of meteoric water during fluid evolution of the ore system. In contrast, stage III fluids have much higher δ18OV-SMOW values (10.0–13.5 ‰), which are interpreted to result from the incursion of formation water with high δ18OV-SMOW values. This study demonstrates that mixing of REE-rich magmatic fluids with different external fluids (i.e., the meteoric or formation water) played a key role in REE deposition at mineralization stages II and III and was also responsible for their mineralogical differences. This study highlights the potential effects of different external fluids on the diversity of REE ores in a specific carbonatite-related deposit or among different deposits in the same metallogenic belt.
[1] We present new analytical data of major and trace elements for the geological MPI-DING glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, GOR132-G, BM90/21-G, T1-G, and ATHO-G. Different analytical methods were used to obtain a large spectrum of major and trace element data, in particular, EPMA, SIMS, LA-ICPMS, and isotope dilution by TIMS and ICPMS. Altogether, more than 60 qualified geochemical laboratories worldwide contributed to the analyses, allowing us to present new reference and information values and their uncertainties ( at 95% confidence level) for up to 74 elements. We complied with the recommendations for the certification of geological reference materials by the International Association of Geoanalysts (IAG). The reference values were derived from the results of 16 independent techniques, including definitive ( isotope dilution) and comparative bulk ( e. g., INAA, ICPMS, SSMS) and microanalytical ( e. g., LA-ICPMS, SIMS, EPMA) methods. Agreement between two or more independent methods and the use of definitive methods provided traceability to the fullest extent possible. We also present new and recently published data for the isotopic compositions of H, B, Li, O, Ca, Sr, Nd, Hf, and Pb. The results were mainly obtained by high-precision bulk techniques, such as TIMS and MC-ICPMS. In addition, LA-ICPMS and SIMS isotope data of B, Li, and Pb are presented.
As measured in air above the glass transition range, the viscosity of an alkali basalt increases markedly with time by
about two orders of magnitude in 12 h. This effect is essentially physical and due to the presence of microcrystals
although partial crystallization of the melt into spinel and an SiO2-poor pyroxene leads to a considerable enrichment
in silica of the residual liquid. Partial crystallization depends strongly on the initial redox state of samples in that the
presence of ferrous iron is required for spinel crystals to form and for pyroxene to nucleate and grow around them.
Other measurements show that the viscosity of the crystal-free liquid decreases slightly with increasing ratios r=Fe2+/Fe because the differences between samples with r=0.16 and 0.83 amount to about 1.5 and 0.3 log-units at 950 and
1400 K, respectively. Comparisons of the viscosities of the residual liquid matrix and of the initially crystal-free basalt
show that physical effects caused by the presence of microcrystals begin to be observed at a low crystal fraction of
5 vol%. Finally, a model of viscosity calculation is developed for the melts which reproduces all data obtained in this
work to better than 10%.
A first attempt was made to estimate an uncertainty budget for the multi-element analysis of glasses using LA-ICP-MS, in accordance with the ‘‘Bottom-up’’ approach of the EURACHEM/CITAC-Guide.1 Analyses of NIST SRM 612, 614 and USGS glasses BCR-2G and BIR-1G were carried out using a 193 nm excimer LA-ICP-MS under routine conditions. Calibration was performed using NIST 610 with internal standardisation using Ca. The uncertainty budgets for the analytes Co, La and Th were studied. Instrumental drift and uncertainties from working values of NIST 610, as reported by Pearce et al.,2 are the dominant sources of uncertainty for a typical individual analysis of NIST 612 and BCR-2G/BIR-1G with mass contents of Co, La and Th ranging from 6 to 52 μg g−1. In contrast, the uncertainty contributions from Poisson counting statistics prevail for those of NIST 614 and BIR-1G with the three elements having a lower range between 0.029 and 0.75 μg g−1. La was an exception. Its combined uncertainties were consistently dominated by its uncertainty from the working value of NIST 610 at all mass content ranges investigated, suggesting that more accurate reference values for the analyte in NIST 610, and for all analytes with large uncertainties, are needed. Additionally, a z-score assessment was carried out using procedures similar to those used in the International Proficiency Test for Analytical Microprobe Geochemistry Laboratories. The z-scores in this study were in the range −2 < z < 2, indicating that there were no significant unsuspected influences in the analytical system. This suggests that the uncertainty budget reported here contains all the significant parameters.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) produces complex, time-dependent signals. These require significantly different treatment both during data acquisition and reduction from the more steady-state signals produced by solution sample introduction. This paper discusses, in detail, data acquisition and reduction considerations in LA-ICP-MS analysis. Optimum data acquisition parameters are suggested. Equations are derived for the calculation of sample concentrations and LOD when time-resolved data acquisition is employed, sensitivity calibration is obtained from reference materials with known analyte concentrations and naturally occurring internal standards are used to correct for the multiplicative correction factors of drift, matrix effects and the amount of material ablated and transported to the ICP.
We report a new volume-optional and low-memory (VOLM) chamber for laser ablation-ICP-MS, which includes an active inner cell and an external cell. The external cell has a gas inlet and is a closed design cell, which can be large enough to accommodate as many targets as required. The inner cell is a transparent cylinder in which the gas outlet is fixed and connected to the outer transfer tube. The VOLM chamber has three outstanding advantages: (1) improved sensitivity (3.5-13.0- and 1.1-2.0-fold greater than for single-pulse and continuous ablation in a standard cell, respectively); (2) good stability (reproducible sampling positions); and (3) low cell-related memory effects (washout time 1-4 s). These advantages mean that the VOLM chamber is suitable for investigating the compositions of small samples in terms of profile and depth analyses.
The dependence of analyte sensitivity and vaporization efficiency on the sampling depth of an inductively coupled plasma mass spectrometer (ICPMS) was investigated for a wide range of elements in aerosols, produced by laser ablation of silicate glass. The ion signals were recorded for two different laser ablation systems and carrier gases. Differences in atomization efficiency and analyte sensitivity are significant for the two gases and the particle size distribution of the aerosol. Vaporization of the aerosol is enhanced when helium is used, which is attributed to a better energy transfer from the plasma to the central channel of the ICP and a higher diffusion rate of the vaporized material. Stable signal is achieved at smaller particle size distribution in laser-generated aerosol. The sensitivity change with sampling depth variation is dependent on m/z of the analyte ion and the chemical properties of the element. Elements with high vaporization temperatures need longer residence time to be atomized and ionized in ICP plasma and reach a maximum at increasing sampling depth than easily vaporized elements, especially for bigger particle size distributions generated by 266 nm laser in Argon.
Laser-ablation ICPMS has become widely accessible as a powerful and efficient multi-element microanalytical technique. One of its key strengths is the ability to analyse a wide concentration range from major (tens of wt.%) to trace (ng/g) levels in minerals and their microscopic inclusions. An ArF excimer laser system (λ = 193 nm) with imaging optics for controlled UV ablation and simultaneous petrographic viewing was designed specifically for representative sampling and quantitative multi-element analysis of microscopic fluid, melt and mineral inclusions beneath the sample surface. After a review of the requirements and recent technical developments, results are presented which together document the reliability and reproducibility of quantitative microanalysis of complex samples such as zoned crystals or fluid and melt inclusions in various host minerals. Analytical errors due to elemental fractionation are reduced to the typical precision achieved by quadrupole LA-ICPMS in multi-element mode (2–5% RSD). This progress is largely due to the small size of aerosol particles generated by the optimized UV optical system. Depth profiling yields representative and accurate concentration results at a resolution of ∼0.1 μm perpendicular to the ablation surface. Ablation is largely matrix-insensitive for different elements, such that silicate and borate glasses, silicates and oxide minerals, or direct liquid ablation can be used interchangeably for external standardization of any homogeneous or heterogeneous material. The absolute ablation rate is material dependent, however, so that quantitative LA-ICPMS analysis requires an internal standard (i.e., an independent constraint such as the absolute concentration of one element).
For imaging of elemental distribution in protein spots blotted onto membranes with a conventional size, we have investigated three different laser ablation cell geometries to find a design of a cell showing a constantly high signal intensity across the cell and possessing short wash-out times. For this purpose the resulting intensity after optimisation ( He carrier gas flow rate, argon make-up gas, generator forward power) was measured for single laser shots at different positions on a steel metal sheet and for continuous ablation of nitrocellulose (NC) membranes during linear translation of the cell. In the latter experiment, ink bar structures have been printed on the NC membranes to simulate blotted protein spots and used to evaluate the local resolution and to determine an adequate translation velocity. The final cell has a volume of about 11.3 cm(3) in which single shot signals are washed out in less than a second so that translation velocities of up to 1.5 mm s(-1) can be applied to baseline separate structures with a distance of less than 2 mm, which will be demonstrated using an example of a phosphoprotein mixture separated by SDS-PAGE and blotted onto a NC membrane.
Major and trace element abundances in two different fragments of reference material basalt glass BCR-2G are reported. The data were obtained by ion and electron microprobe and represent both random point and profile analyses. Major and trace element abundances are constant within a few per mil and a few percent, respectively. This overall homogeneity is valid for scales of a few tens of micrometres to a few tens of centimetres. It is shown that the difference in the scatter of apparent element abundances is not due to chemical heterogeneity but reflects analytical uncertainty. Within error, the concentrations of both the major and lithophile trace elements in BCR-2G appear to be identical to the bulk dry weight abundances in BCR-1. Possible exceptions are the alkali metals.Les abondances d'éléments majeurs et en trace dans deux fragments différents du verre basaltique de réference BCR-2G sont présentées. Les données sont obtenues par microsondes électronique et ionique, et correspondent à des analyses de points et à des profils. Ces abondances, pour les éléments majeurs comme pour les éléments en trace, sont constantes à quelques pourmil et quelques pourcent près, respectivement. Cette hétérogénéité globale est valide à des échelles allant de quelques dizaines de micromètres à quelques dizaines de centimètres. On montre que la dispersion apparente des abondances élémentaires n'est pas due à des hétérogénéités chimiques, mais reflète les incertitudes analytiques. Les concentrations des éléments majeurs et des éléments en trace lithophiles dans BCR-2G semblent être identiques aux abondances globales déterminées dans BCR-1 à l'erreur analytique près. Les métaux alcalins constituent peut-être des exceptions.
National Institute of Science and Technology (NIST) silicate glass SRM 610 is widely used as a certified reference material for various micro‐analytical techniques such as SIMS or laser ablation ICP‐MS. SRM 610 has been nominally doped with sixty one trace elements at the 500 μg g ⁻¹ level, but certified concentration data exist for only a few of these elements. This study reports concentration data for fifty nine trace elements obtained by ICP‐MS, SSMS, LIMS, TIMS, INAA, AAS, and PIXE analyses of two different SRM 610 wafers. Most elements fall within a 10% band around a median value of about 440 μg g ⁻¹ . The REE concentrations are shown to be constant to 3% (1 σ), thus emphasizing the value of SRM 610 as a reference material for REE analyses.
Comparison of our values with published data suggests that different SRM 610 wafers are, within errors, chemically identical for most elements. Exceptions to this general rule appear to be restricted to elements which were partly lost during the production of the glass, e.g. Ag and Br. On the basis of six independent determinations of Rb concentrations, which are systematically lower by a few percent than the reported NIST value, we argue that the certified Rb concentration may not be representative for all distributed SRM 610 wafers.
This review of laser ablation-inductively coupled plasma-mass spectrometry includes research that employed quadrupole instruments, and single-collector and multicollector magnetic sector field instruments. The most important trend in 2004–2005 was the growing appreciation that small matrix effects in LA-(MC)-ICP-MS need to be addressed in order to produce highly precise and accurate data by the method. The issue is most acute for isotope ratio measurements that require standard-sample-standard bracketing but can also be important for certain elemental analysis. Matrix-dependent elemental and isotopic fractionations were studied from the standpoint of laser-sample interactions and the behaviour of laser-generated particles in the ablation cell, transfer tubing and ICP torch. Innovations in LA-(MC)-ICP-MS involved signal smoothing, in torch laser ablation, on-line isotope dilution and molecular oxide monitoring. Other important research was carried out on the calibration and homogeneity of various reference materials; and the exploration of mature (in situ U-Pb geochronology) and emerging (apatite fission-track chronometry, U-Th/He thermochronology, boron/strontium/uranium-series isotopic microanalysis) applications in the Earth sciences.
Eight silicate glasses were prepared by directly fusing and stirring 50-100 g each of basalt, andesite, komatiite, peridotite, rhyolite, and quartz-diorite. These are referred to as MPI-DING glasses and were made for the purpose of providing reference materials for geochemical, in-situ microanalytical work. Results from various analytical techniques indicate that individual glass fragments are well homogenised with respect to major and trace elements at the μm to mm scale. Heterogeneities due to quench crystallisation of olivine have been observed in small and limited areas of the two komatiitic glasses. In order to obtain concentration values for as many elements as possible, the glasses were analysed by a variety of bulk and microanalytical methods in a number of laboratories. The analytical uncertainties of most elements are estimated to be between 1% and 10%. From the analytical data, preliminary reference values for more than sixty elements were calculated. The analytical uncertainties of most elements are estimated to be between 1% and 10%.
A description of an analyzer for solid surfaces with high spatial resolution is presented.
Microscopic fluid inclusions in minerals are the main source of information about the chemical composition of fluids associated with large-scale material transport in the Earth's interior. Hydrothermal transport processes are responsible for the natural enrichment of metal resources in many ore deposits. For the multi-element analysis of the microscopic fluid inclusions (typically 5-50 μm in diameter), LA-ICP-MS has become one of the most promising techniques owing to the recent progress in laser optics design and the development of high-sensitivity ICP mass spectrometers. The quantitative analyses of 19 major, minor and trace elements covering a concentration range of five orders of magnitude were carried out on 39 single natural fluid inclusions, together with a number of experiments to optimise controlled ablation and to test the calibration procedure. A modified commercial ICP-MS instrument was used together with a prototype ablation system based on a 193 nm excimer laser. In a stepwise opening procedure for complex polyphase inclusions, a small hole (4 μm pit) was first drilled for the partial release of liquid and vapor, followed by complete drilling out using a pit covering the entire inclusion. Controlled ablation improves the reproducibility of element ratios to less than 20% for most major, minor and trace elements measured in an assemblage of cogenetic inclusions (including elements that are initially present as solid precipitates within the inclusion), provided that the entire transient ICP-MS signal is integrated. Element ratios were calculated from integrated intensity ratios using an external standard, either a NIST SRM glass or an aqueous standard solution ablated directly through a plastic film. Absolute concentrations were calculated from the element ratios via an internal standard element, whose concentration was determined prior to ablation. Microthermometric measurements of phase transitions were used to determine total salinity from known phase diagrams, by measuring either the depression of ice-melting temperature, or the temperature of dissolution of NaCl crystals. Salinity can be related to the concentration of Na (or in some cases Cl), which serves as the internal standard element for the quantification of trace element concentrations. Calculated limits of detection are in the ng g -1 to μg g -1 region, depending on the volume of the inclusions. The accuracy of the overall analysis, including internal and external calibration, is typically between 5 and 20%, as demonstrated on alkali elements in synthetic fluid inclusions of known composition.
The coupling of a laser-ablation microprobe (LAM) to an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) has produced a relatively simple and inexpensive multi-element, high-sensitivity trace-element microbeam analytical system with characteristics ideally suited to research in the Earth Sciences. The LAM should be designed to allow for flexibility in sampling a wide variety of materials of various physical sizes and shapes, at variable, but small-scale, spatial resolution. The data acquisition and processing protocols of the LAM-ICP-MS system must allow the use of time-resolved analytical data for routine analytical work. The method is now capable of unique applications in mineralogical and geological research. Of particular importance is its ability to characterize, not only the chemical concentration of trace elements at ppm to ppb levels in minerals, but also the nature of their distribution. Time-resolved analysis of the analytical data allows distinction between trace elements incorporated in the host crystal-structure and those located in other phases. -from Authors
In situ trace element compositions of single minerals in eclogites from the CCSD main hole(100 ∼ 1100m) were analyzed using LA-ICP-MS. Trace element partitioning between garnet and omphacite suggests that Ti and Co are controlled by Mg(for example, DCoGrt/Omp = 3.43DMgGrt/Omp - 0.34), and REE, Sr and Y are controlled by Ca. Concentrations of REE, Pb and Th in omphacite are significantly controlled by presence of apatite. Petrologic and geochemical features suggest that trace element compositions of the minerals formed by retrograde metamorphism were controlled by original minerals, the mineral assemblage and fluid activity. For example, presence of epidote decreased greatly the LREE and Sr concentrations of the coexisting amphibole compared with the omphacite, parent mineral of the amphibole based on the petrologic features; and decomposition of phengite increased Rb and Ba concentrations of amphibole. MREE enrichments in the rim of garnets in several samples imply that the eclogites could suffer a short-lived heating dining exhumation based on variations of partition coefficients with temperature and pressure in eclogite, as suggested by overprinting of granulite facies on eclogites and widespread partial melting of UHP rocks in the Sulu UHP terrane. On the other hand, the highly variations of Nb and Ta in rutile could provide additional evidence for the hypothesis that rutile in the eclogite was transformed from Ti-bearing magnetite during UHP metamorphism.
For many years it has been possible to measure accurately the small-scale variations in the major and minor element chemistry of minerals by the electron microprobe technique, in which the sample surface is bombarded with an electron beam and the X-ray signal is measured (Chapter 2). Abundances of isotopes, trace and ultra-light elements (e.g. H and Li) which cannot be determined by this method can, however, be measured by secondary ion mass spectrometry (SIMS; Shimizu, Semet and Allègre, 1978; Shimizu and Hart, 1982; Reed, 1989; Zinner, 1989). The ion microprobe is a SIMS instrument with a focused primary ion beam, which permits in situ microanalysis of minerals in samples prepared as standard polished sections. Nearly all elements from H to U can be detected and many can be analysed quantitatively down to part-per-million levels, or below.
The primary factors limiting accuracy and precision using inductively coupled plasma mass spectrometry (ICP-MS) in matrix-matched external standardization are machine drift and variation of the instrument response as a function of mass. Because drift is usually non-linear, the degree of drift differs from one mass to the next, and the direction of drift can change frequently when analyzing over large mass ranges. Internal standardization results in minimal improvement of data quality. An analytical procedure and an off-line data reduction algorithm have been developed that correct for these variations and produce a significant improvement in analytical accuracy and precision. In this technique, a “drift correction” standard is analyzed after every four or five samples. A polynomial curve is fitted to each isotope analyzed, and a correction based on this curve is applied to the measured intensity of the respective isotopes in the samples and standards. This data reduction algorithm has been developed into a Microsoft Excel™ 3.0 Macro that completely automates all calculations. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with the Excel macro for the Macintosh computer and sufficient instructions for its use. The main article discusses the scientific aspects of the subject and explains the purpose of the macro.
Production rates of molecular oxides (M16O+/M+) of Ba and light rare earth elements (LREE: La, Ce, Pr and Nd), have been measured by Laser Ablation ICP-MS (LA-ICP-MS) analysis via ablation of a Ba and LREE-doped synthetic silicate glass. Our work confirms that oxide production is related to the strength of the M–O bond in the MO+ ion, and in agreement with solution-based measurements and theoretical considerations, M–O bond strength correlates linearly with log(MO+/M+). Oxide production is also strongly dependent on plasma conditions and increases markedly at higher nebulizer gas flow rates (and corresponding lower plasma temperatures), although relative differences between oxide production rates for Ba and LREE do not remain constant. Oxide production is also influenced by availability of oxygen within the plasma. Immediately after opening the ablation chamber to the atmosphere, oxide production rates can be 50–100% higher than those measured after the ablation chamber has been purged of atmospheric oxygen. Differences in plasma load related to differences in ablation rates appear to have little influence on oxide production. Calculations based on our data confirm that the widespread approach of tuning plasma conditions so that measured ThO+/Th+ ratios are less than a few percent is largely suitable for reducing isobaric interferences from Ba and LREE oxides on middle light rare earth element isotopes to levels suitable for trace element analysis for most geological materials. However contributions to Gd from LREE oxides may exceed analytical uncertainties in moderately to highly LREE-enriched materials ([La/Gd]N > 3). Contributions from BaO to Eu are only significant for materials with Ba/Eu ratios ≫1000.
In laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), the term elemental fractionation is normally used to summarize all non-stoichiometric effects occurring during sample ablation, aerosol transport and vaporization, atomisation and ionisation within the ICP. Nevertheless, there are different types of elemental fractionation occurring between different sized particles within an aerosol, as previously shown for metal alloy ablations. In the present work, laser generated aerosols from glass samples were filter collected before entering the ICP to study their total and particle size dependent composition. Furthermore, elemental concentrations in different particle size fractions on filters were compared with their response measured in the ICP. For the NIST SRM 610 glass, elemental fractionation effects between small particles (<125 nm and <340 nm), and the total aerosol containing all particle sizes up to 1 µm or even larger, were measured for 42 major and trace elements using a 266 nm Nd∶YAG laser and scanning ablation conditions to produce the aerosol. Particles above 125 nm and 340 nm were separated from the aerosol by a particle separation device and the remaining particles were collected on a filter, digested and measured using solution nebulization ICP sector field MS (SFMS). Results show an enrichment of certain elements such as Cu, Zn, Ag, Tl, Pb and Bi of up to 90% relative to Ca within the small particle size fraction of an aerosol in comparison with the total composition of the aerosol. The same elements are depleted in large aerosol particles measured from deposited particles within the ablation cell. However, the total transportable aerosols produced using different laser wavelengths (193/266 nm), and gas environments (He/Ar), which were also filtered and digested show no significant deviation in their overall stoichiometry from the original sample (except Be, Fe, Cd for all lasers and gases) within the uncertainty of the measurements. Therefore, the composition of filter collected aerosol of glass samples indicates that the elemental fractionation in LA-ICP-MS, detected at the beginning of a 266 nm single hole ablation, is predominantly caused by incomplete vaporization of large particles within the ICP and is not dominated by non-stoichiometric ablation of the glass.
Single shot laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) has been developed as a method for the rapid identification of alloy samples. This technique provides good accuracy for elemental concentrations greater than 0.1 percent by mass from samples with a range of different matrix compositions. Through the simultaneous measurement of all elements present within a cloud of ablated particles, relative percent composition values are measured that can be directly compared with certified concentrations. Cluster analysis has been used to successfully classify 33 metal alloys based on the measurement of 15 elements. Additionally, cluster analysis was used to identify the samples from a library of standard reference values. For the 15 alloys used to train this method, the correct standard was identified in greater than 99% of measurements. The only failed identification in the training set may have been due to elemental fractionation
experienced with a brass sample. For the 18 standards used to validate the technique, samples were identified with a 93% success rate. Misidentifications may have been caused by inaccurate certified data. Several alloys investigated in this study were less than 500 µm in length at their largest dimension and weighed less than one milligram.
For more than a decade liquid calibration has been proposed and selectively applied as a calibration strategy for laser-generated aerosols. However, matrix independent calibration is not a well-accepted technique for quantification in direct solid analysis using LA-ICP-MS. In this study three synthetic calibration solutions were used for the analysis of three silicate reference materials (BCR-2G, ATHO, and NIST 610). The calibration solutions were introduced into the ICP using an Aridus liquid sample introduction system with aerosol desolvation, while argon was used as the carrier gas. A 193 nm ArF excimer laser ablation system generated sample aerosols using helium as carrier gas. The argon carrier gas containing the solution nebulization aerosols was mixed, using a sheath gas adaptor in front of the ICP, with the laser aerosol carried in helium. Two different calibration strategies were applied for the multielement quantification of three geological reference materials. The first calibration technique used internal standardization with Ca as the internal standard. The second approach used synthetic calibration solutions containing all major, minor, and trace elements, in which the concentration ratios and concentrations of the elements were known. A normalization algorithm was used which calculated the sum of all of the determined element concentrations as oxides to 100%. The data shown for Ca indicate that both procedures are well suited for multi-element determinations. The 100% oxide normalization strategy allowed the calculation of the Ca concentration based on the total matrix used as internal standard. This Ca concentration was then used for the determination of the trace element composition of the sample. The advantage of this calibration is the possibility of element analysis in silicates without knowing the element concentration of at least one internal standard element prior to analysis. However, this study also shows that the composition of the solution used for the calibration can lead to losses of some elements during the desolvation process in the Aridus or during aerosol transfer to the ICP, which will be shown for Cu.
Single-shot laser ablation (one laser pulse per analysis) combined with inductively coupled plasma mass spectrometry offers tremendous potential for the direct elemental analysis of solid samples with high spatial resolution. However, the precision of the method is usually limited by variations in the laser irradiance and in the specimen being sampled. In this study, two data analysis techniques were evaluated to improve single-shot measurement precision. Both methods exploit the simultaneous full-spectrum acquisition capability of a time-of-flight mass spectrometer. In the first approach, a normalization factor is computed from the summed signal generated by all sample constituents, the reasoning being that the summed spectrum should be proportional to the total mass of sample ablated. This scheme results in a greater than factor of two improvement in precision, moderately better than is possible with a single internal standard. The enhancement in measurement precision was found to be concentration dependent, with the greatest improvement (10–50 fold) experienced by high concentration elements. The second method correlates the attenuation of plasma matrix ions to analyte intensities. The attenuation technique demonstrated no statistically significant improvement in precision, limited by the relatively low signal-to-noise ratio of the attenuated signals.
Laser ablation-ICP-MS is a sensitive and accurate technique for major to trace multi-element analysis at high spatial resolution on the scale of 10 µm. A wide variety of samples can be studied quantitatively, including minerals and their solid, liquid or melt inclusions as required for geochemical studies. As the desired spatial resolution increases, however, detection limits become severely constrained by the total amount of sample material reaching the ICP. Detection limits are therefore determined by the ablation rate and by the efficiency of removal of ablated aerosol particles from the ablation spot and their transport into the plasma. Properties of the carrier gas are known to affect the ablation process and the efficiency of particle transportation. This study explores the effects of different ablation-cell configurations and the use of helium, dry argon and argon moistened with water for the transport of aerosols into an ICP-MS, using a prototype 193 nm ArF excimer laser. Deposition of visible particles deposited around the ablation pit is significantly reduced when helium is used instead of argon. A moderate flux of helium through the chamber, mixed with moistened argon immediately downstream from the ablation chamber, leads to at least a 2-3-fold increase in the signal intensities across the entire mass range when compared with argon gas only. Background intensities above mass 85 are significantly reduced, but polyatomic interferences in the low mass region increase by an order of magnitude, owing to oxide formation caused by the water load. A high flux of helium, mixed just behind the ablation cell with dry argon, yields a 2-3-fold sensitivity enhancement, in addition to greatly reduced background intensity across the entire mass range. This results in one order of magnitude improvement in detection limits for most elements. These modifications permit the routine determination of minor concentrations of chlorine in microscopic fluid inclusions or the analysis of minerals, such as trace element concentrations in quartz (e.g., Na and Li down to 500 ng g
–1
, using a 40 µ ablation pit). Furthermore, this improved sensitivity has recently yielded the first quantitative determination of gold concentrations (∼0.1 µg g
–1
) and full rare-earth element patterns in single 25 µm fluid inclusions.
Microscopic fluid inclusions in minerals are the main source of information about the chemical composition of fluids associated with large-scale material transport in the Earth's interior. Hydrothermal transport processes are responsible for the natural enrichment of metal resources in many ore deposits. For the multi-element analysis of the microscopic fluid inclusions (typically 5–50 µm in diameter), LA-ICP-MS has become one of the most promising techniques owing to the recent progress in laser optics design and the development of high-sensitivity ICP mass spectrometers. The quantitative analyses of 19 major, minor and trace elements covering a concentration range of five orders of magnitude were carried out on 39 single natural fluid inclusions, together with a number of experiments to optimise controlled ablation and to test the calibration procedure. A modified commercial ICP-MS instrument was used together with a prototype ablation system based on a 193 nm excimer laser. In a stepwise opening procedure for complex polyphase inclusions, a small hole (4 µm pit) was first drilled for the partial release of liquid and vapor, followed by complete drilling out using a pit covering the entire inclusion. Controlled ablation improves the reproducibility of element ratios to less than 20% for most major, minor and trace elements measured in an assemblage of cogenetic inclusions (including elements that are initially present as solid precipitates within the inclusion), provided that the entire transient ICP-MS signal is integrated. Element ratios were calculated from integrated intensity ratios using an external standard, either a NIST SRM glass or an aqueous standard solution ablated directly through a plastic film. Absolute concentrations were calculated from the element ratiosviaan internal standard element, whose concentration was determined prior to ablation. Microthermometric measurements of phase transitions were used to determine total salinity from known phase diagrams, by measuring either the depression of ice-melting temperature, or the temperature of dissolution of NaCl crystals. Salinity can be related to the concentration of Na (or in some cases Cl), which serves as the internal standard element for the quantification of trace element concentrations. Calculated limits of detection are in the ng g–1to µg g–1region, depending on the volume of the inclusions. The accuracy of the overall analysis, including internal and external calibration, is typically between 5 and 20%, as demonstrated on alkali elements in synthetic fluid inclusions of known composition.
Many geological, environmental and industrial applications can be enhanced through integrated microbeam and bulk geochemical determinations of major and trace element concentrations. Advantages of in situ microanalysis include minimal sample preparation, low blanks, information about the spatial distribution of compositional characteristics and the ability to avoid microscopic inclusions of foreign material. In this paper we compare trace element data obtained by laser ablation ICP-MS, solution ICP-MS, electron microprobe analysis and proton microprobe analysis for a variety of silicate glasses and minerals. New determinations for 36 trace elements in BCR-2G, a microbeam glass standard, are presented. Results obtained by the various microbeam and solution methods agree well for concentrations ranging over several orders of magnitude. Replicate analyses of BCR-2G demonstrate an analytical precision of 2-8% relative (1σ) for all elements by laser ablation ICP-MS and ≤3% by solution ICP-MS, except for Li (5%). These data emphasize the utility of laser ablation ICP-MS as a quantitative microbeam technique capable of rapid, precise determinations of sub-ppm trace element abundances in a variety of targets.
An ArF excimer laser emitting at 193 nm is used in order to minimize fractionation during ablation. A diagram of the optical system is presented. The laser beam (2 cm × 1 cm; 1-10 Hz; 0.05-1.5 mJ per pulse) is homogenized and collimated into a field of 5 mm × 5 mm in front of a field lens, behind which is a masking aperture that controls the diameter of the ablation crater (<4-100 µm). A 45° dielectric mirror then reflects the beam to a Schwarzchild objective, which images the beam on the sample surface and also permits visual observation of the sample (in reflected or transmitted light) with a petrographic microscope and monitoring of the ablation with a charge-coupled-device camera. The pulse energy can be measured either after the aperture or at the sample. The sample is maintained in a 20 cm3 cell, with a 0.4 mm thick fused-silica window, from which the ablated material is carried to the ICP in a stream of Ar. Fractionation is insignificant in comparison with the precision of quadrupole MS. Good results were obtained for trace-element determinations in hornblende, augite and garnet after calibration against NIST SRM 612 with Ca as internal standard. Detection limits <10 µg/g and a precision of <4% at <1 µg/g could be attained.
During the electron microprobe analysis of sepiolite, the net count rate for sodium increased up to sixty-fold after fifteen minutes' exposure to the electron beam. In contrast, count rates for sodium in nepheline declined by 15% in the same period. The observed increase of sodium X-ray intensity during analysis was greater if the specimen was uncoated, and appeared to be due to a build up of negative charge at the surface. Sodium in sepiolite is associated with zeolitic water in channels within the structure of the mineral. The zeolitic water acts as an electrolyte in which the sodium ions migrate freely; dehydration before analysis reduced the enrichment effect considerably. The mechanism differs from that of ionic migration in the solid state proposed to account for similar compositional changes in glasses.
Application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) as a method for identification of arsenic in a single hair strand was investigated. Using a single point ablation method detectability of 75As and other two elements (208Pb and 64Zn) were evaluated. Arsenic (75As) signal is improved with enhanced laser ablation conditions. For the arsenic determination in hair single spots or single linear scans with enhanced laser ablation conditions described in the paper are satisfactory although ∼800 μm linear scans may be preferable. Arsenic levels in a single strand of hair from individuals who were chronically exposed to arsenic contaminated drinking water from a village in the Atacama Desert in northern Chile were determined by LA-ICP-MS. These results were satisfactorily correlated with total As concentration previously measured by hydride generation (HG)-ICP-MS. The sample throughput is high and it takes ∼3 min per each hair sample including mounting, focusing and analysis. LA-ICP-MS method can be used for the rapid identification and screening of toxic and nutritionally important elements in hair.
To study mass load dependent matrix effects in LA-ICP-MS, different masses of aerosols from the NIST 610 glass were generated using a 193 nm ArF excimer laser and a 266 nm Nd:YAG laser and introduced into an ICP-MS. The different mass loads in the ICP were achieved using different crater diameters, the application of an aerosol dilutor, a tandem ablation setup and mixing of a single element matrix (desolvated solution) with the laser generated aerosols. The comparison of results acquired using these different experimental setups supports the existence of a significant matrix effect dependent on the mass load of the ICP. The proof of such effects on 266 nm laser generated aerosols was limited by temporal changes of element ratios due to the generation of a broad particle size distribution and the related incomplete vaporization within the ICP. However, the differences in the particle size distributions measured for various crater diameters as well as the temporal changes of the element ratios using the 193 nm ArF excimer laser were insufficient to explain mass load related changes of the element ratios. It is shown that an increase of the mass load of the ICP by a factor of 16 (crater diameter from 30 to 120 μm) leads to a decrease in certain intensity ratios (e.g., Cu/Ca, Zn/Ca, Cd/Ca, Pb/Ca) up to 25%. Even after taking into account the fact that smaller crater diameters might be partially influenced by laser-induced fractionation, an excessive mass load of the ICP using two 193 nm laser ablation systems demonstrates a further decrease in ion signal intensities of volatile elements in comparison with Ca. In contrast, applying dilution up to a factor of 30 to the aerosols generated using different crater diameters leads to a stabilization of the intensity ratios (e.g. Cd/Ca) to a constant value. The mass load enhanced matrix effect is element dependent and most severe for elements with low melting points (e.g., Cu, Zn, Ag, Cd, Pb). Based on the changes of e.g. As/Ca, Sn/Ca and the constant Be/Ca ratios, an explanation of the plasma induced effects dependent on parameters such as 1st or 2nd ionization potential was impossible. Furthermore, the mass load dependence on easily ionizable elements (Cs, Rb) indicates the absence of incomplete vaporization related effects. In contrast, Al/Ca, Ti/Ca, Th/Ca ratios, for example, remained constant (within 2–3%) with and without dilution. The induction of matrix effects independently of the ablation process by adding various Rb concentrations to the laser aerosols indicates that elements (Cu, Zn, Cd, Pb, U) previously described to be dominantly influenced by laser-induced elemental fractionation undergo significant ICP-induced matrix effects. These matrix effects are mass load dependent and for most elements exceed the contribution of laser-induced fractionation.
We present a new approach to determine the composition of silicate melt inclusions (SMI) using LA-ICPMS. In this study, we take advantage of the occurrence of SMI in co-precipitated mineral phases to quantify their composition without depending on additional sources of information. Quantitative SMI analyses are obtained by assuming that the ratio of selected elements in SMI trapped in different phases are identical. In addition Fe/Mg exchange equilibrium between olivine and melt was successfully used to quantify LA-ICPMS analyses of SMI in olivine. Results show that compositions of SMI from the different host minerals are identical within their uncertainty. Thus (1) the quantification approach is valid; (2) analyses are not affected by the composition of the host phase; (3) the derived melt compositions are representative of the original melt, excluding significant syn- or postentrapment modification such as boundary layer effects or diffusive reequilibration with the host mineral. With this data we established a large dataset of mineral/melt partition coefficients for the investigated mineral phases in hydrous calc-alkaline basaltic-andesitic melts. The clinopyroxene/melt and plagioclase/melt partition coefficients are consistent with the lattice strain model of Blundy and Wood [Blundy, J., Wood B., 1994. Prediction of crystal-melt partition-coefficients from elastic-moduli. Nature372, 452–454].
Methods for correcting electron microprobe data are reviewed and a new theory is outlined. The theory gives an accurate description of the measured depth distribution of X-ray production. li also makes theoretical predictions of the functional variation of the experimental parameters that are in good agreement with observation. The empirical value for the Lenard law σ of the ZAF method is shown to be an approximation to the more accurate approach. Improved electron range formulae are also put forward and preliminary applications of the new theory to combine and replace the absorption and atomic number corrections are discussed.
Résumé
Les méthodes de correction de données obtenues à la microsonde sont revues et une nouvelle théorie est formulée. La théorie donne une description précise de la pénétration des rayons-X produits, De plus elle permet de faire des prédictions sur la variation des paramètres experimentaux qui sont en bon accord avec les observations. La valeur empirique obtenue pour σ dans la loi de Lenard d'aprés la méthode ZAF, n'est qu'une approximation de la valeur obtenue par methode précise. Des formules amélioriées pour le parcours efficace des électrons sont eénoncées et des applications préliminaires de la nouvelle théorie qui combine et remplace les corrections pour l'absorption et le nombre atomique sont discutées.
Qualitative microprobe analysis of sodian potassian hydroxonian meta-autunite failed to reveal any sodium, although nearly 3% was present. Potassium, magnesium and calcium were underestimated to a smaller extent in related natural and synthetic structures. The effect is due to the migration of these interlayer cations from the analysed region—almost instantaneously in the case of sodium—and a consequent decrease in count rates, under the influence of the space-charge resulting from the incident electron beam. Experiments with the autunites and with a soda-glass subjected to various coating treatments showed that the effect of charging can be dramatic. Such charging also occurs when alkali metals are not present, a fact which has important implications for all microprobe analyses.
This study reports a series of applications of UV laser ablation ICP-MS in the geological sciences. The advantages and disadvantages of the PQ "S" option and the use of nitrogen in the carrier gas are discussed. A general problem common to all ablation techniques is the calibration technique and experiments involving synthetic calibration samples are covered. Zircon geochemistry and geochronology by LA-ICP-MS are discussed and data are presented for REE, Hf and U for a standard zircon (91500) as well as a series of zircons from Zimbabwe. The potential of using Ce and Eu anomalies in petrologic studies is illustrated by zircons from a fractionated gabbroic-granite in the Urals. The potential of the LA-ICP-MS method to utilise standard X-ray fluorescence glass discs is demonstrated as a useful semi-quantitative tool in determining REE patterns. LA-ICP-MS is a powerful tool in the analysis of the platinum group elements (and Re) and some examples are given in the successful application of the technique to partitioning in iron meteorites.
Incompatible trace element abundances have been determined in mantle-derived clinopyroxenes by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in a comparative study with established microanalytical and bulk techniques. Individual clinopyroxene grains were sampled for the laser ablation study from sieved mineral separate fractions from which similar mineral grains had been previously extracted for microprobe (SIMS) and bulk (INAA and ID-TIMS) analysis. Mineral grains were ablated with variable degrees of surface spatial resolution (50-200 mu m) in order to maximise ICP-MS analyte count rates and to improve detection limits. A comparison of results from the different techniques reveals that for the most homogeneous samples LA-ICP-MS can achieve excellent levels of agreement with other techniques (+/- 10%) and good precision for most of the studied elements (1-5% RSD). Variations in calculated concentrations by LA-ICP-MS confirm inter- and intra-mineral heterogeneity determined by SIMS, reflecting changes in sample composition and texture. The long-term reproducibility of the technique is shown by the consistency of results for one sample analysed on thirteen occasions over a period of nine months.
New glass reference materials GSA-1G, GSC-1G, GSD-1G and GSE-1G have been characterised using a prototype solid state laser ablation system capable of producing wavelengths of 193 rim, 213 nm and 266 nm. This system allowed comparison of the effects of different laser wavelengths under nearly identical ablation and ICP operating conditions. The wavelengths 213 nm and 266 nm were also used at higher energy densities to evaluate the influence of energy density on quantitative analysis. in addition, the glass reference materials were analysed using commercially available 266 nm Nd:YAG and 193 nm ArF excimer lasers. Laser ablation analysis was carried out using both single spot and scanning mode ablation. Using laser ablation ICP-MS, concentrations of fifty-eight elements were determined with external calibration to the NIST SRM 610 glass reference material. instead of applying the more common internal standardisation procedure, the total concentration of all element oxide concentrations was normalised to 100%. Major element concentrations were compared with those determined by electron microprobe. in addition to NIST SRM 610 for external calibration, USGS BCR-2G was used as a more closely matrix-matched reference material in order to compare the effect of matrix-matched and non matrix-matched calibration on quantitative analysis. The results show that the various laser wavelengths and energy densities applied produced similar results, with the exception of scanning mode ablation at 266 nm without matrix-matched calibration where deviations up to 60% from the average were found. However, results acquired using a scanning mode with a matrix-matched calibration agreed with results obtained by spot analysis. The increased abundance of large particles produced when using a scanning ablation mode with NIST SRM 610, is responsible for elemental fractionation effects caused by incomplete vaporisation of large particles in the ICP.
The direct analysis of nickel sulfide fire assay buttons by UV laser ablation ICP-MS was used to determine the platinum-group elements and gold in the following reference materials: UMT-1, WPR-1, WMG-1, GPt-4, GPt-6 and CHR-Bkg. The instrument was calibrated with buttons prepared using quartz doped with the appropriate standard solutions. Analytical precision (RSD) was generally better than 10%, although occasional higher RSDs may infer local heterogeneities within nickel sulfide buttons. Good or excellent agreement was observed between analysed and reference material values except Rh in UMT-1 and WMG-1, which suffered an interference from copper. Detection limits calculated as 10 s quantitation limits were Au (1.7 ng g−1), Pd (3.3 ng g−1), Pt (8.3 ng g−1), Os (1.3 ng g−1), Rh (1 ng g−1), Ru (5 ng g−1) and Ir (0.7 ng g−1).L'analyse directe par ICP-MS coupléà un système d'ablation laser de pastilles obtenues par essai pyrognostique avec du sulfure de nickel est utilisée pour déterminer les concentrations en éléments du groupe du platine et en or dans les matériaux de référence suivants: UMT-1, WPR-1, WMG-1, GPt-4, GPt-6 et CHRBkg. L'instrument a été calibré avec des pastilles fabriquées en dopant du quartz avec les solutions standards appropriées. L'incertitude analytique (RSD) est généralement meilleure que 10% bien que des incertitudes plus élévées soient occasionnellement trouvées, probablement dues à des hétérogénéités locales au sein des pastilles. A l'exception du Rh dans UMT-1 et WMG-1, qui souffre d'une interférence avec le cuivre, l'accord est bon et même excellent entre les valeurs mesurées et recommandées. Les limites de détection (prises égales à 10s) sont: 1.7 ng g−1 pour Au, 3.3 ng g−1 pour Pd, 8.3 ng g−1 pour Pt, 1.3 ng g−1 pour Os, 1 ng g−1 pour Rh, 5 ng g−1 pour Ru et 0.7 ng g−1 pour Ir.
The SRM 600 series of glasses, SRM 611 to SRM 619, which nominally contain 500 (SRM 610, 611), so (SRM 612, 613), 1 (SRM 614, 615) and 0.02 (SRM 616, 617) mu g g-' of sixty one elements are now being extensively used as microprobe standards. Recent compilations of the trace element concentrations, which include many new multi-element bulk analyses, do not all give the some value within the stated uncertainty; this observation appears to raise questions about the degree of homogeneity on a microscale reported from probe measurements. The ion microprobe cannot give absolute concentrations, but can accurately measure the abundance ratios between glasses of similar major element chemistry Recent and new probe measurements show that although the absolute concentrations are significantly lower than the nominal values, the average dilution factors are 12 : 1 :0.02 :0.0004 and close to weighed amounts. The consistency between the ratios of random samples of glasses (SRM 610/SRM 612 and SRM 611/SRM 613) strongly supports a high degree of homogeneity on all scales. The measured abundance ratios between two glasses can, therefore, act as a useful check on bulk measurement accuracy. A clear correlation in the SRM 610, 611/SRM 612, 613 ratios measured by ion probe and SRM 612 trace concentrations measured by bulk techniques demonstrates that SRM 610, 611 has a much more uniform trace content than SRM 612, 613.
Forty two major (Na, Mg, Ti and Mn) and trace elements covering the mass range from Li to U in three USGS basalt glass reference materials BCR‐2G, BHVO‐2G and BIR‐1G were determined using laser ablation‐inductively coupled plasma‐mass spectrometry. Calibration was performed using NIST SRM 610 in conjunction with internal standardisation using Ca. Determinations were also made on NIST SRM 612 and 614 as well as NIST SRM 610 as unknown samples, and included forty five major (Al and Na) and trace elements. Relative standard deviation (RSD) of determinations was below 10% for most elements in all the glasses under investigation. Consistent exceptions were Sn and Sb in BCR‐2G, BHVO‐2G and BIR‐1G. For BCR‐2G, BHVO‐2G and BIR‐1G, clear negative correlations on a logarithmic scale exist between RSD and concentration for elements lower than 1500 μg g ‐1 with logarithmic correlation coefficients between ‐0.75 and ‐0.86. There is also a clear trend of increasing RSD with decreasing concentration from NIST SRM 610 through SRM 612 to SRM 614. These suggest that the difference in the scatter of apparent element concentrations is not due to chemical heterogeneity but reflects analytical uncertainty. It is concluded that all these glasses are, overall, homogeneous on a scale of 60 μm.
Our first results on BHVO‐2G and BIR‐1G showed that they generally agreed with BHVO‐2/BHVO‐1 and BIR‐1 within 10% relative. Exceptions were Nb, Ta and Pb in BHVO‐2G, which were 14‐45% lower than reference values for BHVO‐2 and BHVO‐1. Be, Ni, Zn, Y, Zr, Nb, Sn, Sb, Gd, Tb, Er, Pb and U in BIR‐1G were also exceptions. However, of these elements, Be, Nb, Sn, Sb, Gd, Tb, Pb and U gave results that were consistent within an uncertainty of 2s between our data and BIR‐1 reference values. Results on NIST SRM 612 agreed well with published data, except for Mg and Sn. This was also true for elements with m/z 85 (Rb) in the case of NIST SRM 614.
The good agreement between measured and reference values for Na and Mg in BCR‐2G, BHVO‐2G and BIR‐1G, and for Al and Na in NIST SRM 610, 612 and 614 up to concentrations of at least several weight percent (which were possible to analyse due to the dynamic range of 10 ⁸ ) indicates the suitability of this technique for major, minor and trace element determinations.
Isotope dilution calibration has been applied to the determination of Zr and Hf in whole rocks by laser ablation (LA)-ICP-MS. Enriched isotopes were added during the preparation of flux-free, synthetic whole rock glasses and homogenised through a combination of grinding and fusion. This method avoids problems, such as solution instability and the chemical resistance of minerals such as zircon, inherent in acid digestion sample preparation. The use of isotope dilution removes the need for external calibration using certified reference material glasses such as NIST SRM 612 for which certified Zr and Hf values are not available. The precision of Zr and Hf determinations were found to be < 1% and 3.5% respectively, limited by Poisson counting statistics which contributed to 50% of the final precision of analysis. Measured values correlate closely with compiled literature values.La méthode de dilution isotopique a été appliquée à la détermination de Zr et Hf en roche totale par ablation laser (LA)-ICP-MS. Des isotopes enrichis ont été ajoutés au cours de la préparation des verres synthétiques de roche totale, verre sans fondant et homogénéisés par une procédure combinant broyage et fusion. Cette méthode évite les problèmes comme l'instabilité de la solution ou la résistance chimique de minéraux tels que le zircon, inhérents à toute préparation d'échantillon par attaque acide. L'emploi de la dilution isotopique supprime la nécessité d'une calibration externe par rapport à des verres de référence certifiés, tel que NIST SRM 612 pour lequel les valeurs certifiées en Zr et Hf ne sont pas connues. La précision des mesures de Zr et Hf est respectivement < 1% et 3.5%. Elle est limitée par le comptage statistique de Poisson qui contribue pour plus de 50%à la précision finale de l'analyse. Les valeurs mesurées sont très proches des données compilées dans la littérature.
Single fluid inclusions in quartz from a Pb-Zn-Ag carbonate replacement deposit were selected for trace element determination by laser ablation ICP-MS. Spikes in element intensities were noted between first breached fluids versus subsequent analyses, suggesting that accurate element concentrations may not be determined in smaller fluid inclusions when only one analysis is obtained before the fluid is exhausted. Elemental concentrations in the fluid inclusions were determined by external standardisation using solutions sealed in microcapillary tubes. Standards and single natural inclusion analyses give repeatabilities (%RSD) of similar to 20% for Rb and Sr. Rubidium and strontium concentrations range from 0.56-5.07 mu g ml(-1) and 1.12-27.4 mu g ml(-1), respectively, whereas Zn and Ag are below detection limits (< 10 ng ml(-1)). The results suggest that nearly all Zn and Ag are removed by the time hydrothermal fluids precipitate gangue minerals.
A Merchantek LUV266(TM) petrographic ultraviolet (UV) laser microprobe has been used in conjunction with a Finnigan MAT ELEMENT(TM) high resolution ICP double-focusing mass spectrometer (HR-ICP-MS) for solid microsampling and geochemical analysis. This new configuration for laser ablation has the advantage of coupling the high sensitivity and fast scanning technology applied in the ELEMENT with the ablation efficiency of a UV laser. Optimisation of the configuration on the synthetic NIST SRM 612 glass standard reference material using Q-switched UV laser energy of 2 mJ and a 5 Hz repetition rate demonstrates: (1) a linear element response factor throughout the mass spectrum, suggesting limited fractionation during laser ablation; (2) a high sensitivity and very low background noise for most elements of interest; (3) limits of detection ranging from 3 ng g(-1) for Sc to 300 pg g(-1) for U; (4) a flat topped peak shape suitable for precise isotopic measurements; and (5) a flat bottomed crater geometry which permits progressive ablation for the analysis of thin sections. Average precision and accuracy estimates based on replicate analyses of synthetic NIST standard reference material and USGS BCR-2G glasses are below 10% for most elements.
Extensive compositional heterogeneity is shown to affect at least twenty four of the doped trace elements in the NIST SRM 610‐617 glasses.
Compositional profiling and mapping using laser ablation ICP‐MS reveals that all NIST SRM 610‐617 wafers examined here contain domains that are significantly depleted in Ag, As, Au, B, Bi, Cd, Cr, Cs, Mo, Pb, Re, (Rh), Sb, Se, Te, Tl and W, and antithetically enriched in Cu (and Pt), with large enrichments in Cd, Fe and Mn also being encountered in some cases. These domains are visible in doubly polished wafers by unaided visual inspection and by transmitted light and schlieren microscopy. They occur in close proximity to the wafer perimeters and also as stretched and complexly folded forms within wafer interiors. The chemical and optical properties of these heterogeneous domains are consistent with those of compositional cords, a phenomenon of glass manufacture where glass bulk composition and physical properties are modified by loss of volatile components from the molten glass surface. The NIST SRM 610‐617 glasses may be considered reliable reference materials for microanalysis of only between one half and two thirds of the trace elements with which they were doped, including Be, Mg, Sr, Ba, Sc, Y, REE, V, Zr, Hf, Nb, Ta, Th, U, Ga, In, Sn, Co, Ni and Zn. These elements show no evidence of significant heterogeneity, indicating that the original glass constituents and possible residues remaining in the furnace from preceding glass batch fusions were well homogenised during manufacture.
The microanalytical capability of laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICP-MS) to determine ultra trace elemental concentrations has been demonstrated by the analysis of two low concentration glass standard reference materials, NIST SRM 614 and 616. Results for fifty two elements at concentrations in the low ng g-1 range are compared with those determined using secondary ion mass spectrometry (SIMS). Both techniques provide results at these concentrations that generally agree within 95% confidence limits, demonstrating the accuracy for ultra-trace level of in situ determinations by the two techniques. At concentrations of less than 20 ng g-1 in NIST SRM 616, an accuracy and precision of better than 10% has been obtained for most mono-isotopic rare earth elements, when a spot size of 50 μm is used. Limits of detection for selected elements were as low as 0.5 ng g-1.Les potentialités de l'ablation laser couplée à un ICP-MS (LAM-ICP-MS) dans le domaine de la microanalyse de concentrations en ultra-traces ont été démontrées par l'analyse de deux verres standards de référence à faibles teneurs, NIST SRM 614 et 616. Les résultats obtenus pour cinquantedeux éléments à des concentrations inférieures à quelques ng g-1 sont comparés avec ceux déterminés par spectrométrie de masse àémission d'ions secondaires (SIMS). Les deux techniques donnent des résultats situés dans l'intervalle de confiance de 95%, démontrant l'exactitude des deux méthodes pour l'analyse in situ d'ultra-traces. Dans l'échantillon NIST SRM 616, dont les concentrations sont inférieures à 20 ng g-1, une exactitude et une justesse meilleures que 10% ont été obtenues pour la plupart des terres rares mono-isotopiques en choisissant un cratère d'impact de 50 micromètre. Les limites de détection pour certains éléments particuliers étaient inférieures a 0,5 ng g-1
Data are reported for rare earth elements (REE) in three geological glass reference materials (BIR-1G, BHVO-2G and BCR-2G) using a UV (266 nm) laser ablation ICP-MS system and the classical (HF-HClO4) acid decomposition method, followed by conventional nebulisation ICP-MS. External calibration of laser ablation analyses was performed using NIST SRM reference materials with internal standardisation using ²⁹Si and ⁴⁴Ca. Replicate analyses of reference basaltic glasses yielded an analytical precision of 1-5% (RSD) for all the elements by solution ICP-MS and 1-8% (RSD) by laser ablation ICP-MS. The relative differences between the REE concentrations measured by solution and laser ablation ICP-MS compared with the reference values were generally less than 11 % for most elements. The largest deviations occurred for La determined by solution ICP-MS in BIR-1G. The results of both solution and laser ablation ICP-MS agreed well, generally better than 7%, with the exception of La, Pr and Sm in BIR-1G. The measured REE laser ablation data for BIR-1G, BHVO-2G and BCR-2G agreed with the previously published data on these basaltic reference glasses, within a range of 0-10% for most elements. No significant influences were observed for the predicted spectral interferences on some REE isotopes in the analysis of basaltic glasses.
Various zircons of Proterozoic to Oligocene ages (1060-31 Ma) were analysed by laser ablation-inductively coupled plasma-mass spectrometry. Calibration was performed using Harvard reference zircon 91500 or Australian National University reference zircon TEMORA 1 as external calibrant. The results agree with those obtained by SIMS within 2s error. Twenty-four trace and rare earth elements (P, Ti, Cr, Y, Nb, fourteen REE, Hf, Ta, Pb, Th and U) were analysed on four fragments of zircon 91500. NIST SRM 610 was used as the reference material and ²⁹Si was used as internal calibrant. Based on determinations of four fragments, this zircon shows significant intra-and inter-fragment variations in the range from 10% to 85% on a scale of 120 μm, with the variation of REE concentrations up to 38.7%, although the chondrite-normalised REE distributions are very similar. In contrast, the determined age values for zircon 91500 agree with TIMS data and are homogeneous within 8.7 Ma (2s). A two-stage ablation strategy was developed for optimising U-Pb age determinations with satisfactory trace element and REE results. The first cycle of ablation was used to collect data for age determination only, which was followed by continuous ablation on the same spot to determine REE and trace element concentrations. Based on this procedure, it was possible to measure zircon ages as low as 30.37 0.39 Ma (MSWD = 1.4; 2s). Other examples for older zircons are also given.
A simple, rapid and precise method is described for determining trace elements by laser ablation (LA)-ICP-MS analysis in bulk geological materials that have been prepared as lithium borate glasses following standard procedures for XRF analysis. This approach reliably achieves complete sample digestion and provides for complementary XRF and LA-ICP-MS analysis of a full suite of major and trace elements from a single sample preparation. Highly precise analysis is enabled by rastering an ArF excimer loser (lambda = 193nm) across fused samples to deliver a constant sample yield to the mass spectrometer without inter-element fractionation effects during each analysis. Capabilities of the method are demonstrated by determination of twenty five trace elements (Sc, Ti, V, Go, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf, To, Pb, Th and U) in. a diverse range of geological reference materials that includes peridotites, basalts, granites, metamorphic rocks and sediments. More than 90% of determinations are indistinguishable from published reference values at the 95% confidence level. Systematic bias greater than 5% is observed for only a handful of elements (Zr, Nb and U) and may be attributed in part to inaccurate calibration values used for the NIST SRM 612 glass in the case of Zr and Nb. Detection limits for several elements, most notably La, are compromised at ultra-trace levels by impurities in the lithium borate flux but can be corrected for by subtracting appropriate procedural blanks. Reliable Pb analysis has proved problematic due to variable degrees of contamination introduced during sample polishing prior to analysis and from Pt-crucibles previously used to fuse Pb-rich samples. Scope exists for extending the method to include internal standard element/isotope spiking, particularly where integrated XRF analysis is not available to characterise major and trace elements in the fused lithium borate glasses prior to LA-ICP-MS analysis.