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On the relationship between the deposits and tectonics of the Sichuan-Yunnan-Guizhou Pb-Zn mineralized belt
Abstract
Discusses the relationship of the ore belts, deposits and shape and occurrence of orebodies with tectonics in the well-known Sichuan-Yunnan-Guizhou Pb-Zn mineralized zone and draws a conclusion of structural grade ore-control. It proposes that the formation mechanism of the carbonate rock type stratabound ore deposits of the Sichuan-Yunnan-Guizhou mineralized zone is that the dispersed elements hosted in a beneficial facies-lithologic zone are precipitated and enriched in the course of the late tectonic movement in the presence of the lead-zinc remobilization in the enclosed high pressure environment and in the open low presure environment.
... The tectonic network is controlled by N-Sstriking structures in the study area, and a number of firstorder N-S-striking faults have controlled the development of the tectonostratigraphic units. In addition to the N-S-striking faults, NE-SW and NW-SE faults (Liu and Xu 1996) formed due to counterclockwise rotation resulting from NE-SW compressional stress (Han et al. 2001(Han et al. , 2007. ...
... The MVT deposit concentration zones are located along the borders of the sedimentary basin, exhibiting an aggregated distribution, and the ore-forming fluids are produced from the compaction of the basin . In this study, the results of the K(r) function show that the known orebodies in the study area exhibit an aggregated distribution, which is consistent with the results reported in previous studies (Liu and Xu 1996;Zhang et al. 2015). ...
... Permian Emeishan basalts are primarily distributed to the northeast and northwest of the deposit. As this basalt is far from the spatial distribution of the orebodies, it bears no direct relation to the genesis of the lead-zinc deposits (Liu and Xu 1996;Mao et al. 2005;Han et al. 2015a). ...
This study explores the spatial relationship between the spatial distribution features and the fracture distribution of deposits in northeastern Yunnan based on spatial point pattern statistics and the Fry analysis method. The K(r) function value of the spatial point pattern analysis shows that the spatial distribution of lead-zinc deposits displays cluster features. Fry analysis shows that the spatial distribution of lead-zinc deposits can be divided into three distinct scales: the 5-km deposit scale, 20-km ore belt scale, and 100-km regional scale. With a change in the measured scale, the dominant direction in the spatial distribution of the lead-zinc deposits changes from northwest at a scale of 5 km to east-northeast and approximately northeast at a scale of 20 km to nearly north-south at a scale of 100 km. At the deposit and ore belt scales, northwest-southeast-striking faults may control lead-zinc mineralization. At the regional scale, north-south-striking faults affect the spatial distribution of lead-zinc deposits. The seven main orebodies in the Xiaohe lead-zinc deposit in Qiaojia County are used to analyze the features of the Xiaohe lead-zinc orebody. The orebodies at the deposit scale are distributed along a northwest-southeast direction, which seems to confirm the relationship between the northwest-southeast-striking faults and the lead-zinc deposits at the mining area scale, which is also consistent with the Fry analysis results.
... The Daliangzi ore district, located in the Dian-Qian-Chuan Triangle region, is one of the most important metallogenic regions belonging to the YB. It is situated spatially close to the Huize Pb-Zn deposit, both of which are placed near the Xiaojiang fault, which cuts across the continental crust ( Fig. 1(B); Liu and Xu, 1996). Its basement is composed of Archeozoic and Mid-Proterozoic crystallographic rocks, with successive sedimentary rocks mainly from the Sinian and Cambrian age forming a cap locally (Zheng et al., 2006;Xu et al., 2007). ...
Sphalerite in the Daliangzai Pb-Zn deposit, one of the hundreds of Pb-Zn deposits in South China, was chosen as an case study for geochemical research using in situ laser-ablation inductively coupled mass spectroscopy analysis. Many kinds of minor and trace elements were investigated and subsequently treated by multivariate statistical analysis, especially principal component analysis (PCA). These research works indicate that the enrichments of Cu, Ga, As, Cd, Ge, Ag, Sb, Pb, Ni in sphalerite from different depths of the super-large No. I orebogy mutually imply a lower-temperature hydrothermal process dominating the mineralization in Daliangzi Pb-Zn deposit. A small temperature gradient controls the almost similar element distribution patterns indicated by the sphalerite samples which were enriched in Fe, Mn, Co, Cu, Ge, Ag, and Cd in the lower orebody whereas those in the upper orebody were enriched in Fe, Mn, Co, Cu, Ge, Ag, Cd, plus Ga and In. The enrichment of Fe in sphalerite matrix assists the incorporation of many metals, for example, Mn, Co, Ge, and (Ag + Sb). Some important coupled substitutions are discovered: 4Zn2 + ↔ 2Fe2 + + Ge4 + + □ (where □ denotes a vacancy), 2Zn2 + ↔ Ag⁺ (Cu⁺) + Sb3 +, and 3Zn2 + ↔ 2Ag⁺ (Cu⁺) + Ge4 +. Moreover, tetrahedrite–tennantite and jordanite–geocronite solid solution series distinctly feature the sphalerite formed in Daliangzi Pb-Zn deposit which differentiates it from other metallogenic types, especially those related to magmatic activities. Results of PCA work to the selected sphalerite samples from deposits of skarn, syngenetic massive sulfide, MVT, special Jinding and Daliangzi reveal that significant differences, which are mainly defined by the concentration of Fe, Mn, Co, and depleted In, exist in the composition of sphalerite from different deposit types and lie along a single dimension of PC2*. Such a conclusion bases a framework established by PCA and proposed to study the base-metal deposit types and the relevant metallogenic process that are typical for deposits located in South China.
... Xu et al. (2009) pointed out that Huize was related to an MVT type deposit, but the grade of lead and zinc, mineral assemblage, single orebody scale, wall rock alteration, and physicochemical conditions of mineralization were different from those of typical MVT type deposits; so, the Huize deposit was named as "Qilingchang type" deposit. Generally, the origins of lead-zinc deposits in CDQ area are divided into two groups: (1) these deposits are related to the Emeishan basalt thermal activity and the main viewpoints are magmatic hydrothermal complex mineralization type (Xue et al., 2006;Xie et al., 2009), sedimentary-transform type (Liu et al., 1999), "passing through ore-forming deep source fluid in deep fountainhead-extraction of vaporizing rocks evaporate layer-structure controlling of structure" (Han et al., 2006), passing through homogenized oreforming fluid (Huang et al., 2004); (2) these deposits are MVT type deposits ( Zhang et al., 2005( Zhang et al., , 2008Liu et al., 1996;Zhou et al., 1998;Wang et al., 2001Wang et al., , 2002 or "Yangtze type" deposits (Hou et al., 2007) and had no relationship with the Emeishan basalt thermal activity. ...
Up to now, the evaporation and condensation, as well as the biological absorption and inorganic absorptions, have been proved to be major factors in Cd isotope fractionation. And Cd isotopes have been widely applied in studies on the universal evolution and marine environment and so on. However, only a few researches have been conducted in applying Cd isotopes to trace the source of metallogenic material and the evolution of the ore-forming fluid in a complex mineralization environment, especially in a hydrothermal ore-formation system. We measured the Cd isotopic compositions of sphalerite, galena, and ores from five lead-zinc deposits in SW China, and found that the δ 114/110Cd values varied from −1.53‰ to 0.34‰, with a total range of 1.87‰, which is greater than most of measured geological samples. Meanwhile, through contrasting the Cd content with Cd isotopic compositions of different deposits, it may be concluded that different genetic lead-zinc deposits have different Cd content and isotopic compositions, which could be a tool for the studies on the origin of ore deposits. Also, the biomineralization and crystal fractionation may also result in Cd isotope fractionation. In a word, although the research of Cd isotopes is presently at the preliminary stage (especially in hydrothermal ore-formation system), this study demonstrated that Cd isotopes can give a clue in tracing the evolution of ore-forming fluid and metallogenic environment.
The lead-zinc mineralization belt along the southwestern margin of the Yangtze Block is one of the important source for lead, zinc, germanium and silver in China. More than 50% of the deposits in the region occur in carbonate rocks ranging in age from late Ediacaran to early Cambrian. Here we investigate the large Zubu F-Pb-Zn deposit located in the southwestern margin of the Yangtze Block. The ore bodies strike nearly NS in the dolomite fracture zone in the second member of the Cambrian Longwangmiao Formation and discontinuously extend for 0.7 km long. We present Sm-Nd isotopic data on the fluorite ore that yield an isochron age of 211±11 Ma. Fluid inclusions in the fluorite show homogenization temperature between 88-247 °C with a peak at 130-180 °C. With salinity ranging between 0.18 and 22.23 wt.% NaCl eqv. (average of 9.24 wt.% NaCl eqv.), the ore-forming fluid has the characteristics of medium-low temperature and medium-low salinity. The rare earth element (REE) signature of fluorite display positive Eu anomaly and negligible negative to weak positive Ce anomaly. The δ¹⁸OV-SMOW values range from 0.6 - 4.7 ‰, δDV-SMOW values range from -41.1 - 27.6 ‰, fluorite Sr isotopic values range from 0.710668 to 0.711585, and galena Pb isotope ratios with the value of ²⁰⁶Pb/²⁰⁴Pb = 18.551 - 18.564, ²⁰⁷Pb/²⁰⁴Pb = 15.676 - 15.693, ²⁰⁸Pb/²⁰⁴Pb = 38.869 - 38.809. The field, petrologic, geochemical and isotopic data from our study lead to the following salient findings. (1) The ore-forming fluid of the F-Pb-Zn deposit was derived from the mixture of metamorphic water flowing through the basement with basin hot brine and meteoric water. (2) The ore-forming material of the deposit comes from the basement and sedimentary strata. (3) In conjunction with the geochronological data of regional ore deposits, the large-scale mineralization is inferred to have formed during a transitional stage from compression to extension setting related to the Indosinian orogeny after the closure of the late Triassic-early Jurassic (220-190 Ma) Paleo-Tethys Ocean.
The Daliangzi Pb-Zn deposit located on the southwestern margin of the Yangtze Craton, with reserve of 1.80Mt and averaging grade of 11.45% (lead + zinc), is one of the famous high-grade Pb-Zn ore fields in the Sichuan-Yunnan-Guizhou metallogenic belt. Geochemistry of Sr, C, H, O, S isotope and trace element in sphalerite is discussed in this paper in an effort to understand the sources of the ore metals and ore-fluids which cause many different opinions in understanding the genesis of the deposit. The results show that the Ge/In and Ga/In of sphalerites with As, Sb and Ag enriched are much bigger than 100 which indicate the metallogenic environment is of mid-low temperature. The origin of a mix of meteoric and metamorphic (formation) water can be inferred after the datum that the δ18 OH2O values range from -6.02‰ ∼ 3.31‰ and the δD values range from -74.6‰ ∼ -40.3‰ of the ore-fluids. δ13 CV-PDB and δ18 OV-SMOW values of the hydrothermal gangue minerals calcite and dolomite are -3.5‰ ∼ + 1.4‰ and +11.6 ∼ + 18.1‰, indicating that the CO2 in the ore-forming fluid was derived from the dissolution of Sinian carbonates and was greatly affected by the meteoric water and organic carbon in the ore bearing rock. The most of δ34 S values of sulfides are 10‰ ∼ 20‰, and the δ34 S values of sulfates are 20.2‰ ∼ 38.1‰, suggesting that the sulfur should be derived from the in-situ thermochemical reduction of sulfates from the sedimentary strata. The initial 87Sr/86 Sr values of the ore-forming fluid are 0.707137 ∼ 0.714588 with the mean value of 0.711951 which are higher than 87Sr/86 Sr values (0.70834 ∼ 0.70861) of the host rock Sinian dolomite and lower than 87Sr/ 86 Sr values (0.7249 ∼ 0.7288) of the basement and some part of the Sinian formation which had high 87Sr/86 Sr values, implying that the ore-forming fluid probably migrated through the basement and the Sinian formation and experienced water-rock reaction and isotope exchange among the ore fluid, the basement and Sinian formation.
In order to find the metallogenic pattern of the Zn-Pb deposits at the junction of Sichuan, Yunnan, and Guizhou provinces, comprehend the metallogenic theory and predict ore prospecting, the author studied the space-time distribution of these Zn-Pb deposits in this area. The conclusions are listed as follows: 1)Zn-Pb deposits are distributed together, and can be divided into three ore-concentration areas. 2)Statistically, Sinian and Carboniferous stratum have a higher metallogenic probability of 51.57%, and Dengying and Baizuo Formation hold 80.98% metal reserve. 3)Tectonic units control the distribution of ore-forming units, but ore-concentration area does not correspond to the second tectonic unit at all. Ore-concentration area I and II are jointly controlled by Kangdian axis, Longmenshan depression, and cross region of Yangtze platform. 4)The space coupling between siderite (hematite) deposits, lead-zinc deposits, and close association of Pb-Zn minerals with siderite (hematite) indicate the genetic relationship between Zn-Pb deposits and Fe deposits. During the early stage of basin evolution, at the depression belt (or sea basin) in the edge of the ancient land mass, two types of iron formations were formed from Llandovery Telychian stratum of Silurian to Dewuan stratum of the Lower Carboniferous and the Lower Kunyang Group (Huili Group) in the middle of Proterozoic. Ore-forming elements, such as Pb and Zn, are pre-concentrated and further enriched by the later circulated hydrothermal fluids during diagenesis to form the deposit. Iron-formations provided the main ore-forming materials for Pb-Zn deposits. 5)The sulfur source, gypsum beds, is derived from the underlain Cambrian stratum of Dengying and Baizuo Formations. 6)Both ore-forming elements and sulfur source beds control the formation of ore concentration areas and the strata bound distribution of orebodies, which are considered to be the most important controlling factors.
Located on the southwestern margin of the Yangtze craton, the Chipu Pb-Zn deposit is one of the major Pb-Zn deposits in the Sichuan-Yunnan-Guizhou region. Based on the field and microscopic observations, three stages of quartz formed in the mineralization phase have been distinguished. In this study 21 samples were used and the primary inclusions preserved in quartz, sphalerite and silicified dolomite were studied intensively. The inclusion types in the deposit are relatively simple, dominated by vapor-liquid inclusions. The ranges of homogenization temperatures and salinities of the fluid inclusions for each stage are: stage I, 230 to 270*C and 2.74 to 19.68 wt% NaCl equiv.; stage II, 150 to 200°C and 3.71 to 16.99wt% NaCl equiv.; stage III, 180 to 220°C and 0.70 to 16.15 wt% NaCl equiv. The homogenization temperatures and salinities of the fluid inclusions for sphalerite in the main mineralization phase range from 127 to 210°C and from 4.34 to 22.17 wt% NaCl equiv. respectively. The homogenization temperatures and salinities of ore-forming fluids of the deposit are 130 to 200°C and 8.5-17.0 wt% NaCl equiv. respectively. The deposit belongs to a low-temperature, moderate-salinity Pb-Zn deposit. Based on the geological and fluid inclusions characteristics of the deposit, the authors think that the ore-forming fluids belong to the H2O-NaCl -CaCl2 system and always remained in a reducing environment. The ore-forming materials were derived from the upper crust and the ore-forming fluids mainly came from the host carbonate rocks. Sulfide precipitation was probably caused by mixing of metal-bearing and reduced sulfur-bearing fluids at the site of mineralization. This deposit should belong to MVT deposits.
There are a lot of orogenic belts with different mineral resources through the geological history in China. After a preliminary study we propose that metallic deposits in the orogenic belts can be divided into collision-and subduction-related. The former one can be further divided into syncollision-and postcollision-related metallic deposits. The syncollisional mineral deposits can be recognized in the Tibetan Plateau, an active orogenic belt. They occur along the extension zones perpendicular to main sutures in the compresional stage, relaxation belts parallel to the main suture, pull-apart basins and detachments along the strike-slip faults. On the whole, all the mineralizations formed during the syncollisional orogenic process occur in the tensional structures. It is difficulty to find syncollisional ore deposits in ancient orogenic belts. They could be eroded or overprinted by subsequent geological processes. Most ore deposits in ancient orogens are of postcollisional age. We take the eastern Tianshan and western Qinling as samples to discuss the nature, characteristics, process, and distribution of the postcollisional metallogenic process. Although porphyry copper deposits formed in the collisional age, the others comprising gold, skarn and vein type copper, skarn copper-iron or polymetallic silver, and Cu-Ni sulfide deposits occur at a range of 290-270 Ma in eastern Tianshan, later than the orogenic age of ca. 320 Ma. The mineralization pulse in western Qinling is 210-160 Ma, which is later than the orogenic age of 240-220 Ma, too. The mineralization on the southwestern margin of the Yangtze Craton is well-known as a region with low-temperature hydrothermal deposit association in China. It comprises Carlin type gold deposits, MVT lead-zinc deposits and flood basalt-hosted copper deposits. We propose that these mineral deposits occur in Jurassic - Cretaceous extensional basins to the east of a Mesozoic N-S-trending orogenic belt caused by the subduction of the Tethys plate, which is similar to the configuration of the Cordillera orogen and great basins. Whatever develop in collisional or subductional orogens, even in syncollisional or postcollisional time, and with different temporal-spatial locations, the distribution of metallic deposits in orogens are controlled by various types of tension structures.
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