Extensive natural gas dissipation linked to late-stage transformation occurred in the northeastern Ordos Basin. However, the existence of long-distance gas migration, accumulation, and dissipation in the Ordos Basin remains a subject of scientific contention. On the basis of outcrop-core data, combined with calcite U-Pb dating, C-O-Sr isotopes, vitrinite reflectance (Ro), fluid inclusions, and gas geochemistry, this research systematically investigated the characteristics and mechanisms of long-distance lateral migration and dissipation of natural gas and revealed a unique gas accumulation model. Research indicates that the alteration phenomena of bleached and carbonate-cemented sandstones (CCSs) associated with long-distance gas migration-dissipation are widespread in the northeastern basin. Organic-derived CCSs are closely related to hydrocarbon-bearing hydrothermal fluids, indicating that large-scale Upper Paleozoic high-maturity coal-derived hydrocarbons provide organic carbon sources. Analyses revealed that natural gas dissipation in the Ordos Basin initiated during the late Early Cretaceous, followed by multiple episodes of large-scale dissipation. The Hangjinqi gas field serves as the preferential zone for natural gas migration-dissipation from the central generation kitchen of the basin. A striking maturity contradiction exists between the local source rocks and the natural gas in the Hangjinqi gas field. The natural gas in this gas field is characterized by multi-source hybrid accumulation. The hydrocarbon accumulation period in Hangjinqi and its southern adjacent gas fields (Sulige-Wushenqi) coincided with or slightly preceded the reservoir densification period. Approximately 36 %-74 % of the natural gas within the field is derived from the Sulige-Wushenqi gas field, with migration distances exceeding 130 km, demonstrating a far-source allochthonous accumulation model. This phenomenon is exceedingly uncommon in continental petroliferous basins. The long-distance lateral hydrocarbon migration in extensive monoclinal zones of large basins results from the coupled interplay of sedimentary continuity, structural-reservoir conduit efficiency, seal integrity, and adequate hydrocarbon sourcing and is predominantly observed in marine petroliferous basins.

Stable intraplate cratonic blocks usually have less structural deformation and fewer earthquakes than other locations on Earth, but with strong compressional deformation around their periphery. Investigating how and why this different deformation occurred is beneficial for understanding why the cratonic block is so stable and how the intraplate in-plane stress is transmitted. In this work, we first investigated the structural deformation changes from the margin to the interior of the western Ordos Block (OB; one of the most tectonically stable area in China) via seismic data. The results show abrupt structural deformation changes from the margin to the interior of the OB in terms of the deformation strength (from strong to weak), structural orientation (high angle oblique relationships), and kinematics (from compression to wrenching). Our investigation also shows that such phenomena are widespread in cratonic blocks worldwide. The abrupt changes are probably induced by special in-plane stress transfer inside the cratonic block: when far-field stress is transmitted into continental interiors from active plate margins, the weak belt around the cratonic block filters and accommodates the in-plane stress. Consequently, this decreases the stress, changes the stress direction, and transmits the in-plane stress along a shallower layer (probably less than 1500 m). Furthermore, the compression stress from the plate margin is converted into shear stress within the cratonic block. This stress transmission manner makes reactivation of the deep preexisting faults difficult under far-field horizontal plate-boundary stresses in the cratonic block without vertical forces from the mantle, guaranteeing long-term stability and low seismicity. This understanding can provide a new perspective for the interpretation of earthquakes in stable continental regions. It can also be applied to appraise the long-term stability of sites for the storage of CO2.

Abstract Topographic highlands commonly develop along convergent plate boundaries through long‐term processes such as subduction and continental collision. However, the pre‐Cenozoic mountain‐building history of deep‐time orogenic systems in northeastern Pangaea remains poorly constrained due to later tectonic overprinting and denudation. Here we present detrital zircon U–Pb–Hf data to reconstruct the Phanerozoic provenance and exhumation of the northern North China Craton (NCC). Our results indicate that the Inner Mongolia Paleo‐uplift of northern NCC margin was the primary source of Late Paleozoic–Mesozoic sediments in the region. Integrated with crustal thickness estimates, thermal histories, and paleogeographic reconstructions, our results demonstrate >300 Myr of continuous exhumation along the northern NCC margin, defining it as a long‐lived topographic highland. We attribute this protracted uplift to the successive closure of the Paleo‐Asian and Mongol–Okhotsk oceans, which maintained a convergent tectonic regime in the northeastern Pangaea.

The detrital record of metamorphic core complex (MCC) exhumation in supra-detachment basins can be affected by the incorporation of magmatic arc in highly extended terrains. However, the interplay between MCC exhumation and arc-related sediment input in such basins remains elusive due to the lack of a natural analogue. Here, we present new detrital zircon U-Pb geochronology data integrated with sandstone petrology to examine the patterns of basin fill of the Jurassic Qiangtang Basin in the Tibetan Plateau. Detrital zircon U-Pb ages of sandstone samples from six sections show significant temporal variations, which can be classified into two distinct groups. Type-1 is characterized by a narrow unimodal age distribution, with a diagnostic peak corresponding to continental arc timings. Type-2, in contrast, exhibits a multimodal distribution with much older populations. Comparison of our new data with existing age spectra shows that the basin was primarily filled by detritus derived from magmatic arcs during the Hettangian and Callovian stages, followed by a reorganization of drainage system that incorporated the MCC as a major sediment source. Provenance cyclicity, which exhibited by alternation of Type-1 and Type-2 age signatures that can extend further back to the Late Triassic, is interpreted to correspond with multistage extension of the MCC and magmatic arc flare-ups. The Jurassic Qiangtang Basin thus not only illustrates the interplay between MCC exhumation and arc magmatism in feeding a supra-detachment basin during the early stage of tectonic development of the Tibetan Plateau, but also highlights the importance of detachment faulting in driving sediment dispersal patterns.

The mechanism of Cenozoic lithospheric thinning in the western North China Craton (NCC) remains debated. To address this issue, we conducted an integrated geochronological, geochemical and isotopic study of the Daihai alkali basalts. Ar-40/Ar-39 dating yields eruptive ages ranging from similar to 24 to similar to 16 Ma, which record multi-episodic magmatism. These eruptions constitute part of a broader, eastward-migrating magmatic phase that initiated in the Late Eocene and comprised four distinct eruptive episodes in the western NCC. Geochemically, these basalts have SiO2 and alkali (K2O + Na2O) contents ranging from 42.54 to 51.90 wt% and from 3.90 to 7.25 wt%, respectively. They display oceanic-island-basalt (OIB)-like trace element and isotopic patterns, characterized by enrichment in incompatible elements (e.g., Nb/U = 37-90, Ce/Pb = 10-21), relative enrichment in light rare earth elements (LREEs; (La/Yb)(N) = 4.8-12.9) and the absence of negative Sr and Eu anomalies. They have low Sr-87/Sr-86 ratios (0.70417-0.705581), high Nd-143/Nd-144 (0.512387-0.512818) and Hf-176/Hf-177 (0.282717-0.282988) ratios and Pb isotopic compositions of Pb-206/Pb-204 = 16.8998-17.8061, Pb-207/Pb-204 = 15.3665-15.5483 and Pb-208/Pb-204 = 37.1192-37.9121. The Daihai basalts show negligible alteration or crustal contamination. They primarily underwent fractional crystallization of olivine and clinopyroxene. Geochemical compositional variations are primarily controlled by 2%-7% partial melting of a peridotitic asthenospheric mantle. Isotopic data further indicate that the mantle source represents a mixture of prevalent mantle (PREMA) and enriched mantle I (EMI) components. The lithospheric thickness beneath the Daihai region is estimated to be < 80 km, locally approaching similar to 50 km, confirming significant Cenozoic thinning with notable spatial heterogeneity across the western NCC. We suggest that both the petrogenesis of these basalts and the associated lithospheric thinning were jointly controlled by mantle flow stagnation, induced by the combined effects of Pacific Plate subduction and the Indo-Eurasian collision. The observed spatial heterogeneity in lithospheric thickness is interpreted to reflect variations in the degree of this mantle flow stagnation and the magnitude of associated upwelling. This study thus provides direct evidence linking intraplate volcanism in the western NCC to deep geodynamic processes and associated lithospheric thinning.

The Carboniferous-Permian source rocks in the Ordos Basin display significant spatial heterogeneity in thermal maturity, highest in the southeast. Previous local studies based on scattered well data suggested gas generation peaked in the Early Cretaceous and deep burial as the primary control. Due to limited data in under-explored areas, a comprehensive understanding of basin-wide thermal evolution and its controls remains lacking. To address this gap, we reconstructed the thermal maturity history by integrating data from 81 drilled and 44 pseudo wells. Our results reveal four subsidence-uplift cycles since 200 Ma, with thermal evolution peaking in the late Early Cretaceous. Thermal evolution exhibits spatial partition controlled by multiple mechanisms. Based on differentiation of burial history and thermal evolution pathways, the whole basin can be divided into four regions. Deep burial heating is ubiquitous but dominant only in the western and northern basin; Early Cretaceous magmatism exerted only a localized effect; the southeastern high thermal anomaly results from superimposed deep burial and a regional tectono-thermal event. We propose that this tectono-thermal event was driven by the superposition of two subduction processes: westward subduction of the Paleo-Pacific Plate during the Early Cretaceous and northward subduction of the Yangtze Plate since the Mid-Late Triassic. This plate interaction triggered deep heat flow diversion, forming a regional high thermal anomaly belt in the southern North China Craton. This study provides critical insights for evaluating and exploring deep coalbed methane resources in the Ordos Basin and offers a new methodology for thermal history reconstruction in data-poor areas.

Black shales play a significant role in the global carbon cycle, serving as sites for organic carbon burial and facilitating matter and energy exchanges between the Earth's spheres. However, the mechanisms driving these processes remain controversial, particularly regarding the onset of the extensive Middle-Late Triassic organic carbon burial in the North China Craton (NCC). In this study, we summarize 5009 detrital zircon UPb ages along with five new samples integrated with seismic reflection profiles, boreholes, field outcrop and sandstone petrographic analyses. Our findings reveal a significant provenance shift in the southern NCC, transitioning from distal to proximal recycling during the deposition of the late Middle Triassic black shale. This shift was driven by coeval tectonic uplift and volcanism in the Qinling Orogenic Belt. Paleogeographic reconstructions indicate that by the Ladinian stage, the western NCC had transformed into an endorheic, underfilled lacustrine basin with potential for intermittent marine transgression. Combining our findings with previous paleoclimate and tectonic studies, we propose that intense regional tectono-thermal activity, triggered by the subduction and closure of the eastern Paleo-Tethys Ocean, rather than global climatic forcing alone, was the driver of the extensive Middle-Late Triassic organic carbon burial in the NCC. This study provides the tectonic insights into the sedimentary processes of black shales and their implications for terrestrial organic carbon burial during the Middle-Late Triassic period.

The Qingyang-Etuokeqi Paleo-Uplift (QEPU) in the Ordos Basin is a significant paleo-structural feature. However, debates persist regarding both the timing of its initial basement uplift-whether it occurred during the Cambrian or Ordovician-and the dominant geodynamic mechanism-specifically, whether it was driven by crustal extension related to adjacent aulacogens or by compressional stresses associated with the Caledonian Orogeny. This study integrates seismic, drilling and well-logging data to identify three regional unconformities and syn-sedimentary normal faults. Seismic facies analysis reveals onlap onto the base of the uplift and truncation at its crest. Middle Cambrian strata maintain a consistent thickness in areas distal from the structure, whereas the Upper Cambrian and Lower Ordovician units progressively thin and pinch out towards the QEPU, and are diachronously overlain by Middle Ordovician deposits. Due to erosional truncation, Middle Cambrian and Middle Ordovician strata are absent in the central part of the uplift. Our results indicate that the QEPU was initiated during the Early Palaeozoic and underwent five distinct evolutionary stages prior to its Carboniferous burial. This evolution was driven by tectonic interplay among the Qinling Ocean to the south, the ancient Qilian-Qinling Ocean to the west, and the Helan Rift Trough to the north. This study clarifies the tectono-stratigraphic evolution of the QEPU and provides an essential framework for regional tectonic reconstruction and hydrocarbon exploration in the southwestern North China Craton.

The deep-seated processes in the Earth's interior significantly influence surficial geological systems by transporting energy and matter upwards, with volcanic and hydrothermal activities being intrinsically linked to tectonic dynamics. However, the mechanisms by which volcanism and hydrothermal circulation regulate sedimentary environments and organic carbon enrichment remain insufficiently constrained. In this study, we investigated fully cored scientific drillholes from a deep-lacustrine depocenter in the southeastern Ordos Basin, obtained by high-resolution continuous sampling of the Chang 7(3) sub-member of the Yanchang Formation. Integrated zircon UPb geochronology, petrography, and multiparameter geochemical analyses identified three distinct sedimentary end-members based on Zr/Al and (Fe + Mn)/Ti ratios: Non-hydrotherma/lvolcanic activity (NHV), hydrothermal-dominated activity (HA), and volcanism-dominated activity (VA). Paleoclimate reconstruction reveals warm-humid conditions during HA deposition, contrasting with aridification under weak VA activity. Redox conditions evolve from anoxic-sulfidic in HA-type intervals to predominantly oxic in NHV-type intervals, while paleoproductivity decreases from exceptionally high values in HA-type deposits to much lower levels in NHV-type deposits. The presence of sphalerite-Ag-pyrite hydrothermal assemblages and seismites (e.g., sandstone dikes, mud-chip rip-ups) confirms syndepositional tectonic activity. Hydrothermally derived elements (Fe, Cu, U, Mo) enhanced organic enrichment through nutrient-driven productivity blooms and sulfidic preservation conditions created by reduced sulfides. Consequently, HA-type shales exhibit consistently high total organic carbon (TOC) content (>6%), with peak values reaching 34%. This supernormal enrichment is primarily attributed to deep-seated hydrothermal activity, as extreme TOC concentrations show a direct correlation with hydrothermal intensity, which sustains organic matter preservation. On this basis, and distinguishing between hydrothermal and volcanic controls, we propose that the subduction-induced extensional setting beneath the South China Block created a tectonic regime with frequent seismicity and intense deep-seated processes, thereby giving rise to a hydrothermal-tectonic enrichment model for anomalous organic-matter accumulation in the Ordos Basin.

The cratonic strike-slip fault is a kind of fault developed by strike-slip motion in relatively stable tectonic settings. Compared to strike-slip faults developed in an active tectonic settings, cratonic strike-slip faults have small-scale characteristics, weak activity and are difficult to identify without high-quality 3D seismic data. To date, there have been few in-depth investigations of this kind of strike-slip fault, leading to a poor understanding of its characteristics and genetic mechanisms. In this study, we extensively investigated the cratonic strike-slip faults discovered in recent years in the Ordos Basins of China via 3D seismic data, and conducted comparative analyses with similar features observed in other intracratonic basins and active tectonic settings. This study suggests that cratonic strike-slip faults have some special characteristics, such as small displacement and low maturity even when they have been active during several orogenic processes, vertical stratified structural style, and decoupling with the basin periphery structures in terms of trending direction and kinematics. This paper proposed an alternative formation mechanism for cratonic strike-slip faults. The cratonic strike-slip faults nucleate from fractures induced by regional compressive stress instead of being directly inherited from preexisting faults or basement faults. These fractures experience brittle shearing movement under various structural processes, such as plane-differential compression, oblique compression, block rotation, and finally evolve into long strike-slip faults. The development of cratonic strike-slip faults probably record the special stress transmission within the stable craton, the weak in-plane tectonic stresses in the intracratonic basin, which mainly operate at shallow depths. This formation mechanism can provide a new perspective for the understanding of brittle deformation on the earth’s surface, and help to elucidate the occurrence of earthquake activity in stable blocks.

The South China Sea (SCS) is located in the region of convergence between the Eurasian, Indo-Australian and Pacific plates. In previous studies, the diachronic movement of these plates led to a complex picture of tectonic evolution of the rifting stage before opening of the SCS. The Yundong Low Uplift (YLU) is a synrift uplift with an asymmetric structure located in the Baiyun Sag in the northern SCS. In this study, the formation process of the YLU is studied on the basis of 3D seismic reflection data. Based on multiple profiles comparing the 3D structures, we determined that the detachment faults controlling the formation of the YLU are composed of several secondary faults. There is significant cross-cutting and uplift on these secondary faults, accompanied by rotation of the fault blocks, denudation of the strata and some synrift magmatism. Therefore, the cross-cutting and merging relationships of multiple faults revealed in the seismic profiles indicate that the formation of the YLU in the northern SCS is consistent with the classical listric normal fault-controlled model proposed for North American metamorphic core complexes. Finally, we determined that the YLU formed during the synrift stage and underwent three uplift processes, and the formation of the YLU corresponded to the Huizhou movement (c. 43 Ma) defined by previous studies in the Zhu 1 Depression. This study enriches the model for genesis of synrift uplift in the northern SCS margin, and also contributes to our understanding of the regional tectonic evolution.

The northeastern Ordos Basin experiences significant natural gas dissipation. As key geological archives for deciphering hydrocarbon migration-dissipation processes, the genesis and timing of carbonate-cemented sandstones (CCSs) from the Zhiluo Formation (northeastern Ordos Basin) remain controversial and lack systematic investigation. In this study, we conducted a comprehensive investigation of CCSs, integrating petrographic characterization, in situ rare earth element (REE) and U-Pb geochronological analyses, coupled with C-O-Sr isotope and fluid inclusion studies. The CCSs represent non-syndepositional diagenetic products with three stages: Calcite 1 (147.4-125 Ma), Calcite 2 (119.78-100.9 Ma), and Calcite 3 (71.84-61.9 Ma). Calcite crystallinity progressively increases from Calcite 1 to 3, with distinct geochemical signatures across stages. The Calcite 1 generation predominantly originated from chemical precipitation during supergenic diagenesis, with diagenetic fluids dominated by alkaline-enriched external surface water. The formation of Calcite 2-3 was controlled by the amalgamation of deep-sourced hydrothermal fluids and hydrocarbon migration-dissipation. Notably, Calcite 2 also records superimposed supergene alteration involving terrigenous inputs, which serves as an intermediate diagenetic product. Hydrocarbon inclusions, which are ubiquitously hosted within Calcites 2-3, exhibit high thermal maturity, and the gas within inclusions has genetic affinity with Upper Paleozoic coalderived natural gases from the Hangjinqi-Sulige field. This genetic linkage directly and compellingly indicates that Upper Paleozoic gas migration-dissipation served as the predominant light carbon source for Calcites 2-3 precipitation. The onset of Upper Paleozoic gas migration-dissipation occurred during the late Early Cretaceous, which may have persisted until present. Approximately 44.66 % of the organic-derived calcite proportion provides conclusive evidence for large-scale gas migration-dissipation.

Investigations of strike-slip faults within cratonic basins reveal distinct vertical stratification, contrasting markedly with large-scale strike-slip faults in tectonically active regions. The underlying causes and geological implications of this phenomenon remain inadequately understood. This study employs high-resolution 3D seismic data to analyze the vertical stratification of strike-slip faults in the Ordos Basin, focusing on their manifestations, controlling factors, developmental patterns, and geological significance. Results indicate that vertical stratification in the Ordos Basin is characterized by the superposition of faults with ENE, NW, and NNE (near N-S) orientations, as well as the stratification of individual faults. The former exhibits a conjugate fault system dominated by one fault group, while the latter features multiple superimposed flower structures with multiphase kinematic transitions. This stratification results from multiphase fault activity, reflecting the tendency of brittle fault deformation to nucleate and propagate at shallow depths under horizontal tectonic stress in stable cratonic regions. The identified “stratification-multistage-shallow nucleation” developmental pattern of cratonic strike-slip faults effectively records multistage changes in the regional tectonic stress field and influences stratified hydrocarbon distribution. This pattern provides new insights into intracontinental tectonic deformation mechanisms and seismic activity in stable regions.

Stable intraplate cratonic blocks usually have less structural deformation and fewer earthquakes than other locations on Earth, but with strong compressional deformation around their periphery. Investigating how and why this different deformation occurred is beneficial for understanding why the cratonic block is so stable and how the intraplate in-plane stress is transmitted. In this work, we first investigated the structural deformation changes from the margin to the interior of the western Ordos block (one of the most tectonically stable areas in China) via seismic data. The results show abrupt structural deformation changes from the margin to the interior of the Ordos block in terms of the deformation strength (from strong to weak), structural orientation (high-angle oblique relationships), and kinematics (from compression to wrenching). Our investigation also shows that such phenomena are widespread in cratonic blocks worldwide. The abrupt changes are probably induced by special in-plane stress transfer inside the cratonic block: When far-field stress is transmitted into continental interiors from active plate margins, the weak belt around the cratonic block filters and accommodates the in-plane stress. Consequently, this decreases the stress, changes the stress direction, and transmits the in-plane stress along a shallower layer (probably less than 1500 m). Furthermore, the compressional stress from the plate margin is converted into shear stress within the cratonic block. This stress transmission manner makes reactivation of deep preexisting faults difficult under far-field horizontal plate-boundary stresses in the cratonic block without vertical forces from the mantle, guaranteeing long-term stability and low seismicity. This understanding can provide a new perspective for the interpretation of earthquakes in stable continental regions. It can also be applied to appraise the long-term stability of sites for the storage of CO2.

The Hangjinqi gas field, a vital tight sandstone gas field on the northern Ordos Basin margin, exhibits a debatable gas origin and accumulation mechanism. Integrating geochemical analyses with gas field data for basin-wide comparisons allows us to resolve the origin of the reservoired gas. Results reveal that the Upper Paleozoic coal-measure source rocks in the Hangjinqi area share similar characteristics with those in other Upper Paleozoic gas fields, where coal seams constitute the primary effective source rocks. However, they exhibit limited hydrocarbon-generating potential coupled with low thermal maturity. Natural gas has a broad range of dryness coefficient values. The carbon-hydrogen isotopes mostly exhibit a positive carbon-hydrogen isotope series, yet 40% of the samples display ethane and propane carbon-hydrogen isotope reversals. The C5-7 and C7 light hydrocarbons are dominated by isoalkanes and methylcyclohexane, respectively. The natural gas data follow the aromatic curve in the cross-plot of the heptane and isoheptane values. The natural gas in the Hangjinqi field is typical coal-derived gas, which is derived primarily from the Carboniferous-Permian transitional facies of humic organic matter, similar to Daniudi and other gas fields. Notably, the natural gas in the Hangjinqi gas field has undergone migration and dissipation (mainly including escape and loss). The Hangjinqi gas field presents an apparent contradiction between low maturity source rocks and high maturity natural gas. Its methane carbon isotope values significantly exceed those of the Daniudi gas field but align closely with those of the Sulige and Wushenqi gas fields, which are mature-type gas fields. Natural gas migration-dissipation is not the controlling factor in regional isotopic signatures. Therefore, approximately 40-76 % of the natural gas in the Hangjinqi gas field is exogenous gas. Moreover, these exogenous gases are derived primarily from the Sulige-Wushenqi gas field to its south, indicating strong genetic affinity. Overall, most Upper Paleozoic gas fields in the Ordos Basin have short migration distances, whereas the Hangjinqi gas field represents mixtures of locally generated hydrocarbons with gases migrating longer distances.

The Ordovician-Silurian transition (OST) is a crucial geological interval in Earth history, coinciding with the first of the 'Big Five' Phanerozoic mass extinction events (ca. 445 Ma). In addition to the dramatic loss of biodiversity, significant environmental change course such as redox conditions and nutrient availability have been the focus of debate. Previous studies have used isotopes of nitrogen (N) to reconstruct the redox evolution of the paleo-ocean and have identified biological nitrogen fixation as the main mode of nitrogen cycling during the OST. However, low delta 15N values, ranging from -2%o to +1%o, possibly correspond to four different redox conditions. The precise roles of these redox conditions and the spatial distributions of phytoplankton communities under different nitrogen cycles remain elusive. Here we present high-resolution nitrogen isotope, carbon isotope and lipid biomarker datasets from two drilled sections located on a submerged high of the Yangtze Basin to unravel the coupling between nitrogen biogeochemical cycling and phytoplankton community structure across the OST. The results suggest that there was a dominantly biological nitrogen fixation with local aerobic nitrogen cycling in the Yangtze Sea, and the nitrate inventory during the OST was smaller than that in the modern ocean. Particularly, before the Late Ordovician mass extinction (LOME), N-fixing cyanobacteria were likely extensively developed in the photic zone, while eukaryotic algae were limited. After the LOME, sea levels rose and the chemocline was higher than before the LOME. There was probably some NO3 � that did not undergo denitrification in the surface ocean, favoring the development of eukaryotic algae. The ecological diversification from prokaryotic cyanobacteria to eukaryotic phytoplankton to eukaryotic zooplankton is likely to be a response to the enhanced biological pump, which generates positive feedbacks among the evolution of eukaryotic phytoplankton, organic matter enrichment, ocean oxygenation and atmospheric oxygen levels.

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

The Shijiutuo Uplift within the Bohai Bay Basin(BBB)has experienced a complex evolutionary history since the Cenozoic. Studies of the Cenozoic evolution of the Shijiutuo Uplift are important for basin tectonics and petroleum geology. The formation of uplifts in rift basins is generally controlled by regional tectonic event and fault-block tilting. In this study, apatite fission track (AFT) data from fourteen samples and seismic data analysis were used to study the processes of regional uplift and fault-block tilting. We further investigated the Cenozoic evolution and formation mechanism of the Shijiutuo Uplift. The results indicated that the Shijiutuo Uplift experienced a two-phase differential tectonic uplift and erosion history (1) Widespread rapid uplift and erosion during the early Cenozoic (65-55 Ma) (2) Widespread uplift and erosion from 40 Ma to 16 Ma. The uplift and erosion substages of 40-38 Ma and 26-16 Ma were mainly caused by regional uplift, whereas those of 38-26 Ma resulted from fault-block tilting. Since the end of the third member from the Eocene Shahejie Formation, the Shijiutuo Uplift began to rise, causing the greater Bozhong Depression to be separated into the independent Qinnan and Bozhong Sags. These tectonic uplift and erosion events have a wide range of responses and regional dynamics in eastern China. The findings of this study will lead to a better understanding of the evolution and formation of uplifts within the BBB.

A Quaternary mass transport complex (MTC), formed by debris flows on a slope with numerous elliptical depressions in the Qiongdongnan Basin, is identified using three-dimensional seismic data. 25 % (5.7 km3) of the total volume of the MTC was deposited on the Upper and Middle slopes, mainly owing to the elliptical depressions capturing the bypassed debris flows. The megascour with slot-like geometry on the base of the MTC trends north-north-east on the Upper and Middle slopes, implying debris flows flowed downslope toward the north-north-east. The steep slope is responsible for the bypassing of the main body of debris flows. Moreover, the steep slope probably accelerated the debris flows, and thus the debris flow plowed, eroded and incorporated the substrate sediments to form the megascour. Asa result, 75 % (17.3 km3) of the total volume of the MTC occurs on the Lower slope, mainly consisting of the lobe-like accumulation zones 1 and 2. Trends of the pressure ridges in the lobe-like accumulation zone 1 suggest debris flows spread in an unconfined manner due to the relatively gentle Lower slope, until it reached the topographic barrier to the north. As a result of the blocking of the topographic high, only a portion of the debris flows continues to flow northeastward evidenced by the small-scale megascour with slot-like geometry on the base of the MTC resulting from the relatively steeper slope. It is clear that the topography of the pre-existing slope plays a significant role in the depositional process and dispersal of the MTC. Topography of the pre-existing slope mainly resulted from tectonic movements and sedimentary infilling processes. It was also complicated by the elliptical depressions that were formed by the normal-drag along the arcuate normal-faults, which are attributed to sediment load that favors the downward slip on the walls of the erosional troughs within the substrate of the MTC. The steep slope and high sedimentation rates probably are important triggers for the occurrence of the MTC. This study is helping to improve current knowledge of the interaction between debris flows and the topography of the pre-existing slope. (c) 2024 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.