Plate Tectonics and sandstone composition

Detrital modes in Lower Mesozoic sandstone of the Wulgai Formation (Pakistan): implications for provenance

Article

Full-text available

Jan 2020

The detrital modes of twenty-five sandstone samples from Triassic Wulgai Formation have been studied in Zhob and Qila Saifullah districts of Balochistan province in order to determine their provenance and tectonic setting. The sandstone is mostly fine-to medium-grained. Quartz is the most abundant framework grain in sandstone, while heavy minerals include rutile, tourmaline, staurolite, zircon, and hornblende. Among the lithic fragments, metamorphic lithic fragments are the most abundant rock fragments. The sandstone of the Wulgai Formation is classified as quartz arenite (Q96F4L0.2). The Qt-F-L (Qt96F4L0.2) and Qm-F-Lt (Qm96F3Lt1) plots show the craton interior as the source terrain for the sandstone, in which metamorphic and plutonic terrains were the most dominant sources. The very-high content of monocrystalline quartz indicates high maturity of the sandstone, which may be attributed to quartz-rich, acidic igneous and high-grade metamorphic terrains. The most quartzose sands are usually derived from stable craton interiors having low relief.

Petrographic and geochemical perspectives on sandstones of the extra‑peninsular Gondwana Group from the Arunachal Himalayas, NE India: Probing provenance, tectonic context and paleoenvironmental conditions

Article

Apr 2025

The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas, India. The bulk of sediments for the sandstones of the Gondwana Group were derived from felsic/acidic to intermediate igneous rocks, with minor mafic input from the upper continental crust (UCC), as supported by various discrimination diagrams based on quantification of detrital minerals coupled with sandstone geochemistry. The inputs from metamorphic sources in subordinate amounts cannot be ruled out, as indicated by quantification of the quartz varieties. These sediments were found to be sourced from the interior part of a craton or shield and recycled platformal sediments which were derived from both passive and active margin settings. The sediments experienced a wide variance in climatic conditions, from arid to humid, suffering low–moderate-intensity weathering (CIA: 63.43; CIW: 86.18; WIP: 44.84; PIA: 75.37; ICV: 2.39; C-value: 0.42; PF: 0.49; Sr/Cu: 9.23 and Rb/Sr: 1.68) within the vicinity of the low plains to moderate hills. Additionally, redox-sensitive elements indicate the deposition of sediments under oxygenated or oxygen-rich conditions (Uau: −2.91; Th/U: 7.37; U/Th: 0.18; V/Cr: 1.71; δU: 0.67 and Ce/Ce*: 0.93).

Genesis of the Upper Jurassic Continental Red Sandstones in the Yongjin Area of the Central Junggar Basin: Evidence from Petrology and Geochemistry

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Full-text available

Mar 2025

The sandstone sections in the Upper Jurassic red beds of the Yongjin area in the central Junggar Basin are important oil and gas reservoirs. The debate over whether red beds are of primary depositional or secondary diagenetic origin persists, leading to uncertainties in the interpretation of reservoir sedimentary facies. This study uses core samples and employs thin section microscope observations, scanning electron microscopy, X-ray diffraction, and major and trace element analyses to investigate the formation period and paleoclimate conditions of red beds and explore the origin of red sandstone. The Upper Jurassic red beds are mainly deposited in arid delta plain environments. The framework grains of the red sandstone are composed of quartz (averaging 22.6%), feldspar (averaging 16.3%), and rock fragments (averaging 36.7%). The rock fragments in the sandstone are mainly composed of intermediate basic volcanic rocks and cryptocrystalline acid volcanic rocks, which are rich in mafic silicate minerals such as olivine, pyroxene, ilmenite, and magnetite. In situ hematitization of ilmenite is observed in the rock fragments, suggesting that the in situ alteration of mafic silicate minerals in the parent rock is the main source of iron ions for hematite. Tiny hematite crystals (2.1 μm) are observed in clay mineral micropores via SEM. Abundant mixed-layer illite/smectite clay indicates early smectite transformation, providing a minor source of iron ions for hematite. Hematite in the red sandstone occurs as a grain-coating type, predating quartz overgrowth, feldspar overgrowth, and (ferroan) calcite and (ferroan) dolomite precipitation. Residual hematite coatings between detrital grain point contacts indicate that hematite is a product of syn-sedimentary or very early diagenetic precipitation, ruling out the possibility that red sandstone formation was caused by later atmospheric water leaching during the fold and thrust belt stage. The average chemical index of alteration (CIA) for the red sandstone is 52.2, whereas the CIA for the red mudstone averages 59.5, and the chemical index of weathering (CIW) reached a maximum of 69. These values indicate that the rocks have undergone mild chemical weathering in arid climates. Additionally, the ratios of trace elements indicate that the water bodies were in an oxidizing state during the sedimentary period. The arid climate and oxidative water conditions were ideal for hematite preservation, thus facilitating red bed formation. The red bed sediments in the study area represent a direct response to the Late Jurassic aridification event and can be compared to global climate change. The results have important implications for stratigraphic correlation and interpretation of reservoir sedimentary facies in the study area while also providing a valuable case study for global research on red beds.

Geochemical studies of the Paleoproterozoic volcano-sedimentary rocks of the Mahakoshal Belt, Central Indian Tectonic Zone (CITZ): Implications for crustal evolution

Thesis

Mar 2025

Kamaal Parvez

The Central Indian Tectonic Zone (CITZ) trending E W to ENE WSW is a suture zone between the North Indian Block (NIB), which includes Aravalli Craton and Bundelkhand Craton, and the South Indian Block (SIB), which includes Dharwar Craton, Singhbhum Craton and Bastar Craton. It consists of three supracrustal basins viz. Mahakoshal Basin, Betul Basin and Sausar Basin from north to south, respectively. The Mahakoshal Basin is the oldest basin among them. It is conjectured that the opening of the Mahakoshal Basin took place at ~2.1 Ga and closed at ~1.8 Ga. The granite gneiss is the basement of the Mahakoshal Group. The Mahakoshal Group consist of three formations viz Saleemnabad Formation, Parsoi Formation and Dudhmaniya Formation from lower to upper, respectively. The lowermost formation (Saleemnabad Formation) mainly consists of metabasalts and meta argillites, with subordinate amount of ultramafic rocks, banded iron formations (BIF), chert and carbonates. The middle formation (Parsoi Formation) mainly consists of meta argillites and meta greywackes, with subordinate amount of pyroclastic rocks. The meta argillites are intercalated with the thin bends of pyroclastic rocks. The uppermost formation (Dudhmaniya Formation) consists of quartzites and BIF. The Mahakoshal Group is intruded by several small granite and granite gneiss plutons, lamprophyre dykes and quartz veins. The present work focuses on the geochemical studies of the Mahakoshal metabasalts, which include major oxides and trace elements data, clastic metasedimentary rocks (meta argillites, meta greywackes and quartzites), which include major oxides, trace elements and Sr Nd isotopic data and Sidhi granite gneiss and Madanmahal granite, which includes major oxides, trace elements and zircon U Pb geochronology. The geochemical studies of the metabasalts were carried out to understand the genesis and the tectonic settings in which they were emplaced. The geochemical studies of the clastic metasedimentary rocks were carried out to identify the probable source rocks, paleoweathering conditions and their tectonic setting. Earlier studies suggest that the Sidhi granite gneiss is the probable source of the meta argillites. So, to verify it, I carried out geochemical studies of Sidhi granite gneiss and Madanmahal granite, including major oxide and trace elements data along with zircon U Pb geochronology. The Mahakoshal metabasalts are restricted in the lowermost formation i.e. the Saleemnabad Formation. They are intercalated with meta sedimentary rocks (meta argillites and chert). These metabasalts show pillow structures in some places, and in some places, massive meta basalts are found. Petrographic studies exhibit that the Mahakoshal metabasalts are fine to medium grained. They are dominantly composed of plagioclase, actinolite and chlorite. The epidote is present as an alteration product. The mineralogy of the Mahakoshal metabasalts suggests that they have undergone up to greenschist facies metamorphism. The elongated chlorite and actinolite in a preferred orientation suggest that the studied rocks have suffered metamorphic foliation. Geochemically, the Mahakoshal metabasalts range in SiO2 from 43.02 wt% to 59.54 wt%, and MgO ranges from 4.56 wt% to 6.52 wt%. The Mahakoshal metabasalts show a high concentration of Fe2O3T, ranging from 12.45 wt% to 17.81 wt%. The magnesium number (Mg#) varies from 0.2 to 0.3, suggesting that the studied metabasalts are evolved in nature. The Mahakoshal metabasalts have a high concentration of Cr, ranging from 121 to 889 ppm; Co, ranging from 19 to 77 ppm; Sc, ranging from 26 to 43 ppm; and Ni, ranging from 70 to 273 ppm. The Mahakoshal metabasalts are sub alkaline and belong to the tholeiitic series. Moreover, they show high Fe tholeiite basalt signatures. The chondrite normalized rare earth elements (REE) patterns show different degrees of fractionation of the light rare earth elements (LREE) patterns. Some samples show highly enriched LREE patterns (fractionation in LREE), and other samples show flat LREE patterns (no fractionation in LREE). However, all samples show similar flat, heavy rare earth elements (HREE) patterns. The REE patterns show no significant anomaly. In the primitive mantle (PM) normalized multi element diagram, the studied rocks do not show any significant anomaly of Nb (Nb/Nb* ranges from 0.7 to 1.3; average = 1.0; except for sample KP 144 which is 0.1) and Ti (Ti/Ti* ranges from 0.8 1.1; average = 0.9; except for sample KP 144 which is 0.1), suggesting that these rocks are not affected by any crustal input and show their pristine nature. The crustal contamination is assessed by using various geochemical proxies, such as Nb/Th, Nb/La and LaN/SmN. The Nb/Th ratios of the Mahakoshal metabasalts range from 5.41 to 11.87, which is close to the primitive mantle (Nb/Th = 8). Further, to evaluate the crustal input, I have plotted Nb/Th vs Nb/La and Nb/Th vs LaN/SmN bivariate diagrams, which show that Mahakoshal metabasalts are not affected by the crustal inputs except for sample KP 144. The source of the Mahakoshal metabasalts is constrained by using various geochemical proxies. The studied metabasalts are produced by the enriched Mid Ocean Ridge Basalt (E MORB) type mantle. The E MORB type mantle source is suggested by Ce/Y vs LaN/YbN and Th/Yb vs Nb/Yb bivariate diagrams. In the Sm/Yb vs Sm bivariate plot, some samples of the Mahakoshal metabasalts are plotted near the spinel lherzolite field and show a higher degree of partial melting, whereas some other samples are plotted near the spinel garnet lherzolite field and show a low degree of partial melting. This may suggest that the studied metabasalts are produced at different depths by different degrees of partial melting. The tectonic settings of the Mahakoshal metabasalt were ascertained by using field evidence clubbed with various tectonic discriminant diagrams. The Mahakoshal Group consists of basalts associated with dacite and rhyolite (pyroclastic rocks). This type of rock association is found in arc related environment. Further, TiO2 vs V and ThN vs NbN tectonic discriminate diagrams reveal that the studied metabasalts are emplaced in the back arc tectonic setting. The clastic meta sedimentary rocks of the Mahakoshal Group include meta argillites, which are present in the Saleemnabad Formation and the Parsoi Formation; meta greywackes, which are present in the Parsoi Formation; and quartzites, which are present in the Dudhmaniya Formation. The meta argillites of the Saleemnabad Formation are intercalated with the metabasalts, and meta argillites of the Parsoi Formation are intercalated with the pyroclastic rocks. The XRD analysis of meta argillites of both formations suggests that they consist of chlorite, muscovite, illite and albite with subordinate amount of quartz. The petrographic studies of the meta greywackes reveal that they are medium to coarse grained and show poor sorting. Mineralogically, they consist of quartz, feldspar, opaque minerals and rock fragments with 15 17% matrix. The quartzites are dominated by quartz with a subordinate amount of fuchsite. Geochemically, the meta argillites of the Saleemnabad Formation consist of SiO2 varying from 48.72 wt% to 64.51 wt%, Al2O3 varying from 11.00 wt% to 20.44 wt%, and MgO ranges from 0.75 wt% to 2.98 wt%. The meta argillites and the meta greywackes of the Parsoi Formation consist of SiO2 which ranges from 43.10 wt% to 68.28 wt% and 71.31 wt% to 82.68 wt%, respectively. The Al2O3 content in the metaargillites and the meta greywackes ranges from 6.01 wt% to 25.04 wt%, and 7.52 wt% to 13.32 wt%, respectively, and MgO content ranges from 0.73 wt% to 9.89 wt% and 0.64 wt% to 3.84 wt%, respectively. The quartzites of the Dudhmaniya Formation contain a high concentration of SiO2, ranging from 90.85 wt% to 97.88 wt%. The Al2O3 content in quartzites varies from 0.12 wt% to 4.43 wt%, and MgO concentration varies from 0.02 wt% to 0.98 wt%. The meta clastic rocks of the Mahakoshal Group (meta argillites of both the formations, meta greywackes and quartzites) are enriched in Cr, Co, V, and Sc, suggesting their affinity with mafic rocks. The REE patterns of the studied meta clastic rocks show highly fractionated patterns with no significant Eu anomaly. However, some meta argillites samples of the both formations (Saleemnabad and Parsoi formations) show prominent negative Ce anomalies. The provenance characterization and tectonic setting of the meta clastic rocks of the Mahakoshal Group have been deciphered by using major oxides, trace elements and Sr Nd isotopic constraints. Th/Sc, La/Sc, La/Co, Th/Co, and Th/Cr ratios suggest that the sources of the meta clastic rocks are heterogeneous. In the La Th Sc ternary diagram, the studied meta clastic rock samples plot along the La Sc array, which suggests that the sediments are contributed from felsic as well as mafic sources. In the V Ni 10*Th ternary diagram, the studied meta clastic rock samples plot along the V 10*Th array, which endorses that the sediments are contributed from felsic as well as mafic sources. The sediments also show arc signatures such as high LILE concentration and low HFSE concentration. The isotopic signatures also suggest the contribution of sediments from the arc as well as the older Archean crust. The εNd(1.894 Ga) vs Th/Sc diagram reveals that the sediments are contributed from the mafic arc and older Archean crust. The f(Sm/Nd) vs εNd(1.894 Ga) also endorse the contribution from the mafic arc and older Archean crust. Moreover, in the La Th Sc tectonic discriminant diagram, most of the studied meta clastic rock samples are plotted in the continental island arc and passive margin field. Hence, we conclude that the mafic component is derived from the continental arc and the felsic component is derived from the Bundelkhand gneiss and granite. The chemical weathering has been quantified by computing the Chemical Index of Alteration (CIA). The average corrected CIA value of the meta argillites of the Saleemnabad Formation is ~79, that of the meta argillites of the Parsoi Formation is ~78, the meta greywackes is ~66, and the quartzites is ~79, suggesting that these rocks have undergone moderate to intense chemical weathering. In the A CN K ternary diagram, the studied meta clastic rocks plot approximately perpendicular to the Al2O3 K2O axis, suggesting that the studied rocks are affected by the K metasomatism. Another weathering index, ‘α’, is also used to assess the chemical weathering quantitatively. The weathering indices for the meta argillites of the Saleemnabad Formation are as follows: αAlCa = 6.50, αAlNa = 4.57, αAlK = 1.26, αAlSr = 8.16, αAlBa = 2.27 and for the meta argillites and the meta greywackes of the Parsoi Formation are αAlCa = 2.32 and 4.69, αAlNa = 6.61 and 1.20, αAlK = 0.98 and 1.54, αAlSr = 6.14 and 4.44, αAlBa = 1.20 and 0.97, respectively and for the quartzites of the Dudhmaniya Formation αAlCa= 8.40, αAlNa= 9.39, αAlK= 0.49, αAlSr= 0.62, αAlBa= 0.97. The studied rock samples have significantly higher values of αAlCa, αAlNa, αAlSr and αAlBa, which also endorse moderate to intense weathering. However, αAlK in the meta argillites of the Parsoi Formation and the quartzites are 0.98 and 0.49, respectively, showing lower values, possibly due to K metasomatism. Previous studies suggest that Sidhi granite gneiss is the source rocks for the meta clastic rocks of the Mahakoshal Group. To validate this and to check whether there is any contribution from Madanmahal granite, I have carried out a geochemical analysis, which includes major oxides and trace elements along with U Pb zircon geochronology of the Sidhi granite gneiss and Madanmahal granite. The petrographic studies of Sidhi granite gneiss and Madanmahal granite show that they consist of plagioclase, quartz and K feldspar, with a subordinate amount of biotite and hornblende. The studied rocks show hypidiomorphic granular texture. The biotite grains show pleochroic haloes, indicating the presence of zircon and apatite as accessory minerals. Perthite texture is observed, which is due to the exsolution of plagioclase from K feldspar. The Sidhi granite gneiss and Madanmahal granite are ferroan in character and categorized as moderate to strongly peraluminous in nature. The chondrite normalized REE patterns show that the studied granite gneiss and granite are highly fractionated and show significant negative Eu anomaly. The N MORB (normal mid ocean ridge basalts) normalized multi element diagram shows negative Ba, Nb, Sr and Ti anomalies and slightly positive anomalies are shown in Rb, Th, Zr and Hf. The Sidhi granite gneiss and Madanmahal granite are akin to A type granite and have average zircon saturation temperatures (ZST) of 955 ˚C and 977 ˚C, respectively. These granite gneiss and granites are enriched in HFSE (Zr and Hf), total alkalis and LREE and depleted in CaO and compatible trace elements such as Ni, Cr and Co show their prominent A type character. These studied rocks are further classified as A2 type granites. (Y/Nb)N>0.18, (Th/Nb)N>2, (Ce/Pb)N<1 and (La/Nb)N>2 accompanied by the Eu, Ba, Sr, Ti and Nb negative anomalies and slightly positive anomalies in Th, Rb, U and La suggest that the studied rocks are derived from the same source i.e. the preexisting crustal source. La/Yb vs La and Zr/Nb vs Zr bivariate diagram further verify that pre existing crust is a dominant source of the studied rock types. To ascertain the tectonic setting in which Sidhi granite gneiss and Madanmahal granite are emplaced, I coupled field evidence with tectonic discriminant diagrams. In the field, deformational structures are observed in the Sidhi granite gneiss and Madanmahal granite, such as regional foliation and feldspar augens aligned in the regional foliation direction. Based on geochemistry, in the Nb vs Y tectonic discriminant diagram, the samples of the studied rocks plot in the WPG (within plate granite) field. This indicates that the studied rock types are emplaced in a rift environment, and the Rb vs Y+Nb tectonic discriminant diagram shows that the studied rock types are emplaced in a post collisional environment. Hence, we conclude that the studied granite gneiss and granite are formed in the post orogenic rift environment. The Mahakoshal Basin which lies in the Bundelkhand Craton was opened during the retreating accretionary orogen. Later, the retreating orogen switched to the advancing orogen, causing the closure of the Mahakoshal Basin. After the closure of the basin, post orogenic rifting occurred in which Sidhi granite gneiss and Madanmahal granite were emplaced.

Petrography of Sandstone Units of Injana Formation in Al-Teeb Area South Eastern Iraq

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Full-text available

Jan 2025

The present study deals with study the sandstone units of injana formation in Alteeb area, east of Missan governorate southeastern Iraq. Ten samples of these sandstone were collected in order thin sectined for petrogtaphic decribtion. these sandstone are composed from quartz (both monocrystalline and polycrystalline), feldspar (potash feldspar and plagioclase feldspar), and rock fragments (sedimentary, igneous, and metamorphic rock fragmentd), the sedimentary rock fragments composed from; carbonate, chert, old sandstone, mudstone, and evaporate rock fragments. Three types of cement will observe these are: carbonate, evaporate, and iron oxide cement.These sandstone classify as litharenite, sedarenite, and calclithite, dure to the predominant of carbonate rock fragment. These sandstone chimachaly and michanicaly unstable due to low percentage of stable componants (quarts and chert).Tectonically the Injana Formation was deposited under convergent plate boundaries: lithic recycled and transitional recycled conditions

Provenance of the Numidian Formation deposits (Oligo-Miocene) in northern Algeria: Insights from sandstone petrography, palaeocurrent data, geochemistry, and zircon geochronology

Article

Jan 2025
SEDIMENT GEOL

The provenance of the Numidian Formation deposits remains a matter of debate as to whether the source rock of the detrital material that fed the Maghrebian Flysch Basin is of European or African origin. The Numidian Formation is built mostly of Oligocene to Miocene deep-sea turbiditic sandstones and mudstones, which are widely exposed across the Mediterranean (Italy, Tunisia, Algeria, and Morocco). This study applies, for the first time, an integrated provenance analysis of the Numidian Formation in Algeria, combining detrital zircon Usingle bondPb geochronology, sandstone petrography, geochemistry, and palaeocurrent orientation to constrain their source rock. Palaeoflow analysis, based on flute and groove casts indicates a predominant flow direction from the southeast to the northwest. Petrographic data show that most samples consist of quartz-arenitic sandstones, derived from igneous and metamorphic rocks. These sandstones exhibit evidence of prolonged transport and sedimentary recycling sediments, characterized by a predominance of rounded to well-rounded grains associated with a minor proportion of subangular grains. Trace elements and REE patterns suggest a felsic-intermediate source, while certain samples indicate intermediate mafic rocks and varying degrees of weathering. Tectonic analysis suggests a passive continental margin setting, though some samples show evidence of a continental island arc influence. Usingle bondPb geochronology conducted on 205 zircon grains yielded three main age groups: (1) Neoproterozoic (980–549 Ma, 24 %); (2) Mesoproterozoic (1527–1000 Ma, 17 %); and (3) Paleoproterozoic (2469–1636 Ma, 24 %). Additionally, a small number of younger grains (1 %) from one sample correspond to the Silurian age (436–428 Ma). Th/U ratio and cathodoluminescence (CL) images highlight the dominance of zircons with igneous origin over those of metamorphic origin. The age and morphological characteristics of zircons, along with petrographic, geochemical, and palaeoflow data, strongly support an African origin for the studied deposits. Their polycyclic nature suggests they were reworked from older sources, including the Continental Intercalaire, Nubian Sandstones, and Cambro-Ordovician sandstones found in southern Libya and Algeria.

Diagenetic Environment of Oligocene Barail Sandstones, North-West of Kohima, Nagaland, India

Article

Jan 2025

Petrographies, Scanning Electron Microscopy (SEM) along with XRD analysis were used to thoroughly examine the physical and diagenetic characteristics of the Oligocene Barail siliciclastics exposed in the NW of Kohima town of Nagaland, India. The hard and compact sandstones of the study area are represented by very fine to medium sand fractions and belong to sublithic arenite/quartz arenite categories. Compaction effects, authigenesis and albitization, silica overgrowth, neo-morphic quartz, modified grain to grain contacts, bending of flaky minerals, and corroded grain boundaries are the diagenetic features observed in the Barail sandstones. Locomorphic and redoxomorphic diagenetic stages are common, while features showing phyllomorphic stage of diagenesis are less common. A progressive diagenetic regime has also been envisaged on the basis of various diagenetic signatures and stages. Preserved diagenetic features and stages suggest a depth range of 3 to 5km and temperature above 150oC. Chemistry of seawater, pH, increasing pressure and temperature were responsible for diagenetic modifications in the Oligocene Barail sandstones. Keywords: Petrography, Diagenesis, Oligocene, Barail sandstone, Nagaland

MODELO SEDIMENTOLÓGICO DEL FLYSCH EOCENO DE LA ISLA DE MARGARITA, ESTADO NUEVA ESPARTA, VENEZUELA

Thesis

Full-text available

Oct 2023

This thesis presents a sedimentological model for the Eocene Flysch deposits of Margarita Island, Nueva Esparta State, Venezuela. The study is based on the analysis of sedimentary facies and facies associations, primarily using the models proposed by MUTTI & LUCCHI (1972) and PICKERING et al. (1986). The facies associations were defined mainly from the sediment gravity flows described by MIDDLETON & HAMPTON (1973, 1976) and the updated studies of SHANMUGAM (2021). The results indicate a predominance of debris flows (clay-rich and sandy), bottom currents, and turbulent flows (turbidity currents), with a lesser proportion of grain flows and evidence of fluidized flows. The deposits generated by these flows define associations ranging from outer platform and slope zones to basin plain zones. At the base of both stratigraphic sections (Pampatar Formation and Punta Carnero Group), mass transport deposits (MTDs) were identified for the first time, encompassing debris flows, slides, and slumps through a continuous intergradational process (POSAMENTIER & MARTINSEN, 2011). Two representative carbonate deposits were defined within the Punta Carnero Group, which exhibit large benthic foraminifera, red algae, and planktonic foraminifera. The fossil content and evidence of reworking indicate that these carbonates behaved as bioclasts, exhibiting typical BOUMA sequence structures, having been deposited by turbidity currents. Notably, within these carbonate deposits, mass transport deposits were consistently present, providing direct evidence of the ability of MTDs to transport sediments from outer platform and upper slope areas, where typical platform carbonates were located, to deeper basin areas exceeding 2000 m in depth (Nereites ichnofacies). The model is divided into four stages, ranging from Middle to Late Eocene, revealing that the Flysch rocks were deposited in a system initially dominated by large mass transport deposits (MTDs), followed by continental shelf carbonates, hemipelagites, and pelagites in distal, deep marine zones dominated by bottom and turbidity currents (Punta Carnero Group), and channelized deposits within a prograding submarine fan, with little presence of carbonates, generated mainly by turbidity currents and grain flows (Pampatar Formation).

Sedimentology and structure of the Paleogene Nummulitic series of Corsica: Reconstruction of the southern termination of the western Alpine foreland basin

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Full-text available

Sep 2024

Nummulitic Limestones deposits are preserved along the tectonic contact between the Variscan basement and Alpine units of Corsica. These marine carbonates, dated from the Late Palaeocene to the Middle Eocene, were deposited within a foreland flexural basin that is considered to be the southern continuation of the Alpine foreland basin of southeast (SE) France. However, in contrast with the Nummulitic Limestones of SE France, those of Corsica are far less documented. This field‐based study constrains the sedimentology, stratigraphy and structure of the Nummulitic Limestones of Corsica in three localities (Balagne, Corte and Sari‐Solenzara) to identify factors that controlled foreland basin development and to clarify its significance within the early alpine orogen. The microfacies, microfaunal assemblages and siliciclastic fractions are characterised throughout the succession at each locality. The results indicate the existence of an important Variscan basement relief to the west of the basin (West Corsican Massif) that supplied early alluvial fans found at the base of the foreland succession in the northernmost Balagne area. Continuous high clastic input strongly reduced the development and diversity of the overlying Nummulitic Limestones facies and fauna. Further south, limestones in the Corte and Sari‐Solenzara areas are thicker and contain richer fauna. Three depositional models corresponding to the carbonate ramp system are proposed for the Nummulitic Limestones and used to construct paleogeographic maps illustrating the transgressive evolution of the Corsican foreland basin from the Early to the Late Eocene. Based on our results and available regional tectonic data and LT thermochronological data, we propose that the Nummulitic marine transgression took place within a continuous foreland basin encompassing southern Corsica and SE France during the early development of the western alpine arc.

Petrography and Heavy Mineral Studies of the Eocene Sediments in Awka and Environs, Southeastern Nigeria: Implication for Provenance

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Full-text available

Aug 2024

Petrography and heavy mineral techniques were employed in the study of the Nanka Formation in order to evaluate sediment provenance and tectonic setting. Petrographic study of the sands shows that quartz is the dominant mineral (64-85%) with high monocrystalline to polycrystalline quartz ratio, feldspars vary from 1-4%, rock fragments range from 1 to 15% whereas matrix is between 8 and 15%. The framework grains are medium to coarse in size, sub-angular to rounded and moderately well sorted to poorly sorted. Quartz grain abrasion and grain coating with iron oxide together with the framework grains that are devoid of cement are characteristics of the sands. The QFL ternary plot indicates that the sands are quartz arenites and sublitharenites. Maturity 246 evaluation shows them to be texturally submature to mature and mineralogically submature to supermature. Heavy mineral assemblages consisting of zircon, tourmaline and rutile with sub-rounded to rounded grains were recovered from the sands. The QFL and QmFLt ternary plots of the sands indicate derivation from Craton Interior, Recycled Orogen and Quartzose recycled. Metamorphic and plutonic rocks of Oban Massif and the sedimentary rocks of the Benue Trough and Anambra Basin are suggested as parents. Weathering of the source rock took place under semi-humid to humid climatic conditions in a low relief.

MYANMAR GEOLOGY AND NEIGHBOURING COUNTRIES GEOLOGY REPORTS COLLECTIONS 20 AUG 2024

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Aug 2024

MYANMAR GEOLOGY AND NEIGHBOURING COUNTRIES GEOLOGY REPORTS COLLECTIONS 20 AUG 2024 GEOLOGICAL RESEARCH REPORT COLLECTION MYANMAR UPDATE 27 th JANUARY 2024 Presentation January 202425 Reads Mingming JiangNoshin SharmiliSaiful IslamKyaing SeinMyo AUNG Myanmar GEOLOGICAL RESEARCH REPORT COLLECTION MYANMAR UPDATE 27 th JANUARY 2024 New Insights Into Active Faults Revealed by a Deep‐Learning‐Based Earthquake Catalog in Central Myanmar Article January 2024 Wiley Geophysical Research Letters Shun YangZhuowei XiaoShengji Wei[...]Mingming Jiang High‑resolution lithostratigraphy and reconnaissance sedimentology of Changotaung structure, Chittagong Tripura fold belt, Bengal Basin, Bangladesh Article October 2023 Scientific Reports Noshin SharmiliSaiful Islam ApuMd. Yousuf Gazi[...]Janifar Hakim Lupin Mantle flow and olivine fabric transition in the Myanmar continental subduction zone Article January 2024 Geology Enbo FanYinshuang AiStephen Gao[...]Kyaing Sein Structural and tectonic evolution between Indo-Myanmar Ranges and Central Myanmar Basin: Insights from the Kabaw Fault Article May 2023 Geosystems and Geoenvironment Kyi KhinAung MoeKyi Pyar AungThan Zaw Isotopic niche modelling of the Pondaung mammal fauna (middle Eocene, Myanmar) shows microhabitat differences. Insights into paleoecology and early anthropoid primate habitats Article April 2023 Frontiers in Ecology and Evolution Sophie Gabriele HabingerOlivier ChavasseauStéphane Ducrocq[...]Hervé Bocherens Add file MYANMAR GEOLOGY AND NEIGHBOURING COUNTRIES GEOLOGY REPORTS COLLECTIONS UPDATE 19 August 2022 Presentation August 2022329 Reads Amanta Resources LtdLAO GEOLOGYDMR[...]Myo AUNG Myanmar Newly discovered gold mine to bolster productivity in Laos https://www.nationthailand.com/international/ann/40015685 https://www.azomining.com/Suppliers.aspx?SupplierID=36 Amanta Resources Ltd. Myanmar offer-Myanmar: Geology, Resources and Tectonics Poster May 20182,313 Reads17 Citations Khin ZawWin SweA J Barber[...]Myo AUNG Myanmar Myanmar is a country vastly rich in gold, silver, base metals, tin–tungsten, gems and hydrocarbons and is one of the last exploration frontiers remaining in the world. Tectonically Myanmar lies at the eastern end o Chapter 7 Cretaceous geology of Myanmar and Cenozoic geology in the Central Myanmar Basin Article November 20171,174 Reads22 Citations Geological Society London Memoirs Naing Maw ThanKyi KhinMyint Thein This chapter presents an account of the Cretaceous System and its tectonic setting in Myanmar, sedimentary sequences of the Bago Yoma, Central Myanmar and the fluvial architecture of the Irrawaddy Sandstone in the Salin Basin. Regional geology Myanmar can be divided into four north–south-trending belts – the Shan Plateau, Shan Scarp,

Petrography and Geochemistry of Lower Jurassic Sandstones in the Eastern Junggar Basin: Implications for Provenance and Tectonic Setting

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Mar 2025

The Junggar Basin basement comprises microcontinental blocks amalgamated through successive paleo-oceanic accretion events. Stratigraphic and provenance studies within the basin are crucial for reconstructing its evolution and understanding the closure of paleo-oceanic systems. This study presents an integrated petrographic and geochemical analysis of the Lower Jurassic Badaowan Formation sandstones in the Dongdaohaizi Depression, located in the eastern Junggar Basin. The results reveal a progressive decrease in lithic fragment content and an increase in quartz content from older to younger strata within the Badaowan Formation, indicating an increase in compositional maturity. Provenance analysis indicates that the sandstones are predominantly derived from tuffaceous rocks, granites, basalts, and minor metamorphic rocks. Heavy mineral assemblages, including zircon, chromian spinel, tourmaline, and garnet, suggest parent rocks consisting primarily of intermediate to acidic igneous rocks, mafic igneous rocks, and metamorphic rocks. Integrated petrographic and geochemical data from the surrounding areas of the Dongdaohaizi Depression confirm that the Badaowan Formation sandstones are primarily sourced from the eastern Kelameili Mountain. The continued uplift and migration of the Kelameili Mountain during the Early Jurassic played a dominant role in shaping the sedimentary provenance. LA-ICP-MS analyses reveal that the rare earth element (REE) concentrations in the Lower Jurassic sandstones are slightly lower than the average REE content of the upper continental crust. The sandstones exhibit weak differentiation between light and heavy REEs, reflecting a depositional environment characterized by anoxic reducing conditions. Geochemical results indicate a tectonic setting dominated by a passive continental margin and continental island arc in the source area. Synthesizing these findings with related studies, we propose that the Kelameili Ocean, as part of the Paleo-Asian Ocean, underwent a complex evolution involving multiple oceanic basins and microcontinental subduction–collision systems. From the Middle Ordovician to Late Silurian, the Kelameili region evolved as a passive continental margin. With the onset of subduction during the Middle Devonian to Early Carboniferous, the eastern Junggar Basin transitioned into a continental island arc system. This tectonic transition was likely driven by episodic or bidirectional subduction of the Kelameili Ocean.

Provenance Determination Of Sandstone Based On Petrographic Analysis In Bambaira And Ako Areas, Pasangkayu District, West Sulawesi Province

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Jan 2025

West Sulawesi has a very connections with the tectonic process of the Makassar Strait, where the Makassar Strait is influenced by the process of plate expansion, as a result of the process formed a sedimentary basin composed of sedimentary rocks with rocks of diverse origin, the determination of rock origin (provenance) can help to reveal the tectonic setting and rock origin in the, to see the mineral content of existing sandstone constituents in the research area microscopically, the parameters used in determining the origin of rocks are quartz, feldspar and lithic fragments, the calculation of rock constituent minerals using the point counting method and then normalized for plotting on the provenance diagram and tectonic setting. The results of petrographic analysis on sandstone obtained the name of the Rock is lithic graywacke and quartz wacke. Rocks of origin in the research area are from Plutonic igneous rocks, volcanic igneous rocks, metamorphic rocks and sedimentary rocks, which are known based on the presence of monocrystalline quartz and polycstaline Quartz minerals, orthoclase minerals, sanidine minerals, volcanic lithic and sedimentary lithic,while the tectonic setting in the research area is magmatic arc and recycle orogen.

Depositional impact on reservoir quality in the Lower Goru Formation, middle Indus basin, Pakistan: insights from well log and sedimentological analysis

Article

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Jan 2025
ENVIRON EARTH SCI

The Lower Goru Formation is the main hydrocarbon target in Middle Indus basin, Pakistan. Its variable reservoir sand intervals complicate facies estimation for optimal production and allow for the investigation of how depositional and diagenetic changes affect reservoir quality in complex stratigraphic traps. We utilized an integrated approach to analyze the main E-sand interval with well log data, seismic data, thin-section petrography, SEM, and XRD analysis, revealing its geological features, depositional environment, spatial distribution, and reservoir quality. This study identifies nine distinct lithofacies with in the Cretaceous lower Goru formation: Massive Sandstone, Bioturbated Sandstone, Parallel Laminated Sandstone, Cross Laminated Sandstone, Massive Mudstone, Sandstone and Mudstone Intercalations, shaly sandstone, Brecciated Sandstone, and shale. Categorized into three primary depositional settings: foreshore, shoreface, and backshore. The findings provide crucial insights into the depositional history and reservoir quality, particularly in the basal sand units that transitions from fluvial to tidal, then to a deltaic front, and finally to a shallow marine setting. The reservoir sand intervals are primarily classified as “subfeldsarenite” to “sublithicarenite”, formed in a recycled orogenic environment. The main diagenetic processes include compaction, carbonate cementation, and the formation of authigenic chlorite and quartz overgrowths, which later significantly influencing reservoir quality. Facies analysis identified clean sand and mixed sand-shale reservoir zones, while petrophysical analysis indicated a net pay of 5 m in the E-sand and Hydrocarbon saturation of about 61%. Scanning Electron Microscopy (SEM) provided insights into pore structure and mineral composition. These findings, along with core plug porosity and permeability measurements, suggest favorable reservoir characteristics. A random forest algorithm was used to extract elastic and petrophysical attributes from seismic and well data, aiding in the development of a petro-elastic relationship and identifying potential gas zones. This study enhances the understanding of how depositional facies and diagenesis affect reservoir quality and highlights that the massive sandstone have superior properties compared to the basal sand.

Minerals-15-92

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Jan 2025

The Yah¸sihan/Kırıkkale sedimentary basin, located in Central Anatolia within the Izmir-Ankara-Erzincan suture zone, mostly consists of Upper Cretaceous to Lower Pliocene sediments developed on the Ankara Melange, which is linked to the Northern Neo-Tethys Ocean. Although the stratigraphic, sedimentological, and tectono-stratigraphic characteristics of the basin have been investigated by many researchers, its mineralogical and geochemical characteristics have not been studied extensively. In this study, the provenance, paleoclimatological properties, and tectonic structure of the sedimentary rocks were interpreted using detailed mineralogical and geochemical analysis data. Formations such as the Karadağ (Cenomanian-Campanian) Çiçekdağ (Santonian-Campanian), Samanlık Maastrichtian), Dizilita¸slar (Paleocene-Early Eocene) Çayraz (Middle Eocene), ˙Incik (Upper Eocene-Lower Miocene), Central Anatolia Group (Middle Miocene-Pliocene), and Quaternary alluvium were deposited in the basin. X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and geochemical analyses were employed to determine the mineralogical and chemical composition of the units. Although highly oxic paleo-environmental conditions predominated in the basin, anoxic and suboxic conditions could also be present in the Dizilita¸slar and ˙Incik formations. The units are primarily felsic with some mafic contributions, suggesting an oceanic island arc environment with varying paleoenvironmental conditions, reflecting seasonal changes between humid and arid periods.

Documenting a coastal sediment routing tract in the sedimentary record: Implications for coastal palaeogeography and sand distribution patterns

Article

Jan 2025
SEDIMENTOLOGY

Coastal sediment transport, primarily driven by littoral drift, is a well-understood process occurring in many wave-dominated modern coasts. This transport can extend over hundreds of kilometres, linking river mouths to sand barriers and coastal dunes. Recognizing the importance of coast-parallel processes in dispersing significant sediment volumes, both source-to-sink and sediment-routing-system concepts emphasize the need to include these processes in comprehensive studies. These processes can lead to volume changes and provenance mixing within specific source-to-sink budgets and should consider sediments near the coast and on the shelf as temporary repositories before their final transit into deep-water sinks. Despite the established methodologies for studying sediment routing systems, the integration of these approaches with the geological record is limited. To address this gap, this article introduces the Coastal Sediment Routing Tract as a segment within any Sediment Routing System. The Coastal Sediment Routing Tract consists of three elements: supplier(s), storage(s) and littoral drift processes. This study presents the conceptual framework for Coastal Sediment Routing Tracts, documents an ancient Coastal Sediment Routing Tract by linking deltaic and shoreface sandstones in the Hauterivian Pilmatue Member (Neuquen Basin, Argentina) and evaluates how characterizing a single Coastal Sediment Routing Tract can refine coastal palaeogeographical reconstructions. Understanding these aspects is crucial for improving mass balance calculations in source-to-sink analyses of ancient systems.

CARACTERIZACIÓN PETROGRÁFICA Y PROCEDENCIA SEDIMENTARIA PRELIMINAR DE LA SEDIMENTACIÓN CARBONÍFERA EN EL CORDÓN DEL PLATA, CORDILLERA FRONTAL DE MENDOZA

Conference Paper

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Nov 2024

En el flanco oriental del Cordón del Plata (Cordillera Frontal mendocina, Fig. 1a), dos unidades neopaleozoicas fueron descritas: la Formación Loma de los Morteritos (FLM) y la Formación El Plata (FEP). Los antecedentes indican que la FLM es equivalente lateral del Miembro Inferior de la FEP (Heredia et al. 2012), registrando ambas unidades los primeros pulsos de sedimentación del Carbonífero Tardío, referibles al ciclo orogénico gondwánico. La presente contribución tiene como objetivo la caracterización petrográfica de ambas unidades y el análisis preliminar de su procedencia sedimentaria. Para ello, se realizó un estudio de diez secciones delgadas en conjunto con un análisis cuantitativo de las modas detríticas en areniscas medianas a finas. Los resultados obtenidos fueron ploteados en los diagramas de clasificación QFL propuestos por Dickinson y Suczek (1979) y Garzanti (2019). Finalmente, se analizaron dos conglomerados, uno por cada unidad, con el propósito de comparar sus composiciones modales. Para la FLM se analizaron siete muestras, de las cuales tres resultaron aptas para el análisis cuantitativo (23EP02, 23EP05 y 23EP06). Las muestras restantes (23EP01, 23EP03, 23EP04) no fueron útiles debido a su tamaño de grano de arena fina a muy fina. Las areniscas cuantificadas comprenden granulometrías finas a medianas de textura clasto sostén, bien seleccionadas con escasa a nula matriz. Se componen principalmente de cuarzo (64.02 %-71,10 %), con la variante monocristalina (63,67 %-64,20 %) siendo más abundante que la policristalina (1,29 %-7,08 %), seguido de feldespatos (22,38 %-29,90 %) donde predominan los potásicos (20,40 %-25,40 %) por sobre las plagioclasas (1,98 %-4,50 %); mientras que la fracción lítica quedó subordinada (< 10 %) y conformada por componentes volcánicos de microtextura seriada y fragmentos metamórficos de bajo grado (Fig. 1b). Por otro lado, para el ortoconglomerado (23EP08, Fig. 1c) predominan los clastos de cuarzo monocristalino de extinción recta y ondulosa en proporciones similares. Le prosiguen fragmentos líticos sedimentarios y metamórficos de bajo a medio grado y, subordinadamente, fragmentos volcánicos de composiciones ácidas. Para la FEP se estudió el Miembro Inferior, analizando tres muestras en total. De estas, sólo la muestra 23EP09 (Fig. 1d) resultó ser la más adecuada para realizar el conteo modal. Dicha muestra corresponde con una arenisca fina a mediana de textura clasto sostén, bien seleccionada y de matriz escasa. Se compone principalmente de cuarzo (71,86 %) donde predomina la variante monocristalina (63,05 %) seguido de la policristalina (8,81 %); seguido de feldespatos (25,08 %) son mayormente potásicos (22,03 %) y, en menor medida, plagioclasas (3,05 %); mientras que la fracción lítica queda subordinada (3,11 %) y se compone de clastos volcánicos de microtextura seriada y metamórficos de bajo grado. Por último, el ortoconglomerado (23EP11) exhibe un predominio en clastos cuarzosos, principalmente monocristalinos de extinción recta y, en menor proporción ondulosa, seguido

Metamorphic Rocks of the Central Eastern Desert, Egypt

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Sep 2024

Haroun A. Mohamed

The central Eastern Desert of Egypt exhibits a diverse array of metamorphic rocks, forming part of the Pan-African orogenic belt. These rocks, primarily low to middle green schist facies, comprise metamorphic volcano-sedimentary sequences featuring metasediments like mudstones, pebbly mudstones, greywackes, and schists, alongside metavolcanics such as metabasalt, meta-andesite, and porphyrites. Petrochemical analyses suggest a mixed origin, with features of calc-alkaline and subalkaline rocks, with mature island arc volcanic rocks prevailing. The schists display various compositions and textures, including chlorite, epidote, biotite, graphite, hornblende, talc, and tremolite-actinolite schists. Petrographic studies hint at a shared origin or protolith among the schists, metasediments, and metavolcanics, evidenced by overlapping chemical compositions. These findings deepen our understanding of the geological evolution of the region, offering insights into the tectonic processes and depositional environments that have shaped the central Eastern Desert of Egypt within the broader Pan-African orogenic belt.

Geología de la cuenca mesozoica sedimentaria peruana occidental entre 13° 30’ y 14° 30’ - [Boletín D 37]

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Dec 2022

Joel Andía

El área en estudio se encuentra ubicada en la zona detransición entre los Andes Centrales del Norte a la partemedia de los Andes Centrales. Corresponde a la partecentro y sur de la cuenca mesozoica sedimentaria peruanaoccidental, ubicada entre las latitudes 13° 30’ y 14° 30’ S, cubreaproximadamente 10 583 km2 y comprende las provincias deSucre, Vilcashuaman, Víctor Fajardo y Huancasancos deldepartamento de Ayacucho, y las provincias de Andahuaylasy Chincheros del departamento de Apurímac. Se presenta el nuevo Boletín Serie D acompañado de un mapageológico a escala 1:50 000 y dos secciones estructurales a lamisma escala. El mapa es el resultado de trabajos de campoy gabinete que sirvieron de base para la actualización de lacarta geológica de los cuadrángulos de Paras, Huancapi,Querobamba, Chincheros y Santa Ana, realizada por Ingemmetentre los años 2002 y 2016. El texto corresponde al formatopropuesto para los boletines de la Serie D e incluye nuevosdatos de superficie, estudios estratigráficos, estructurales,petrológicos, de proveniencia, cortes balanceados, dataciones,anexos, además de una base de datos.

Impact of Slab Rollback on the Surface of Overriding Plate: Late Cretaceous Extension and Topographic Evolution to the West of the Xuefeng Orogen in the South China Block

Article

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Mar 2025
TECTONICS

The South China block (SCB) preserves abundant evidence of Mesozoic magmatism, extensional basins, and intracontinental deformation that is crucial for understanding the influence of subduction dynamics on surface processes of the overriding plate. However, no consensus has yet been reached regarding the Late Mesozoic geodynamic interpretation of the SCB interior because Late Cretaceous structural and sedimentary records to the west of the Xuefeng orogen are poorly understood. In this study, field structures, paleocurrent directions, heavy mineral assemblages, sandstone petrography, and detrital zircon U‐Pb ages of the Late Cretaceous Jianshi, Enshi, Laifeng, and Qianjiang basins are reported. A NW–SE extensional tectonic regime is inferred from fault‐slip inversion results of the basins. Paleocurrent directions are found to be dominantly from the SW and SE. Heavy mineral analysis indicates that the sources of sandstones in the basins are mainly sedimentary and metamorphic rocks. The sandstone composition and zircon U‐Pb ages are also similar between the basins and surrounding source areas showing the sources from the Sichuan basin and Xuefeng orogen. Considering the westward paleocurrents from topographic highlands into the Sichuan basin during the Jurassic‐Early Cretaceous in the previous work, we propose that slab rollback caused the regional extension, topographic evolution, and the change in paleocurrent direction during the Late Cretaceous. The impact of the slab rollback on the lithospheric extension of the SCB extends to the west of the Xuefeng orogen, with the Late Cretaceous extensional basins potentially marking the westernmost product of lithospheric thinning.

Textural characteristics of channel bed sediments and heavy minerals of the Cauvery River, Southern India: implications on depositional environments, provenance, tectonics and climate

Article

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Feb 2025

A systematic study of river sediments on a basin scale might help to understand prevalent environmental, climatic, tectonic, and source rock dynamics. The study attempts documentation of textural properties of the channel bed sediments and heavy mineral distributions from the origin to the confluence of the Cauvery River, within a tropical region of southern India, along with the interpretations on environmental, tectonics, and climatic conditions, as well as affinity with source rock lithologies. Cauvery flows on various lithologies and landscapes that experience multitudes of structural and land-use characteristics and shows the dominance of Peninsular gneiss and Southern granulite. The grain size variations between very coarse sand and fine sand exhibited tripartite sediment size characteristics. The sorting character showed maximum-to-minimum values from the origin to the delta head, and a progression within the moderate–well-sorted nature from the delta head to the confluence. Similarly, the skewness varied from strongly fine to coarse skewed, and most of the samples exhibited platykurtic-to-leptokurtic distributions. An average of 9% of the grains were heavy minerals, with their abundance increasing from a mere 1.9–23.7% towards the downstream, albeit with sporadic very high proportions in some samples in the upper regions of the basin. The heavy mineral roundness also increased from origin to confluence, and its energy-dispersive X-ray analysis (EDAX) mapping revealed variations in elemental composition between the upper, middle, and lower parts of the river channel. Overprinting of natural and anthropogenic interventions might have led to a deviation of sediment characteristics from normal trends. Results from heavy mineral, grain size, textural, and provenance analysis offer valuable data for reconstructing past climates, tracing sediment pathways, and identifying tectonic activities, predicting changes in sediment distribution, and assess the impact of human activities on fluvial environments, making this work significant for global environmental studies and hazard mitigation.

Multiple provenance of inter-eruptive fluvial sandstones of the Albian Cerro Castaño Member, Patagonia

Article

Feb 2025
J S AM EARTH SCI

The Albian Cerro Castaño Member is a volcanogenic fluvial-alluvial succession deposited in the Somuncurá- Cañadón Asfalto Basin, extra-Andean Patagonia, Argentina. During the deposition of the unit, the basin was affected by recurrent volcaniclastic inputs from sources including either directly active volcanoes or secondary volcanogenic material from upstream positions. In this study, we analyzed the provenance of fluvial sandstones of the Albian Cerro Castaño Member, for which detailed palaeoenvironmental interpretations have been previously established suggesting accumulation during inter-eruptive phases. The methodologies included the petrographic analysis of thirty-seven thin sections with the definition of petrofacies, as well as U-Pb zircon dating of a tuff layer from the underlying stratigraphic unit, located approximately 2 m below the contact with the Cerro Castaño succession. The new U-Pb depositional-crystallization age of 114.86 ± 0.44/0.56 Ma is consistent with the previous geochronological framework and constrains the Cerro Castaño Member to the Albian. The fluvial sandstones are predominantly composed of volcanic lithic framework grains both effusive and volcaniclastic, spanning the acidic to basic geochemical spectrum, with subordinate quartz, feldspars, intraclasts, micas, olivines, pyroxenes, amphiboles, and opaques. They were classified as feldspatho-lithic to quartzo-lithic, indicating provenance from tectonic settings associated with arc (both undissected and transitional) and recycled orogen sources. Four lithic petrofacies, designated A to D, were identified to distinguish sediment sources. The data indicate that the majority of samples from the western sector of the study zone are derived from volcanic rocks with effusive and explosive origin, with a minor contribution from mafic to intermediate volcanic rocks (petrofacies A). In contrast, samples from the eastern sector indicate a source-rock lithology dominated by siliceous rocks, similarly formed by effusive and pyroclastic eruptions but with minimal input from mafic to intermediate volcanic sources (petrofacies B). Additionally, specific samples from the western basin sector display a significant contribution of volcanic lithic grains, likely indicating substantial contributions of siliceous volcaniclastic sediments (petrofacies C and D). The combination of the information obtained with the literature data set, primarily comprising paleocurrents and paleogeological reconstructions, led to the conclusion that the principal source rocks are Jurassic intraplate volcanites, which are extensively distributed in extra-Andean Patagonia. In particular, the rocks of the Lonco Trapial and Marifil Formations constitute the main sources for sandstones in the western and eastern sectors of study zone, respectively. Furthermore, in the western localities, the subordinate participation of the Paleozoic- Triassic crystalline basement as source rocks was identified, as well as the probable contribution of intrabasinal Jurassic volcanites.

Petrography and Provenance of Eze-Aku Sandstones in Afikpo Basin, Southeastern Benue Trough

Article

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Jan 2021

Petrographic study of the Eze-Aku sandstones exposed within the Afikpo basin were analysed to determine the petrography, provenance and tectonic setting of the area. Petrographic studies showed that the Eze-Aku sandstones were predominantly quartz, feldspar and lithic fragments. The QFL triangular plot shows that the Eze-Aku sandstones are mainly sub-arkoses with subordinate amount of arkoses and quartz arenites. The ternary plot of the provenance category showed that the Eze-Aku sandstones were plotted within the basement uplift continental block, indicating that the sandstones could have been a product of high relief and erosion from the Oban and Cameroon Massifs, located east part of the Abakaliki anticlinorium and Afikpo Basin.

Tectonic setting, paleoweathering, and maturity of beach sediments along the West Atlantic Coast of Cameroon

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Feb 2025

Grain size parameters and major, trace, and rare earth elements of beach sands along the west Atlantic coast of Cameroon between the coastal basins and the Cameroon Volcanic Line were evaluated to decipher their source, weathering, depositional conditions, textural maturity, and tectonic settings with the application of new formulae. Grain size analysis shows that most of the sediments are fine to medium-grained, moderately sorted to well sorted, and deposited in moderate to low energy environments with clear fluvial and beach signatures. Log(Fe2O3/K2O) vs log (SiO2/Al2O3) indicates that most of the sediments are iron sands while trace element plots such as 10*Th/Co, Cr/Th, 100*Th/Sc, Th/Yb, and 10*La/Co indicate mafic to intermediate sources for most of the sediments. This is further confirmed by rare earth elements (REE) normalized patterns revealing enriched light rare earth elements (LREEs) over heavy rare earth elements (HREEs) by moderate amounts, positive Eu anomalies from Post Archean Australian Shale (PAAS), and upper continental crust (UCC) normalized plots. Newly developed indices CIX and PIX, from elimination of CaO, suggest moderate to high weathering intensity which conforms with the climatic conditions of Cameroon. La/Yb chondrite normalized vs Zr plots positioned a significant portion of the sediments in a mantle environment, with minimal zircon enrichment. The volcaniclastic sands were identified as first cycle, non-recycled sediments. High ICV values (ICV > 1) indicate that most of the sands are immature, but the newly introduced ICVnew, whereby oxides of Fe and Ca are eliminated, shows that some of the sediments are mature and recycled, confirmed also by SiO2/Al2O3 ratios especially at the tail ends of the study area. DF(A-P)M and DF (A-P)MT plots indicate that the sediments are of the passive margin setting.

Paleohydrological features and detrital compositions of the Late Triassic Chinle Formation in southwestern Utah, U.S.A

Article

Mar 2025
SEDIMENT GEOL

Depositional age and provenance of Triassic sedimentary succession from Northwestern México: Evidence from petrography and detrital zircon U-Pb geochronology

Article

Jan 2025

Provenance and tectonic settings of sandstones of Jhuran Formation (Kimmeridgian to Tithonian); Mundhan dome, Kachchh, Western India

Article

Full-text available

Dec 2024

The study focuses on the sandstones of the Jhuran Formation (JF) (Kimmeridgian to Tithonian age) exposed in the Mundhan dome (MD), Kachchh, analyzing their provenance and tectonic setting through petrography, heavy mineral analysis, and geochemistry. Petrographical work, including modal analysis, reveals that these sandstones are predominantly composed of quartz, feldspars, and rock fragments in a modal ratio of Q87F8L5. Geochemical analysis shows high SiO2 levels, a higher concentration of Na2O compared to K2O, and relatively low Fe2O3, which aligns with the petrographical findings. The heavy mineral data points to the origin of these sediments from plutonic and metamorphic sources. Combined petrographical and geochemical evidence suggests that the sandstones were deposited in a passive continental margin with minimal recycling, which is further corroborated by paleo-weathering indices. Tectonic discrimination diagrams suggest a quartzose sedimentary provenance, indicating that the sediments were primarily derived from a cratonic interior area. These findings imply that the sediments from the JF in the MD were sourced from plutonic and/or metamorphic terrains, probably from the Aravalli craton, and were deposited in a passive continental setting within a non-marine to transitional settings of deltaic environment. The findings of the present study will aid in understanding the sedimentation history of the correlatable Mesozoic outcrops in the Kachchh basin.

Middle Triassic transcontinental connection between the North China Craton and the Paleo-Tethys Ocean

Article

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Dec 2024

Middle Triassic paleogeography is essential for the paleoclimate change and ecosystem recovery after the end-Permian mass extinction, but is highly debated in the Paleo-Tethys Ocean and North China Craton, eastern Pangaea. Here we report a detailed provenance fingerprinting dataset from Middle Triassic sediments across the North China Craton, Qinling and Songpan-Ganzi and identify the paleo-uplift in the northern North China Craton as a primary sediment source. We propose that a Middle Triassic transcontinental drainage system flowed from the northern North China Craton through the central Qinling into the eastern Paleo-Tethys Ocean along the gradually descending landform, challenging the suggestion that the North China Craton was a great endorheic basin. The finding of this study will provide a better understanding of Middle Triassic physiography and paleogeography of the North China Craton. Such heterogeneous paleotopography and transcontinental drainage played a critical role in the marine-terrestrial ecosystems of the eastern Pangaea.

Geochemical Characterization of Campanian-Maastrichtian Shale’s from Akukwa and Amansiodo wells, Amanbra Basin, SE Nigeria: Implication for Weathering History, Provenace and Paleoenvironments

Article

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Jan 2023

The "greywacke problem" explored in the Neoproterozoic of Saxo-Thuringia: new insights into sediment composition and metamorphic overprint

Article

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Feb 2025
INT J EARTH SCI

Greywackes make up a substantial part of the Cadomian basement of Saxo-Thuringia. Here, their classification as greywackes and the timing of metamorphic overprint are re-evaluated using a multi-method approach. Immature monotonous greywacke sequences from the Lausitz (Lausitz Block) and Leipzig groups (North Saxon Anticline), as well as from the eastern Thuringian Basin and parts of the Weesenstein Group (Elbe Zone) probably belong to a coherent unit, based on microscopic investigations supported by SEM Automated Mineralogy analyses and point counting data. However, due to the low matrix content (< 15%), the sedimentary rocks are more likely classified as lithic sandstones. The heterogeneous composition and in particular the highly mature character of the Clanzschwitz Group (North Saxon Anticline) and parts of the Weesenstein Group (Seidewitz Formation) suggest a younger, Late Cambrian to Early Ordovician sedimentation age. Typically, the metamorphic overprint of the “greywacke units” is very weak. Previous assumptions of Cadomian contact metamorphism triggered by Early Cambrian intrusions (ca. 540 Ma) could not be confirmed due to the local differences in the determined metamorphic ages. Late Cambrian to Early Ordovician (521–461 Ma) Th–U–Pb monazite ages are likely related to the tectonic transition from the collisional regime of the Cadomian orogeny to extensional processes in the course of the opening of the Rheic Ocean. Sporadic Late Ordovician (458–445 Ma) Th–U–Pb monazite and K–Ar fine-fraction ages were also obtained but the specific thermal trigger is still subject of debate. The Permo-Carboniferous metamorphic ages (314–286 Ma) indicate high-temperature metamorphism related to the post-Variscan extensional processes of Central Europe during this period. The youngest dated monazites are Jurassic in age and may have grown in association with the hydrothermal activity known from Central Europe at that time. Graphical abstract

978-620-8-11405-3 Spanish version

Book

Full-text available

Oct 2024

Haroun A. Mohamed

Metamorphic Rocks of the Central Eastern Desert, Egypt

978-620-8-11406-0 French version

Book

Full-text available

Oct 2024

Haroun A. Mohamed

Metamorphic Rocks of the Central Eastern Desert, Egypt

Basin Research - 2024 - Caylor - The real McCoy A record of deep‐water basin deposition in southwestern North America

Article

Full-text available

Aug 2024
BASIN RES

The McCoy Mountains Formation (McMF) in southern California–Arizona preserves an anomalously thick record of sedimentation during the Mesozoic at a critical time when western North America experienced contrasting tectonic events related to intracontinental rifting along the Mexican Border rift system and consolidation of the North American Cordilleran system. The spaciotemporal interactions among these events and the development of the McCoy basin challenge our understanding of the evolution of the southern extent of North America. At its type locality in the McCoy Mountains, the McMF consists of ~ 7 km of low‐grade metasedimentary rocks, originally interpreted as meandering fluvial to alluvial‐fan deposits. Uncertainty in the initial timing of sedimentation in the McCoy basin has resulted in multiple tectonic models. We measured ~ 7160 m of detailed stratigraphy and present new sedimentological and detrital zircon results showing that the McCoy basin was occupied by deep‐water turbidite systems. These systems deposited an upward‐coarsening succession of fine‐ to coarse‐grained detritus during the Cretaceous (ca. 137–70 Ma). Provenance data indicate that the McCoy basin received sediment from Proterozoic basement rocks and metamorphosed Palaeozoic to early Mesozoic sedimentary units. These source rocks are equivalent to the stratigraphy found in the Grand Canyon and Colorado Plateau regions and were likely shed from the southward‐advancing Maria fold‐thrust belt and possibly the southern Sevier belt in southern Nevada and California. These results, combined with subsidence curves typical of foreland basins, favour deposition within a subaqueous flexural foreland basin system. The presence of a Cretaceous foreland basin this far southwest challenges previously proposed models and suggests that the contractional tectonic regime associated with the North American Cordillera extended into the southwestern most United States during the Early–Late Cretaceous.

Provenance of Upper Paleozoic Sandstones from the Western Carpathians (Slovakia): Petrofacies analysis and U-Pb detrital zircon geochronology

Article

Full-text available

Jan 2024

The provenance of Upper Paleozoic sediments in the Western Carpathians was derived by a petrofacies analysis of sandstones, including the U-Pb geochronology of detrital zircons. The Upper Paleozoic sedimentary basins were formed sequentially by tectonic processes associated with the Variscan continental collision, as well as by subsequent transpressional/transtensional and extensional regimes. Fore-arc related and proforeland basins were formed in the Late Tournaisian/Visean and subsequently in the Bashkirian/Moscovian. Transpressional/transtensional and exten-sional basins were formed successively on both sides of the continental collisional suture, both in the proforeland and retroforeland parts in the Late Pennsylvanian and later in the Cisuralian and Guadalupian. The sandstone petrofacies, as well as the detrital zircon distribution, indicate source areas directly from the underlying crystalline basement: a mag-matic arc, an uplifted continental block for the Central Western Carpathian basins, and a recycled orogen for the Inner Western Carpathian basins. Detrital zircon age spectra record distinct stages of protracted Ediacaran to Carboniferous tectonosedimentary processes. This indicates a different palinspastic position of source areas along the peri-Gonwanan realm, the West African Craton, and the Sahara Metacraton in the Neoproterozoic.

Provenance of Neogene sedimentary rocks in Sabah and paleogeography of northern Borneo and surrounding areas

Poster

Full-text available

Sep 2024

Sabah forms the northern part of the island of Borneo, which is situated at the southwestern South China Sea (SCS) margin. The Cenozoic sedimentological record includes deposits related to the formation of the SCS and the demise of its predecessor, the Proto-South China Sea (PSCS). The Paleogene was characterised by deep marine turbidite sedimentation on the south side of the PSCS, which was subducted beneath the Cagayan Arc and North Sabah. The Early Miocene Sabah Orogeny eliminated the PSCS and several mélanges were formed. Zircons from the mélanges and turbidites indicate magmatism associated with the PSCS subduction continued until c. 19.6 Ma. Immature mineral assemblages and detrital zircon age spectra suggest a partly northern source. The collision deformed and exhumed the deep marine rocks, and is marked by the Top Crocker Unconformity (TCU). Post-TCU Neogene sedimentary rocks were deposited in fluvio-deltaic to shallow marine environments and are compositionally mature with a quartzose recycled orogenic source, and ultra-stable heavy mineral assemblages dominated by zircon, tourmaline and rutile (ZTR). The lower Neogene formations have substantial amounts of chrome spinel, while upper Neogene formations are almost devoid of chrome spinel and have higher contents of ZTR, suggesting two Neogene sedimentation cycles, both with sources in Sabah. Based on sandstone petrography, heavy mineral assemblages and detrital zircon ages, sediment sources for the first cycle included recycled Paleogene turbidites with input from uplifted peridotites, while the second cycle was mainly sourced from recycling of older Neogene fluvio-deltaic formations with input from Paleogene turbidites.

Provenance of Upper Paleozoic Sandstones from the Western Carpathians (Slovakia): Petrofacies analysis and U–Pb detrital zircon geochronology

Article

Full-text available

Aug 2024
GEOL CARPATH

Evolution of a confined gravelly river to a braided-meandering river in the Late Cretaceous Khasi Group, southern Shillong Plateau, NE India

Article

Aug 2024

This paper intends to unravel the depositional condition of the Basal Conglomerate/Jadukata Formation and the Lower Mahadek Formation in southern Shillong Plateau, NE India deposited during the Late Cretaceous period. The studied succession is entirely siliciclastics in composition and was built up on the Precambrian basement rocks. State-of-art facies analysis and palaeocurrent evidence helped us to reconstruct the palaeogeography and palaeoenvironment. The facies tracts reveal that frequent hyperconcentrated mass flow deposits dominated the proximal part of the river channels. Gradually, the river evolved to a sandy braided and finally mud-dominated, meandering system. The river channel changed its pattern through onlapping and progressive elimination of the accommodation space created by the tectonic subsidence/upliftment. Major shifts in palaeocurrent direction at different stages of the river evolution confirm the role of tectonics on the river channel evolution. QFL detrital modes of the sandstones reflecting lithic wacke composition and the recycled orogeny corroborate the interpretation. Rapid lateral and vertical facies transition suggests a pull-apart type basin due to ongoing rifting. Geochemical analyses also show signatures of the overlapping tectonic conditions supporting the pull-apart basin model.

Geological reassessment of syn‐rift extensional sequences in the Shine Usny Tolgod and Dzun Shakhai fossil localities, Eastern Gobi Basin, Mongolia

Article

Mar 2025
SEDIMENTOLOGY

Sedimentary infill patterns in the Eastern Gobi Basin of southern Mongolia record a complex, polyphased history. Asynchronous timing and intensities of extensional tectonism during the Early Cretaceous fragmented the Eastern Gobi Basin into a series of sub‐basins within an extensional rift (horst‐graben) setting, which likely infilled penecontemporaneously to asynchronously. Of these sub‐basins, the north‐eastern Sainshand sub‐basin preserves a nearly continuous Lower Cretaceous syn‐rift succession. However, many outstanding uncertainties concerning intra‐sub‐basinal and inter‐sub‐basinal biostratigraphic correlations persist, including stratigraphic linkages locally at the Dzun Shakhai and Shine Usny Tolgod localities, regionally across the eastern Sainshand sub‐basin, along with the adjacent Zuunbayan and Unegt sub‐basins. This study confirms that Dzun Shakhai and Shine Usny Tolgod are hosted within a horst‐graben setting with sedimentary successions composed of locally sourced (para‐autochthonous to autochthonous) detritus. Facies analysis reveals a broad suite of evolving transitional depositional environments, including alluvial, fluvial and lacustrine environments. Basin infill initiated in a retrogradational setting (underfilled‐starved stage) that transitioned to an aggradational and a subsequent progradational setting (filled stage). Based on the identification of six syn‐rift sequence boundaries (SR1 to SR6), this study determined that this portion of the Sainshand sub‐basin fits a gradual subsidence model. Additionally, this study presents significant sedimentological evidence for: (i) the designation of a new member, the Ikh Ulaan Nuur Member of the Shinekhudag Formation; and (ii) the subdivision of the Khukhteeg Formation into an informal lower and upper member. These novel sedimentological data improve lithostratigraphic and palaeoenvironmental correlations across the Sainshand sub‐basin, with strengthened correlations to the adjacent Zuunbayan and Unegt sub‐basins and more peripheral linkages to the Erlian, Yingen and Songliao basins of north‐eastern China. These findings provide an important foundation for assessing the spatiotemporal distribution of syn‐rift fossil‐bearing units across the greater Eastern Gobi Basin and the North China Block.

Grain‐fabric alignments in a mixed carbonate–siliciclastic mass‐transport complex: The Cutoff Formation, Permian Basin, Texas

Article

Feb 2025
SEDIMENTOLOGY

Mass‐transport complexes undergo fabric modification during emplacement that results in the alignment of elongated grains. Grain‐fabric alignments promote mechanical and petrophysical anisotropy, which has broad implications for hydrocarbon extraction, carbon sequestration and geohazard assessment. These implications are likely more pronounced in mass‐transport complexes with carbonate components, where the proportion of elongated grains can be much higher as compared to siliciclastic mass‐transport complexes. However, the characteristics of grain‐fabric alignments in mass‐transport complexes are poorly understood. This study inspects the predictive properties of grain‐fabric alignments that include three‐dimensional orientation, fine‐scale heterogeneity, as well as the control of grain lengths and clay‐mineral abundance. The mixed carbonate–siliciclastic mass‐transport complex of the Cutoff Formation contains prolific spicule bioclasts (prolate‐shaped), which enabled qualitative and quantitative grain‐fabric analysis. Investigation of over 29 000 spicule bioclasts from oriented thin sections indicates that: (i) the long‐axes of elongated grains rest on the plane of lamination, which can be parallel or tilted/folded with respect to bedding; (ii) the long‐axes are transverse to palaeotransport direction; (iii) the homogeneity of alignment (termed here ‘H‐index’) of elongated grains are variable across samples, as well as locally within the same sample; (iv) H‐index increases with greater grain lengths (approximately constant aspect ratio) and with the presence of clay minerals; and (v) H‐index is likely controlled by differential stress and/or variation in microstructure types. These results improve current understanding and predictability of grain‐fabric alignments and deformation in mass‐transport complexes, as well as the associated mechanical and permeability anisotropy.

Provenance and source area weathering of sandstones from the Tarkwaian Group at the northeastern extent of the Paleoproterozoic Ashanti Belt, Ghana: Constraints from petrography and geochemistry

Article

Apr 2025
J AFR EARTH SCI

Reshetnikovka Formation of South-West Primorye—A Fragment of Deposits of the Late Paleozoic Passive Continental Margin

Article

Dec 2024
RUSS J PAC GEOL

A. I. Malinovsky

GEOLOGI DAERAH BUMELA KECAMATAN BILATO KABUPATEN GORONTALO

Article

Full-text available

Dec 2024

Daerah penelitian berada di Desa Bumela Kabupaten Gorontalo tepatnya di Desa Dulupi dan sekitarnya. Daerah penelitian memiliki kondisi geologi yang cukup kompleks dan secara geomorfologi didominasi oleh daerah perbukitan. Selain itu, secara stratigrafi terdiri dari batuan Tersier hingga Kuarter. Tujuan penelitian ini yaitu memetakan kondisi geologi Daerah Bumela. Metode penelitian yang digunakan berupa survei geologi dan analisis laboratorium petrografi. Hasil yang didapatkan berupa kondisi geomorfologi daerah penelitian terdapat tiga satuan yaitu perbukitan denudasional, satuan perbukitan vulkanik, dan satuan dataran alluvial. Stratigrafi daerah penelitian terdiri dari empat satuan yaitu conglomeratic sandstone, sandstone, muddy sandstone dan tuff. Sebaran batupasir pada lokasi penelitian menunjukkan bahwa conglomeratic sandstone menempati luasan sekitar 24%, sandstone menempati luasan 21%, dan muddy sandstone menempati luasan sekitar 32%. Untuk jenis batupasir dari analisis laboratorium petrografi hanya terdiri dari batupasir greywacke. Struktur geologi daerah penelitian berdasarkan analisis liniament dari pola kelurusan memiliki arah umum timur laut-barat daya.

Neoproterozoic basin evolution of the northern Tarim craton from back-arc rift to passive continental margin: Implications for the opening of the South Tianshan Ocean

Article

Dec 2024
PRECAMBRIAN RES

Detrital zircon provenance links between outcrop and subsurface, Rocas Verdes and Magallanes-Austral Basins, Patagonia

Article

Nov 2024
GEOSPHERE

Analyzing how provenance signatures of tectonically complex ancient sedimentary basins vary between the outcrop and the subsurface provides a more complete sediment provenance history. The 500+-km-long outcrop belt of the Rocas Verdes and the Magallanes-Austral Basins in southern Patagonia and its subsurface to the east allow us to constrain relationships between longitudinal and transverse sediment sources feeding the basin. New detrital zircon U-Pb ages (n = 2558) from nine subsurface core samples from the Springhill, Piedra Clavada, and La Anita Formations along a 140 km E-W seismic reflection transect (50°S, 71.5°W–69.5°W) reveal the provenance of the basin’s eastern subsurface extent and the influence that tectonic activity can have on sediment capture. Detrital zircon ages (n = 1068) were also collected from four outcrop Springhill Formation samples 140 km NW from the transect near Lago San Martín. Maximum depositional ages (MDAs) from the Springhill Formation cores range from 159 to 157 Ma, which are older than correlative outcrop ages of 151–148 Ma. MDAs from the Piedra Clavada and La Anita Formations range from 93.7 to 91.5 Ma and from 79.3 to 78.3 Ma, respectively, and overlap in age or are slightly younger than outcrop ages. The unimodal Late Jurassic age distribution from the Springhill Formation suggests that it almost exclusively was sourced by recycling of the underlying El Quemado Complex. Early–Middle Jurassic ages in the Early Cretaceous Piedra Clavada Formation samples suggest the basin was either sourcing from the North Patagonian Massif to the N-NE and from the Deseado Massif to the NE or recycling exhumed volcaniclastic sequences in the northern margin of the basin. By the Late Cretaceous, the basin fill was more locally sourced, as suggested by the muted abundance of Early–Middle Jurassic ages in La Anita Formation samples and a second mode of Late Jurassic–Early Cretaceous ages locally derived from recycling of the exhumed El Quemado Complex from the Patagonian fold-and-thrust belt. We suggest that the latitudinal and local transverse drainages that sourced the Magallanes-Austral Basin outcrop belt also fed the eastern, subsurface extent of the basin. Results of this work highlight the importance of using several types of provenance methods and a three-dimensional approach to study the erosional history of sedimentary basins.

Alt Paleozoyik Yaşlı Sultandede Metasedimanter Kayaçların Jeokimyası, Kökeni ve Tektonik Yerleşimi (Dinek, Şarkikaraağaç-Isparta, GB Türkiye)

Article

Full-text available

Jan 2025

Alt Paleozoyik yaşlı metasedimanter kayaçlar (Sultandede Formasyonu) Türkiye’nin güneyinde bulunan Batı Toroslar’daki Sultandağ Bloğu’nun (Isparta) Dinek (Şarkikaraağaç-Isparta) güneydoğusunda yüzlek vermektedir. Bu çalışmanın amacı, Geyikdağı Birliği içerisindeki düşük dereceli metamorfizma geçiren Alt Paleozoyik yaşlı Sultandede metasedimanter kayaçlarının kökenini, kaynak kayacını ve tektonik ortamlarını petrografik ve jeokimyasal analizler ile ortaya koymaktır. Sultandede Formasyonu sleyt, fillit, metakumtaşı, metakarbonatlar, yumrulu metakireçtaşı, kalkşist, muskovit-serizit-kuvars şist, metakuvarsit ve mermer türü litolojilerden meydana gelmektedir. Petrografik analiz temelinde şist numuneleri muskovit, serizit, kuvars, barit, opak mineral ve demiroksit ayrışma mineralleri, kalkşist numuneleri de kalsit, kuvars, barit, serizit, muskovit ve limonit içermektedir. Kondrite göre normalize edilmiş nadir toprak elementlerinin (NTE) dağılım desenlerinde Sultandede metamorfik kayaçlarında hafif nadir toprak elementlerinden (HNTE) ağır nadir toprak elementlerine (ANTE) doğru bir azalmanın olduğu, HNTE'lerin ANTE'lere göre göreceli olarak zenginleştiği gözlenmektedir. Eu (Eu/Eu*= 0,55-0,98) ve Ce belirgin negatif anomali gösterirken, Gd pozitif anomali gösterir. Metasedimanter kayaçların felsik, tortullaşma sonrası oluştuğu ve kıta kenar rejimini karakterize ettiği tespit edilmiştir. Ana element jeokimyası ve iz-nadir toprak element oranları ile yapılan sınıflama ve kaynak kayaç diyagramlarından (La/Th ve Hf) elde edilen veriler, bu kayaçların mağmatik (felsik ve ortaç) ve geri dönüştürülmüş önceden var olan sedimanter kaynaktan türediğini ve üst kıtasal kabuk eğilimi gösterdiğini belirtmektedir. Şist ve kalkşist numunelerinin ortalama Th/U değeri (6,87) üst kıta kabuk değerinden (3,82) daha yüksektir. Bu sonuç, önceki aşınma eğilimini takip ettiğini ve metasedimanter kayaçların yoğun aşınmaya maruz kaldığının işaretidir. Ni/Co ve V/(V + Ni) jeokimyasal parametreleri, metasedimanter kayaçların oksik ortamı ve disoksik, anoksik ve öksinik koşulları altında biriktiğini göstermektedir.

Late Ordovician Bentonites From the Southern Ordos Basin: Response to the Subduction of the Proto‐Tethys Ocean

Article

Oct 2024

The connection between the Ordovician bentonites on the southern margin of the Ordos Basin and the Early Palaeozoic volcanic rocks of the North Qinling Orogenic Belt is crucial for understanding the subduction and collisional closure of the Shangdan Ocean during the Early Palaeozoic. This paper investigates zircon U–Pb ages, geochemistry and Lu–Hf isotopic compositions of zircons in the Upper Ordovician Zhaolaoyu Formation bentonites located on the southern margin of the Ordos Basin. U–Pb dating of zircon indicates a coeval age of 453.3 ± 1.4 Ma (MSWD = 0.99), which represents the crystallisation age during the Late Ordovician Katian stage. The bentonites exhibit higher SiO 2 (57.94–77.95 wt.%) and Al 2 O 3 (9.21–14.33 wt.%), classifying them within the low‐potassium alkali basalt to medium‐potassium calc‐alkaline series. The parent rock of the bentonites is likely intermediate to felsic volcanic rocks. The rare earth element partitioning curves of the bentonites are right‐dipping, with a more pronounced negative Eu anomaly ( δ Eu = 0.48–0.67). The zircons in the bentonites yield two‐stage model ages ranging from 546 to 956 Ma, along with ε Hf ( t ) values between 5.56 and 13.55. These results indicate that the bentonites are products of volcanic arc magma formed in a subduction–collision environment. The interbedded bentonites in the Upper Ordovician limestones of the southern margin of the Ordos Basin may be associated with the northward subduction of the Shangdan Oceanic crust, reflecting the subduction and consumption of the Proto‐Tethys Ocean along the southern margin of the North China Block.

Provenance Analysis Based On Petrographic Samples On EXIA-1 Well, Banggai Basin, East Sulawesi, Indonesia

Article

Full-text available

Jun 2024

The structure of Exia is composed of Miocene built-up carbonates formed by shear faults. The buildup carbonate feature in the Exia prospect can be seen from the high elevation surrounded by lows with an NNE-SSW and NE-SW trending. The MA-1, SE-1, MI-1 wells are several wells in the Tiaka and Senoro Fields which are proven to have large gas reserves. Tiaka Field is located to the west of the Exia Well, while Senoro Field is to the northeast. The study used primary data from the Exia-1 well in the form of cutting samples. The wet and dry cutting samples were further processed into thin section. This thin section is then carried out for petrographic, XRD, and SEM analysis. Tomori Formation starts from the deeper environment FZ1 upwards to the shallower FZ5 –FZ6 (reef) with open marine and restricted areas. The allochem that composes the limestone at The Matindok Formation consists of red algae fragments and benthic forams which indicate the facies zone of formation in FZ 4 (slope). In the upper Mantawa Formation, it is still quite clear the presence of large forams indicating a reef association environment (FZ5-FZ6), but the presence of a large number of planktonic forams indicates a deeper depositional environment / slope, so it is possible that large forams were transported from a shallower environment. The Kintom Formation have rock provenance ranging from continental blocks in the interior of the craton to a recycled orogeny section of recycled quartz zone.

LITHOLOGY AND CONDITIONS FOR ACCUMULATION OF LOWER CRETACEOUS DEPOSITS IN THE ZHURAVLEVSKY TERRANE NOTHERN PART (KHABAROVSK TERRITORY)

Article

Jan 2024

The authors present the study and paleogeodynamic interpretation of the Lower Cretaceous deposits material composition from the northern part of Zhuravlevka terrane. In their composition, the sandstones correspond to petrogenic graywackes, formed due to the mechanical destruction of parent rocks. Interpretation of the results shows that sediments accumulated along the continent-ocean boundary in a basin, associated with strike-slip dislocations along transform faults. The sources area united the sialic land composed of acidic igneous and sedimentary rocks, as well as a mature, deeply eroded ensialic arc.

The Triassic Buntsandstein sedimentary basins of Sardinia (Italy) and their transition to the Brianzonese Ridge (W Alps): crossroads through the W-Tethys areas

Article

Sep 2024

Luca Giacomo Costamagna

Sardinia represented a key area during the Western Tethys opening in late Early-early Middle Triassic times since it was located at the nodal point of several paleogeographic domains. New and revised sedimentological data and petrographical investigations evidence that the Sardinian Buntsandstein Group formational units differ from each other and were deposited in different alluvial to transitional depositional systems related to Alpine rifting basins. Petrographic analysis revealed directional NS and EW compositional differences: they hint at morphotectonic rises separating the diverse depositional areas through lasting barriers related to paleoeuropean ridges in progressive dismantling. The data suggest that 1) the dominating environmental and (micro)climate conditions were diverse from area to area, 2) the sedimentary basins evolved differently through time, and 3) were diachronous in timing. Moreover, the sources of debris were variable, both in morphology and substrate composition, with reliefs from articulated to smoothed. A stratigraphic and sedimentological framework for the Sardinian Buntsandstein is suggested. Comparison analysis with close coeval successions of the Western Tethydian area, particularly regarding the Upper Permian? - Lower Middle Triassic deposits of the Brianconnais ridge have been attempted, as well as their palaeogeographic localization, to frame the Sardinian Buntsandstein Group with the coeval units of SW Europe.

Sedimentary Petrology and Basin Analysis of the Mamu Formation: Insights into Provenance, Depositional Environments, and Paleohydrodynamic Conditions

Preprint

Full-text available

Jul 2024

The Mamu Formation, a sedimentary unit of significant geological and economic interest, remains incompletely understood. This study employed sedimentary petrology and basin analysis techniques to investigate the provenance, depositional environments, and paleohydrodynamic conditions associated with the formation. Sediment samples (MA.1 through MA.8) were collected from various stratigraphic levels to capture the lithological variations within the Mamu Formation. A three-step methodology was implemented. First, samples underwent standard preparation techniques (washing, sieving, drying, crushing, homogenization). Second, petrographic analysis involved creating thin sections from each sample for examination under a polarizing microscope. Modal composition (quartz, feldspar, rock fragments) was quantified using the point-counting method. Finally, a ternary diagram was utilized to visualize the compositional data and classify the sandstones based on their detrital grain composition (quartz, feldspar, rock fragments). The dominance of quartz suggests a likely igneous or metamorphic source area, while the presence of feldspar and rock fragments indicates a potentially mixed source and relatively short transport distances. Grain size distribution points towards a high-energy environment like a fluvial or beach setting. Poor sorting and variable skewness values suggest fluctuations in flow strength during deposition. This analysis provides valuable insights into the origin, transport, and depositional history of the Mamu Formation sediments.

Plate Tectonics and sandstone composition

Abstract

No full-text available

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