Search Results (682)

Prior studies have shown that socio-economic and structural risks can be correlated with earthquake effects. The quantification of these effects was used to formulate robust disaster risk reduction (DRR) strategies and building codes. This is more pronounced in countries with complex tectonic settings, such as the Philippines, where strong-to-major earthquakes can occur. Here, we report the evaluation of deterministic ground shaking (GS) intensity measurements for Camarines Norte, the Philippines, with the objective of assessing and mapping the susceptibility of communities to intense ground motion. GS intensities and peak ground acceleration (PGA) were computed using the Rapid Earthquake Damage Assessment System (REDAS) software developed by the Philippine Institute of Volcanology and Seismology (PHIVOLCS). The PGA was computed as a fraction of acceleration due to gravity, while GS used the PHIVOLCS Earthquake Intensity Scale (PEIS). Simulations were based on recorded earthquakes and mapped active faults near the province. Geographic information systems were used to stack and refine each simulation. Results showed that 13 earthquakes and 13 seismic source zones classified most of the province as PEIS VIII or higher, with the PGA maximum at 0.66 g. The results implied that the province is susceptible to very destructive to completely devastating ground shaking, and it is recommended to incorporate these results into DRR policymaking. Full article

This research reveals the coupling mechanism between structural deformation and hydrocarbon accumulation. The Dibei area in the Kuqa Depression represents a key hydrocarbon exploration domain within the northern Tarim foreland basin. Although extensive studies on stratigraphy, sedimentology, and accumulation mechanisms have been conducted, the control of segmented deformation on traps remains poorly understood. Furthermore, the synergistic regulation mechanism involving paleo-uplifts, salt thickness, synsedimentation, and erosion is still ambiguous. Based on high-quality 2D and 3D seismic data, this study integrates tectonic evolution balanced restoration with physical modeling. We conducted two sets of 3D sandbox experiments: “differential paleo-uplift and salt thickness” and “synsedimentation-erosion.” This approach systematically investigates the control of tectonic evolution on trap formation. Results show a strong correspondence between the “subsalt–salt–supra-salt” structural deformation and trap types. The supra-salt layer is dominated by detachment fold traps, whereas the subsalt layer features thrust-fold anticline traps. The basement paleo-uplift governs structural segmentation and trap distribution. Salt thickness modulates strain partitioning and trap stability. Synsedimentation optimizes trap conditions via tectono-sedimentary coupling. Erosional unconformities serve dual functions as both migration pathways and seal beds. These four factors work synergistically throughout the entire petroleum system, from “trap formation–migration–accumulation–preservation.” It enriches the genetic theory of salt-related structures in foreland basins. The findings provide a reference for predicting favorable exploration zones, evaluating trap characteristics, and assessing resource potential in the Kuqa Depression. Full article

The West Kunlun represents one of the largest and most economically significant rare metal metallogenic belts in NW China. The newly discovered Dahongliutandong Li deposit is the first Li deposit identified within the Permian Huangyangling Group in this region, and its discovery has important implications for regional lithium exploration. In this study, whole-rock major and trace-element geochemistry and cassiterite U–Pb isotope data from both Li-poor and Li-rich pegmatites of the Dahongliutandong deposit were analyzed to constrain the mineralization age and tectonic setting. Geochemically, the pegmatites are characterized by high SiO₂ (70.57–78.50 wt%), low TiO₂, MnO, and MgO (<0.2 wt%), and strongly peraluminous signatures (A/CNK = 1.45–1.95). They exhibit coherent chondrite-normalized REE patterns with LREE enrichment and negative Eu anomalies (Eu/Eu* = 0.03–0.77), along with consistent enrichment in LILEs (e.g., Rb, U, K) and depletion in HFSEs (e.g., Nb, Ti) on primitive mantle-normalized spider diagrams, suggesting a common magmatic source or evolutionary path. Cassiterite U–Pb dating yielded consistent lower-intercept ages of 208 ± 11 Ma (MSWD = 0.86) for Li-poor pegmatites and 206 ± 5 Ma (MSWD = 1.7) for Li-rich pegmatites, both indicating Late Triassic mineralization. Combined with regional geology, these data suggest that Li mineralization was likely related to post-collisional extension following the closure of the Paleo-Tethys Ocean. This study provides new insights into regional rare metal mineralization in the West Kunlun orogenic belt. Full article

The Permian Wargal Formation of the western Salt Range preserves a shallow marine carbonate-ramp succession, in which heterogeneity reflects coupled depositional architecture, facies-selective diagenesis, and deformation-related structural compartmentalisation of the Wargal interval. This study integrates balanced restoration with stratigraphic logging, microfacies analysis, paragenetic reconstruction, and quantitative pore-network topology to evaluate how stratigraphic packaging and diagenetic overprint govern connected pathway development within a structurally partitioned fold–thrust setting. Balanced restoration of a representative transect yields 1.1336 km of minimum tectonic shortening (18.7%) and indicates shortening shared between thrust slip and distributed folding, providing an admissible geometric framework for assessing compartmentalisation. The Wargal succession is ~130 m thick and organised into three carbonate packages bounded by laterally persistent argillaceous marker intervals (~21–23 m and ~98–105 m), with grain-supported shoal to shoal-margin facies dominating intervening units. Diagenesis is strongly facies-selective; grain-supported microfacies record progressive calcite cementation that occludes pore throats, whereas mud-supported facies retain microporosity but are preferentially modified by neomorphism, compaction, and pressure-solution fabrics. Image-based analysis of 20 thin-section fields of view shows that pore connectivity varies systematically among microfacies and that a connectivity-weighted index ($I_{\mathrm{conn}}$) covaries more closely with skeleton-derived connectivity than with segmented areal porosity (${\varphi }_{2D}=0.124$–9.750%). The combined results quantify the decoupling between pore volume and connectivity and provide a basis for predicting reservoir-quality evolution from facies architecture, diagenetic sequence, and structural segmentation, with direct relevance to subsurface characterisation of marine carbonate successions in hydrocarbon systems. Full article

The Circum-Rhodope Belt fringes the Rhodope and Serbo-Macedonian zones in the Alpine orogen of the northern Aegean region. This belt contains Late Paleozoic and Mesozoic metasedimentary successions that record depositional history along the continental margin of Eurasia. Critical successions of the eastern Circum-Rhodope Belt, such as those exposed in the Fanari and Petrota areas, are studied here, integrating their structure, whole-rock geochemistry and U-Pb LA-ICP-MS zircon geochronological context. The Fanari turbiditic succession contains quartz arenite, while the Petrota succession consists of Fe-rich shale and sandstone, and both successions are distinguished by REE-depleted and REE-enriched characteristics and acidic and intermediate arc-related sedimentary sources, respectively. Detrital U-Pb zircon geochronology reveals a Late Carboniferous–Early Permian maximum depositional age of 301.2 ± 8.4 Ma for Fanari quartz arenite and a Late Jurassic maximum depositional age of 147.0 ± 2.0 Ma for Petrota Fe-shale. The results are interpreted in terms of Late Paleozoic continental slope deposition of the Fanari succession along the Eurasian margin and trench-arc sedimentation of the Petrota succession linked to the development of a Jurassic island arc system pertinent to the eastern Circum-Rhodope Belt. These tectonic settings and depositional environments can be used to restore an overall picture of a Late Paleozoic to Mid-Mesozoic sedimentation at the Rhodope–Serbo-Macedonian continental margin of Eurasia. Structures that developed in greenschist facies conditions and N-directed kinematics of the studied successions unequivocally relate them to other units of the eastern Circum-Rhodope Belt and its Late Jurassic tectonic evolution. Full article

The Early Cretaceous Hongshanwan landform in the Lanzhou Basin hosts distinctive multicolored rhythmic sedimentary layers, yet the factors controlling their coloration remain debated. This study integrates mineralogical observations, whole-rock geochemistry, and detrital zircon U-Pb geochronology to investigate the controls on sediment coloration and basin evolution. Sharp and stratigraphically consistent color boundaries indicate that coloration was largely established during sedimentation and early diagenesis, with limited influence from late-stage weathering. Geochemical data suggest that the sediments were predominantly derived from intermediate-to-mafic igneous rocks under low-to-moderate chemical weathering and dominantly oxidizing conditions. Reddish-brown strata are mainly colored by fine-grained authigenic hematite formed during early diagenesis, whereas bluish-gray and pale-yellow layers inherit their colors from calcareous and mafic components with limited post-depositional alteration. Detrital zircon age distributions reveal three principal age populations (1322–1994 Ma, 331–376 Ma and 217–286 Ma), providing first-order constraints on provenance evolution and episodic sediment supply linked to multiple orogenic cycles in a back-arc foreland basin setting. Overall, the multicolored stratigraphy reflects a coupled influence of provenance composition, depositional redox state, diagenetic processes, and tectonic forcing, offering new insights into the origin and evolution of continental red-bed systems in inland basins of northern China. Full article

The Duobaoshan porphyry copper–molybdenum deposit is located in the Great Xing’an Range, eastern segment of the Xing-Meng orogenic belt. It is the largest porphyry Cu-Mo deposit in NE China. Based on the contact relations of intrusive rocks and the results of LA-ICP-MS zircon U-Pb ages, we found that there were five stages of magmatism in the mining area, including the Early Ordovician (478.1 ± 3.2 Ma) granodiorite, the Middle Ordovician (462.1 ± 3.3 Ma, 459.5 ± 2.3 Ma) granodiorite porphyry, the Late Triassic (226.3 ± 0.4 Ma) oligoclase granite, the Middle Jurassic (170.1 ± 5.6 Ma) andesitic porphyrite, and the Early Cretaceous (118.1 ± 6.6 Ma) diorite. The Early and Middle Ordovician granodiorite and granodiorite porphyry are the principal host rocks for the mineralization in the deposit. However, Cu-Mo mineralization was also observed within the Late Triassic oligoclase granite, indicating that there are two stages of Cu-Mo mineralization in the Duobaoshan deposit. Combined with the previously reported Late Triassic skarn Cu mineralization occurring in the Xiaoduobaoshan deposit, and the Early Jurassic skarn Cu mineralization in the Sankuanggou and Yubaoshan deposits, we conclude that there are four metallogenetic stages in the Duobaoshan ore-concentration area. Regionally, there are five stages of Cu-Mo mineralization occurring in the northern Great Xing’an Range, including the Ordovician, Late Triassic, Early Jurassic, Late Jurassic, and Early Cretaceous. After discussing the tectonic setting for the generation of these deposits, we propose that the Duobaoshan ore-concentration area was influenced by the subduction of the Paleo-Asian Ocean, Mongol-Okhotsk, and Paleo-Pacific Plates during the Phanerozoic. Full article

The Middle Tonian tectonic setting of the Jiangnan Orogen, South China, remains intensely debated, and is centered on two competing models: subduction–collision versus mantle plume. This study addresses this critical knowledge gap through an integrated, multi-proxy investigation of the Middle Tonian Fanjingshan Group. This region preserves a continuous volcano-sedimentary and magmatic record, offering key insights into the orogen’s full lifecycle. To test these hypotheses, we employed a synthesis of geological survey, sediment provenance analysis, detrital zircon U-Pb geochronology of clastic rocks to determine sediment provenance and basin evolution, and petrogenetic study of coeval magmatic suites (pillow lava, mafic–ultramafic sills, and granitoids) to evaluate their magmatic processes and tectonic setting. Analysis of 1736 detrital zircon U-Pb ages from Middle Tonian strata reveals a four-stage provenance evolution: (1) SW Yangtze sources in a passive margin basin before 870 Ma; (2) bidirectional sources in an 870–835 Ma arc-derived basin; (3) syn-collisional detritus during 835–820 Ma amalgamation; and (4) post-collisional and northern Yangtze inputs in an 800 Ma rifting basin. Geochemical data from ~845–840 Ma basalts and coeval sills reveal calc-alkaline affinities and marked subduction-fluid signatures. Their calculated mantle potential temperature (1404 °C) is significantly lower than that expected for plume-derived melts (1570 °C), which is consistent with melting in a subduction-modified mantle wedge, supporting a continental rear-arc basin setting. The ~845–832 Ma mafic–ultramafic sills exhibit symmetrical geochemical zoning and two-stage emplacement, recording sustained magma recharge in the rear-arc basin. Furthermore, the ~830 Ma Fanjingshan granite is identified as a crust-derived, syn-collisional S-type granite. Synthesizing these findings, we demonstrate that the sedimentary and magmatic records collectively point to plate margin setting. A four-stage tectonic model is suggested: (1) pre-870 Ma passive margin without significant magmatic activity; (2) 870–835 Ma continental arc development at an active continental margin; (3) 835–820 Ma Yangtze–Cathaysia collision; and (4) post-820 Ma post-orogenic rifting. This work provides a robust regional case study, demonstrating that integrating records of deep magmatic processes with coeval shifts in sedimentary provenance and basin architecture is essential to reconstruct the complete evolution of ancient orogens. Full article

To address the challenges of strong tectonic stress anisotropy, multi-scale pore networks, and complex seepage pathways in the tight sandstone reservoirs of the Shaximiao Formation, southern Sichuan Basin, this study integrates petrophysical analysis with machine learning techniques to develop an intelligent flow unit identification methodology applicable to complex structural settings. Based on core petrophysical properties, mercury injection capillary pressure (MICP) data, and production dynamics, the reservoirs were classified into a fracture-type plus four conventional-type (I–IV) flow unit system. Quantitative identification of flow units was achieved using conventional well-logging curves (Gamma Ray, Spontaneous Potential, Caliper, etc.—eight curves total) using the Gradient Boosting Decision Tree (GBDT), Backpropagation Neural Network (BPANN), and Supervised Self-Organizing Map (SSOM) algorithms. Key findings include the following: The SSOM algorithm delivered optimal performance, achieving a 90.1% average accuracy on the test set, significantly outperforming GBDT (87.8%) and BPANN (85.5%), particularly in capturing nonlinear responses of fracture-type reservoirs and class-overlapping samples. Flow unit spatial distribution exhibits dual sedimentary-structural control: High-quality units (Types I/II) are enriched at the base of distributary channels in deltaic plain facies (J₂S1²), while fracture-type units cluster near fault peripheries. Strong planar heterogeneity is observed in the J₂S1³ sub-member: Near-source areas (south/southwest) develop banded Type I/II units, whereas distal regions are dominated by Type IV units. This methodology provides a theoretical foundation and intelligent technological pathway for the efficient development of highly heterogeneous tight sandstone reservoirs. Full article

The Yaojia Formation in the northeastern Songliao Basin is a primary target horizon for sandstone-type uranium mineralization in the area. Understanding its provenance, composition, and depositional paleoclimate is of great significance for uranium exploration in the region. This study analyzed 58 sandstone and mudstone samples using petrographic thin-section observation, elemental geochemistry, and detrital zircon U-Pb geochronology. The results show that Yaojia Formation sandstones are feldspathic lithic quartzose sandstone (averaging 47% lithics, 32% quartz, and 21% feldspar, mainly K-feldspar), with moderate sorting and predominantly angular to subangular grains, indicating rapid denudation in the source area, medium- to short-distance transport, and rapid deposition. The chemical weathering index (CIA, 52–68) and the index of compositional variation (ICV, 0.83~1.26) are generally low, indicating moderate chemical weathering. Rb/Sr, Sr/Cu, Al₂O₃/MgO, CIA, MgO/CaO ratios indicate that the Yaojia Formation was deposited under predominantly arid–semiarid conditions, with later stages being wetter than earlier ones. Rare earth element (REE) characteristics indicate light REE enrichment, heavy REE depletion, and significant negative Eu anomalies. Combined with A-CN-K diagrams and discriminant plots such as La/Th-Hf and Co/Th-La/Sc, the provenance is primarily derived from felsic magmatic rocks in a post-orogenic extensional tectonic setting. Detrital zircon U-Pb ages are mainly concentrated at 119–153 Ma (64%), 160–183 Ma (14%), and 318.3–327.7 Ma (6%), showing the highest similarity to zircon age spectra from magmatic rocks in the Great Xing’an Range. The comprehensive results indicate that the clastic rocks of the Yaojia Formation in the study area were mainly sourced from Early Cretaceous felsic magmatic rocks in the Great Xing’an Range and have undergone short- to medium-distance transport and sedimentation under arid to semi-arid paleoclimatic conditions. Full article

Continental rift lacustrine basins typically feature multiple sediment sources under the combined controls of volcanism, tectonics, water balance and sediment supply, resulting in complex stratigraphic successions. This complexity is particularly pronounced in fine-grained successions, which are of high interest for their potential to generate and accumulate hydrocarbons. Nevertheless, the mechanisms governing the sedimentary transition from volcaniclastic to siliciclastic-dominated fills within a rift cycle remain poorly constrained. The Lower Cretaceous Xiguayuan Formation in the Luanping Basin accumulated in a lacustrine setting influenced by explosive volcanism, providing an excellent archive of siliciclastic–volcaniclastic interaction. Based on field observations, core descriptions, and petrographic analysis, sixteen lithofacies have been grouped into seven facies associations, including subaqueous ignimbrite, volcanically sourced turbidites, subaqueous volcanic ridge, central-lake sedimentation, shallow-lacustrine margin deposits, low-density turbidites, and high-density turbidites. Their spatial relationships reveal two volcanic pulses and document the lake’s environmental evolution, with deep-water background sediments overlying volcaniclastics and a marked increase in siliciclastic input upsection, reflecting a transition from an underfilled, volcaniclastic-dominated underfilled lake to a siliciclastic-dominated lake. Notably, the fine-grained sediments associated with volcanism exhibit excellent hydrocarbon potential. Organic-rich claystones and carbonate laminae form a microscopic source–reservoir system, in which volcanic inputs appear to enhance organic matter preservation and promote the development of reservoir-quality layers. This study elucidates how volcanic activity modulates sedimentation and sediment supply in a deep-lacustrine rift, offering new insights into volcano-sedimentary interactions and related hydrocarbon systems in continental rift basins. Full article

In recent years, an ion-adsorption type REE deposit has been discovered for the first time in the weathering crust of epimetamorphic rocks in Ningdu County, Jiangxi Province, which provides a new idea for the exploration of ion-adsorption-type REE deposits. However, most previous studies on the ore-forming parent rocks of ion-adsorption-type REE deposits have focused on granites and volcanic rocks, while studies on epimetamorphic rocks remain extremely scarce. In this paper, petrographic analysis of epimetamorphic rocks, LA-ICP-MS U–Pb dating and trace element analysis of zircon and apatite were conducted on the metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, so as to constrain the formation age and tectonic dynamic setting of the rock mass, investigate the petrogenesis and material source of the rock mass, and reveal the metallogenic potential of the rock mass. The results of zircon and apatite U–Pb dating show that the protolith of the metamorphic tuff from the Kuli Formation formed at ca. 770 Ma, representing a product of mid-Neoproterozoic magmatic activity. The protolith restoration of metamorphic rocks suggests that the protolith of the metamorphic tuff from the Kuli Formation is magmatic rock. The estimated results of zircon Ti thermometry indicate that the magmatic crystallization temperature ranges from 623 to 723 °C, with an average value of approximately 696 °C, and the calculated zircon oxygen fugacity values vary from −18.7 to −9.4, with an average of −13.8, implying that the rock formed under conditions of relatively low temperature and high oxygen fugacity. The correlation diagrams of trace elements and element ratios in zircon and apatite reveal that the magmatic evolution involved extensive fractional crystallization of minerals such as zircon, monazite, apatite, titanite, rutile, and plagioclase during the formation of the rock mass. The discrimination diagrams of trace elements in zircon and apatite demonstrate that the metamorphic tuff from the Kuli Formation was formed in a continental margin arc or arc-related orogenic belt, and the magmatic source is characterized by crust–mantle mixing. Combined with previous research findings on regional tectonic-magmatic activities, it can be concluded that the metamorphic tuff from the Kuli Formation was formed in a tectonic setting of back-arc extension and intra-arc rifting caused by the rollback of the subducting oceanic slab. The upwelling of the asthenospheric mantle induced the partial melting of arc-derived sediments in the continental crust, which was subsequently mixed with mantle-derived magma, ultimately generating the parent magma of the metamorphic tuff. The metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, has high REE abundance and relatively easily weathered REE mineral assemblages, which can provide sufficient material sources for ion-adsorption REE mineralization and have a great metallogenic potential for ion-adsorption REE deposits. Full article

The geochemical characteristics of major elements in lake sediments provide insights into aquatic environmental variations, the regional geological background, and the intensity of weathering processes. This study investigates Dongping Lake (DL) using 20 surface sediment samples, analyzing nine major elements. Spatial interpolation was used to characterize their distribution patterns, while principal component analysis, self-organizing maps, and absolute factor analysis–multiple linear regression methods were applied to identify element sources and interpret their geological significance using weathering indicators. Results show that surface sediments are dominated by SiO₂ (46.49%), Al₂O₃ (13.10%), and CaO (11.25%). Controlled by hydrodynamic conditions, major elements are mainly concentrated in the southern part of the lake near the inflows of the Dawen and Liuchang Rivers, with concentrations decreasing from south to north. Riverine transport is the primary source of major elements, with the Dawen River contributing the most followed by the Liuchang and Yellow rivers. Weathering indicators suggest that source rocks have experienced moderate chemical weathering, reflecting initial sedimentation in a tectonically active setting under warm and humid conditions and relatively short transport distances. These findings provide a geochemical basis for understanding sedimentary processes and environmental evolution in the Dongping Lake basin and offer valuable support for regional water resource management, ecological restoration, and sustainable watershed governance. Full article

The Jiaodong Peninsula hosts one of the largest gold provinces in the world. The Xincheng gold deposit, located within the Jiaojia gold metallogenic belt, is the largest deposit in this belt and represents a super-large fractured alteration-type gold deposit hosted in fracture zones with relatively well-preserved conditions. Mineralization and hydrothermal alteration are controlled by the Jiaojia Fault zone and its subsidiary faults. The Jiaojia Fault (JJF) serves as the principal ore-hosting structure of the Xincheng deposit, and its multi-stage activity has governed the mineralization, subsequent modification, and preservation of the deposit. However, the post-mineralization cooling, uplift, and exhumation history of the deposit remains poorly constrained. In this study, zircon and apatite fission-track thermochronology analyses were conducted, and inverse thermal history modeling of apatite was performed to reconstruct the tectonic-metallogenic evolution of the Xincheng gold deposit. The zircon fission-track ages range from 90.0 ± 4.0 to 118.0 ± 5.2 Ma, which are younger than the mineralization age (~120 Ma), indicating that the region experienced widespread cooling during the Late Early Cretaceous. This cooling event was likely related to crustal uplift and exhumation triggered by a transformation of the tectonic regime. The apatite fission-track ages range from 15 ± 1.8 to 38 ± 2.7 Ma, recording the Cenozoic cooling and uplift history after mineralization. The inverse thermal history modeling results show that the post-mineralization cooling process can be divided into three stages. The first stage, from 42 ± 5 to 30 ± 4 Ma, is characterized by rapid cooling, with an average cooling rate of 4.23 °C/Myr. The second stage, from 30 ± 4 to 12 Ma, represents a period of slow cooling, with an average cooling rate of 0.98 °C/Myr. Since 12 Ma, the third stage has been marked by renewed rapid cooling, with an average cooling rate of 4.17 °C/Myr. Variations in cooling rates among different stages reflect adjustments in the regional tectonic stress field and the influence of activity along the JJF. Based on the fission track thermochronological data and a reasonable estimate of the geothermal gradient, the total amount of exhumation since 120 Ma is calculated to be approximately 8.22 km. Integration of these results indicates that the shallow portion of the deposit has undergone a certain degree of erosion; however, the overall preservation conditions remain favorable, and significant exploration potential persists at depth and along strike. This study constrains the post-mineralization cooling and erosion history of the Xincheng gold deposit, reveals the controlling role of multi-stage tectonic activity on deposit preservation, and provides new temporal constraints and a scientific basis for preservation assessment and deep exploration of gold deposits in the Jiaodong Peninsula and in regions with similar tectonic settings. Full article

This study investigates the rare-earth element (REE) geochemistry of twenty-nine clastic rock samples from the Paleogene Liushagang Formation in the Weixi’nan Sag. The primary objectives were to quantitatively evaluate the depositional paleoenvironment, determine the provenance lithology, and constrain the tectonic setting of the source area. Results reveal distinct chondrite-normalized REE distribution patterns characterized by light REE (LREE) enrichment, relatively flat heavy REE (HREE) segments, and pronounced negative Eu anomalies. The cerium anomaly index (Ce_anom, normalized to the North American Shale Composite) ranges from −0.06 to 0.00, implying broadly suboxic to anoxic-reducing conditions in the water column during deposition. The chondrite-normalized (La/Yb)_N ratio, utilized as a proxy for relative depositional residence time, decreases stratigraphically from member 3 to member 1, reflecting a transition to shorter residence times and higher relative sedimentation rates. Laterally, (La/Yb)_N increases toward the basin center, accurately recording progressively lower sedimentation rates basinward. Provenance analysis indicates that the sediments were predominantly derived from felsic igneous rocks of the upper continental crust. Spatially, the northern steep-slope belt reflects a uniform source, whereas the southern gentle-slope belt and the Weixi’nan low-uplift periphery record multisource mixed inputs. Finally, tectonic discrimination reveals an “active continental margin” affinity. This geochemical signature represents the inherited tectonic environment of the Mesozoic parent rocks in the surrounding source uplifts, rather than the Cenozoic extensional rift setting of the Weixi’nan Sag itself. Full article