Pre-existing faults play an important controlling role in the formation and later evolution of sedimentary basins. The oblique extension of strike-slip faults cause subsidence and lead to the formation of pull-apart basins, this foundational mechanism is verified by fault interpretations from seismic reflection data, laboratory experiments, and numerical models. While this mechanism is observed in contemporaneous faults, how pre-existing thrust faults affect the formation of an overlying rift basin is still being studied. Here we reveal a set of Indosinian thrust faults and their reactivation effects within the basement of the offshore Bohai Bay Basin (OBBB), eastern China. These faults provide insights into the influence of pre-existing faults on the overlying basin. Structural analysis of seismic profiles of the OBBB show that its basinal basement developed a series of NWW-trending pre-existing faults, most of which cease at the top of the basement, though some were profoundly reactivated, crossing the unconformity upward into Cenozoic strata, hence, influencing the morphology and structural evolution of the Cenozoic Bohai Bay Basin (BBB). The NWW-trending faults were in response to the collision between the South China and North China blocks. Zircon and apatite fission-tracks reveal the fault-controlled basement suffered three intervals of uplift-cooling processes during the Late Triassic−Early Jurassic, Late Cretaceous, and Oligocene, and three corresponding intervals of subsidence-heating stages during the Early Cretaceous, Paleogene, and Neogene. The reactivations during the Early Cretaceous and Paleogene induced NWW-trending half-grabens. The strike-slip activity of the NNE-trending Tanlu Fault zone formed a set of NNE-trending pull-apart sags in the eastern BBB and reactivated some NWW-trending pre-existing thrust faults reversely with slight rotation. The two orthogonal extensions on interconnected half-grabens and strike-slip faults drove the formation of the pull-apart BBB. Broadly, pre-existing faults could partially be reactivated by later orthogonal strike-slip faults and jointly form a pull-apart rhomboid basin characterized by multiple sags.

Knowing the past temperature of the Earth is crucial for understanding the mechanisms driving climate change and biosphere evolution, but there is significant debate about the range of past temperature variation. Previous interpretations, largely based on oxygen isotope records, suggest that global temperature has generally declined over the past 539 million years, but substantial uncertainties persist. In this study, we introduce an independent estimate for long-term Phanerozoic temperature trends based on a large database of chemical weathering indices from siliciclastic sedimentary rocks, globally upscaled using a state-of-the-art general circulation paleoclimate model. Our results imply that Phanerozoic global temperatures remained within 10-30 °C, and that Paleozoic oceans had comparable temperatures to Mesozoic and Cenozoic oceans, in contrast to previous work suggesting that they were anomalously hot. This finding supports the idea that negative feedback processes, such as silicate weathering, have maintained long-term global average temperatures within a relatively tight range, contributing to the continued long-term evolution of the biosphere.

Contemporary glaciers are retreating at an alarming rate, an irreversible trend closely associated with ongoing global warming. Approximately 290 million years ago, Earth experienced a comparable large-scale glacial retreat, marking a pivotal transition of the Late Paleozoic Ice Age (LPIA) toward a greenhouse condition. This profound climatic shift, termed the Artinskian Warming Event (AWE), has been extensively attributed to volcanic degassing. Nevertheless, how continental weathering shaped climate dynamics throughout this period remains enigmatic. To address this issue, we integrated multiple geochemical proxies indicative of the carbon cycle, volcanism, and weathering, and applied the Celine Model to constrain silicate weathering fluxes. Based on the coupled variations between mercury enrichment and estimated weathering flux during the Artinskian, we propose that the AWE was not only driven by volcanic degassing but also amplified by an abrupt drop in low-latitude mafic weathering flux, rendering this interval the most intense deglaciation phase of the LPIA.

The Yangtze Block occupies a key paleogeographic position during the Ediacaran-Cambrian period. Nevertheless, its paleogeographic location and tectonic setting in global plate reconstructions for this timespan remain controversial. In this study, Ediacaran–lower Cambrian siliciclastic samples from the northwestern Yangtze Block were analyzed using detrital zircon U-Pb geochronology and trace element composition, complemented by regional geochronological datasets. Our results suggest a tectonic regime transition from extension to compression at Ediacaran–early Cambrian time. The appearance of ∼1.0 Ga and 0.7–0.5 Ga zircon age groups in the lower Cambrian strata records changing sediment provenance during Gondwana amalgamation. Provenance shifts and crustal evolution suggest a rapid paleogeographic reorganization of the Yangtze Block, linked to the assembly of Gondwana. Detrital zircon trace element signatures are compatible with a passive to convergent margin transition, synchronous with East Gondwana accretion. The northwestern Yangtze Block experienced rapid uplift and coarse clastic influx at ∼520 Ma, suggesting progressive incorporation into the Gondwana margin system

The Anisian stage of the Middle Triassic was a crucial period for Earth's surface system recovery and life radiation, which followed the long-term, oscillatory extreme warmth of the Early Triassic. The atmospheric CO2 concentrations declined rapidly from extremely high levels (2181-2610 ppmv) to near-modern values, being a key phase in the re-establishment of Earth's habitability after the Permian-Triassic Mass Extinction (PTME). The restoration of low-latitude carbonate factories and the weakening of volcanic degassing are considered the main factors for CO2 drawdown during this climate transition. Recently, successive discoveries of marine organic-rich shale intervals in cores from wells Y-2 and T-1 (Upper Yangtze Block), within the Middle Triassic Leikoupo Formation, indicate that short-term marine anoxia expanded into shallow carbonate intraplatform sag during this period. However, the connection among marine anoxic expansion event, climate, and carbon cycling remains unclear. Here we reconstructed the sedimentary environment and distribution of this organic-rich shale interval based on 31 drilling wells. Subsequently, the geochemical proxies of the paleo-water column, including primary productivity, redox conditions, paleo-salinity, and terrigenous input were restored via coring samples of wells Y2 and T-1. The results show that the Anisian stage was characterized by a window of high primary productivity and marine anoxia, synchronous with the Pelsonian Humid Climate Event. Furthermore, the enhanced reducing conditions and persistent high-salinity water in the intracratonic sag of Upper Yangtze Block promoted the efficient burial of low-latitude marine organic matter. Our findings highlight that organic-rich shale formation served as a significant carbon sink and an important driver of the establishment and maintenance of a habitable Earth during the Middle Triassic.

The Emeishan Large Igneous Province (ELIP) offers a canonical setting to examine plume-lithosphere interaction and its imprint on carbonate diagenesis on sedimentary basins. In the Sichuan Basin, Lower to Middle Permian stratiform dolomites archive ELIP-related fluid evolution. Here we integrate petrography, stable-isotope geochemistry (C-O-Sr), trace and rare-earth element data and in situ U-Pb geochronology to resolve the mechanisms and timing of dolomitization. Two dolomitization stages were identified. The first stage of dolomitization was driven by seawater convection through open fault systems and porous grainstones of the Chihsia Formation during the early phase of ELIP activity (similar to 273.2-269.1 Ma). The second stage of dolomitization took place at the peak of ELIP activity (similar to 260-259 Ma), when intensified tectonism reactivated basement faults. Seawater mixed with minor proportions of hydrothermal fluids convected along fractures, promoting both dolomite replacement and cement precipitation. Basin-scale comparisons of oxygen isotopes reveal a shift from localized thermal effects during the early stage to late-stage fluid homogenization, consistent with strong magmatic-fluid coupling. Collectively, we reveal that fault-controlled thermal convection in open-platform settings was the dominant driver of dolomitization, with hydrothermal fluids providing a limited overprint. These findings clarify the multiphase influence of ELIP on fluid dynamics and carbonate diagenesis, and provide new insights into the regulation of Large Igneous Provinces on basin-scale diagenetic systems.

To reveal the core mechanisms controlling the large-scale accumulation of ultra-shallow natural gas in the ultra-deep water Lingshui 36-A area of the Qiongdongnan Basin, to solve the scientific problems that are difficult to explain by traditional accumulation theory, and to provide theoretical support for the exploration and development of similar gas fields, this study takes the LS36-A ultra-shallow gas field as the research object. Based on the regional geological background, the key accumulation conditions and accumulation model were systematically investigated by adopting an integrated multidisciplinary method, including geochemical analysis, microscopic observation of reservoir characteristics, fluid inclusion homogenization measurements, seismic interpretation, and burial history simulation using PetroMod software. The results showed that the shallow gas in the gas field was of mixed origin, mainly thermogenic gas generated from the source rocks of the Yacheng Formation in the Lingshui Sag. The reservoir was composed of submarine fan sandstone of the Quaternary Ledong Formation, exhibiting high-quality reservoir properties such as high porosity and high permeability. The caprock was composed of gas hydrate-bearing strata, deep-sea mud, and mass transport deposits, which were spatially superimposed to form a composite sealing system. Conduction channels included long-distance lateral migration channels and short-distance vertical migration channels, with lateral migration contributing more significantly to gas accumulation. Analysis of key accumulation conditions showed that conduction was the prerequisite for ultra-shallow natural gas accumulation, and preservation was the fundamental factor determining the location and scale of accumulation. Through fluid inclusion homogenization temperature measurements and burial history restoration, it was determined that the gas field experienced ultra-late-stage dynamic charging since 2 Ma. A dynamic accumulation model dominated by long-distance lateral migration superimposed by short-distance vertical migration was established. It was clarified that the LS36-A gas field was a large quasi-steady secondary ultra-shallow gas reservoir exhibiting unique oil and gas migration characteristics. This study clarifies the gas source supply, migration pathways, and accumulation process of the gas field, providing an important reference for ultra-deep water and ultra-shallow oil and gas exploration worldwide.

The Late Paleozoic Ice Age (LPIA) represents a unique interval in Earth history, characterized by long-lived glaciation on a vegetated continent and a protracted transition toward greenhouse climate. The LPIA culminated in the Early Permian (early Asselian) and subsequently underwent sustained deglaciation from the late Asselian onward, coincident with a pronounced peak in marine biodiversity. Despite this temporal association, the mechanisms linking climatic warming to marine biological expansion during the early Permian icehouse remain poorly constrained. Here, we investigate a well-preserved marine carbonate succession from the Dian–Qian–Gui Basin, South China, integrating sedimentological observations with multiple geochemical proxies to reconstruct paleoenvironmental evolution across the Carboniferous–Permian transition. The proxy records unveil a three-stage paleoenvironmental evolution. Notably, Interval 2 (late Asselian) is marked by a coherent shift toward intensified perturbations of carbon cycle, enhanced continental weathering, elevated marine primary productivity, and improved seawater oxygenation. These coupled changes are likely driven by a global climatic event (Late Asselian Warming Event, LAWE), indicating that, under warming conditions within an icehouse climate, synergistic feedbacks among continental weathering, marine productivity, and oceanic redox state collectively promoted more habitable marine environments, thereby facilitating marine biodiversity expansion. This study provides a new deep-time case of how feedback mechanisms linking marine environmental evolution with climatic warming under Earth icehouse state.

The Central Asian Orogenic Belt (CAOB), an accretionary orogen with components of oroclinal bending locally, underwent complex accretionary-compressional orogenesis and characterized by a series of ranges and basins within its landscape since the Paleozoic. But how did the CAOB’s tectonic history couples with its interior basin evolution remains unclear. Based on detrital zircon U-Pb geochronology, and Lu-Hf isotope analysis, we quantitatively investigate the variations of the source-to-sink system from the Late Permo-Triassic sedimentary rock of the CAOB’s Bogda region and constrain the related tectonic evolution history and geodynamic processes. The results show that the Late Permo-Triassic sediments in the Bogda are mainly derived from the Central Tianshan, followed by the North Tianshan, East Junggar, and internal Bogda basement that launched in the Middle-Late Triassic, implying these surrounding ranges, the Tianshan, East Junggar, and Bogda, successively experienced varied uplift. Combined with the reported igneous age population, interpretation of basinal seismic profiles, and sedimentological stratigraphic frame, our results of the source-to-sink restoration reveal Bogda underwent the evolution process that was from the Early-Middle Permian a back-arc rift basin of strike-slip feature to the Late Permian-Early Triassic a depression basin, and evolved into a strongly compressed foreland basin during the Middle-Late Triassic. The Late Permian-Early Triassic tectonic inversion recorded by the unconformity was a response to the counterclockwise rotation of blocks that was caused by the oroclinal bending of the CAOB collage process, which possibly resulted from long-term effects of the final closure of Paleo-Asian Ocean (PAO) from west to east during the Permo-Triassic. These episodes of the basin and ranges system evolution signify the transition of the CAOB from an extensional accretionary orogeny to a compressional accretionary orogeny.

The Jurassic sedimentary rocks in the Sichuan Basin are a natural archive for resolving the controversy about the Early and Middle Jurassic tectonic evolution of the Qinling Orogenic Belt (QOB) after the closure of the Paleo-Tethys Ocean. This study focuses on the Nuoshuihe and Guanghuicun sections in the northeastern margin of the Sichuan Basin, providing new data on sandstone petrography, heavy minerals, and detrital zircon geochronology. The evolution of drainage pathways in the Early to Middle Jurassic is quantitatively reconstructed using the DZmix program and both new and published detrital zircon geochronology data. The sediments of the Lower Jurassic Ziliujing Formation, corresponding to the post-orogenic extension stage revealed by published igneous rocks, were mainly derived from the Yangtze Craton (YZC; average 98 %), sediment supply to the Middle Jurassic Lianggaoshan Formation transitioned gradually from the northern margin of the YZC (average 72.6 %) in the Lower Member to the QOB (average 84.2 %) in the Middle and Upper members. The percentage derived from the YZC increased again in the Shaximiao Formation (75 %). Previous sedimentological studies in the Sichuan Basin show that the lacustrine depocenter of the various members migrated from southeast to northwest, together with the deformation time of strike-slip shear zones in the QOB published by mylonitic rocks Ar-40/Ar-39 data (similar to 178-143 Ma), all suggesting the short-time intracontinental orogenic uplift of the QOB during the deposition of Lianggaoshan Formation after post-collision extension. Based on these findings, we can infer that the long-range effects of the Paleo-Pacific Plate subduction along the East Asia or/and asynchronous closure of the Paleo-Tethys Ocean, could be potential mechanisms driving block rotation and intracontinental orogenic adjustments in the Middle Jurassic, rather than continuous collisional orogeny since Middle Triassic.

The Emei Mountain large igneous province (ELIP) affected the formation of Middle Permian dolomite in the Sichuan Basin, but the specific mechanisms of this influence remain unclear. We combined data from petrology, geochemistry, laser U-Pb isotope dating and fluid inclusion microthermometry to determine the properties of the diagenetic fluids and the diagenetic model of dolomitization. We also considered the relationship between the dolomitization process and the ELIP. We identified four types of dolomite: micritic to finely crystalline matrix dolomite with a preserved original structure (Md1, <50 mu m); fine- to medium-grained crystalline euhedral-subhedral matrix dolomite (Md2, 50-300 mu m); medium- to coarse-grained crystalline allotriomorphic matrix dolomite (Md3, 250-800 mu m); and coarse-grained to macrocrystalline saddle-shaped cemented dolomite (>500 mu m). The Md1 dolomite shows a dark orange-red fluorescence under cathodoluminescence. The rare earth element (REE) + Y distribution pattern, Mn content, delta C-13, delta O-18 and Sr-87/Sr-86 ratios of the Md1 dolomites are similar to those of marine carbonates from the same time period. This suggests that the diagenetic fluid was seawater that did not undergo significant evaporation during the penecontemporaneous period. By contrast, the homogenization temperature and salinity of the inclusions in the Md2 dolomites are higher than both the temperature of shallowly buried strata and the salinity of seawater from the same time period. The U-Pb isotope age of the Md2 dolomites (262.1 +/- 6.5 Ma) is consistent with the stratigraphic age. The diagenetic fluid was high-salinity seawater that had been concentrated as a result of an increase in the residual temperatures in the formation pores. The Md3 and cemented dolomites appear bright red under cathodoluminescence and show a positive Eu anomaly in the REE + Y distribution pattern. The Mn content, Sr-87/Sr-86 ratio, homogenization temperature and salinity of the inclusions are significantly higher than those of the other types of dolomites. The U-Pb isotopic age of the Md3 dolomites (254.2 +/- 6.4 Ma) is closer to the active period of the ELIP (259-258 Ma), whereas the U-Pb isotopic age of the cemented dolomites (244.5 +/- 3.2 Ma) suggests that the hydrothermal activity of the strata had weakened and its formation is more likely to be a result of burial diagenesis. The diagenetic fluids associated with the Md3 and cemented dolomites are primarily hydrothermal fluids that had migrated along faults. In our diagenetic model, the Md1 dolomites resulted from seepage reflux dolomitization, the Md2 dolomites from thermal convection dolomitization, the Md3 dolomites from the superposition of thermal convection and tectonic-hydrothermal transformation, and the cemented dolomites from the precipitation of a mixed hydrothermal-seawater dolomitization fluid. Among these, the Md3 dolomites form most promising reservoir rocks and should be the focus of future exploration. This study offers valuable insights for research on high-temperature hydrothermal systems.

Recent exploration has confirmed industrial gas flows from several wells in the western Ordos Basin, suggesting considerable hydrocarbon exploration potential. However, prior research on characteristics of tight sandstone reservoirs, diagenetic evolution, and controlling factors in the Upper Paleozoic of western Ordos Basin remains limited. Here, underpinned by extensive cast thin-section identification and integrated with field emission scanning electron microscopy, nuclear magnetic resonance, and mercury intrusion porosimetry, we investigated the characteristics of tight sandstone reservoirs in the western part of the Upper Paleozoic strata of the Ordos Basin and examined the impact of various factors on the formation of high-quality reservoirs. There are differences in sandstone composition and type, and reservoir properties among different formations of the Upper Paleozoic of western Ordos Basin. The main pore types in the Carboniferous Yanghugou Formation and the Permian Taiyuan Formation were intergranular pores and dissolution pores of lithic fragments, whereas in the Permian Shanxi Formation and He 8, the main pore types were intercrystalline pores of clay minerals and dissolution pores of lithic fragments. In terms of physical properties, the reservoirs of the Upper Paleozoic in the western Ordos Basin have low porosity and low permeability. However, the Permian Taiyuan Formation and He 8 demonstrate better pore-throat connectivity than other stratigraphic levels. The formation of high-quality reservoirs in the Upper Paleozoic of the western Ordos Basin is governed by multiple factors. The Permian Shihezi and Shanxi formations within the alluvial plain facies, Taiyuan Formation barrier bar facies, and Yanghugou Formation delta front facies exhibited the best physical properties. Variations in the original parent rock led to different types of reservoir rock fragments, with a higher content of porosity-enhancing rock fragments correlating to stronger dissolution effects. Diagenetic processes influence reservoir preservation and development, with rapid burial and compaction being the main causes of densification in the Yanghugou Formation. Cementation impacts reservoir interactions differently over time. Fracture systems in the study area play a key role in improving reservoir permeability. This study offers a scientific foundation for energy-efficient exploration of low-permeability craton basins and new insights for predicting unconventional resources in global marine-to-continental sedimentary systems.

The formation of large-scale dolomite reservoirs in the Middle Permian of Northwest Sichuan shares a good temporal correlation with the occurrence of major events in the Emeishan Large Igneous Province (ELIP). However, because the dolomitized fluids, the timing of dolomitization and the genesis mechanism of the dolomites are not comprehensively understood, its developmental pattern requires further analysis. This paper identified the diagenetic fluids of different types of dolomites via petrological characteristics of dolomites, carbon and oxygen isotopes, strontium isotopes, and other geochemical data, as well as fluid inclusions and laser U-Pb isotope dating. The dolomite genesis model related to the dynamical formation mechanism of the ELIP was also reconstructed. The Middle Permian dolomites in Northwest Sichuan are divided into matrix dolomite (Md) and cement dolomites (Cd). Importantly, the matrix dolomites include very finely to finely crystalline matrix dolomite (Md1), finely to medium crystalline matrix dolomite (Md2), and medium to coarsely crystalline matrix dolomite (Md3). The dolomites were primarily modified by three phases of dolomitizing fluids. The Md1 phase yields a U-Pb age of 262 +/- 9.2 Ma, consistent with the host stratigraphic age, and exhibits 87Sr/86Sr ratios matching Permian seawater values. These features indicate Md1 formed dominantly through penecontemporaneous seawater reflux dolomitization. In contrast, the Md2 phase shows a U-Pb age of 261.3 +/- 7.4 Ma-also stratigraphically consistent-but contains later-stage subsurface cements with a distinct U-Pb age of 245.7 +/- 1.9 Ma. This significant age offset demonstrates that Md2 resulted from overprinting by multiple dolomitizing fluid phases. These fluids were mainly formed owing to the temperature difference between the warming stratigraphic water and the cold seawater in the ELIP under the geothermal warming effect. The cold seawater on the slope creates a fluid potential energy difference, generating lateral open circulation and causing thermal convection. Furthermore, Md3 and Cd have negatively skewed delta 18O values, along with higher Th and Eu/Eu* values, suggesting that the diagenetic fluids were substantially shallow buried strata water, which resembled Permian seawater. They were mostly produced under the higher geothermal temperatures during the ELIP active period, which generated a substantial fluid potential energy difference, and were driven by a more rapid thermal convection cycle. This study quantitatively constrains the timing of dolomitization using laser U-Pb isotope dating, aiming to give a reliable and valuable reference for the impact of tectonic activities on dolomite genesis caused by the Large Igneous Province.

Dolomitization is a critical diagenetic alteration that impacts the formation of carbonate hydrocarbon reservoirs. In the offshore Bohai Bay Basin, the Lower Paleozoic carbonate reservoirs in buried hill traps, and the basement highs unconformably overlain by younger rock units, are emerging as a prospective target and predominantly occur in dolomite layers. Meanwhile, the formation mechanisms of the dolomite are not clear, which affects the understanding of the occurrence of deep dolomite reservoirs and hinders oil and gas exploration. Based on comprehensive observations of the thin sections of the carbonate samples, the dolomite types were meticulously categorized into micritic dolostone, fine-crystalline dolostone, and saddle dolomite. Then, carbon, oxygen, and strontium isotope and trace elements were examined to elucidate the dolomitization fluids and propose diagenetic models for the three kinds of dolomite formation. The mineralogical and geochemical evidence reveals that there were two kinds of dolomitization fluids, including penecontemporaneous seawater, and hydrothermal fluid. The diagenetic fluid of the micritic dolostone and fine-crystalline dolostone both involved penecontemporaneous seawater, but fine-crystalline dolostone is also affected by later burial dolomitization processes. The saddle dolomite, filling in pre-existing fractures or dissolution pore cavities, is attributed to a hydrothermal fluid associated with magmatic activities. Notably, the extensive layered fine-crystalline dolostone was the predominant reservoir rock. The initial mechanism for its formation involves penecontemporaneous seepage reflux dolomitization, which is superimposed by later burial dolomitization. The burial dolomitization enhanced porosity, subsequently facilitating the formation of a fracture-related dissolution pore cavity system, and partly filled by saddle dolomite during the Cenozoic hydrothermal events. The findings highlight that the layered fine-crystalline dolostone that underwent multiphase dolomitization is the most potential target for hydrocarbon exploration.

The Late Paleozoic Ice Age (LPIA) was a series of modulated glacial-interglacial pulses that characterized the climate of the late Carboniferous through Permian. Although the ages and durations of the main major episodes of the LPIA have been calibrated from glacial deposits in eastern Australia and elsewhere, the causal factors for the final transition from the oscillating icehouse climate to a continuous hothouse remains uncertain. To aid in unraveling the potential causes for this climatic turnover and its characteristics in the tropical latitudes, we measured the weathering indices and redox proxies recorded by the Lopingian (Late Permian) strata in the Shangsi section of the Upper Yangtze region in South China. The multiple weathering indices derived from the geochemical composition of the acid-insoluble residues in the carbonate rocks exhibit consistent trends. These trends, when combined with published coeval weathering data from other regions, trace four global phases of weathering changes during the late Permian. After the middle Wuchiapingian, the observed increase in the weathering indices and a negative excursion in carbon isotope are apparent responses to gradual warming. The simultaneous increase in ocean oxygenation may have also played a role in the deglaciation. Based on the changes in tropical exposed land area through the late Permian, we quantitatively estimated the low-latitude chemical weathering flux by combining contemporaneous weathering indicators. The curve of that estimated flux support the hypothesis that a sustained decrease in low-latitudes weathering flux, the implied apparent decrease in the amount of exposure and total weathering of silicate rocks, may caused a weakening of the carbon sink and a continuous accumulation of atmospheric CO2, which in turn facilitate the stepwise deglaciation of LPIA and the onset of a long-term hothouse climate.

Significant uncertainties persist regarding the depositional environment, tectonic affinity, and geodynamic significance of the extensively exposed Neoproterozoic Yaolinghe Group rocks in the South Qinling Belt (SQB) and the northern margin of Yangtze Block (NYZB), hindering the interpretation of their sedimentary record, regional tectonic evolution, and role in Rodinia assembly-breakup dynamics. This study conducted comprehensive investigations on sedimentary rocks in both the Zhenping and Langao areas. By utilizing LA-ICP-MS zircon U-Pb isotope analysis and integrating previous data, our findings indicate that these sedimentary rocks were deposited during the early to middle Cryogenian period. Lu-Hf isotope analysis reveals a wide range of epsilon Hf(t) values for sample ZP-4, ranging from -17.22 to 10.47 with an average of -4.7, indicating reworked ancient crust as their source material. Sample LG-6 from Langao exhibits a range of epsilon Hf(t) values, ranging from -18.56 to 11.18, with an average value of -2.7; a subset of younger detrital zircons (<750 Ma) displays positive epsilon Hf(t) values, suggesting the incorporation of material eroded from juvenile crust. Furthermore, the presence of sedimentary rock fragments within the Yaolinghe Group deposits suggests the exhumation and subsequent redeposition of ancient sedimentary sequences, such as the Wudang Group, Nantuo Formation, and Liantuo and Gucheng Formations, took place along the northern margin of the Yangtze Block and South Qinling Belt. Notably, the Zhenping area lies within an intracontinental rift zone. In contrast, the Langao area in the SQB appears to have been closer to the outer continental margin and significantly influenced by adjacent sources, including early or contemporaneous magmatic zones. In conjunction with regional data, we propose that the SQB transitioned from early subduction accretion to late-stage extensional rifting during the Cryogenian. This sequence of events may represent the response of the marginal blocks of the Rodinia supercontinent to the final rifting during the Middle to Late Neoproterozoic.

The Leikoupo Formation of the Middle Triassic is one of the earliest strata for oil and gas exploration in the Sichuan Basin, but its exploration has long been limited to scattered small gas fields. Recent studies reveal that the Leikoupo Formation holds dual prospects for marine conventional and unconventional oil and gas reservoirs, but the existing paleogeographic pattern is inadequate for the new exploration needs. This study focused on the Leikoupo Formation in the southern Sichuan Basin. Based on the detailed analysis of sedimentary facies in outcrops and drill cores, the lithofacies paleogeography was reconstructed and the sediment and reservoir development patterns were studied. The sedimentary environment types in the Middle Triassic Leikoupo Formation of the southern Sichuan Basin included platform tidal flats, tidal shoals, shelf bays, and saline lagoons. During the transgression period (members 1 and 3 of the Leikoupo Formation), relatively high-energy marine conditions favored the development of high-energy shoal facies and organic-rich mudstone or marl. During the regressive period (members 2 and 4 of the Leikoupo Formation), the energy was relatively lower, favoring the development of dolomite and evaporite successions. The development of conventional carbonate rock reservoirs in the Leikoupo Formation of the southern Sichuan Basin was primarily controlled by the paleogeomorphic pattern. The combined effects of wave and tidal actions led to the extensive distribution of thin shoal-facies dolomite reservoirs. The transgression during the depositional period of member 3 of the Leikoupo Formation played a significant role in the formation of unconventional reservoirs of organic-rich mudstone or marl. It not only altered the original paleogeomorphic pattern but also transported organic-rich clastic materials from the Badong Formation into the interior of the Upper Yangtze Craton. Under intense evaporation during the later stages, intersalt hydrocarbon reservoirs with a "salt rock and marl" cycle were formed. The paleogeographic reconstruction in both conventional and unconventional domains of the Leikoupo Formation in the southern Sichuan Basin not only reveals a new exploration area for marine intersalt unconventional resources, but also confirms the favorable conditions for the development of high-quality source rocks within the formation.

The Permian-Triassic mass extinction was one of the worst crises for life on earth, killing >90% of marine species, which induced the carbon cycle perturbation during the entire Early Triassic. Previous studies indicated the global CO2 concentration dropped sharply from 2,800 ppmv to a level of approximately 450 ppmv (comparable to the present) at the Early–Middle Triassic boundary. This optimal CO2 level, a stabilized record of 2‰ δ13Ccarb, persisted throughout the Middle Triassic. While how this long-term habitable CO2 level was maintained remains puzzling. Here, we examined the sedimentary succession that spans the duration from Late Olenekian (late Early Triassic) to Anisian (Middle Triassic), Upper Yangtze Block. The results show that the volume content of microbialites in the carbonate succession increased significantly after the transition from lower thin-bedded dolostones to upper thick-bedded microbialites, indicating the carbon pump shifted from a low-rate chemical carbonate production system to a high-rate microbial carbonate factory. The expansion of microbial mats responded to enhanced terrigenous input and elevated primary productivity. Coincidentally, the δ13Ccarb curve records a change from strong oscillations to a long-term stability. This turnover coincided with the occurrence of plant fossil assemblages (e.g., from northern Italy) and marine fossil assemblages (e.g., from South China). The findings indicate that the enhanced microbial pump, as a dynamic mechanism for atmospheric CO₂ sequestration, was a key modulator of the Middle Triassic global climate system and helped sustain more resilient ecosystems.

The Cisuralian-Guadalupian transition (CGT) was a key conversion period from the Late Paleozoic Ice Age (LPIA) to the Mesozoic Greenhouse. This period witnessed a dramatic increase in seawater temperature, atmospheric pCO2 and sea level, accompanied by the Kungurian Carbon Isotope Excursion (KCIE) event. Large-scale carbon cycle perturbation is closely linked to ocean redox condition, playing a profound role in both ecological and environmental evolution. However, the temporary changes and underlying mechanisms of ocean redox condition remain unclear in this period. The Yangtze Platform of South China developed a continuous shallow-water carbonate record during the CGT period, providing an excellent archive for deciphering shallow marine redox conditions. In this study, we analyzed carbon isotope and Ce anomaly from the Chihsia Formation at the Dukou section, Upper Yangtze Platform. Our results unveil that the shallow marine underwent four intervals of oxidation, anoxia, oxidation and suboxic condition during the CGT period. The positive Ce anomaly coincides to the negative carbon isotope excursion, indicating a close connection between ocean anoxia and the KCIE event. Volcanic activities, methane seepage, and wildfires combine to release light carbon into the atmosphere and triggered the KCIE event, causing rapid climatic warming and melting of high-latitude glaciers associated with P2 glaciation. Furthermore, the weakening of ocean ventilation, the expansion of the oxygen minimum zone (OMZ), and extensive transgression drove widespread ocean anoxia during the KCIE event, ultimately may play an important role in significant decline in biodiversity.

In contrast to the high-frequency, large-scale carbon isotope fluctuations of the Early Cambrian, the Miaolingian delta 13Ccarb record exhibits notably stable, disrupted only by a brief and minor negative excursion, known as the Drumian Carbon Isotope Excursion (DICE) event. Despite this apparent stability in the carbon cycle, limited research on the Miaolingian marine environment raises questions about whether the paleoceanographic conditions were similarly stable. This study addresses these uncertainties by analyzing carbon isotope and major and trace element data from carbonate fractions of samples from the Wangcun section in South China to reconstruct the evolution of the Miaolingian paleoenvironment. During the pre-DICE phase, continental weathering and primary productivity were relatively low, and redox conditions were relatively oxygenated. During the DICE event, concentrations of water-insoluble elements (Al, Ti, Zr, Sc, Th, and Hf) increased significantly, indicating intensified continental weathering. Concurrently, productivity-sensitive indicators (Ba/Al, Ni/Al, Cu/Al, and Zn/ Al) suggest heightened primary productivity, driven by increased weathering. Redox-sensitive indicators (U/Al, V/Al, Mo/Al, and Mo/U) reveal that bottom waters became anoxic during the DICE event. Following the DICE, continental weathering and primary productivity returned to low levels with minor fluctuations. However, redox conditions transitioned back to stable oxygenated levels similar to those observed in the pre-DICE phase, exhibiting partial decoupling from productivity. This may reflect the overall stability of the Miaolingian marine environment. Notably, no mass extinctions were recorded during the DICE period, further underscoring the resilience of the ecosystem. This stability might be attributed to the co-evolution of life and the marine environment during the Cambrian explosion, fostering a relatively resilient and stable marine ecosystem throughout the Miaolingian Epoch.