Reconstructing oroclinal orogens along the Fuegian Andes-northern Antarctic Peninsula provides critical constraints on the pre-opening tectonic evolution of the Drake Passage, although such efforts are limited by a lack of reliable Cretaceous paleomagnetic and geochronological data. Here, we present new paleomagnetic, 40Ar/39Ar, and apatite U-Pb geochronological data to reconstruct the oroclinal bending of this belt. Our results reveal that oroclinal bending in the northern Antarctic Peninsula (similar to 67 degrees-63 degrees S) and the Fuegian Andes both occurred at similar to 100-90 Ma, mainly driven by compression from the northward-moving Antarctic Peninsula and southeastward-moving Cordillera Darwin Metamorphic Complex. We propose that the orocline Drake Passage boundary primarily formed during this period. This oroclinal weak zone served as a fundamental prerequisite in opening the Drake Passage, facilitating the separation of the Fuegian Andes and Antarctic Peninsula.

The timing, extent and paleogeographic position of Neoproterozoic glaciations remain debated. Here we review Neoproterozoic Nanhua System glacial deposits in South China and present new, high-quality paleomagnetic data from the Leigongwu Formation (Jiangshan). Thermomagnetic and stepwise thermal demagnetisation of well-oriented tillite cores yield a stable high-temperature characteristic remanent magnetisation (ChRM), from which we calculate a site-mean direction corresponding to a paleolatitude of similar to 14 degrees N (alpha 95 = 6.8 degrees, k = 77.8). This result, together with regional paleomagnetic data, supports a mid-low latitude position for the South China Block during the Marinoan interval and thus provides independent regional evidence relevant to the Snowball Earth hypothesis. In addition, we discuss implications for inter-regional correlation of Nanhua glacial strata.

Current studies predominantly focus on macroscopic tectonic evolution, addressing the scientific challenges of insufficient understanding of the distribution and evolution of bedrock in source areas and unclear mechanisms of proximal sediment supply within regional provenance system research. However, research on the fine classification of bedrock types within source areas and their dynamic linkages with the 'source- to-sink' system remains notably inadequate. Based on high-resolution 3D seismic data, drilling and logging information, this study provides a new case for understanding the distribution patterns and evolution of bedrock in the source area of the 'source-sink' system, as well as a reference for studying depressions that supply sediments in close proximity. Our study demonstrates the following: (1) The Enping-Yangjiang low uplift area encompasses three bedrock types-granite, volcanic and sedimentary rocks-each corresponding to distinct seismic facies (SF1-SF3). Granite basement is directly intersected by multiple wells; sedimentary rocks exhibit stratified reflection characteristics; whereas volcanic rocks are characterised by a strong reflection envelope with weak, chaotic internal reflections. (2) The distribution of bedrock shows significant zoning. Jurassic granite dominates the main body, sedimentary rocks are concentrated in the northern arcuate fault zone, volcanic rocks are distributed in the southwest and there is a mixed zone of sedimentary and volcanic rocks in the southeast. (3) Governed by diverse tectonic systems, the evolution of bedrock has undergone three stages: compressional uplift during the Late Jurassic-Early Cretaceous, extensional processes in the Late Cretaceous and re-compressional uplift during the Late Cretaceous-Paleogene. This study clarifies the geological attributes of the Enping-Yangjiang low uplift area as a hub for proximal sediment supply, with its bedrock distribution pattern and evolutionary stage directly regulating the composition and structure of sediments in surrounding depressions. It provides a replicable research paradigm of 'source area characterisation-sink area response' for provenance analysis in rift basins and has significant guiding implications for predicting hydrocarbon accumulation patterns under similar tectonic settings.

Abstract As a major tectonic boundary along the eastern margin of the Tibetan Plateau, the Longmen Shan tectonic belt (LMSTB) underwent pronounced crustal shortening and thickening during the Cretaceous. However, the spatiotemporal evolution of Cretaceous shortening and the boundary's response to far‐field tectonic forcing remain incompletely resolved. We conducted systematic anisotropy of magnetic susceptibility (AMS) measurements across a 724.1‐m‐thick continuous stratigraphic interval at the Jinmenguan section in the Western Sichuan Basin, which is constrained by a previously published, high‐resolution magnetostratigraphic age model. Using existing paleomagnetic data, we reconstructed time‐dependent rotations of the Jinmenguan section from 128 to 64 Ma. By integrating AMS fabrics dominated by layer‐parallel shortening (LPS) with time‐equivalent rotations, we restore a time‐resolved record of maximum horizontal shortening directions for the LMSTB in a consistent time‐geometry reference frame. The results indicate that shortening direction for the LMSTB from 128 to 64 Ma was dominated at the million‐year scale by a persistent NW–SE‐trending direction, while an additional shear component may have been superimposed during 102–90 Ma under oblique shortening conditions. These results provide a testable, high‐resolution time series of Cretaceous shortening directions, clarify how the eastern plateau margin responded to far‐field tectonic forcing, and place new constraints on models for Cretaceous shortening and crustal thickening in the LMSTB.

Determining the size of Greater India is a prerequisite for studying the India-Asia collision; however, it remains controversial. Here, we report a new paleomagnetic and biostratigraphic study of limestone of the Bolinxiala Formation, dated to the Cenomanian-Santonian stages, from the Zhada area in the western Tethyan Himalaya. After systematic thermal and alternating-field (AF) demagnetization, a high-temperature or coercivity component is isolated and it passes the fold test. We obtained a reliable mid-Cretaceous paleopole for the Tethyan Himalaya at 22.9 degrees N, 228.7 degrees E, A95=3.5 degrees, yielding a paleolatitude of 28.3 +/- 3.5 degrees S. Then, based on Early-Middle Jurassic and mid-Cretaceous results from the Zhada area, we propose a new joint paleolatitudinal approach to estimate the size of Greater India, during which India was extended in a nearly east-west direction compared to the present-day N-S direction. According to this new approach, the size of Greater India in the Zhada area was 944 +/- 510 km, which strongly supports hypotheses that the size of Greater India (-900 km) was similar from west to east. Our findings indicate that crustal shortening in the western Himalaya occurred along a NE-SW direction since the India-Asia collision. This direction was nearly perpendicular to the NW-SE (-317 degrees) orientation of the southern margin of the Lhasa terrane before the collision, indicating an approximately orthogonal collision of India-Asia in this region.

The Scotia Sea serves as a critical region for understanding global land-ocean-atmosphere interaction processes and plate tectonic mechanisms. Investigating the lithospheric structure and tectonic evolution of microplates in the Scotia Sea is pivotal to unraveling the Cenozoic opening dynamics of the Drake Passage and its subsequent impact on circulation patterns and material exchange among the Pacific, Atlantic, and Southern oceans. Combining gravity and magnetic data with seismic tomography constraints, this study delineates the deep lithospheric structure of microplates in the Scotia Sea and the tectonic characteristics of the Central Scotia Sea. Furthermore, from an Earth system perspective that investigates the multi-interface interactions among land, ocean, and atmosphere, as well as the intricate cross-sphere interactions involving the asthenosphere, lithosphere, and hydrosphere, this study reveals the relationship between the formation and evolution of the Scotia Sea and the cooling events during the Eocene-Oligocene Transition. In general, the Scotia Sea is a complex basin that gradually developed through a rift system that experienced regional extension from the early Eocene to the late Oligocene. The crust of the Central Scotia Sea primarily comprises continental crust that underwent thermal weakening, extensional deformation, and rift-induced subsidence during the subduction of the South American Plate beneath the Scotia Microplate. This process was accompanied by localized basaltic magmatism, which facilitated the accretion of nascent oceanic crust during subsequent spreading phases. The Scotia Sea and adjacent regions exhibit cross-sphere coupling within their deep-shallow systems, characterized by interconnected variations between deep mantle flow channels and shallow oceanic circulation pathways. The spreading of the Scotia Sea and the opening of the Drake Passage triggered deep mantle convection beneath the Scotia Sea and adjacent regions, leading to the establishment of a new surface ocean circulation system. The mantle flow dynamics have influenced the lithospheric structure and composition in the Scotia Sea region, potentially serving as a deep-seated driving force for the formation of new tectonic features, including spreading ridges, seamounts, and deep-sea basins. Concurrently, the reorganized ocean circulation system controls the transport of heat, salinity, and nutrients around the Southern Ocean, thereby influencing climate change and the biodiversity distribution patterns from the Antarctic continent to global scales.

The uplift history of the Tibetan Plateau remains a pivotal scientific frontier in Earth Science, with broad implications for continental dynamics and environmental change. Along the southern margin of the Lhasa terrane, the Gangdese batholith offers an exceptional natural laboratory for investigating plateau uplift. This study focuses on the Quxu batholith and its surrounding volcanic-sedimentary strata in the Gangdese belt. We systematically collected seven representative rock samples, including diorite, granite, sandstone and andesite. By integrating apatite and zircon (U-Th)/He thermochronology, we have precisely constrained the Cenozoic thermal evolution of the Quxu batholith. Weighted-mean apatite (U-Th)/He ages range from 6.9 +/- 1.6M to 13.98 +/- 0.82Ma. The sample nearest the Yarlung River yields a distinctly younger age (6.9 +/- 1.6Ma), plausibly reflecting enhanced fluvial incision, whereas the remaining samples cluster around the mid-Miocene (similar to 13Ma). Zircon (U-Th)/He weighted-mean ages span 17.0 1.6Ma to 39.4 +/- 9.2Ma; only the northernmost sample preserves an Eocene age (39.4 +/- 9.2Ma), with the others indicating Miocene cooling (similar to 17Ma). Thermal history modeling resolves two episodes of rapid cooling: (1) mid-Eocene to early Oligocene (43 similar to 30Ma), likely associated with crustal thickening in the southern Lhasa terrane; and (2) early to mid-Miocene (21-10Ma), probably driven by deep-seated processes such as lithospheric delamination and asthenospheric upwelling. Integrated with existing thermochronological datasets from the Gangdese batholith, these results indicate that its Cenozoic differential exhumation reflects the combined effects of regional tectonics, deep lithospheric dynamics, and fluvial incision. Collectively, these mechanisms place critical constraints on tectonic-geomorphic coupling and uplift along the southern margin of the Tibetan Plateau.

Abstract Current understanding of past ice dynamics in the Amundsen Sea—the most vulnerable part of the West Antarctic ice sheet (WAIS)—remains incomplete, hampering future predictions. Here, sediments from International Ocean Discovery Program Site U1532 on the continental rise reveal that ice-sheet dynamics strongly influenced detrital magnetic minerals supply. Minimal magnetite concentration during ~4.1-3.8 Ma reflects the smallest WAIS extent in the Amundsen Sea sector since ~4.33 Ma. Since ~4.1 Ma, WAIS expansion was closely linked to long-term global cooling. After ~3.2 Ma, elevated fine-grained magnetite indicates a sustained increase in sediment contribution from the Thwaites Glacier catchment. The abrupt ice-sheet expansion at ~3.2 Ma may reflect the crossing of a climatic threshold that triggered qualitative transformations in ice-sheet development. Cessation of major WAIS growth after ~0.9 Ma aligns with stabilized long-term CO 2 levels and ocean temperatures. Collectively, these results underscore the high sensitivity of the Amundsen Sea sector to global climate forcing.

The Iranian Plateau is a complex puzzle composed of continental and oceanic fragments that amalgamated during the prolonged convergence between Eurasia and Gondwana-derived microplates, particularly during the closure of the Paleo-Tethys and Neo-Tethys oceans and the subsequent Arabia-Eurasia convergence. Studying the lithospheric structure of the Iranian Plateau is crucial for a deep understanding of the multi-phase amalgamation and deep geodynamic mechanisms within the Tethys tectonic domain. This study conducted an integrated analysis of potential field data, lithospheric density structure, microplate tectonics and Cenozoic intraplate deformation within the Iranian Plateau. The results show that deep geophysical anomalies effectively delineate the linear boundaries of microplates within the Iranian Plateau, which are demarcated by major thrust and strike-slip fault systems, exhibiting significant variations across distinct tectonic units. The subduction of the Arabian Plate forms a crustal root beneath the Zagros Orogenic Belt, with northeastward progressive crustal thickening from the Arabian Plate toward the Iranian Plateau. Additionally, gradient anomalies in the residual crustal gravity and lithospheric density structure provide new constraints on the spatial distribution of both the Neo-Tethys and Paleo-Tethys suture zones. Generally, the lithospheric structure and microplate tectonics are controlled by multi-phase tectonic-thermal evolution events dominated by complex subduction processes. Influenced by the final closure of the Neo-Tethys Ocean and the ongoing Arabia-Eurasia convergence, the lithospheric structure of the microplates has experienced progressive modification, and the microplate tectonics of the Iranian Plateau have experienced a transition from rifting-related (Late Permian to Late Triassic) to subduction-modified (Late Jurassic to Paleocene) and eventually to collision-affected (Eocene to present). The ongoing oblique subduction has induced significant lithospheric thinning and produced low-density anomalies in the uppermost mantle beneath central Iran. Meanwhile, the persistent oblique subduction and compression of the Arabian Plate have created intense horizontal convergent stresses, triggering intense seismicity throughout the Zagros Orogenic Belt. The break-off of the subducted Arabian lithospheric slab at similar to 15-10 Ma has led to the upwelling of hot mantle materials. Furthermore, subduction-related metasomatism and dehydration processes, combined with upwelling mantle materials, have significantly modified the overlying lithosphere through mechanical weakening and thermal erosion. These deep processes ultimately led to intense Cenozoic intraplate deformation, frequent seismicity, and extensive magmatic activity across the Iranian Plateau.

As potential targets for deep-sea hydrocarbon exploration, continental slope canyon–fan systems preserve records of sea-level fluctuations and paleoclimatic changes. The Quaternary canyon–fan system in the Baiyun sag represents a potential reservoir for sand-rich deposits. However, the mechanism governing its Quaternary spatiotemporal evolution, which is influenced by multiple factors, remains unclear, significantly constraining the prediction accuracy of sand-rich deposits in this area. Based on three-dimensional (3D) seismic, drilling/logging, and paleontological datasets, a Quaternary isochronous stratigraphic framework was established for the northern continental slope of the Baiyun sag. Seismic interpretation techniques were employed to delineate the morphology and architecture of slope canyon group and associated slope fans, which enabled the development of a spatiotemporal evolutionary pattern for canyon–fan systems and the revelation of their multifactorial driving mechanisms. Our study demonstrates that: (1) Within the Quaternary target strata, one second-order (T0) and five third-order sequence boundaries (SB1–SB5) have been identified, leading to the delineation of five third-order sequence units (Sq1–Sq5) with distinct structural characteristics; (2) Sedimentary geomorphic units such as shelf-margin deltas, submarine gullies, canyons, and slope fans have been recognized, collectively forming a complete deep-water source-to-sink (S2S) system; (3) The evolution of canyon–fan systems commenced during the canyon–fan formation stage (Stage 1) under a transgressive background, progressed through the peak stage of canyon incision and fan progradation (Stages 2–3) under a regressive background, and culminated in the canyon–fan decline stage (Stage 4) under another transgressive background; (4) Macroscopic factors, including tectonic activity and climate–sea level changes, controlled sediment supply and the development of canyon–fan systems, while local factors such as sediment provenance patterns and the distance between canyons and the shelf margin regulated the structural configuration and spatial distribution of these systems. The dominant controlling factors undergo shifts over time. Elucidating the spatiotemporal evolutionary patterns of Quaternary continental slope canyon–fan systems, revealing their multifactorial driving mechanisms, and deepening the understanding of dynamic processes within deep-water S2S systems will provide a theoretical basis for subsequent predictions of sand-rich deposits and offer a practical paradigm for global canyon–fan research.

Magmatic flare-ups are widely recognized as pivotal features of continental arc magmatism, yet their driving mechanisms remain poorly understood. In this study, we present new radiometric ages and geochemical data for normal calc-alkaline, high-magnesian, and Nb-enriched arc magmatic rocks from the Northern Yili Arc (Western Tianshan, China), which coincide with the Late Devonian magmatic flare-up in the region. The normal arc magmatic rocks likely originated from partial melting of a slab fluid-metasomatized mantle wedge, possibly accompanied by fractional crystallization and crustal assimilation processes. In contrast, the high-magnesian andesites (HMAs) and Nb-enriched basalts (NEBs) were derived from sediment melt and slab melt-metasomatized mantle sources, respectively. The systematic decoupling of Nd-Hf isotopes in contemporaneous mafic-intermediate lavas further indicates mantle source heterogeneity. The clustered eruption of HMAs and NEBs, alongside enriched continental signatures in their mantle sources, implies intensified slab-mantle interactions. We attribute this to enhanced interaction efficiency driven by a unique geodynamic process. We propose that the most plausible mechanism for the Late Devonian-Early Carboniferous magmatic fluctuations involves seamount/oceanic plateau subduction followed by slab retreat or rollback. The Late Devonian seamount subduction scenario provides new insights into the geodynamic evolution of the North Tianshan Ocean, the distribution of Au-Cu deposits, and the polarity of subduction in ancient oceanic plates within the Yili microcontinent.

Abstract Eocene magmatism in southern Tibet records deep geodynamic processes associated with the India‐Asia collision. The Quxu batholith, a representative segment of the Gangdese magmatic belt, hosts widespread mafic microgranular enclaves (MMEs) indicating magma mixing. However, the nature of the mafic and felsic end‐members, the evidence for magma mixing, and the role of the Neo‐Tethyan slab break‐off in triggering the magmatism remain debated. In this study, we integrate field observations, petrography, mineral chemistry, zircon U‐Pb geochronology, whole‐rock geochemistry, zircon Lu‐Hf isotope analyses, and phase equilibrium simulations to systematically delineate the genetic relationship between the host monzogranites and the MMEs. Our results indicate that the host monzogranites and the MMEs are contemporaneous (∼47 Ma). The felsic end‐member was derived from partial melting of juvenile lower crust, whereas the mafic end‐member formed via decompression melting of the upwelling asthenospheric mantle. Evidence for magma mixing includes amphibole microtextures, plagioclase with distinct core‐mantle‐rim zoning textures and variable anorthite (An) contents, and abundant acicular apatite within the MMEs. Geochemically, linear covariant relationships in major elements between the two lithologies further support magma mixing, whereas contrasts in SiO2 and Mg# values reflect a substantial mantle‐derived contribution to the MMEs. Both the host rocks and MMEs show typical arc‐like features, marked by enrichment in light rare earth elements and depletion in heavy rare earth elements. The host monzogranites yield (La/Yb)N ratios of 9–16, while the MMEs show high (La/Yb)N ratios of 16–23. Zircon εHf(t) values were similar in the host monzogranites (+2.2 to +7.0) and MMEs (+2.6 to +7.7). Binary mixing models suggest that mantle‐derived compositions account for approximately 60%–85% of the MMEs and 15%–30% of the host monzogranites. Taken together, we propose a two‐stage petrogenetic model for the Quxu batholith, involving initial mixing of basaltic and felsic magmas at deep crustal levels, followed by re‐mixing of hybrid magmas at shallower depths. This pulsed magmatism and widespread mixing were genetically associated with the Neo‐Tethyan slab break‐off during the early stage of the India‐Asia collision.

The Cenozoic crustal deformation characteristics and underlying mechanisms in the southeastern Tibetan Plateau (TP) are critical for constraining tectonic models of plateau growth during this era. Paleomagnetic analyses and U-Pb zircon dating were conducted on the syenite pluton and adjacent sandstones in the Jianchuan Basin (26 degrees 38 ' 43 '' N, 99 degrees 49 ' 18 '' E), located at the southeastern margin of the TP. The site-mean direction obtained from syenite rocks is D = 7.1 degrees, I = 42.9 degrees, k = 88.6, alpha 95 = 7.2 degrees at 35.54-33.14 Ma and the tilt-corrected site-mean direction obtained from the sandstones is D s = 17.5 degrees, Is = 43.4 degrees, k = 141.0, alpha 95 = 3.1 degrees at 28.0-24.0 Ma. Combined with Cenozoic paleomagnetic data sets from regions surrounding the Eastern Himalayan Syntaxis (EHS), the results indicate that although clockwise rotational crustal deformation initiated at the southeastern margin of the TP around similar to 28.0 Ma, no significant latitudinal displacement has occurred since then. In contrast, the central and southeastern TP have experienced significant northward crustal convergence since the Late Eocene, relative to the reference poles of the Tarim and Qaidam Basins. These contrasting patterns of crustal movement suggest that the convergence between India and Asia has not led to substantial lateral crustal escape from the southeastern TP since the Oligocene, and that the ongoing northward migration of the EHS represents the primary driving force that quasi-synchronously caused the southeastern margin of the TP to undergo significant clockwise crustal rotational deformation while maintaining a stable latitudinal position since approximately 28.0-24.0 Ma.

As one of the most significant global warming events of the Cenozoic Era, the Middle Miocene Climatic Optimum (MMCO, 17 ~ 14 Ma) had profound impacts on the climate and environment of the arid inland regions in northwestern China. The Linxia Basin, located at the northeastern edge of the Qinghai-Xizang Plateau, offers an ideal setting for studying the climatic evolution of this region due to its continuous Cenozoic terrestrial sedimentary record and abundant mammal fossils. This study employs multiple proxies, including rock magnetism, colorimetry, and environmental magnetism, alongside palaeoecological findings, to examine thespacefluvial-lacustrine deposits of the Dongxiang Formation from the Niujiacun section in the eastern part of the Linxia Basin. These deposits were calibrated by a precise magneto-biostratigraphic chronology. The Dongxiang Formation consists of reddish-brown clay/silt sediments interbedded with thin grayish-green and grayish-white muddy layers, with age constraints between ~ 17.2 Ma and ~ 13 Ma. Rock magnetic analyses reveal distinct mineralogical assemblages: maghemite and goethite are the dominant magnetic minerals in the brownish-yellow and brownish-red clays, while hematite and maghemite are more prevalent in the reddish-brown clays, and paramagnetic iron-silicates and pyrite are found in the grayish-green muddy layers. Based on changes in chromaticity and environmental magnetic parameters, two climatic stages are identified within the zebraic sequence of the Dongxiang Formation. Stage I (17.2 ~ 15 Ma) is characterized by frequent alternation of reddish-brown and gray-green/gray-white clay layers, reflecting fluctuations in water level of the lake system and indicating climate variability against a generally warm and humid backdrop. Stage II (15 ~ 13 Ma) shows reduced redox fluctuations and increased aeolian deposition, pointing to a gradual intensification of aridification. This stage aligns with the climatic transition of increasing aridity in interior Asia during the Middle Miocene Climate Transition (MMCT). The warm and humid climate of Stage I is consistent with the paleoenvironmental data revealed by the fossil records of the Galijia and Shinanu faunas, which are interpreted as having adapted to a warm, humid climate. A comparison of the paleoenvironmental records from Linxia Basin and other adjacent basins suggests that this climatic feature was primarily driven by global warming during the MMCO.

As a convergent zone of multiple plates, the Caribbean Sea and its adjacent areas have experienced a complex tectonic evolution process and are characterized by prominent microplate development. This region provides a natural laboratory for studying the formation mechanism of continental margins, the evolution process of ocean basins, and the tectonics of microplates. However, the crustal structure and microplate tectonics in this region remain unclear due to limitations of conventional planar gravity inversion methods, which neglect the Earth’s curvature in large-scale areas, as well as the uneven coverage of regional seismic networks. To precisely delineate the crustal structure and microplate boundaries in the Caribbean Sea region, this study employs a nonlinear gravity inversion method based on a spherical coordinate system. By utilizing GOCO06s satellite gravity data, ETOPO1 topographic data, and the CRUST1.0 crustal model, we performed inversion calculations for the Moho depth in the Caribbean Sea and its adjacent regions and systematically analyzed the crustal structure and microplate tectonic characteristics of the region. The results indicate that the gravity inversion method in the spherical coordinate system has good applicability in complex tectonic regions. The inversion results show that the Moho depth in the study area generally presents a spatial distribution pattern of “shallow in the central part and deep in the surrounding areas”. Among them, the Moho depth is the largest (>39 km) at the junction of the Northern Andes and the South American Plate, while it is relatively shallow (<6 km) in regions such as the Cayman Trough, the Colombian Basin, and the Venezuelan Basin. Based on the Moho undulation, gravity anomalies, and topographic features, this study divides the Caribbean Sea and its adjacent areas into 22 microplates and identifies three types of microplates, including oceanic, continental, and accretionary. Among them, there are 10 microplates with oceanic crust, 6 with continental crust, and 5 with accretionary crust, while the Northern Andes Microplate exhibits a mixed type. The crustal structure characteristics revealed in this study support the Pacific origin model of the Caribbean Plate, indicating that most of the plate is a component of the ancient Pacific Plate with standard oceanic crust properties. Locally, the Caribbean Large Igneous Province developed due to hotspot activity, and the subsequent eastward drift and tectonic wedging processes collectively shaped the complex modern microplate tectonic framework of this region. This study not only reveals the variation pattern of crustal thickness in the Caribbean Sea region but also provides new geophysical evidence for understanding the lithospheric structure and microplate evolution mechanism in the area.

The Cretaceous tectonic evolution of the South China Block was jointly influenced by the Pacific and Tethys dual tectonic domains.Existing research on the Cretaceous tectonic evolution of South China mainly focuses on regions with intense intracontinental deformation,while the tectonic characteristics of weakly deformed areas remain poorly understood.This lack of data limits our ability to spatially constrain the extent,orientation,and magnitude of the far-field stress regime imposed on the South China Block by the Pacific-Tethys dual tectonic domains since the Cretaceous,thereby restricting a comprehensive understanding of the block's tectonic response during different evolutionary stages.This study investigates the magnetic fabric(Anisotropy of Magnetic Susceptibility,AMS)of Cretaceous sedimentary strata in the eastern Sichuan fold-and-thrust belt,integrates existing AMS data from the South China Block,and combined with the regional tectonic framework,elucidates the coupling mechanisms by which the Pacific-Tethys dual tectonic domains influenced South China's tectonic evolution during the Cretaceous.The results indicate that the Huaying Shan fault zone represented a stress boundary between the Tethys and Pacific tectonic domains during the Cretaceous.Specifically,the closure of the Meso-Neotethys Ocean and subsequent intracontinental shortening controlled the tectonic evolution west of the Huaying Shan fault zone.Meanwhile,the Izanagi and paleo-Philippine Sea plates jointly constituted the western margin of the paleo-Pacific domain,and both subducted continuously beneath the eastern margin of Eurasia during the Cretaceous.The subduction of the Izanagi Plate underwent multiple episodes of high-angle reorientation.When superimposed on the cyclic'multi-stage subduction initiation-slab rollback'process associated with the paleo-Philippine Sea Plate,this gave rise to a dual dynamic coupling mechanism.This mechanism drove repeated switches of the regional stress regime in South China between NW-SE-directed extension and compression.Through far-field transmission,the NW-SE stress field exerted persistent control on the tectonic evolution of the eastern Sichuan fold belt east of the Huaying Shan fault zone,significantly influencing the development of its fold-thrust systems.

Based on three-dimensional (3D) seismic, drilling, and logging data, this study utilized seismic sedimentology and quantitative analysis methods, under the constraints imposed by the source-to-sink system, to investigate the sediment distribution patterns of the Wenchang Formation in the steep slope zone of the Enping 17 Depression and predict potential hydrocarbon exploration areas. Through the reconstruction of the paleogeomorphology during the depositional period of the Wenchang Formation, two types of sediment transport pathways were identified: fault-controlled gullies (FCGs) and erosion-dominated gullies (EDGs). In the study area, the steep slope zone was characterized by the development of contiguous fan delta plain and front deposits, whereas semi-deep lacustrine source rocks were formed within the depression. Quantitative analysis revealed that catchment area (A), topographic relief (H), and basin length (L) serve as key parameters for characterizing the sediment supply intensity of different catchments, with FCGs exhibiting stronger sediment supply capacities. Based on the “gully-fan” correspondence relationship, fan bodies controlled by FCGs are of larger scale, featuring well-developed front deposits showing good continuity, which form favorable source-reservoir-seal assemblages with laterally adjacent source rocks. Consequently, the fan delta front distribution areas in the steep slope zone of the Enping 17 Depression exhibit favorable conditions for hydrocarbon migration and accumulation, thus representing potential exploration targets. This study enriches the quantitative analysis aspects of source-to-sink systems, clarifies the control exerted by source-to-sink systems on sediment distribution in the sink area through tectono-sedimentary coupling, and offers a reference for hydrocarbon exploration in faulted basins with similar sedimentary environments globally.

A break in the spatial pattern of bedrock cooling ages, derived from low-temperature thermochronology data, is evident across the western and northern boundaries of the Namche Barwa Syntaxis (EBS) since the Pliocene. This break has been interpreted as evidence of the growth of the EBS, which has driven the evolution of the Yarlung Tsangpo River in the syntaxis region. However, the Pliocene cooling and exhumation history of the eastern boundary, as defined by an eastward-bulged curvilinear mylonitic shear zone and strike-slip faults, is still unclear due to sparse low temperature thermochronology data. In this study, 12 bedrock apatite fission-track (AFT) samples were collected in the Motuo area of Tibet. Most of these samples yielded cooling ages ranging from 4.65 to 2.62 Ma. These ages are older than the existing data (1.7-2.4 Ma) that were confined within the EBS, from Beibeng to Duoxiong-La. Comprehensive tectonic analysis and thermal history modeling reveals that 1) the AFT cooling age-break exists across the eastern boundary of the EBS; 2) this break reflects the differential rock exhumation that occurred in this area after the Pliocene, which was most likely accommodated by the activity of the Aniqiao-Motuo shear zone and regional NE-SW compression ranging from Beibeng to Duoxiong-La. In this tectonic context, variations in precipitation may play only a secondary role in modulating the exhumation of the Motuo area. Based on the regional exhumation history, we infer that the peak period during which the Yarlung Tsangpo River followed its present course through the EBS may have occurred after 2 Ma.

The deformation center of the Eastern Himalayan Syntaxis (EHS) has migrated southeastward, but the migration process and its coupling mechanism with regional tectonic evolution remain unclear. To address this issue, the present study conducted paleomagnetic and rock magnetic analyses of Pliocene to Holocene volcanic rocks in the Tengchong Terrane (TCT), located on the southeast side of the EHS. The results show that the northern TCT experienced clockwise rotation between 3.6 +/- 0.8 Ma and 1.5 +/- 0.5 Ma. However, since no later than 0.5 +/- 0.2 Ma, the rotation has transformed to counterclockwise. By integrating crustal rotational deformation, fault activity, basin evolution, and volcanic records, this study further reveals the eastward lateral extrusion of the Burma and Assam blocks since ca. 11 Ma. The results indicate that the eastward extrusion of the Assam and northern Burma blocks, interacting with the Eurasian continental margin, has controlled the crustal rotational deformation and volcanic activity within the TCT, driving the southeastward migration of the EHS deformation center. The lateral extrusion of the Assam and Burma blocks may be linked to the acceleration of the Indian plate's northward movement during the late Miocene and the stress field adjustments associated with the uplift of the Himalayan orogeny.