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Heavy metals were analyzed in rhizosphere soils and rice grains collected from typical black shale areas. The concentrations of As, Cd, Cu, and Zn in the rhizosphere soil exceeded the current soil environmental quality standards. Cd exhibited the highest bioaccumulation capacity, with 45% of rice grains exceeding food safety limit. Structural equation modeling (SEM) revealed that soil organic matter indicated that 34.79% of rice Cd accumulation and approximately 10%–25% of other metals were inhibited. Multiple regression modelling showed that in areas with high geological background of black shales, the screening and intervention values for soil Cd were adjusted to 0.24 mg kg−1 and 0.42 mg kg−1 for pH ≤ 5.5 and 0.27 mg kg−1 and 1.66 mg kg−1 for pH 5.5 – 6.5 respectively. Primary exposure pathways for non-carcinogenic risks were identified as food ingestion and skin contact. This study provides fundamental information for land use application and development in region with high geological background. [ABSTRACT FROM AUTHOR]

The country's national scale geochemical mapping can provide crucial geochemical support for Zambia's foundational geology, agricultural productivity, environmental conservation, mineral exploitation, and other domains. This study aims to determine the overall abundance and regional distribution of B and Se in Zambian stream sediments, as well as their impact on the environment and on the agricultural output. The median concentrations of B and Se are 12.74 and 0.056 μg/g, respectively. While the concentration of Se was more noticeable, the distribution patterns of B concentration seemed to be more consistent and lacked distinct indicators for agricultural output. It also offers more robust recommendations for future land planning and agricultural growth. In comparison to other tectonic belts, the Domes Region, Lufilian Arc and Choma-Kalomo Block have greater median and average concentrations of Se. Black shales and vast epithermal metallogenic zones are common in the Kawana-Solwezi-Ndola and the Mansa-Mporokoso- Kasama regions, which also have high Se contents. These regions could serve as promising places for the advancement of selenium-enriched agricultural practices. [ABSTRACT FROM AUTHOR]

The mid-Proterozoic (ca. 1.8–0.8 Ga) is broadly characterized by low atmospheric oxygen and pervasive oceanic anoxia punctuated by pulses of oxygenation. However, the causes underpinning these transient events remain elusive. Here, we report on 1.64 billion-year-old black shales and dolostone from the Chuanlinggou Formation in the North China Craton that represent sediment deposited during the break-up of the supercontinent Columbia. The rocks are characterized by high initial 187Os/188Os values, comparable to modern seawater values, alongside positive isotopic compositions of copper similar to those found in shales deposited during the Great Oxidation Event between 2.5 and 2.2 billion years ago. Additionally, we note high Th/U ratios and Chemical Index of Alteration values. Collectively, our data suggest a positive feedback initiated by continental fragmentation, with increased oxidative weathering on land, greater nutrient supply to the oceans, enhanced primary production of marine cyanobacteria, and ultimately, higher rates of oxygen production, perpetuating the feedback loop. [ABSTRACT FROM AUTHOR]

The Anambra Basin of Nigeria, part of the larger West and Central African Rift System (WCARS) across Africa, contains primarily Cretaceous to Palaeocene shallow to marginal marine and freshwater sedimentary deposits. The organic‐rich deposits of the Cretaceous Nkporo and Mamu formations within the Anambra Basin and the Palaeocene Imo Formation of the Niger Delta Basin constitute important conventional source rocks. Despite its economic significance, research on organic matter characterisation, palynofacies, sea‐level fluctuations, palaeoclimate, hydrogeography, basin restriction, palaeobathymetry and the factors controlling organic matter preservation remains largely undocumented. The here presented new inorganic and organic geochemical and organic petrography data of the Cretaceous to Palaeocene deposits serve to refine the regional interpretation at a basinal scale and within the supra‐regional context of the WCARS. Geochemical palaeotemperature proxies suggest a warm and humid tropical palaeoclimate during the Late Cretaceous within the study area. Furthermore, the measured TOC values indicate poor to very good organic content. Palynofacies analysis revealed high abundances of opaque and translucent phytoclasts and low amounts of palynomorphs with negligible amorphous organic matter (AOM) in the studied mudrocks. Two palynofacies groups suggest shallow‐marine conditions in a proximal shelf setting and a heterolithic oxic basin. The palynofacies of the upper Imo Formation reveal higher percentages of dinoflagellate cysts during the early highstand phase, with equidimensional, opaque phytoclasts representing the maximum flooding phase, accompanied by warmer conditions. Additionally, abundant terrestrial phytoclasts, Deltoidospora spp., Classopollis spp. and geochemical indicators collectively indicate warm tropical climatic conditions consistent with geochemical interpretations. The palaeobathymetry reconstructions suggest a shallow seaway during the Upper Cretaceous in the Anambra Basin. [ABSTRACT FROM AUTHOR]

The article presents the results of studies of obtaining a ferroalloy from a mixture of coal beneficiation tailings and cake from leaching of vanadium-containing quartzites (black shales) of the Balasauskandyk deposit. The study was carried out using the HSC-6.0 software package, using the Equilibrium Compositions module and the second-order rotatable planning method (Box-Hunter plan), followed by geometric optimization of equilibrium process parameters. Based on the studies on the interaction of coal beneficiation tailings and cake from leaching of vanadium-containing quartzites in the presence of iron, it was found that under equilibrium conditions, an increase in the ratio of coal beneficiation tailings to leaching cake, which allows increasing the degree of silicon extraction in FeSi, Si, is accompanied by undesirable development of SiC formation and positive decrease in the degree of gaseous SiO formation. In the temperature range of 1500–2000 °C, an increase in the tailings to the cake ratio from 0 to 1.7 increases the degree of silicon extraction into the alloy to 67.8% at 1900 °C and aluminum to 33.94% at 2000 °C. Ferrosilicon of the FeSi45 grade, with 51.1–66% Si extraction into it, is formed in the temperature range of 1703–1900 °C from a mixture of tailings and cake with their ratio from 0.38 to 1. By electric smelting of a mixture of tailings (containing 30–47% C) with cakes with a ratio from 1.0 to 0.32 together with steel cuttings, a ferroalloy − ferrosilicon of the FeSi45 grade with a content of 37–42% Si was obtained. [ABSTRACT FROM AUTHOR]

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[Display omitted] Lacustrine systems since the Mesozoic have sequestered large quantities of organic carbon, which may have important value for global climate cooling, but there is still a lack of geological evidence of this sequestration. Taking the Songliao Basin in China as a case study, we elucidate the important function of lacustrine basins as sinks of a large amount of organic carbon, particularly when the contemporaneous marine sediments were poor sinks of organic carbon. Volcanic activities and orbital forcing were likely key factors influencing the water transportation between the land and oceans, as well as the alternating burial of organic carbon in the oceans and land. Microorganisms related to methane metabolism may have been highly involved in the mineralization and sequestration of lacustrine organic carbon. This study provides new insights into the coupled carbon–water cycle between the land and oceans and the influence of this process on global climate evolution. [ABSTRACT FROM AUTHOR]

Introduction: The Lower Jurassic Beipiao Formation in the western Liaoning of northeast China represents a significant case study for understanding the interplay between volcanic activity, sedimentary processes, and organic matter enrichment. Methods: This study aims to investigate the lithofacies, depositional environments, and hydrocarbon potential of the Beipiao Formation, using core, outcrop, thin-section, and geochemical data. Results: Thirteen lithofacies types were identified, which reflect a complex depositional history influenced by volcanic processes and gravity flows. The sedimentary facies analysis revealed three key depositional environments: shallow lake, semi-deep to deep lacustrine, and fan delta. The basin evolution suggests a transition from fan delta deposits to deep lake deposits and then back to fan delta, with volcanic and gravity flow deposits interbedded. Volcanic activity not only provided nutrient-rich environments conducive to biological productivity but also helped create conditions favorable for organic matter preservation. The earthquake, flooding or stormed events induced gravity flow, which favored plant fragments dispersal to the deep-lake and formed type III kerogen in the deep-lake developed area. Discussion: These findings suggest that the Jurassic Beipiao Formation in western Liaoning Province, exhibit significant hydrocarbon potential. This challenges previous assumptions regarding the dominance of shallow water environments and limited exploration prospects within the Yanshan Orogenic Belt. Furthermore, this study highlights the crucial role of volcanic activity and gravity flow in organic matter enrichment, transportation, and preservation within a volcanic-rift basin, with potential applicability to similar basins worldwide. [ABSTRACT FROM AUTHOR]

In this study, an innovative breakthrough pressure detection system for shale oil is introduced. Experiments were conducted on source rocks from three main rock types in the upper member of the Lower Ganchaigou Formation in the Western Qaidam depression, in Qinghai, China. The results show that the differences between the breakthrough pressures of laminated calcareous mudstone (LCM), siltstone (SS), and massive mixed mudstone (MMM) in the formation are of several orders of magnitude. In particular, the shale oil breakthrough pressure of laminated calcareous mudstone is more than five times greater in the vertical bedding direction than in the horizontal bedding direction. As black medium shale oil turns into yellow light shale oil, the breakthrough pressures in the same lithology and direction are reduced by two-thirds. In laminated mudstone the horizontal breakthrough pressure is lower than the vertical, while in massive mixed mudstone the vertical breakthrough pressure is lower. A composite migration model for shale oil in hybrid strata—horizontal migration along bedding and vertical migration through micro-fractures—is proposed. The results are of great significance for understanding the accumulation of shale oil and for identifying exploration targets. [ABSTRACT FROM AUTHOR]

The Middle Eocene lignite-mudstone deposits of the Kutch (Kachchh) Basin, western India, manifest a highly restricted marginal-marine depositional setting, in which an unusual preservation of Rosselia erecta can be observed within organic-carbonaceous-rich mudstone beds. It is the earliest Cenozoic record of the ichnospecies hitherto reported. Rosselia erecta occurs in a paucispecific R. erecta–Trichichnus isp. ichnofabric within thinly laminated mudstones that are intercalated with lignite seams and laminae. The burrows are primarily vertical, characterized by cone-in-cone structures that are penetrated by a centrally positioned cylindrical shaft with concentric or intermittently eccentric lining. The lining intermittently contains sulfide-mineralization, often with the framboidal pustules that probably formed as a result of anaerobiosis by chemautotrophic symbiotic bacteria. The cone opening at the bedding surface displays radial striae, indicating surface-detrital foraging behaviour. We propose that the burrow serves as a facultative multifunctional structure, with the tracemaker employing two distinct feeding mechanisms: (1) surface-detritus-feeding (fodinichnia) and (2) cultivating microbial colonies (agrichnia) of sulfate-reducing bacteria in a mutualistic symbiotic relationship. The well-preserved morphological features in the newly examined specimens facilitate a reassessment of the constructional mechanisms and functional implications of the ichnospecies R. erecta reminiscent of the recently established ethological category sequestrichnia. [ABSTRACT FROM AUTHOR]

This paper gives a brief description of all structural–formational zones in the Southern Urals. Riphean and Paleozoic black shale sediments with strong positive anomalies of gold and a number of other elements are widely developed within this region. This paper reports that carbonaceous shales are a very favorable geochemical environment for the primary accumulation of many industrially important elements. Under certain conditions (in the areas of magmatism, zonal metamorphism, and tectonic activity), they can serve as a source of metals and concentrate deposits, and occurrences of gold, silver, and platinoids. Among these deposits, a new type of vein-embedded gold–sulfide mineralization with dispersed gold and platinum metals, localized in rocks rich in organic carbon, has been detected. In this study, we made an attempt to summarize and systematize research materials on this issue. The presented data indicate a high potential of carbonaceous sediments in the Southern Urals, providing a good basis for further prospecting works and analytical studies. [ABSTRACT FROM AUTHOR]

Few studies have systematically investigated the factors controlling organic matter enrichment in shales from the Qiongzhusi Formation, within and surrounding the Sichuan Basin, under different depositional environments. This has resulted in different academic understandings and limited clarity on the mechanisms of organic matter enrichment. On this premise, in this study, the basic geological characteristics and depositional paleoenvironments of shales along the passive continental margin, the western Hubei Trough, and the western Sichuan Trough were compared and analyzed using core, outcrop, and mineral testing. Furthermore, data from organic geochemical and elemental analyses were utilized to investigate the different enrichment mechanisms and formation modes of the organic matter in different periods. The results reveal that the organic matter enrichment in this region should be mainly influenced by the preservation conditions, paleo-productivity, and terrigenous input. However, there were clear differences in the main controlling factors in the different periods. In the Q1 phase, the region had a high sea level, had the strongest rifting, had the largest accommodation space, and exhibited characteristics of low terrestrial input and bottom water hypoxia. The changes in the paleo-productivity caused by upwelling currents were the main factors controlling the variations in the organic matter enrichment. In the Q2 phase, the weakened decreasing sea level co-occurred with a reduction in the accommodation space across the region. The organic matter enrichment was significantly controlled by the paleoproductivity, preservation conditions, and terrigenous inputs, and the organic matter enrichment conditions deteriorated from the passive continental margin to the western Hubei Trough and western Sichuan Trough. The total organic carbon (TOC) content of the shale decreased significantly. In the Q3 phase, the entire region entered an infilling stage, which was dominated by an oxygen-rich environment, and the preservation conditions were the decisive factor controlling the organic matter enrichment. The TOC content was low overall, and there were no evident differences across the different zones. [ABSTRACT FROM AUTHOR]

The Ediacaran Period, immediately following the Neoproterozoic Cryogenian glaciations, marked a crucial phase in the Earth's evolutionary history. The paleo‐oceanic environment helped shape the habitability, yet the links between oceanic redox state, hydrochemistry, biological activity, and elemental cycling during this time remain poorly understood. Here, we address this scientific issue based on high‐resolution geochemical data from black shale‐hosted, manganese (Mn)‐rich carbonates within the upper Ediacaran Doushantuo Formation, located on the northern margin of the Yangtze Block, South China. Multiple redox proxies indicate that while the open ocean may have been intermittently oxygenated during the late Ediacaran glaciation, the continental margin slope was characterized by redox stratified conditions with a fluctuating redox interface. These fluctuations were driven by climatic shifts. During the deposition of black shales, a relatively warm and humid climate caused a notable increase in freshwater runoff and glacial meltwater, raising water levels and lowering salinity. The influx of bioessential elements carried by terrestrial runoff promoted primary productivity. By contrast, the deposition of the Mn(II) carbonates occurred under colder, more arid conditions, with limited terrigenous nutrient input, leading to lower organic carbon production. This resulted in the deepening of the redox chemocline over the continental shelf, promoting Mn(II) oxidation and subsequent mineralization. Paleoclimate‐driven redox fluctuations were key in controlling elemental cycling during the late Ediacaran. This may offer insights into similar processes throughout Earth's history. Plain Language Summary: If the late Ediacaran ocean is oxygenated or reducing remains a topic of debate. Here we propose a stratified scenario with an intermittently fluctuating redox interface between O2‐bearing surface waters and O2‐depleted deep waters on the continental margin slope as represented by the Doushantuo Formation of South China. We further establish coupled links between the ancient oceanic redox state, paleoclimate, marine hydrochemistry, biological activity, and Mn‐cycle during this period based on multiple geochemical proxies. Warm and humid climate supplied nutrient elements that fueled high primary productivity, sustaining higher redox interface and widespread H2S‐bearing conditions conducive to black shale deposition. In contrast, a colder, more arid climate limited nutrient supply and productivity, leading to diminished organic carbon synthesis, descending redox interface, and contracted deep O2‐depleted zone, which favored Mn(II) carbonate formation. The fluctuating redox interface created optimal conditions for Mn(II) oxidation, Mn(IV) reduction, and Mn(II) carbonate mineralization during the transformative phase of oxygenation event in the late Ediacaran. This might be general throughout geological history. Key Points: The redox conditions along the continental marginal slope were stratified and fluctuating in the late Ediacaran oceanPaleoclimate variations influenced the basin's hydrochemistry and biological activity, driving shifts in the redox chemoclineThe shifts in the slope's redox chemocline regulated distinct oceanic manganese cycling and mineralization processes in South China [ABSTRACT FROM AUTHOR]

Analyses of the three predominant types of sedimentation – siliciclastic, carbonate and black shale – revealed their discontinuity/continuity across various facies environments within the Middle and Late Devonian of the central part of the Volga-Urals petroleum province. These environments include condensed and non-condensed depressions, slopes of depressions and shallow water settings located on tectonic arches or local biohermal uplifts.The regional zonation of conodonts, correlated with the International chronostratigraphic chart, confirms the general stratigraphic completeness of the Middle-Upper Devonian geological record in this area. Meanwhile, sedimentation exhibited a discontinuous pattern, which enables to speak about the socalled “discontinuous continuity”. In particular, the sedimentation of organic-rich black shales, traditionally considered as oil-source rocks, lasted more than 29 million years, from the Late Eifelian up to the Devoniancarboniferous boundary. The longest hiatus (ca. 2.5 Ma) in the accumulation of black shales (as well as carbonates) took place at the end of the Givetian. Notably, this interval contains the most productive siliciclastic reservoirs.During the Early Eifelian to Early Frasnian (ca. 17 Ma), siliciclastic sediments demonstrate the highest accumulation rates and the maximum discontinuity caused by short marine transgressive episodes. Simultaneously, the most complete sequences were deposited in the depressions where carbonate and black shale sediments accumulated. During the Famennian (ca. 12 Ma), siliciclastic sedimentation completely ceased, leading to the stable accumulation of carbonate sediments on the slopes of depressions and in shallow waters; the deposition of organic-rich black shales continued in the deep axial settings of the troughs. Our results highlight the complexity of the spatial relationship between various coexisting sedimentation types and the incompleteness of the geological record in different environments.

The work studied the lithological and geochemical characteristics of oil and gas source rocks of the central part of the Volga-Ural oil and gas bearing province. The purpose of the work was to reconstruct their formation conditions, study the generation potential and maturity of organic matter, and examine prospects for industrial development. The rocks were studied macroscopically, as well as X-ray analysis, pyrolysis using the Rock-Eval method, SARA analysis, and gas chromatography-mass spectrometry. The formation of the Domanik deposits, Bobrikovsky and Pashiysky horizon mudstones, and Upper Kazan substage clays have all been proven to have occurred in a maritime environment. The content of organic matter in the rocks varies from 0.35 to 11.16%. Minute amounts of organic matter that are difficult to accurately in terms of their geochemical properties can be found in the clayey deposits of the Vereisky and Timan horizons. The Upper Kazan substage clays contain type II/ III kerogen. Mudstones of the Bobrikovsky and Pashiysky horizons, as well as Domanik deposits, contain organic matter represented by type II kerogen. The data obtained may indicate common mechanisms for the accumulation of sapropelic organic matter on the territory of the Volga-Ural basin from Pashian (Frasnian stage) to Bobrikovian (Visean stage) times. It was revealed that the studied deposits are at the stage of catagenesis (PC-MK1). At the same time, Domanik deposits have very good and excellent generation potential, which is characterized by the greatest maturity. Mudstones of the Bobrikovsky horizon have similar generation potential.

The organic-rich strata of the Lower and Middle Jurassic occur within separate blocks, covering significant areas of the Carpathian Foredeep basement, the Bârlad Depression and the Dobrogean Foredeep. The deposition of these strata resulted from an anoxic event, leading to the formation of a globally important source rock level. The Rock-Eval pyrolysis results for the Middle Jurassic rocks in the Ukrainian part of the Carpathian Foredeep basement indicated a total organic carbon content of 1.61â14.98 wt%, with type II/III kerogen at an early mature to mature stage. Based on time-temperature index calculations, the top of the oil window occurs at the depth of 2200 m in the Ukrainian part of the Carpathian Foredeep basement, and at 1000 m in both the Bârlad Depression and the Dobrogean Foredeep. The former achieved thermal maturity during the Neogene period, while the latter two entered the oil window towards the end of the Cretaceous period. Across the entire study region, the Lower and Middle Jurassic strata are situated in the oil window over extensive areas, suggesting their potential inclusion in the petroleum system. Hydrocarbons generated by the ToarcianâBathonian organic-rich rocks may contribute to the formation of MesozoicâMiocene accumulations in the Carpathian Foredeep basement and some oil fields in the Carpathian flysch sequence. In the Bârlad Depression and the Dobrogean Foredeep, hydrocarbon occurrences may be expected in the Upper Jurassic reservoir rocks, potentially sourced by the Middle Jurassic black shales.

The tectonic of the Middle and Late Ordovician in the western margin of the north China Platform is complex, and the accumulation models of organic matter of the Wulalike Formation formed during this period are still unclear. Total organic carbon (TOC) content, mineral composition, organic carbon isotope composition, as well as the major and trace elements in the shale samples were all measured in this study. The Wulalike Formation was formed during a tectonic transition from a passive continental margin to an active continental margin. Hydrocarbon-forming organisms are mainly algae. Primary productivity, terrigenous input, and sedimentation rates influence input, dilution, and degradation of organic matter. The degree of degradation, redox, and basin restriction control the preservation of organic matter. The TOC of the Wulalike Formation is determined by the input and preservation degree of organic matter at different sedimentary periods. The organic matter accumulation model in the Wulalike Formation is controlled by regional structures, dominated by sedimentation rate and preservation conditions. [ABSTRACT FROM AUTHOR]

The changes in the thermal behavior of shelly phosphorite ore from Toolse deposit along the drill-core PH014B (depth 21.1–26.7 m) cut into sub-samples with a length of 0.1 m have been studied. The primary phosphorus-bearing mineral in Estonian phosphorite is fluorcarbonate apatite (francolite) originated from lingual brachiopod shells which during the following millions of years of deposition has partially transformed into fluorhydroxyl apatite. The experiments on a Setaram Labsys Evo 1600 thermoanalyzer coupled with Pfeiffer Omnistar Mass Spectrometer were carried out under non-isothermal conditions at the heating rate of 10 °C min−1 up to 1200 °C in an oxidizing atmosphere containing 79% of Ar and 21% of O2. XRD, FTIR, and XRF methods were used to estimate the mineralogical and chemical composition of the sub-samples. In all studied sub-samples, two minerals prevailed—apatite and quartz. The content of apatite in general decreased moving upwards and the content of quartz increased—both minerals with certain fluctuations depending on the changes in the geological scale of formation of these sediments. Pyrite was also present in all sub-samples, clay minerals (K-mica, illite, chamosite) almost in all, but K-feldspar (sanidine, orthoclase), mostly, in the upper layers. Carbonates (dolomite, calcite) were present in many sub-samples along the drill-core, at that, the content of dolomite was especially high in the deepest sub-samples—between 26.3 and 26.7 m. Organic carbon was concentrated in the upper layers (21.1–23.0 m) of the drill-core, which contained black shale interbeds. Analysis of the results showed a good correlation between the thermal behavior of sub-samples and the changes in their mineralogical and chemical composition along the drill-core. [ABSTRACT FROM AUTHOR]

The editorial discusses the differences in shale oil and gas reservoirs across various sedimentary environments, focusing on theories and applications. It highlights the significance of shale oil and gas as unconventional resources crucial for global energy optimization and carbon neutrality goals. The text explores the development of shale oil and gas in the United States and China, emphasizing technological advancements, resource estimates, and exploration efforts. Additionally, it delves into the characterization of shale pore structure, hydraulic fracturing techniques, and the influence of depositional environments on shale properties, providing valuable insights for future research and development in the field. [Extracted from the article]

Mantis shrimp (Stomatopoda) are extant, marine, predatory arthropods, but these malacostracan pancrustaceans are also occasionally preserved in fossil assemblages, particularly in Carboniferous and Cretaceous deposits. Carboniferous species fall into two suborders—Palaeostomatopodea and Archaeostomatopodea—and represent the ancestral forms that gave rise to modern lineages. Herein, we describe hitherto unknown specimens belonging to the archaeostomatopod genus Tyrannophontes from the Pennsylvanian-aged Wea Shale Member, eastern Nebraska. We explore the preservation of these fossils using scanning electron microscopy and energy dispersive X-ray spectroscopy. These approaches reveal additional morphological characteristics, including unique appendicular data, such as the earliest occurrence of biramous gilled appendages in Stomatopoda. We suggest that further examination of black shales will likely uncover novel records of these rare pancrustaceans. [ABSTRACT FROM AUTHOR]

The source of uranium is an important research topic related to the exploration of sandstone-type uranium deposits, and potential uranium sources in deep basins are often overlooked. Black organic-rich shale is a common uranium-bearing rock in deep sedimentary basins. However, relatively few studies have investigated the migration of uranium during hydrocarbon generation in and release from uranium-rich shale. In this study, the uranium-rich shale in the Chang 7 member of the Yanchang Formation of the Upper Triassic in the Ordos Basin was selected to investigate the migration of uranium and other trace elements during the thermal maturation of uranium-rich shale via a semiopen pyrolysis simulation system. The gas and liquid products as well as the solid residue were thoroughly analysed by means of multiple instruments. The results showed that uranium significantly migrated before hydrocarbon generation (Ro < 0.61%), with a leaching rate between 12.1% and 18.8%. The leaching rate of uranium during the hydrocarbon generation stage (0.63% < Ro < 1.35%) was relatively low, ranging from 0 to 7.2%. Cu, Pb, Zn, Mo, and other trace elements also migrated considerably during the early stage of thermal evolution, with leaching rates ranging from 2.9 ~ 11.6%. The yield of low-molecular-weight organic acids (LOAs) was the highest in the early stage of thermal maturity, and the LOA yield exhibited a good correlation with the leaching rates of Cu, Pb, Zn, Co, Mo, etc. The generation of LOAs from source rocks was conducive to the leaching and migration of trace elements. Moreover, according to a statistical analysis of published geochemical data, the total organic carbon (TOC) content, uranium content, and U/TOC ratio in shale decreased significantly with increasing burial depth, indicating that uranium migrated significantly upon kerogen hydrocarbon generation during thermal evolution. Therefore, uranium-rich shale is an important deep uranium source in sedimentary basins. [ABSTRACT FROM AUTHOR]

This study focuses on the implications of a global hyperthermal event, the Paleocene–Eocene Thermal Maximum (PETM) for the origin, preservation and maturation of organic matter (OM) in the Late Paleocene Patala Formation, Himalayan fold-and-thrust belt, Pakistan. The OM present in the full array of lithofacies of the Patala Formation is characterized by petrographic (vitrinite reflectance) and geochemical techniques (total organic carbon (TOC), total organic nitrogen (TON), Rock-Eval pyrolysis and stable C and N isotopes). These analyses record deposition of the formation in a Late Paleocene shallow marine shelf environment. The organic geochemical proxies indicate the presence of Type III mixed with subordinate Type II kerogen as well as thermally immature to early mature source rocks. OM is derived both from terrestrial and marine sources. Rather high TOC (> 2 wt.%) and a negative carbon isotope excursion (CIE) reveal that the prevalence of anoxic conditions, at least for short periods, enhanced OM preservation. The quantity and quality of OM, as well as the thickness and thermal maturity of the Patala Formation, make it a potential target for shale-gas exploration. During PETM, the extensive biological activity and addition of organic carbon into shallow marine eastern Tethyan settings provided precursor materials for hydrocarbon source rocks and shale-gas generation within the Patala Formation. The high organic influx and suboxic to anoxic conditions during PETM also facilitated OM preservation within the formation. Thus, the transient global warming PETM event significantly contributed to the OM accumulation and its preservation, which implies the suitability of such source rocks for shale-gas exploration within the Potwar Basin (Pakistan) and similar basins in neighboring areas. [ABSTRACT FROM AUTHOR]

Environmental perturbations of the Toarcian Anoxic Event and its associated carbon isotope excursion (CIE) occurred in a cyclic fashion indicating an orbital control mechanism. Sedimentary strata of the E. elegantulum ammonite subzone in the Lorraine Sub-basin, Luxembourg, exhibit eight sedimentary cycles, most of which postdate the CIE, implying that its termination did not coincide with a full recovery from environmental stress. Sea-level and temperature fluctuations of the Toarcian crisis were linked to a cryosphere demise in the Northern Hemisphere, which modulated stadial versus interstadial phases on the orbital 100 ka eccentricity frequency band. Upon stadial phases, enhanced wind strength in combination with lowered sea level disrupted stratified shelf waters and shifted the storm wave base close to the sea floor. Ventilation of bottom waters interrupted accumulation of laminated and organic-rich black shales, but formed organic-lean and non-laminated gray claystones enriched in terrigenous wax lipids and spores provided via aeolian transport from the hinterland due to the enhanced wind strength. Wind systems are assumed to have been driven by high pressure differences between the cryosphere in the North of the Tethyan shelf and the warmer costal lowland. This distinguishes the atmospheric turbulences after the CIE from the postulated intensification of the cyclones that accompanied the rapid warming at the beginning of the CIE. The deep-water ventilation event following the CIE in the Lorraine Sub-basin was accompanied by a parallel evolution in the SW German Basin, indicating a supraregional driving mechanism in paleobathymetric sub-basins susceptible to lowering of storm wave base. In sub-basins with greater water depth on the NW-Tethyan shelf, post-CIE orbitally driven atmospheric turbulences had a minor or no effect on water column stratification and deposition of organic-rich laminated black shales persisted. [ABSTRACT FROM AUTHOR]

The Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic) is marked by widespread marine deoxygenation and deposition of organic carbon (OC)-rich strata. The genesis of the T-OAE is thought to be associated with environmental changes caused by the emission of 12C-enriched greenhouse gasses (CO2, CH4), manifested in a negative Toarcian carbon isotope excursion (nT-CIE). The nT-CIE is commonly used to stratigraphically define the T-OAE, and despite the complex interrelationship of the different environmental phenomena, both terms (nT-CIE and T-OAE) are commonly used interchangeable. We here demonstrate that occurrence of OC-rich strata is diachronous and not restricted to the nT-CIE, reflecting the interaction of global- and regional-scale processes. Thus, the interchangeable use of T-OAE and nT-CIE should be discarded. The nT-CIE, however, hosts the T-OAE climax, marked by the widest extent of OC-rich strata. Early Toarcian environmental changes, particularly sea level rise and rising temperatures, may have made marine areas more susceptible to develop oxygen deficient conditions, favoring OC-accumulation. [ABSTRACT FROM AUTHOR]

The contents of 25 elements were established in prospective reference materials, black shales SChS-1A and SLg-1A, using a developed analysis technique based on fusing samples with lithium metaborate and determining elements by external calibration with an internal standard on an ELEMENT high-resolution mass spectrometer. The passport characteristics of Russian reference materials of magmatic and sedimentary rocks SG-3, SGD-2A, ST-2A, SI-2, and BIL-1 and technical standards ZUK-1 and ZUA-1 have been clarified. New data of rare-earth elements were obtained for SI-2 and ZUA-1, which were missing during certification. Based on the inductively coupled mass-spectrometry analysis of standards SG-3 and SI-2 from 2005 to 2024, their applicability now has been confirmed. The new obtained ICP-MS results make it possible to expand the number of certified parameters of reference materials and clarify their results and can be used in analytical practice. [ABSTRACT FROM AUTHOR]

As a large gold-bearing province, the Yenisei Ridge does not show elevated background gold concentrations. All types of its sedimentary, metamorphic, and igneous rocks, except only the carbonaceous black shales, contain concentrations of the noble metal at the level of its Clarke values. All local gold deposits are constrained within the regional Central Metallogenic Belt, in which geological–geochemical conditions occurred that were favorable for the deposition of gold and gold–uranium ore mineralization: most of the deposits are constrained within a trough structure, the area was affected by several pulses of plume magmatism, which introduced, redistributed, and concentrated gold and uranium, and the developing ore-concentrating and ore-controlling systems formed economic deposits and associated zones of hydrothermal metamorphism with geochemical aureoles of Pb, Zn, Ag, Au, Bi, and As. [ABSTRACT FROM AUTHOR]

The lack of in-depth analysis on the reservoir characteristics and the paleoenvironmental conditions of the Niutitang Formation in the study area has led to an unclear understanding of its geological background. In this study, core samples from well SZY1 were selected, and X-ray diffraction (XRD), scanning electron microscopy (SEM), and quantitative elemental analysis were employed to systematically investigate the reservoir properties and paleoenvironment of the shales. The results indicate that the Niutitang Formation shales form a low-porosity, low-permeability reservoir. By utilizing indicators such as the chemical index of alteration (CIA) and elemental ratios, the study delves into the paleoclimate and paleoproductivity of the region. The (La/Yb)n ratio is approximately 1, indicating a rapid deposition rate that is beneficial for the accumulation and preservation of organic matter. The chondrite-normalized and North American Shale Composite (NASC)-normalized rare earth element (REE) distribution patterns of the shales show consistent trends with minimal variation, reflecting the presence of mixed sources for the sediments in the study area. Analysis reveals that the Niutitang Formation shales are enriched in light rare-earth elements (LREEs) with a negative europium anomaly, and the primary source rocks are sedimentary and granitic, located far from areas of seafloor hydrothermal activity. The NiEF and CuEF values suggest high paleoproductivity, and the shales were deposited in an anoxic-reducing environment. The depositional environments of the Marcellus and Utica shales in the United States, the Wufeng-Longmaxi black shales in the Changning area of the Sichuan Basin, and the shales in the study area are similar, characterized by anoxic reducing conditions and well-developed fractures. The thermal evolution degree of the study area is relatively moderate, currently in the peak gas generation stage, with the reservoir quality rated as medium to high, indicating good potential for hydrocarbon accumulation and promising exploration prospects. [ABSTRACT FROM AUTHOR]

The Nanhua Basin of South China recorded complete Cryogenian stratigraphic sequence from the Sturtian Glaciation (~717-660 Ma) to the Marinoan Glaciation (~?654-635 Ma). The interglacial Datangpo Fm in the Nanhua Basin is divided into two members, and the first member consists of the Mn-carbonate unit and the overlying black shale unit, containing a series of large and superlarge manganese deposits. The metallogenic process of manganese deposits is not clear, and the Mn-carbonates formed through the precursor of Mn-oxide/oxyhydroxide reduction or directly precipitated from an anoxic water column. Moreover, the redox conditions in the deep Nanhua Basin during the precipitation of manganese deposits are also controversial. In this study, the high-resolution nitrogen contents (TN), isotope compositions, carbon isotope compositions of organic and inorganic matter from the first member of the Datangpo Fm are analyzed. The δ15N values of the Mn-carbonate unit (+1.53‰ to +5.26‰, mean +3.36‰) are higher than those of the overlying black shale unit (-3.74‰ to +3.54‰, mean +0.89‰). The Mn contents show a negative relationship with TN but a positive relationship with δ15N in the Mn-carbonate unit, implying that the formation of Mn-carbonates is related to redox variations. The relatively higher δ15N values in the Mn-carbonate unit indicated oxic conditions, and NH4+ can be released and partially oxidized during the mineralization of organic matter, resulting in the residual 15N-enriched NH4+ being transferred into clay minerals. Meanwhile, the lower δ15N values in the black shale unit indicated anoxic conditions, which recorded primary N isotope signals. The Mn-carbonate unit is characterized by negative δ13Ccarb values (-11.17‰ to -5.22‰, mean -8.30‰), which show a positive relationship with δ13Corg, but a negative relationship with Mn contents, implying that the negative δ13Ccarb excursions were related to the organic matter degradation during Mn-carbonate formation. The findings of this study indicated that the metallogenesis of manganese deposits in the Cryogenian Nanhua Basin was constrained mainly by the oxic interval in the deep basin. The nitrogen and carbon cycling process can provide new insights into geochemical cycling after the Sturtian Glaciation. [ABSTRACT FROM AUTHOR]

Black shales have attracted the attention of numerous researchers not only due to their high potential as hydrocarbon source rocks and shale gas reservoirs, but also to the enrichment of critical metal elements in black shale series. Black shale of the Cambrian Shuijingtuo Formation is one of the most important black shales in the Yangtze platform. This paper conducts integrated research on the mineralogical and geochemical characteristics of this black shale from the Luojiacun section in Western Hubei Region, aiming at elaborating the enrichment mechanism of elevated critical metal elements in the Shuijingtuo black shale. Minerals in the Shuijingtuo black shale are predominantly composed of quartz (avg. 43.0%) and clay minerals (avg. 32.5%), with small proportions of calcite, albite, clinochlore, and pyrite. The Shuijingtuo black shale is characterized by high total organic carbon (TOC, avg. 3.9%) content and enriched in V-Ni-Cr-U and Sr-Ba critical metal assemblages. The elevated V, Cr, Ni, and U present dominant organic affinities, while Sr and Ba are closely correlated to calcite and pyrite, respectively. The enrichment of V-Cr-Ni-U critical element assemblages in Shuijingtuo black shale are ascribed to the high primary productivity, anoxic depositional conditions, marine biologic production, and low-temperature hydrothermal activities. The enrichment of Sr and Ba is related to the high primary productivity and anoxic depositional conditions, respectively. [ABSTRACT FROM AUTHOR]

Climate changes are known to have been a key regulator of the biodiversity in Earth's history. However, the dry‐humid degrees and alternating patterns throughout the Phanerozoic remain largely unconstrained. In this study, we report high contents (2.4 ± 3.8 mg N kg−1) and 17O anomalies (11.0 ± 7.4‰) of nitrate (NO3−) in the early Cambrian black shale from South China, likely caused by atmospheric NO3− intrusion under dry climates that followed tectonic uplift. By developing new methods to quantify aridity indices (AI, 0.06 ± 0.08) in combination with observational data with paleoclimate models, we reconstructed the historical AI variations. Our analyses revealed three significant dry‐to‐humid transitions which include Cambrian‐Ordovician to Silurian‐Permian, Permian‐Triassic boundary to middle Triassic‐early Jurassic, and Jurassic‐Paleogene to Neogene. This study quantitatively unlocked the Phanerozoic climate changes in South China, offering important evidence for understanding the co‐evolution of ecological and climatic systems in Earth's history. Plain Language Summary: Climate changes have played a critical role in shaping the biological evolution during the Phanerozoic, but the precise degree of dry‐humid fluctuations and their patterns remain unclear. This study observed high contents and 17O anomalies of nitrate in Cambrian black shale from South China, attributed to atmospheric deposition during dry periods following tectonic uplift. By integrating isotopic and sedimentological data with climate models, we quantified historical aridity and reconstructed its variations in South China. We identified three major dry‐to‐humid transitions in the Phanerozoic. These findings improve our understanding of how climate dynamics interacted with biological and geological changes. Key Points: High 17O anomaly (11.0 ± 7.4‰) of NO3− in Cambrian black shale was not explained by early diagenesis and modern surface processesA new framework using the ∆17O of sedimentary NO3− to quantify the deep‐time aridity was developedThe data suggest three alternations of dry‐humid climates in the Phanerozoic were recorded by sedimentary geochemistry in South China [ABSTRACT FROM AUTHOR]

The Upper Cretaceous Qingshankou Formation black shales, deposited in the late Turonian (LTB shales), are the main source rocks of the Songliao Basin. The origins of organic matter enrichment of the shales is a contentious subject fuelling many ongoing debates. This study investigates the genesis of the organic matter‐rich shale by using molecular geochemistry. The LTB shales can be divided into three sections. The Section I shales were deposited in saline, stratified and anoxic water conditions, which are related to seawater incursion events. At least three episodic and periodic seawater incursion events were recognized during Section I shale deposition. The Section II shales deposited in brackish to fresh and deep lake‐level conditions with high primary productivity, which are related to lake‐level transgression. The Section III shales were deposited under fresh and slightly oxidized water conditions, which are related to lake‐level regression. Two organic matter enrichment models for the LTB shales are identified, that is, the seawater incursion model and the maximum lake‐level transgression sedimentation model, which act on different shale sections, both playing significant roles in the enrichment of organic matter. [ABSTRACT FROM AUTHOR]

The Jenkyns Event, more widely known as the Toarcian Oceanic Anoxic Event (T‐OAE), is marked by globally distributed negative carbon‐isotope excursions, widespread oxygen depletion, and large‐scale organic carbon burial, which indicate major climate/environmental perturbations in Earth's surface systems during the Early Jurassic. Although extensive research has been conducted in European continental settings, particularly in the western peri‐Tethys regions, the impacts of this event beyond Europe remains largely unexplored. Here, a multiapproach study including investigations into the spore‐pollen assemblages, pyrite framboids, clay minerals, total organic carbon (TOC) levels, and organic carbon isotope (δ13Corg) levels in a lacustrine borehole section (MED1) from the Yin'gen–Ejinaqi Basin, North China, provides evidence of the occurrence of the Jenkyns Event and its extensive sedimentary responses in the eastern Tethys terrestrial systems. Two distinct spore‐pollen assemblages have been identified in MED1 (drilling depth: 982.4 m to 1267.5 m), with the Cycadopites–Protopinus–Osmundacidites assemblage in the lower part (1267.5 m to 1132.9 m) indicating a middle Early Jurassic age and the Classopollis assemblage in the upper part (1132.9 m to 985.7 m) suggesting a Toarcian age. Framboidal pyrite data suggest more anoxic conditions during the deposition of black mudstone and shale intercalations in the lower part of the Classopollis assemblage (1132.9 m to 1066.9 m), which combined with organic carbon enrichment and negative δ13Corg excursions, are considered the paleoenvironmental response to the Jenkyns Event in the study area. Furthermore, the evolution of vegetation groups changed from plant groups characterized by bisaccate and cycad pollen, as well as fern spores, to vegetation groups represented by Cheirolepidiaceae pollen across the Jenkyns Event, as evidenced by spore‐pollen data, together with the clay mineral assemblage change characterized by a notable increase in illite at the expense of kaolinite, suggests that while a subtropical‐temperate climate persisted, a change toward warmer and drier conditions most likely occurred in the early Toarcian in the study area. In contrast to the humidification evidenced in many coastal settings, this aridification trend in the Yin'gen–Ejinaqi Basin aligns with the conditions in many inland areas. It is hypothesized that the underlying cause of these divergent changes may be linked to certain patterns of spatially variable water availability on land, potentially driven by extremified hydrological conditions. [ABSTRACT FROM AUTHOR]

This study thoroughly investigated the compressive and tensile strength characteristics of black shale using both experimental and analytical approaches. Uniaxial compression tests were conducted to determine the elastic constants of black shale modeled as idealized, linear elastic, homogeneous, and transversely isotropic. Additionally, Brazilian tests were carried out on shale, considering it a transversely isotropic material. Strain measurements were recorded at the center of disc specimens subjected to diametric loading. By placing strain gages at the disc centers, the five elastic constants were accurately estimated. The effects of experimental methods and diametric loading on the elastic constant determination were evaluated and analyzed, and the indirect shear strength of the black shale, considering anisotropy, was determined using the estimated stress concentration coefficient. This study revealed that the indirect tensile strength of black shale is significantly influenced by the angle between the anisotropic planes and the diametric loading direction. Moreover, it was revealed that the stress concentration coefficients for anisotropic rocks vary from those of isotropic rocks, depending on the inclination angle of the bedding planes. This study confirms that the shear (tensile) strength of anisotropic black shale is not constant but varies with the orientation of the anisotropic planes in relation to the applied load. [ABSTRACT FROM AUTHOR]

In order to clarify the hydrocarbon migration mechanism and accumulation mode under the condition of less faults, this paper takes the Upper Cretaceous in the Guyana Basin as an example, and studies the petroleum geological characteristics of the Upper Cretaceous in the Guyana Basin by using seismic data, drilling data and source rock analysis data. We have defined the reservoir-forming model of the study area and divided the favorable exploration areas. The results show that the source rocks of the Upper Cretaceous in the basin are huge thick black shales deposited in the Toulon-Coniacian stage. The TOC range of organic matter is 4%-7%, and the organic matter types are mainly type I and type II, The reservoirs in the study area are Kampan-Maastrichtian channel, embankment and foliar subfacies sandstone. The study area is mainly covered by mudstone and thick siltstone with poor physical properties deposited in the Early Paleogene. The migration system of "sand body superposition and fault oblique transport type" is developed in the continental shelf area of the basin, and the reservoir formation model of "source rock and reservoir close proximity, fault and sand body matching, and channel gathering" is formed. The migration system of 'sand body superposition and fracture vertical transport type" is developed in the deep water area, and the reservoir formation mode of "source rock and reservoir separation, fracture and sand body matching and high point gathering" is formed. The overlapped area of source rock development and channel development in the deep water area of the central basin is the first exploration target, and the overlapped area of source rock development and bank development in the north or the channel development area that does not coincide with source rock development is the second exploration target. The results are of guiding significance to the exploration of basins with similar geological conditions. [ABSTRACT FROM AUTHOR]

The Chuanlinggou Formation in the northern North China preserves the world's earliest multicellular eukaryote microfossils. Here we present a high‐precision zircon U–Pb CA–ID–TIMS age of 1,641.7 ± 1.2 Ma for a tuff layer within the black shales of the Chuanlinggou Formation. The new age is similar to those obtained for black shales from the Cuizhuang Formation in the southern North China, and the Barney Creek and Fraynes formations in the North Australia, indicating synchronous deposition of large volumes of black shales across both the North China and North Australia at ca. 1640 Ma. Global correlations and analysis of the spatial distribution of ca. 1640 Ma black shales and large igneous provinces (LIPs) and associated magmatic rocks in paleogeographic reconstruction reveal a spatiotemporal link between the ca. 1640 Ma LIPs and black shales. The widely distributed ca. 1640 Ma LIPs and black shales in Columbia supercontinent can provide a natural marker for the Statherian/Calymmian boundary at 1,640 Ma. Plain Language Summary: Phanerozoic boundaries and the base of the Ediacaran in the international chronostratigraphic time scale are defined by Global Boundary Stratotype Sections and Points (GSSPs). However, the pre‐Ediacaran geological time scale is formally subdivided by approximate absolute ages not tied to any geological units. Our new high‐precision zircon U–Pb CA–ID–TIMS dating of a tuff horizon within black shales of the Chuanlinggou Formation in the North China combined with geochronology on black shales on other crustal blocks reveals synchronous deposition of voluminous black shales at ca. 1640 Ma across the North China, North Australia and other cratons, and a spatiotemporal and possible causal link between the ca. 1640 Ma LIPs and black shales in the Columbia (Nuna) supercontinent. The global‐scale geological event represented by the ca. 1640 Ma LIPs and coeval black shales can provide a natural marker for the Statherian/Calymmian boundary at ca. 1640 Ma in the international chronostratigraphic time scale. Key Points: A tuff layer within black shales from the Chuanlinggou Formation has a high‐precision U–Pb CA–ID–TIMS zircon age of 1,641.7 ± 1.2 MaDeposition of large volumes of black shales occurred synchronously at ca. 1640 Ma across the North China, North Australia and other cratonsThe global‐scale ca. 1640 Ma LIPs and black shales can provide a natural marker for the Statherian/Calymmian boundary at 1,640 Ma [ABSTRACT FROM AUTHOR]

Weathering processes gradually alter the physical and mechanical attributes of slope materials, weakening the structural integrity and stability of slopes. This paper presents an in-depth analysis of slope stability in an open-pit mine, emphasizing the pivotal role of weathering effects in determining slope stability. To accurately capture the impact of weathering on slope stability, a comprehensive analysis model was developed, incorporating field observations, laboratory testing, and numerical simulations. The effects of weathering on the mechanical properties of black shale were studied through extensive laboratory tests. The uniaxial compressive strength, shear strength, and modulus of elasticity significantly decreased with increasing weathering, indicating a heightened vulnerability to slope failure. The correlation function between mechanical parameters and weathering time was obtained, providing the basis for evaluating the stability of mine slopes. It was found that more severe weathering conditions were strongly correlated with elevated risks of slope failure, including landslides and collapses. Based on these findings, practical recommendations are provided for slope reinforcement and management strategies, aimed at mitigating slope failure risks and ensuring the safe and efficient operation of the mine. By incorporating weathering effects into slope stability analysis, mine operators can make informed decisions that account for the dynamic nature of slope materials and their susceptibility to weathering, thereby improving overall mine performance and safety. [ABSTRACT FROM AUTHOR]

The effects of Cd-rich venting fluids on the Cd contents and isotopic compositions of continental margin sediments remain poorly understood. Characterization of the Cd isotopic composition of sediment over-printed by venting fluids is critical, as this may provide insights into how mixing between the venting fluids and bottom waters affects the Cd isotopic composition. Our study determined the Cd isotopic compositions of Lower Cambrian metalliferous sediment deposited on the passive continental margin of the southeastern Yangtze Block, South China. The Cd is predominantly hosted in sphalerite of sulfide-bearing barite sediments, V deposits, and Ni-Mo–platinum group element (PGE) sulfide layers. The Cd isotopic compositions of samples from these three units indicate that the distribution of Cd at this type of continental margin was controlled by submarine hydrothermal activity. Following the venting of hydrothermal fluids onto the seafloor, Cd2+ reacted with a limited amount of H2S generated mainly by thermochemical sulfate reduction near the vents. This resulted in isotopically lighter Cd in the sulfide-bearing barite sediments and V deposits, which have δ114/110Cd values of 0.00‰ ± 0.13‰ and 0.00‰ ± 0.14‰, respectively. The residual dissolved Cd in the fluids migrated with the upwelling seawater and ultimately precipitated almost entirely as sphalerite in the sulfidic wedge, which resulted in Ni-Mo–PGE sulfide layers with a narrow range of high δ114/110Cd values (0.35‰ ± 0.03‰). The presence of Cd-rich venting fluids can alter the Cd contents and isotopic compositions of passive margin sediments, particularly those located within long-term stratified seawater and fault depressions. Previous studies may have underestimated the migration distance and affected areas of hydrothermal activity involving Cd-rich fluids. [ABSTRACT FROM AUTHOR]

We conducted research to determine neodymium model dates (TDM), εNd values, and the relative proportions of rare earth elements (REEs) of Paleozoic black shales from the Midcontinent United States to constrain their sediment sources. Twenty-one Cambrian to Pennsylvanian shale formations of the Illinois, Cherokee, Forest City, and Arkoma basins, the Ozark Dome, and the Ouachita Mountains were examined. Findings reveal that these midcontinental shales consist primarily of felsic detrital minerals that originated from the craton. The Cambrian Mt. Simon, Eau Claire, and Tunnel City shales of the northern Illinois Basin exhibit REE patterns and Nd isotopic signatures similar to those of the Ordovician Mazarn and Womble shales of the Ouachita Mountains, which indicates derivation from a similar sediment source. Sediment was likely derived from the Superior and/or TransHudson cratonic provinces. The dominant sediment source shifted during deposition of the Middle Ordovician Womble Shale due to the uplift of the Appalachian Mountains during the Taconic orogeny, as suggested by the younger TDM dates, less negative εNd values, and similar REE patterns compared to those of the older Cambrian and Early Ordovician shales. The Grenville province and Appalachian Basin remained the primary sediment source into the Pennsylvanian. [ABSTRACT FROM AUTHOR]

The Iberian Pyrite Belt (IPB) represents one of the largest districts of volcanogenic massive sulfide (VMS) deposits in the world, and is a critical source of base metals (Cu, Pb, and Zn) for Europe. Confirmed resources exceed 1700 Mt of massive sulfides with grades of around 1.2% Cu, 1% Pb, and 3% Zn as well as more than 300 Mt of stockwork-type copper mineralization. Significant resources of Sn, precious metals (Au and Ag), and critical metals (Co, Bi, Sb, In, and Se) have also been evaluated. The genesis of these deposits is related to a complex geological evolution during the late Devonian and Mississippian periods. The geological record of such evolution is represented by three main lithological units: Phyllite–Quartzite Group, the volcano–sedimentary Complex (VSC), and the so-called Culm Group. The sulfide deposits are located in the VSC, associated with felsic volcanic rocks or sedimentary rocks such as black shales. The massive sulfide deposits occur as tabular bodies and replacement masses associated with both volcanic and sedimentary rocks. Their mineralogical composition is relatively simple, dominated by pyrite, chalcopyrite, sphalerite, and galena. Their origin is related to three evolutionary stages at increasing temperatures, and a subsequent stage associated with the Variscan deformation. The present paper summarizes the latest developments in the IPB and revises research areas requiring further investigation. [ABSTRACT FROM AUTHOR]

Imagine the vast Palaeozoic oceans: graptolites (Pterobranchia, Graptolithina) appear as small and inconspicuous benthic faunal elements in the early Cambrian, later becoming one of the dominating planktic groups of macrofauna in Ordovician and Silurian marine environments. Their unusual organic housing secretions (tubaria) in the fossil record makes them one of the most important biostratigraphic markers for the Ordovician to early Devonian time intervals. The occurrence, especially of the planktic graptolites, in black shales led to the common notion of a life style that related them to anoxic or dysaerobic environments, but is merely a preservational aspect. Their demise in the early Devonian may be related to the origination and diversification of large plankton feeding organisms in the marine realm as the graptolites were unable to complete with the much faster growth and reproduction of smaller, non-colonial organisms that did not need to waste time producing a housing construction. Thus, from the later Devonian onwards, the graptolites were largely gone and the oceans were teeming with fast reproducing and growing micro-and macroplankton. Larger predatory animals evolved as plankton feeders, that may have preyed on the graptolites. Only a few cryptic benthic species survived into the modern world. [ABSTRACT FROM AUTHOR]

In order to acknowledge the enrichment mechanism of organic matter in the black shale of the Middle Ordovician Yanxi Formation in central and southern Hunan area, the shale samples of the Yanxi Formation in the Maduqiao, Jinweixiang, Hejiadong and Mianhuaping are selected to test abundance of organic matter, major, trace and rare earth elements. The results show that the average total organic carbon (TOC) of black shale in study area is 2.03%, indicating the high abundance of organic matter in the Yanxi Formation. The CIA values and w(Sr)/w(Cu) ratios show that the Yanxi Formation had a warm and humid climate. The concentrations of Zn, V, Ni and Cu imply a medium primary productivity in the Yanxi Formation, whereas they have weak correlations with TOC. The element concentrations of V, Cr, Ni, and Mo reveal that the black shales were deposited in anoxic-euxinic conditions. The accumulation of organic matter is jointly affected by paleoclimate, primary productivity, redox conditions, sea level change and terrigenous debris. The organic matter enrichment model of the Yanxi Formation shales is a 'deepwater retention basin' controlleded by anoxic conditions. [ABSTRACT FROM AUTHOR]

Pelagic, outer-shelf sedimentary successions across the Devonian-Carboniferous boundary (DCB) in the western Graz Paleozoic at Trolp (Eastern Alps, Austria) display exceptional, continuous limestone facies of the Hangenberg Crisis interval. These enable the study of conodont successions, lithofacies, and geochemistry without noteworthy interruptions by siliciclastic intervals, which are equivalents of the Hangenberg Black Shale and Hangenberg Sandstone. The praesulcata, kockeli, and sulcata/kuehni conodont Zones are recognized by stratigraphically significant markers in the early siphonodellids and early protognathodids within thin-bedded limestones. The major conodont biofacies change and initial mass extinction phase (costatus-kockeli Interregnum) of the Hangenberg Crisis is succeeded by radiations among conodonts in the kockeli and sulcata/kuehni Zones. Carbon isotopes (d13Ccarb) record positive excursions and enhanced Corg burial episodes; the characteristic signals can be used as chemo-indicators of the early, middle and late phases of the Hangenberg Crisis. The global common Siphonodella sulcata Morphotype 5 and Protognathodus kuehni have their first occurrence at the base of the Tournaisian at Trolp and elsewhere in Europe, Asia and North Africa, and thus can be used to define the base of the sulcata/kuehni Zone and the current DCB level. 'Protognathodus' faunas with a high morphological variability are recorded in the praesulcata and kockeli Zones, but spread mainly in the sulcata/kuehni Zone, or even later in the lower Tournaisian. Therefore, the extended kockeli Zone suggested recently, and even leaves the current DCB level undivided, as well as the use of Protognathodus kockeli as index fossil for the DCB, are not applicable as suggested herein. A precise biozonation concept as well as multidisciplinary approaches used at Trolp are needed for understanding ultimate causes of the 1st order Hangenberg mass extinctions and major environmental changes at the DCB. Multidisciplinary approaches comprise taxonomically significant index conodonts, extinctions and radiations, as well as lithofacies and isotopic analyses. These markers at Trolp can be well correlated with those from many other settings worldwide, reflecting the global significance of the Graz Paleozoic. [ABSTRACT FROM AUTHOR]

The article discusses the collision between the India-Ladakh arc and India-Asia during the Early Eocene period, around 55 million years ago, based on evidence from the Shimla hills in India. Different schools of thought propose varying ages for the collision, with the study suggesting that the collision occurred around 55 Ma. The analysis of shale samples from the Subathu Formation in the Shimla hills revealed the presence of volkonskoite, indicating the contribution from the ophiolite and supporting the theory of the India-Ladakh arc collision. The study provides insights into the geological history of the region and the processes involved in the collision. [Extracted from the article]

The article presents the results of the study of dictyonema shales of the Baltic basin (Leningrad Oblast, Kaibolovo-Gostilitsy prospecting area) for uranium (updated data on uranium mineralization of dictyonema shales) and rare earth elements (for the first time – as a new promising raw material source). At the same time, updated author’s data on the total metalliferous content of dictyonema shales was made In relation to uranium, its average content in dictyonema shales has been clarified, the distribution of uranium in the section of sedimentary strata according to new well profiles has been given, and the features of its distribution have been clarified, in comparison with earlier authors’ publications on this object of research. For rare earth elements in dictyonema shales, the results on their concentrations on a much larger analytical material are presented (670 samples, instead of 88, data on which were published earlier). For the first time, the features of the distribution of rare earth elements over the prospecting area and in the section of sedimentary strata along the profiles of wells are illustrated. New data on the petrographic composition of dictyonema shales are presented. An additional study of mineral impurities of dictyonema shales was carried out using a new method of areal scanning of preparations with an electron probe microanalyzer using the “Feature” software module. The correlations between the concentrations of uranium and rare earths with other micro- and macroelements, the forms of uranium and rare earth elements in dictyonema shales, geochemical indicators, conditions and genesis of the formation of uranium and rare earth mineralization developed in them was clarified. Based on an earlier assessment of the resource potential of uranium and rare earths, a modern assessment of their prognostic mineral resources and possible recoverable industrial reserves and the cost of potential ore raw materials of the studied acute-deficient metals for energy and a number of important industries has been made. The authors express the opinion that the mineral resource base of uranium and rare earth elements in Russia can be significantly increased due to the presence of these critical metals in the dictyonema shales of the Baltic sedimentary basin, since only within the studied Kaibolovo- Gostilitsy prospecting area the largest uranium resources and large resources of rare earths have been discovered, which may increase even more with further geological research in the conditions of a developed infrastructure of the middle zone of the Russian Federation.