The Late Carboniferous–Permian magmatic and sedimentary records in the Alxa area are crucial to understanding the tectonic evolution of the Paleo-Asian Ocean. We present petrological, whole-rock geochemical, zircon U-Pb geochronological and Hf isotopic data for magmatic and siliciclastic rocks from northern Alxa. Rhyolite and granite porphyry related to the Amushan Formation crystallized at ca. 309–304 Ma, derived from juvenile to moderately evolved lower crust reworked by oceanic subduction. Sandstones from the Quagan Qulu and Engger Us tectonic belts display contrasting detrital-zircon age spectra. Quagan Qulu samples, characterized by an early Paleozoic peak at ca. 430 Ma, record mixed input from early Paleozoic arc rocks, Precambrian basement and recycled cover strata, whereas Engger Us samples are dominated by a Devonian peak at ca. 381 Ma and were supplied by a nearby Devonian arc source. Together with published data, our results support a segmented Late Carboniferous–Permian forearc–arc–retroarc system along the northern margin of Alxa. Continued southward subduction of the Quagan Qulu oceanic lithosphere beneath the Nuru–Langshan continental arc is the preferred interpretation, whereas Late Carboniferous to early Permian slab rollback is a plausible mechanism for the ensuing magmatic flare-up, arc uplift and provenance shift.

Mesozoic exotic tectonic fragments in the Yarlung Zangbo suture zone (YZSZ) preserve key records for reconstructing Neo-Tethyan evolution. This study investigates basalts and limestones from the Buma area in the central segment through petrology, calcite U-Pb geochronology, and whole-rock geochemistry. Calcite U-Pb dating of two recrystallized limestone samples yields ages of ca. 244 Ma and ca. 246 Ma. The Buma basalts are subalkaline, with SiO₂ contents of 37.95–53.61 wt.% and high TiO₂ (1.63–3.43 wt.%). Their rare earth elements (REEs) and trace element patterns resemble Hawaiian ocean island basalts (OIBs), and they exhibit moderately depleted Nd isotopic compositions (ε_Nd(t) = +4.20 to +4.93). The pronounced negative Ce anomalies in limestones and the absence of terrigenous clastic components in collapse conglomerates indicate deposition in an open-ocean setting. Integrated evidence indicates that the basalt–limestone association in the Buma area represents a Neo-Tethyan ocean island-seamount system. Combined with the 253 Ma continental rift basalts from the Zhongba area, this result suggests that the opening of the Neo-Tethys Ocean in the central segment of the YZSZ occurred no later than the Early Triassic, providing key empirical evidence for the spatiotemporal framework of the early evolution of the Neo-Tethys Ocean.

The Changchengian System represents one of the earliest sedimentary covers deposited on the Archean–Paleoproterozoic basement of the North China Craton. We report zircon U-Pb-Hf isotope data for Changzhougou Formation sandstones in the Chaiguan area, central–southern Taihang Mountains. The youngest detrital zircon ages (∼1782 Ma) constrain the maximum depositional age to ∼1.78 Ga. Combined with regional constraints, deposition is bracketed between ∼1.76 and ∼1.64 Ga. Detrital zircon age spectra exhibit a dominant peak at ∼2.5 Ga, with secondary peaks at 2.8–2.6, 2.2–2.0 and 1.9–1.8 Ga, alongside rare ∼3.25 and ∼3.70 Ga grains. Coupled with Hf isotopic signatures, these diverse populations suggest derivation primarily from the basement of the Trans-North China Orogen. Although the age spectra are broadly similar to the Archean-dominated Yanliao Rift, the presence of subordinate Paleoproterozoic and minor Paleoarchean grains, coupled with a predominant southeast-to-northwest paleocurrent, implies a closer affinity with the Xiong'er Group. These results suggest deposition in an extensional setting—likely associated with the breakup of the Columbia supercontinent—and record a northward marine transgression from the Xiong'er Rift Basin. Consequently, the central–southern Taihang Mountains served as a critical transition zone connecting the Xiong'er Basin with the Yanliao Basin.

The Beishan Fold-Thrust Belt (BFTB), located in the southern part of the Central Asian Orogenic Belt (CAOB), underwent complex intracontinental deformation during the late Mesozoic and is a key tectonic unit for deciphering the remote effects of plate margin orogenesis. In this study, we selected the Yemaquan region in southern Beishan and conducted remote sensing interpretation, field mapping, seismic profile interpretation and low-temperature thermochronological analyses. The Permian pluton and Carboniferous strata thrust over the Jurassic strata and developed a series of SEE-trending thrusts, NE-striking left strike-slip faults, and several SEE- and NE-trending folds. This area experienced two directions (NE and NW) of compression deformation. Under the joint influence of compression stress and pluton blocking, fold structures related to strike-slip faults also developed (the Big Ear syncline). The above constituted the Yemaquan Fold-Thrust system (YFTS). Zircon (U-Th)/He (ZHe) data reveal cooling events at ∼175–165 Ma; combining the regional deformation, it may indicate the compression time. We concluded that the intracontinental deformation of the BFTB in the southern CAOB was driven by the far-field effects. NE compression is related to the closure of the Mongol–Okhotsk Ocean and the collision of the Lhasa–Qiangtang block; NW compression is related to westward subduction of the Paleo-Pacific plate.

The Sichuan Basin, adjacent to the Himalayas in China, exhibits complex structural deformation and stress regimes, necessitating systematic structural and stress analysis. The Luzhou region in the southern Sichuan Basin is cut by three sets of faults, which trend NNE (NE)–SSW (SW), E (NEE)–W (SWW), and N (NNW)–S (SSE). Late Ordovician to early Silurian strata lie between the basement and cover sequences, and the faults are mainly extrusion thrust faults. Integrated geophysical data and finite element numerical modelling reveal that the maximum horizontal principal stress (S_H) is 76–131 MPa, the minimum horizontal principal stress (S_h) is 64–113 MPa, and the vertical stress (S_v) is 69–125 MPa, consistent with a strike-slip regime (S_H > S_v > S_h). Consequently, the present-day stress regime differs from that of existing thrust-fault models. The NNE (NE)–SSW (SW) trending faults have the greatest impact on the magnitude and orientation of the stress, and the E (NEE)–W (SWW) faults have the greatest impact on the horizontal stress differences (ΔS). ΔS is negatively correlated with the total gas content and negatively correlated with borehole deformation in seven wells in the Luzhou region; therefore, E (NEE)–W (SWW) trending faults should be avoided during petroleum exploration in the Luzhou region.

Using a novel thermo-mechanical model, this study explores the role of multi-ordered 3D convective dynamics of the mushy region in modulating the strongly heterogeneous stress fields in mid-ocean ridge (MOR) systems. This model couples the sub-ridge mushy (fluid) regions with the elastic (solid) crustal layer within a mathematical framework of fluid–structure interaction (FSI) mechanics. Model-based calculations of the total stress tensor provide quantitative estimates of the across- and along-axis horizontal tension/compression (and σ^∥) and across-axis horizontal shear stress (σ^#) that dominantly control the ridge-axis morphologies. The stress analysis forms an alternative explanation for the off-axis ridge-parallel second-order hill topography, located at a distance of 20–50 km. This study also shows how along-axis compressional σ^∥ can localise a row of ridge-normal narrow, 10–30 km wide stripes on a wavelength of 40–150 km. Their overall patterns conform to the second-order magmatic segmentation structures of MORs. The σ^# mapping suggests that ridge-transverse discontinuities, including transform offsets, transpression and transtension zones, originate spontaneously from FSI interactions during MOR evolution. The article finally presents a set of MOR examples from modern plate tectonic settings to support model interpretations.

A dense seismological profile with 45 stations at a spacing of 5–10 km across the Longmenshan fault zone was deployed from 2018 to 2020. It complemented an array of 80 stations deployed in the region from 2012 to 2013. Using data from both deployments, dispersion curves were obtained from ambient noise Green's functions. Subsequently, a 3D shear (S) velocity model was derived using tomographic methods. Combining this S-wave velocity model with an existing 3D compressional velocity model, a 3D Poisson's ratio model was derived. These models show that the Precambrian Pengguan complex, which cores this part of the Longmenshan, is approximately 20-km thick and displays high velocities and low Poisson's ratios. The result of this study is that, along the dense profile, the complex is underlain between 20 and 40 km depth by low S velocities, which likely extend out beneath the Sichuan Basin in a 10-km thick basal crustal layer. These low S velocity zones have high Poisson's ratios and are best explained as a result of the compressive forces and push exerted by the Tibetan Plateau, causing processes such as ductile shearing and fluid/melt infiltration to occur.

The Central Asian Orogenic Belt (CAOB) is Earth's largest Phanerozoic accretionary orogen, yet the tempo and mechanisms of arc magmatism remain incompletely constrained. Carboniferous island-arc volcanism in the Zhongguai Uplift, northwestern Junggar Basin, is investigated to establish magmatic cyclicity during closure of the Paleo-Asian Ocean. Integrated 3D seismic interpretation and well-log correlation, together with zircon U-Pb geochronology, whole-rock major–trace element geochemistry and Sr-Nd-Pb isotopes, subdivide the Carboniferous volcanic succession into three volcanic cycles. Cycle I (ca. 335–322 Ma; Early Carboniferous) is dominated by intermediate to mafic lavas and volcanic breccias and exhibits typical subduction-arc characteristics. Cycle II (ca. 321–317 Ma; Late Carboniferous) comprises a felsic-dominated interval (dacite–tonalite) and is interpreted to relate to slab-window processes. Cycle III (ca. 313–303 Ma; latest Carboniferous–earliest Permian) forms a thick bimodal assemblage from andesite to rhyolite, consistent with arc–continent collision and subsequent tectonic reworking. Geochemical–isotopic signatures evolve from a fluid-modified depleted mantle source in Cycle I, to highly fractionated and slab-influenced melts in Cycle II, and to mixed mantle–crust magmas with locally developed A-type affinities in Cycle III. The cycle-based stratigraphic and geochemical framework documents a transition from oceanic subduction to collision along the West Junggar margin, refines the timing of Paleo-Asian Ocean closure and highlights that Carboniferous arc magmatism occurred in discrete pulses linked to tectonic events. This integrated approach provides constraints on episodic arc magmatism and associated continental crustal growth in accretionary orogens.

The mid-Neoproterozoic tectonic evolution of the western Jiangnan Orogen in the context of the Rodinia supercontinent remains unresolved due to debates regarding the interpretation of the petrogenesis of igneous rocks. In this study, we present an integrated dataset of petrology, whole-rock geochemistry, zircon U-Pb ages, and Hf isotopes for granitic samples from the Fanjingshan area in the western Jiangnan Orogen. LA-ICP-MS zircon U-Pb dating indicates that they crystallised ca. 810 Ma. Whole-rock geochemical data demonstrate that they exhibit typical features of S-type granites and were derived from dehydration melting of a metasedimentary protolith. Zircon ε_Hf(t) values range from −7.9 to 1.6, with a main peak value of −3.5. Two-stage Hf model ages of 1.5–1.9 Ga suggest that these granites were derived from ancient crustal materials. Extensive fractional crystallisation and magmatic–hydrothermal interactions are inferred from low rare earth element (REE) contents, low Nb/Ta and Zr/Hf ratios, and a distinct REE tetrad effect. Combined with coeval arc-related magmatism and rift basins, the Fanjingshan granites were most likely emplaced in a back-arc setting. Available data indicate that rift basins occurred extensively at the periphery of the Yangtze Block ca. 810 Ga, implying their involvement in the breakup of the Rodinia supercontinent.

The Zouzan pluton in the Lut Block (eastern Iran) comprises coeval gabbro–diorite and felsic intrusions that contain abundant mafic enclaves (MEs). Integrated zircon U-Pb dating, whole-rock Sr-Nd isotopes and amphibole-apatite chemistry are used to investigate ME formation. Zircon ages indicate synchronous emplacement of the gabbro–diorite, MEs, and granodiorite ca. 40 Ma. The MEs plot along a Sr-Nd isotopic mixing line between mantle-derived gabbro–diorite and more crustally contaminated granodiorite, supporting a magma-mixing origin. Mineral chemistry, however, reveals more complex interactions. Apatite in MEs is acicular with trace element compositions intermediate between those of mafic and felsic magmas, indicating rapid crystallisation from a hybrid melt. Amphiboles display two distinct compositional groups: one matching gabbro–diorite amphiboles and the other resembling those in the granodiorite. This bimodality suggests that ME formation involved incomplete mixing, crystal transfer between magmas and variable re-equilibration rather than simple hybridisation. A dynamic model is proposed in which mafic magma globules were injected into a partly crystallised felsic chamber, producing mingling, quenching and crystal exchange that ultimately shaped the petrographic and geochemical features of the Zouzan pluton.

The Qaradagh Batholith in northwestern Iran, adjacent to the Meghri–Ordubad pluton (MOP) within the South Armenian Block, is dominated by granodiorite, which represents its earliest intrusive phase. Both the Qaradagh Batholith and the MOP formed in a subduction-to-post collisional setting linked to the closure of Neo-Tethys Ocean between middle Eocene and early Miocene. U–Pb zircon dating of the granodiorite was conducted to constrain its emplacement age, yielding a ²⁰⁶Pb/²³⁸U weighted mean age of 43.81 ± 0.18 Ma and a U–Pb concordia age of 44.04 ± 1.00 Ma, placing intrusion in the middle Eocene, earlier than previously suggested Oligocene ages. In situ zircon Lu–Hf isotope analyses, conducted to determine magma source characteristics, yielded ε_Hf(t) values between +8.7 and +11.1, indicating derivation from a depleted, juvenile mantle source with minimal crustal contamination. This is supported by low initial ⁸⁷Sr/⁸⁶Sr (0.7037–0.7041), positive ε_Nd(i) (+2.69) and low zircon U and Th contents relative to Miocene intrusions in NW Iran, which have higher crustal contribution. Model T_DM ages of zircons (256–354 Ma) indicate a Carboniferous–Permian source material, consistent with late Paleozoic subduction. These results place the Qaradagh granodiorite among the earliest manifestations of Paleogene magmatism in the region.

The tectonic affinity of the quartzite unit is essential for reconstructing the Cenozoic evolution of the Eastern Himalaya Syntaxis. We presented new petrographic and zircon U-Pb geochronological data from the quartzite unit collected from the western boundary of the Namche Barwa syntaxis. The maximum depositional ages indicated multiple depositional stages at >1800, 1122–1136, 885, 451–493 and 54 Ma. Detrital zircon ages spanned from 50 to 3269 Ma with dominant populations at 500–900, 950–1400, 1550–1700 and 1750–2000 Ma. These age distributions suggested that the detritus were derived mainly from the Central Indian Tectonic Zone, Shillong Plateau and the Eastern Ghats Orogeny of the northeastern Indian subcontinent, and Western Australia. This provenance signature was distinct from the typical sequences of the Lesser Himalayan Sequence, Greater Himalayan Sequence and Tethyan Himalayan Sequence in the central–western Himalayas. Integrating our results with existing data from the Nyingchi Complex in the southern Lhasa terrane and Lesser Himalayan Sequence in the Eastern Himalayan Syntaxis, we proposed that the Namche Barwa syntaxis, Nyingchi Complex and Lesser Himalayan Sequence shared common source regions. Long-lived fluvial systems likely transported detrital material from northwestern Australia and the northeastern Indian subcontinent to these tectonic units.

As products of deep fluid-tectonic-sedimentary coupling, mud volcanoes have scientific value for oil–gas exploration, indicate neotectonic activity and aid global climate change studies. This study focuses on mud volcanoes in China's offshore areas (northern South China Sea, Okinawa Trough of the East China Sea), investigating tectonic control on their development and fluid activity's impact on shallow gas and gas hydrate accumulation. Through numerical simulation, stress field analysis and comparative geological background analysis, key findings include: (1) Tectonically controlled distribution: strike-slip extensional basins host large mud diapirs, extensional basins small–medium ones and compressional back-arc basins show zonal clustering; intensified tectonic activity exacerbates fluid seepage. (2) Formation relies on coupling of ‘material basis-dynamic conditions-triggering mechanisms’: Early Cenozoic mud-rich strata (material), overpressure (driven by undercompaction/hydrocarbon generation, dynamics), and tectonic/seismic activity (triggers). (3) Fluid seepage correlates with parameters: overpressure coefficient positively correlates with eruption intensity; shallower source layers and increased compressive stress enhance seepage efficiency. (4) Mud volcanoes influence accumulation via ‘gas supply-channel transport-temperature-pressure regulation’, acting as a ‘source-channel-trap’ system to promote enrichment, though deep thermal fluid upwelling may cause hydrate dissociation and hazards. This study elucidates their formation mechanisms and resource-environmental effects, providing theoretical support for deep-water oil–gas exploration and geohazard early warning.

The structural evolution and deformation conditions of ore-controlling shear zones in the large-scale Jinshan orogenic gold deposit were studied through structural mapping, petrographic analysis and electron backscatter diffraction (EBSD) observation. Four distinct deformation events are identified, including pre-mineralisation ductile deformation (D₁ and D₂), syn-mineralisation brittle-ductile shearing (D₃) and post-mineralisation brittle faulting (D₄). Gold-bearing quartz veins are confined to D₃-stage NE–SW-trending shear zones characterised by thrust plus sinistral slip movement under NW–SE-oriented compression. The mineral assemblage includes pyrite, arsenopyrite, chalcopyrite, galena, and native gold associated with quartz-sericite alteration. The quartz can be divided into two groups: pre-mineralisation coarse (>100 µm) grains and gold-related fine (<50 µm) grains. The coarse-grained quartz displays dominant prism <a> and rhomb <a> slip with intermediate- to high-temperature deformation fabrics (400°C–600°C) and has undergone sub-grain rotation recrystallisation after its formation. In contrast, the gold-related quartz distributed along the margins of coarse-grained quartz displays bulging recrystallisation with dominant basal <a> slip, indicating intermediate- to low-temperature conditions (300°C–400°C). The intermediate- to low-temperature gold mineralisation event overprinted earlier intermediate- to high-temperature fabrics. This study highlights that the reactivation of the pre-mineralisation shear zones provided fluid pathways for subsequent auriferous fluid flow and gold deposition.

The Jinqingding gold deposit in eastern Jiaodong is a significant gold mineralization within the Muping–Rushan metallogenic belt. This study integrates structural analysis and trace element geochemistry of sulphides to elucidate ore-controlling mechanisms and metallogenic models. The deposit occurs as pyrite-quartz veins and polymetallic sulphide veins/disseminations hosted in biotite monzonitic granite, controlled by the NNE-striking Jiangjunshi–Quhezhuang fault. Structural analysis reveals that mineralization was controlled by conjugate shear joints, tension fractures, and en échelon faults formed under a tectonic stress field with σ₁ oriented NE–SW. LA-ICP-MS trace element analysis of pyrite reveals dual geochemical affinities—high-temperature magmatic signatures (elevated Co, Ni, Ti) and medium-low temperature hydrothermal signals (enriched As, Pb, Bi)—suggesting episodic fluid inputs from magmatic-hydrothermal and meteoric sources. Rare earth elements (REEs) are low in pyrite and show slight LREE enrichment. The results suggest that the main ore-controlling structures formed under a stress field with σ₁ oriented NE–SW during the Early Cretaceous, and the mineralization may be related to episodic fluid pulses, as reflected by the changes in trace elements during the crystallization of pyrite. Furthermore, this study reveals an NEE-trending set of potential ore-controlling structures for epizonal gold mineralization, which is of great significance for regional gold exploration in Jiaodong.

The Wunugetushan (Wushan) porphyry Cu–Mo deposit is located in the southwestern segment of the Derbugan metallogenic belt. In this study, geochemical analyses of zircon and apatite from pre-mineralization biotite granite (BG) and inter-mineralization monzogranitic porphyry (MGP) were conducted, aiming to discuss petrogenesis and their constraints on mineralization. BG apatites have distinctly lower ε_Nd(t) (−4.28 to −1.03) and higher two-stage Nd model ages (1063–1328 Ma) than MGP apatites, showing values of −0.23 to +1.31 and 860–984 Ma. MGP zircons have higher Ce/Nd, Ce⁴⁺/Ce³⁺, δEu, 10,000 × δEu/Y and (Ce/Nd)/Y values, and lower Yb/Gd values than those in BG zircon. These geochemical features suggest that the MGP has a higher oxidation state and higher water content of magma than BG. Trace element concentrations in zircon and apatite reveal that the MGP is less evolved and exhibits amphibole-dominated fractionation. In contrast, the BG is evolved and shows plagioclase- and apatite-dominated fractionation. We propose that the key factors making the MGP fertile for mineralization, including its high Cl, S and H₂O contents, high oxidation state, significant fluid exsolution and multiple recharges of deep-seated mafic magma, were all critical for the Wushan porphyry Cu–Mo deposit.

The W–Sn–Ag–Pb–Zn polymetallic deposit in the Bozhushan ore concentration area is closely related to Late Cretaceous magmatic activity, and the diagenetic age of the granite body is 88.8–87.1 Ma. The granites in the Bozhushan ore district are characterized by high silica and aluminium contents, high abundances of Rb, Sr, Sn and Th, and low contents of Ba, P and Ti. The granites are peraluminous S-type granites that underwent fractional crystallization during magmatic evolution. The ε_Hf(t) values of the zircons from −17.92 to −1.77, with T_DM2 age ranging from 1.1 to 2.0 Ga, indicate that they may be mainly derived from partial melting of the lower crust without the addition of mantle-derived materials. The Late Cretaceous magmatic activity in the Bozhushan area formed in a syn-collisional tectonic environment and transitioned to a post-collisional orogenic environment. In the later stage, it transforms into a post-collisional extensional environment. The upwelling of deep-seated asthenospheric melts has provided substantial fluxes of W, Sn, Pb, Zn and other ore-forming elements. The ore-forming fluid and materials carried by magma rise and migrate along favourable parts of the structure to precipitate and mineralize. Therefore, understanding the tungsten-tin metallogenic history in the Bozhushan ore district is important.

Hydration of the lithospheric mantle is a critical part of deep water cycling and is essential in shaping Earth's habitable environments. At low water/rock ratios, water is stored in nominally anhydrous minerals or hydrous minerals; however, at high water/rock ratios, the leaching effect of water on mantle minerals remains poorly understood. Here, we present hydrothermal experiments of the ‘phlogopite + H₂O’ system at 500°C–950°C and 0.9–1.8 GPa, showing that incongruent dissolution of phlogopite in water produces corundum (Al₂O₃) as an insoluble residual phase at pressures above ∼1.5 GPa. Water leaches soluble components (K, Mg and Si) from phlogopite, leaving corundum as the residue under lithospheric mantle P-T conditions. This provides a mechanistic explanation for sapphire formation in the lithospheric mantle, consistent with natural sapphire gemstones occurring as mantle xenoliths and xenocrysts within alkaline basalts. Sapphires form through hydrous leaching of phlogopite at depths greater than ∼50 km and are subsequently transported to the surface by alkaline basaltic magmas originating from at least ∼70 km depth. The widespread sapphire deposits associated with alkaline basalts in East China indicate extensive hydrous leaching of the lithospheric mantle, with water ultimately sourced from the subducted slab, mantle transition zone or mantle plumes.

The synrift basins of the West and Central African Rift System (WCARS) contain Lower Cretaceous lacustrine shale, which is considered to be the main source rock of hydrocarbons that accumulated in these basins. Recent studies of these lacustrine shales do not consider the diversity of organic-rich lithofacies within these basins. This study aims to investigate Lower Cretaceous organic-rich facies in the Babouri–Figuil Basin, part of the WCARS. The samples collected (n = 173) were subjected to bulk geochemical and elemental analyses and organic petrological observations. Oil shales exhibit a higher average total organic carbon (TOC) value of 17 wt%, whereas the associated facies contain less than 2 wt% TOC. The oil shales display an average hydrogen index (HI) value of 769 mg HC/g TOC. However, the associated facies generally exhibit HI values below 300 mg HC/g TOC. Oil shales and associated facies contain well-preserved kerogen, ranging from Types I to III, indicating good to very good potential for hydrocarbon generation. Rock-Eval pyrolysis reveals relatively similar thermal maturity across the studied organic-rich facies, with an average T_max value of 430°C, displaying an immature to early oil window stage of maturation. These results suggest that the WCARS basins generally hold promise for further petroleum exploration efforts.

Investigation of the dynamic transformation characteristics of hydrocarbon generation and evaluation of hydrocarbon potential and expulsion are of guiding significance for the evaluation of lacustrine shale oil and gas resources. A total of 1977 pyrolysis dataset points were collected from lacustrine shale samples selected from 202 wells across eight regions within five basins in China. The kinetic parameters were derived, and the original hydrogen index was obtained to identify the kerogen types. Subsequently, the original total organic carbon was estimated to analyse organic matter enrichment. Finally, the hydrocarbon generation, retention and expulsion characteristics of the lacustrine shales were compared. The results demonstrate that lacustrine shales in China exhibit different hydrocarbon generation, retention and expulsion characteristics, which are controlled by both basin lake type and primary productivity. Type I kerogens exhibit the largest hydrocarbon generation and retention amounts and the highest hydrocarbon expulsion efficiency. These kerogens also exhibit the narrowest hydrocarbon generation window and the earliest hydrocarbon expulsion. However, when the source rocks have a high sulphur content, hydrocarbon generation and expulsion occur earlier. Furthermore, when the source rock contains large amounts of terrestrial organic matter input, the hydrocarbon generation and expulsion windows broaden.

As a rare marine carbonate reservoir developed after the Eocene in the world, the oil and gas source of Palaeogene carbonate reservoirs in Kekeya area and the evolution process and mechanism of hydrocarbon accumulation are not clear, restricting the reasonable and effective development of Kekeya area. By the use of drilling cores and experimental data, oil and gas source correlation, reservoir evaluation, accumulation period and reservoir formation process were studied. Results show that the source rocks in the study area are mainly Permian lacustrine mudstone and Jurassic coal-bearing source rocks. The Palaeogene carbonate reservoirs are generally low porosity and ultra-low permeability, with secondary dissolution pores as the main reservoir space. The oil–gas source correlation shows that the Palaeogene crude oil is derived from the Permian source rock, and the natural gas is derived from the Jurassic source rock. The ancient and present reservoirs have experienced two oil and gas filling stages. The first stage is the middle and late Pliocene and the second stage is the early Pleistocene. The hydrocarbon accumulation mode was built as ‘source-reservoir separation, fracture dredging, multi-stage filling’. The research results guide exploration in Tarim Basin and similar basins.

Submarine canyons critically control reservoir heterogeneity in deep-water settings, yet their erosional surfaces often evade seismic detection. This study integrates the instantaneous phase, variance coherence, spectral whitening and acoustic impedance inversion of advanced seismic attributes to resolve the morphology of the Cretaceous Matruh Canyon (Egypt's Western Desert) and quantify its impact on the Alam El Bueib IIIG reservoir. Conventional 2D seismic data initially obscured the canyon's basal erosional surface due to velocity push-down artefacts and sparse line spacing. Our workflow successfully delineated a U-shaped, fault-controlled incision system, revealing stark thickness variations (> 440 ft locally) where canyon infill replaced reservoir sands with sealing Matruh Shale. Paradoxically, while this erosion disrupted continuity evidenced by shale-plugged wells (e.g., Emry Deep_04), it concurrently created stratigraphic traps through lateral sand-shale juxtaposition and shale-drape seals. Note that shale gouge ratio analysis confirmed robust lateral seals (> 80%) along bounding faults, notably where shale thickness exceeded 200 ft. We initially struggled to reconcile the abrupt transition from productive sands (Emry Deep_01X) to non-reservoir intervals until spectral whitening resolved thin (< 138 ft) SII sand remnants. Global analogues (Brazil Pre-salt, Niger Delta) highlight Matruh's uniqueness: its syn-rift tectonic setting and > 400-m incision depth create traps distinct from post-rift carbonates or shale diapirs.

Several sandstone-type uranium deposits were identified within the Upper Cretaceous red-variegated strata in the Qianjiadian area of the Songliao Basin, NE China. However, a consensus regarding the genesis of multilayer tabular ore bodies within a sandstone reservoir remains elusive. This paper investigates the provenance, palaeoenvironment, and unique mineralisation characteristics of the Qingshankou Formation within the newly discovered Dalin deposit on the basis of lithofacies, element–environment–organic geochemistry and stable isotopes. The results indicate that the fragment provenance of the ore-bearing strata is primarily composed of intermediate–felsic rocks, and the source areas are characterised by a complex tectonic background that encompasses both passive and active continental margins, as well as continental arcs. Its sedimentary environment shows a general (semi-) arid and hot palaeoclimate, with ancient lacustrine water exhibiting both fresh and brackish properties. Pure grey mudstone (PGM) features low Fe₂O₃^T but exhibits elevated levels of ferrous iron, uranium, molybdenum, Fe²⁺/Fe³⁺ ratio and reduction capacity; pure red mudstone (PRM) displays contrasting characteristics; and certain geochemical indicators of mottled mudstone (MD) are intermediate between those of the above-mentioned mudstones. Green alteration within the MD is identified as having a syn-sedimentary origin, as opposed to the previously assumed secondary reduction of foreign hydrocarbons. The associated organic matter is classified as Type-III kerogen, initially derived from aquatic plankton and herbaceous plants. Finally, a sedimentary model is proposed for the red-variegated Qingshankou Formation in the study area, where the original interbedded architecture with varying geochemical properties is influenced by alternations in palaeoclimate and associated redox stratification of ancient lacustrine water. Some lenticular native grey beds, which were deposited in local low-lying lands during semi-arid and pluvial interphases, exhibit pronounced uranium pre-concentration due to phreatic oxidation during the sedimentary stage. Subsequently, differential redox activities in the Cenozoic era led to the development of multilayer geochemical zoning and tabular ore bodies in a reservoir. This research offers valuable insights into the uranium mineralisation of oxidative red-variegated strata within global basins and contributes to the development of uranium exploration strategies.

Alunite is a common sulphur-rich mineral in high-sulphidation epithermal deposits and can occasionally form independent alunite deposits, demonstrating a close spatial relationship with epithermal mineralization. In situ sulphur isotope analysis of alunite offers valuable insights into detailed mineralization processes. In this study, using LA-MC-ICP-MS, we evaluated matrix effects, spectral interferences and instrumental parameters that influence measurement accuracy, leading to the development of a high-precision microanalytical method for sulphur isotopes in alunite. In order to verify the results of the in situ method, LA-MC-ICP-MS measurements were compared with GS-IRMS analyses on two natural alunite samples: MT-1 and MTS-1. The internal precision of the in situ δ³⁴S measurement was better than 0.22‰ when the ³²S signal exceeded 5 V. The long-term reproducibility for these two samples was better than 0.33‰ (2SD). These results suggest that either of the two materials can serve as an in situ sulphur isotope standard. Based on GS-IRMS results, recommended δ³⁴S values for MT-1 and MTS-1 are 9.37‰ ± 0.13‰ and 3.42‰ ± 0.31‰, respectively.