Abstract The low dimensionality of basalt geochemical data has long been inferred but has not been quantitatively evaluated from the relationships among elemental contents. We developed regression‐based machine learning models and examined the relationships among elemental contents for basalts. We applied an extended gradient boosting algorithm (natural gradient boosting), which allows predictions with associated probability distributions, to a training data set of global basalt compositions, including midocean ridge, ocean island, and volcanic arc basalts. From four input elements (Th, Nb, Zr, and Ti), the trained models can successfully predict the contents of 12 trace elements (Rb, Ba, U, La, Ce, Pb, Sr, P, Nd, Y, Yb, and Lu; R 2 > 0.7) and 5 major elements (SiO 2 , MgO, Na 2 O, CaO, and K 2 O; R 2 > 0.67). The adopted model interpretation techniques quantitatively identified key input features for output element estimations, such as similar elemental incompatibility (e.g., Th‐Rb contents) and elemental ratios/products involving different incompatible elements (e.g., Zr/Th ratios for Yb contents). This is consistent with well‐established geochemical principles related to elemental incompatibility and tectonic setting and was achieved without prior geochemical knowledge of the samples. On a projection of a reduced two‐dimensional map constructed from the four input elements, numerical variations of the identified key input features were correlated with the output contents. Given the successfully constructed regression‐based models based on only four input elements, basalt geochemical data have a low dimensionality. Moreover, our approach can potentially provide a more comprehensive understanding of the link between basalt geochemistry and geological processes.

ABSTRACT Many Banded Iron Formations (BIFs) have been identified in Precambrian microblocks located in the northeastern segment of the Central Asian Orogenic Belt (CAOB). The type and genesis of these BIFs, which provide valuable insights into the evolution of the Precambrian geological environment, have been barely researched. The Dongfengshan iron deposit from the Liangzihe Formation in the Xing’an block and the Yangbishan iron deposit from the Dapandao Formation in the Jiamusi block, both previously considered to be superior-type BIFs based on an unsubstantiated age hypothesis, were selected for analysis to investigate the formation of these deposits using published research data. The geochemical features of ore-hosting rocks from the Yangbishan iron deposit, including high Al2O3 and TiO2 contents with a strong positive correlation, a moderate Y/Ho ratio, and the decoupling of Light Rare Earth Elements (LREE) and Heavy Rare Earth Elements (HREE), indicate a mixed source of terrigenous debris and chemical sediment. In contrast, the Dapandao Formation exhibits a more homogeneous sediment provenance. The La/Sc-Ti/Zr tectonic plot and REE compositions indicate that both of them formed in a continental island arc setting, rather than a passive continental margin as previously proposed, which is consistent with Algoma-type deposits. The detrital zircon age spectra from the deposits suggest that the breakup of the Rodinia supercontinent likely provided the metallogenic materials for the mineralisation event around 820 Ma.

The growing demand for high-quality, locally available construction materials has intensified interest in evaluating alternative rock sources for aggregate production. This study examines the potential of Kamila Amphibolites, extensively exposed in Kuza Drushkhela of the Matta region, District Swat, Khyber Pakhtunkhwa, Pakistan, for use as coarse aggregates in concrete and other structural applications. The study area lies within the southern portion of the Kohistan Island Arc, a terrain dominated by medium- to high-grade metamorphic rocks. Representative samples, including both aggregate and bulk rock specimens, were systematically collected and subjected to comprehensive petrographic and geotechnical investigations. Petrographic analysis identified Amphibole, Epidote, Hornblende, and Plagioclase as the principal mineral phases, displaying predominantly anhedral to subhedral textures with minor mica and accessory minerals. Engineering evaluation followed ASTM, AASHTO, BS, and National Highway Authority (NHA) standards. The determined properties include specific gravity (3.015 g/cm³), water absorption (0.270%), bulk density (3.031 g/cm³), soundness (1.022%), flakiness index (12.10%), uniaxial compressive strength (63.83 MPa), and Los Angeles abrasion value (9.84%). These results are within the acceptable range for high-performance construction aggregates. The findings demonstrate that Kamila Amphibolites possess the requisite strength, durability, and physical characteristics, confirming their suitability for concrete manufacturing and large-scale civil engineering works.

Recent tectonic studies provide a new view of the evolution of the New Guinea Orogen. The Mesozoic–Cenozoic orogen has undergone crustal shortening and thickening with accompanying uplift and almost continuous magmatism since the Early Cretaceous. Ten terranes have been identified in the orogen, with major faults forming the boundaries between these terranes. Terranes display various stages of active collision–accretion. The Australian craton’s deformed northern margin is a complex zone of para-autochthonous and accreted allochthonous terranes. Periods of convergence and compression have occurred within the orogen during sustained westward sinistral movement with intra-plate deformation, microplate formation and large-scale sinistral translations. Major sinistral horizontal dispersals and counterclockwise rotations of terrane fragments have occurred, with blocks of the Owen Stanley terrane and Waria terrane dispersed westward for up to 800 km. Westward dispersal may also account for the 700 km length of the middle–late Miocene Maramuni magmatic arc. The largest allochthonous terrane is the mostly submerged Nakanai terrane, consisting of Lower Cretaceous–Oligocene oceanic crust and island arc rocks along the northern New Guinea mainland and throughout the New Guinea islands and Solomon Islands. Docking of the allochthonous Ontong Java Plateau terrane with the New Guinea Orogen was initiated at 25–20 Ma (Oligocene–Miocene boundary) and is associated with widespread unconformity. Renewed convergence since 4–2 Ma is associated with intra-plate deformation of the Nakanai terrane, including break-up of the terrane into a series of microplates, asymmetric sea-floor spreading in the Manus Basin (3.5 Ma) and Woodlark Basin (6.2 Ma), rotational collision of the South Bismarck microplate with the Owen Stanley terrane (3.7–3.0 Ma), late Miocene (7.0 Ma) deformation of the Aure–Moresby terrane and buckling and formation of a double chain of islands in the Solomon Islands and a series of ridges (Tabar–Lihir–Tanga–Feni arc; Pliocene–Holocene) in the New Ireland region.

Abstract A variety of geological processes shape and modify the morphology of volcanic islands over a range of temporal timeframes. Amongst the most conspicuous are aerial and submarine landslides that are frequently observed in both island arc and intra-plate volcanic settings. Identifying and understanding the triggering mechanisms of these landslides is crucial to geohazard mitigation as they pose major threats to coastal communities as well as critical onshore and submarine infrastructure. Christmas Island, located in the northeast Indian Ocean rises steeply, more than 5000 m, from the surrounding ocean floor. In this study, we compile a seamless bathymetric surface from a number of sources and systematically describe four large-scale submarine landslides for the first time, with a combined areal coverage of 1711 km 2 , and numerous smaller mass-movements covering 339 km 2 . Based on their geomorphic characteristics observed from the high-resolution bathymetry data, two of the identified landslides can be classified as volcanic debris avalanches and the remainder as slumps. The distribution of landslides and planform orientation of the remnant headlands suggest the presence of volcanic rift zones that may have controlled the location of large landslides and the present-day shape of the island. In addition, we postulate that many of the major landslides formed prior to the emergence of the island as evidenced by relatively undisturbed onshore terraces interpreted as paleo-shorelines. Whilst the smaller slumps are likely triggered by subsequent volcanic eruptions and seismic activity associated with subduction at the adjacent Sunda Trench.

Abstract Sponsored by the National Science and Technology Council of Taiwan, the programs Sailing to the Blue Sea (SBS), Kuroshio to Turbulence Exchange (KTEX), and the U.S.-Taiwan collaboration program Island Arc Turbulent Eddy Regional Exchange (ARCTERX) jointly conducted a multidisciplinary field campaign aboard the R/V New Ocean Researcher 1 from March 25 to April 19, 2024. The cruise completed a round trip from Kaohsiung to Palau, executing coordinated oceanic and atmospheric observations in the western North Pacific. The scientific objectives of this campaign were to: (1) investigate the physical, biological, and biogeochemical properties of a targeted cyclonic mesoscale eddy in the western North Pacific and its impact on oceanic weather through air-sea interactions; (2) quantify water mass transformation and nutrient flux variability from the North Equatorial Current (NEC) to the Kuroshio; (3) examine the diurnal warm layer and its coupling with atmospheric boundary layer variability in the subtropical and tropical regions; (4) detect potential ground motion in the Philippine Sea basin at the eastern flank of the Gagua Ridge, east to Taiwan; and (5) measure along-track gravity anomaly across the Philippine Sea basin. The campaign successfully sampled a cyclonic eddy centered at (131°E, 18°N), hydrographic transects across the Kuroshio and the NEC, and high-resolution upper ocean temperature profiles in the tropical ocean. To facilitate detailed analyses of the complex cruise data, the ship-based and autonomous observations are introduced here.

Abstract The Paleogene magmatic arc in Luzon marks the onset of island arc formation within the Philippine island arc system. This study examines the Late Eocene to Late Oligocene Bangui Formation, the oldest sedimentary sequence exposed in Northern Luzon. Whole-rock geochemical compositions of its clastic rocks are presented for the first time to provide key insights into its provenance and tectonic setting. Bivariate and ternary diagrams, using major (e.g., TiO2 vs Al2O3) and trace element compositions (e.g., low La/Th and low Hf), suggest multiple sources for the Bangui Formation. Tectonic discrimination diagrams, showing low La (< 20) and Th (< 5) concentrations, indicate an oceanic island arc setting. The mineral chemistry of the Bangui sandstones was also analyzed for the first time. The results reveal that the plagioclases contain low orthoclase content, with some grains exhibiting a more albitic composition. Whole-rock geochemistry and mineral chemistry data suggest that the clasts of the Bangui Formation were derived from the volcanic unit of the Caraballo Formation, with contributions from intermediate to felsic units in the Caraballo Range. It is inferred that an Early Eocene (or older) proto-North Luzon Arc source (pNLA) contributed to the Bangui clastic rocks. Our results show that the integrated use of whole-rock geochemical and mineral chemistry data, complementary to field geological data, offers a robust approach to deciphering the provenance and tectonic setting of clastic rocks in northern Luzon. The field geological and geochemical signatures of these clastic rocks provide crucial information on the early Cenozoic history of the Philippine island arc system. This hopefully can contribute to unravelling the complex geologic history of this part of the Western Pacific region.

The lithology, composition, U-Pb LA-ICP-MS ages of detrital zircons from sediments of the Western Kamchatka Basin (Russian Far East) provide important insight into paleogeography and tectonic setting of the Sea of Okhotsk in the Eocene. Our study is based on mapping, structural observations, descriptions of the sections and lithology, composition of the sandstones, and U-Pb LA-ICP-MS dating and morphology analysis of detrital zircons from the Eocene sandstones of the Western Kamchatka Basin. The provenance for the sandstones is mainly associated with orogen recycling in magmatic arcs. The analysis of heavy minerals indicates mafic to sialic sources. The mafic terranes of the Asian margin on the west or/and Olyutorka-Kamchatka ensimatic island arc affected the mechanism transferring the basic material to the Western Kamchatka Basin in the Eocene. The sialic clasts originated from continental blocks of the Asian margin and the Okhotsk-Chukotka volcanic belt.New data allow us to prove that the erosion of the Okhotsk-Chukotka belt had a significant influence on the sedimentation system in the north of the Sea of Okhotsk in the Eocene. We can assume that the Paleo-Penzhina River system already existed in the Eocene. The existence of the sialic sources in Eocene allows us to assume the possibility of finding the good quality collectors in the Eocene deposits of the Western Kamchatka Basin and the north of the Sea of Okhotsk.

Abstract The Philippine archipelago comprises accreted terranes, including ophiolites, island arcs, and continental fragments. It absorbs the approximately 9 cm/year convergence between the Sundaland Plate to the west and the Philippine Sea Plate to the east. Understanding the crustal thickness variations across the Philippines is crucial for distinguishing collision boundaries and comprehending the complexities of tectonic evolution. In this study, we conducted ambient noise autocorrelation combined with receiver function analysis to estimate crustal thickness in the northern Philippines. To resolve ambiguities in the PmP phase in autocorrelation signals, Moho depth information from receiver function was utilized. We successfully identified coherent signals of PmP autocorrelation from 20 vertical seismograms, with two-way travel time ranging from 6.64 s to 13.79 s. These times correspond to crustal thicknesses of 19.8 to 46.0 km, respectively, as derived from the average CRUST1.0 P-wave velocity model. Our main findings and interpretations indicate that the crust beneath Luzon is slightly thicker in the western regions compared to the eastern parts. This suggests a limited influence of magmatic processes in the latter. Furthermore, our observations identified a tear in the slab at 17°N and 14°N latitude, characterized by thinner crust. We observed that the crust beneath Mindoro thickens in proximity to the collision of the microcontinental fragments with Mindoro-Panay island, whereas it thins toward the extension of the Pleistocene Macolod Corridor rifting.

ABSTRACTNb‐enriched basalt is a distinct type of island arc basalt characterised by unique geochemical signatures. The basalts and basaltic andesites of the Dahalajunshan Formation, primarily composed of plagioclase and olivine phenocrysts, constitute the dominant lithology of the Early Carboniferous marine strata in the Wusun Mountain region of the Yili Block. Thirty LA‐ICP‐MS zircon U–Pb measurements yielded a concordant 206Pb/238U age of 343.8 ± 5.7 Ma (MSWD = 1.3), confirming an Early Carboniferous age, which is temporally consistent with spatially associated adakites. Geochemically, the basalts exhibit arc‐like signatures (LREE enrichment, HREE depletion, pronounced Nb, Ta and Ti negative anomalies) but are distinguished by elevated TiO2 (1.66–3.04 wt%), P2O5 (0.47–1.74 wt%) and significant enrichments in Nb (> 7 ppm), Sr (> 500 ppm) and Zr (> 170 ppm; Zr/Y > 4). Their low (La/Nb)PM (avg. 2.59) and high (Nb/Th)PM (avg. 0.64), coupled with uniform Sr–Nd isotopes (87Sr/86Srᵢ = 0.70440–0.70494; εNd(t) = +1.58 to +3.08), confirm affinities to Nb‐enriched basalts rather than normal island arc basalts, implying a unique subduction‐modified mantle source. Comprehensive analysis suggests that the Nb‐enriched basaltic magma of Wusun Mountain was derived from a spinel‐phase lherzolite source. It is proposed that adakitic melts, generated by the partial melting of subducting slabs, metasomatically interact with the mantle peridotite, inducing partial melting and the formation of Nb‐enriched basaltic magma. The discovery of Nb‐enriched island arc basalts in the Wusun Mountain region provides new evidence for the subduction‐related tectonic setting of the Yili Block during the Early Carboniferous and temporally constrains the closure of the Tianshan palaeo‐ocean basin to post‐date this period. These findings offer valuable insights into the mechanisms of Nb enrichment in arc magmas and the prolonged subduction evolution of the Chinese Western Tianshan orogenic belt.

The evolution of the Meso-Tethys Ocean of the Tibetan Plateau involved a complex history of subduction and accretion. The composition, deformation features, and ages of major rock units in accretionary complexes, preserved in the mélanges of the Bangong-Nujiang suture zone, provide important insights into the nature, polarity, and timing of subduction events. Investigations of the accretionary complexes in the eastern segment of the Bangong-Nujiang suture zone, along with coeval extrusive rocks, reveal two magmatic arc systems at 196 Ma and 163−153 Ma. The sedimentary units represent an Early Jurassic island arc and a Middle Jurassic−Early Cretaceous forearc trench-basin deposited in response to the northward subduction of the Meso-Tethys Ocean. The detritus in the Early Jurassic island-arc deposits preserves the records of the 196 Ma intraoceanic arc alongside contributions from oceanic crust during the early development of the basin. Geochemical data indicate that the basalts were derived from an enriched mantle source with negligible continental crust contamination. In contrast, detritus within the Middle Jurassic−Early Cretaceous arc-accretionary system reveals a mixed source, including contributions from continental marginal arcs dated to 163−153 Ma, oceanic crust, and northern terranes. Furthermore, the 163−160 Ma high-Mg andesites originated from the melting of sediments derived from a subducted slab and their subsequent interaction with the overlying mantle wedge. The Middle−Late Jurassic high-Mg andesite layers within the accretionary complex, along with the previously identified forearc basalts and boninites, indicate a subduction initiation event. Structural analysis reveals that the Late Jurassic−Early Cretaceous deformation of the accretionary complex is primarily characterized by north-dipping thrust faults and locally tight folds. The deformation features, combined with the records of magmatic arcs and sedimentary units, indicate a northward subduction polarity. Consequently, the Bangong-Nujiang Meso-Tethys Ocean experienced at least two episodes of northward subduction initiation. The initial Middle−Late Jurassic subduction may be related to the southward migration of the subduction zone, triggered by the northward accretion of terranes.

The heavy mineral-rich wadi deposits sourced from various wadis close to Gabal Homret Waggat in the central eastern Desert of Egypt are being analyzed to assess their genesis and paleoenvironment. This study integrates remote sensing (ALOS/PALSAR DEM and ASTER imagery), mineralogical, and geochemical analyses (XRF and SEM-EDX). Remote sensing analysis (ASTER and ALOS/PALSAR) delineated three main watersheds and identified granitic plutons as the primary source rocks. Mineralogical analysis revealed a diverse heavy mineral assemblage, including zircon, rutile, ilmenite, magnetite, staurolite, and sillimanite, indicative of a provenance dominated by granitic and metamorphic rocks. Grain size analysis shows that the samples range from very platykurtic to extremely leptokurtic (Kg: 0.598–5.350 φ), indicating deposition in predominantly fluvial environments. Geochemical data show enrichment in SiO2, Al2O3, K2O, and Na2O, indicating a felsic (granitic) source with low Chemical Index of Alteration (CIA: 41.89–51.83) and Plagioclase Index of Alteration (PIA: 37.97–52.78) values, and indicating that the source rocks show low to moderate chemical weathering. Tectonic discrimination diagrams suggest that the source rocks were formed in a continental island arc or active continental margin, consistent with the Arabian–Nubian Shield. The presence of economically valuable minerals like zircon and rare-earth-element-bearing monazite and columbite highlights the significant resource potential of these placer deposits.

The West Qinling Orogenic Belt (WQOB) contains a sedimentary succession that is approximately 15 km thick, spanning from the Carboniferous to the Jurassic period. This succession offers critical insights into the tectonic evolution of the Paleo-Tethys Ocean. While previous models have suggested various depositional environments, the late Paleozoic to Mesozoic tectonic evolution of the WQOB is still not fully understood. In this study, we incorporate new detrital zircon U-Pb age data and whole-rock geochemical analyses from six stratigraphic units, dating back to the Carboniferous to Triassic periods in the Xiahe–Hezuo region, alongside existing datasets. The detrital zircon age spectra from the WQOB reveal three distinct groups: Devonian–Carboniferous strata exhibit dominant Neoproterozoic (~800–900 Ma) zircon populations, whereas Permian–Triassic rock samples show prominent Paleoproterozoic (1840–1880 Ma) and Archean (2450–2500 Ma) peaks. A minor Neoproterozoic component in Permian spectra disappears by the Triassic, while Jurassic–Cretaceous assemblages lack Precambrian grains. These trends reflect evolving source terranes linked to Paleo-Tethyan subduction dynamics. Furthermore, the geochemical signatures of the Devonian–Triassic clastic rocks align with the composition of upper continental crust, indicating a tectonic relationship with continental island arcs and active continental margins. By synthesizing these findings with established detrital zircon ages, magmatic records, and geophysical data, we propose that the WQOB underwent pre-Triassic tectonic evolution that was marked by pre-Triassic subduction and localized extension during the process of continental underthrusting.

COMPOSITION, GEOLOGICAL STRUCTURE, AND FORMATION MODEL OF THE SUBDUCTION MÉLANGE OF THE ALAMBAY MÉLANGE ZONE OF SALAIR (<i>northwestern Central Asian orogenic belt</i>)

Subduction polarity reversals around the Solomon Island Arc associated with interaction of mantle domains in the Southwest Pacific

Zircon U-Pb ages, geochemical and Sr-Nd-Hf-O isotopic data of newly discovered ultrapotassic and adakitic rocks in the Kohistan Island Arc, North Pakistan: Constraints on petrogenesis and post-collisional alkaline magmatism

ABSTRACT The southeastern part of the Sandur Schist Belt, particularly the Obulapuram area, was investigated to understand the genesis and geochemical evolution of iron ores along with associated volcano-sedimentary sequences. The iron ore bodies up to 5 km long and 50 to 100 m wide are strata-bound and comprise Banded Magnetite Quartzite (BMQ), Banded Hematite Quartzite (BHQ), massive hematite, and friable hematite of Precambrian age. Major, trace, and Rare Earth Element (REE) geochemistry of BHQ suggests a mixed origin involving deep-sea pelagic sediments and hydrothermal input, while BMQ exhibits signatures predominantly of hydrothermal derivation. The massive and friable hematite ores likely formed through extensive silica leaching and hydrothermal alteration of precursor BIF units, producing hematite-martite assemblages. Despite regional metamorphism and post-depositional fluid activity, the preserved geochemical patterns, particularly the REE distributions, suggest a depositional environment in a back-arc basin, possibly near immature island arcs, with geochemical affinities to mid-ocean ridge basalts (MORB). These interpretations integrate primary depositional features with subsequent overprints to reconstruct the complex genesis of the Obulapuram iron ores.

Abstract The Paleoproterozoic supercontinent cycle likely began with a mountain-building event around 2.1 Ga, following a global tectono-magmatic lull occurred around 2.3 Ga, during which there was a notable decrease in magmatic activity. The nature of tectonic activity between 2.2 and 2.1 Ga remains unclear. This paper focuses on the discovery of low δ¹⁸O zircon-bearing potassic magmatic rocks in the Taihua Complex on the southern margin of the North China Craton (NCC). Through zircon U-Pb dating, Hf-O isotopic analyzes, whole-rock major and trace elements, as well as apatite Sr-Nd isotopic studies, we have constructed a model for the related geological evolution. Zircon U-Pb dating results clearly indicate active magmatism around 2.2–2.1 Ga, including granites at ~2.13 Ga, quartz monzodiorites at 2.16–2.12 Ga, and mafic cumulate rocks at 2.19 Ga. These potassic rocks show high K2O content, ranging from 0.95 wt.% to 7.00 wt.%, with a mean value of 3.95 wt.%, K2O/Na2O ratios, varying from 0.44 to 3.40, with a mean value of 1.24. These characteristics suggest contemporaneous formation of various mafic to intermediate-felsic rock types during the same period. The quartz monzodiorites and regionally distributed mafic dikes/intrusions show a variation in major element compositions, with trace element patterns characteristic of island arc settings, and consistent zircon Hf isotopic and apatite Sr-Nd isotopic characteristics, indicating a common origin in continental arc magmatic system. The 2.2–2.1 Ga granites possibly formed from partial melting of metasedimentary rocks. The zircon Hf-O isotopic features suggest that high-temperature hydrothermal activity induced by mantle upwelling may have played an important role. The zircon δ¹⁸O values from magmatic events during this period show a wide range (1.7, 5.7‰), but most are close to mantle values, further supporting the involvement of mantle-derived mafic magma processes. These findings provide important insights into the Precambrian tectonic evolution following a global tectono-magmatic lull.

Abstract Strike-slip faults on the plate tectonic scale in arc settings significantly contribute to the movement of crustal blocks, crustal deformation, and orogeny associated with back-arc spreading, arc–arc collisions, and the subsequent evolution of arcs. The Tanakura Fault Zone, which was active during and after the opening of the Sea of Japan, is one of the main strike-slip faults in Japan. An understanding of the kinematic history of the Tanakura Fault Zone would provide insights into the tectonics of the opening of the Sea of Japan, the ensuing collision of the Honshu and Izu–Ogasawara (Bonin)–Mariana arcs, and the subsequent evolution of the Japanese island arc system. We investigated the activity of the Tanakura Fault Zone during the Miocene based on a field study along the Tanakura Western Marginal Fault in the Tanakura Fault Zone, analysis of deformed Miocene conglomerates, and provenance analysis of detrital zircon in Miocene strata. These results indicate that dextral faulting has occurred in the Tanakura Fault Zone since ~ 16 Ma. We obtained evidence of dextral movement along the Tanakura Western Marginal Fault from fault outcrops. This movement resulted in the formation of elongated granitic clasts in the deformed conglomerate through cataclastic deformation related to the faulting. In addition, cataclasite samples contain Paleozoic zircon grains, suggesting that some clasts were derived from the Paleozoic Hitachi Metamorphic Rocks. Paleozoic clasts were probably supplied as gravel to the area west of the southern Abukuma Mountains and were then transported several kilometers to the north-northwest by dextral movement on the Tanakura Eastern Marginal Fault in the Tanakura Fault Zone to reach their present location. Our findings suggest that dextral faulting of the Tanakura Fault Zone occurred due to NE–SW compression resulting from the collision between the Honshu and Izu–Ogasawara (Bonin)–Mariana arcs, which occurred as a result of the initiation of subduction of the Philippine Sea Plate, just after the opening of the Sea of Japan.

The provenance of the Middle-Upper Permian in the Lintan and Jiangligou areas, remnants of rift basin sedimentation within the West Qinling, remains controversial, hindering understanding of the basin-range coupling evolution of the Qinling Orogenic Belt and its periphery. Heavy minerals, major and trace elements, rare earth elements, detrital zircon U-Pb dating, and in situ Lu-Hf isotopes were analyzed to determine the provenance of the Middle-Upper Permian sandstones. Results were integrated with previous studies to investigate basin-range coupling processes. The results reveal the following: (1) The Upper Member of the Shilidun Formation in the Lintan area was deposited during the Late Permian. Heavy minerals are dominated by moderately to highly stable species. Source rocks were derived from intermediate-acidic magmatic rocks and low- to medium-grade metamorphic terrains. The provenance was primarily situated in a continental island arc tectonic setting. Diverse source rock types were identified, including materials from felsic igneous, quartzose recycled, and mafic igneous provenances. Detrital zircon U–Pb age spectra display two major peak ages at 285 Ma and 442 Ma, along with five subordinate peaks at 818 Ma, 970 Ma, 1734 Ma, 1956 Ma, and 2500 Ma. The εHf(t) values range from –44.95 to 42.67, and TDM2 ages vary from 367 Ma to 4106 Ma. It is concluded that the sedimentary materials were mainly derived from the North Qinling Orogenic Belt, with minor contributions from the basement of the North China Craton. (2) In the Jiangligou area, the Shiguan Formation is characterized by highly and stable heavy minerals. The provenance is dominated by intermediate-acidic magmatic rocks, within an oceanic island arc tectonic setting. Detrital zircon U–Pb age spectrum displays a prominent peak at 442 Ma. The εHf(t) values range from –0.5 to 10.55, with TDM2 ages ranging from 744 Ma to 897 Ma. These results indicate that the sedimentary materials were derived from the North Qilian Orogenic Belt. (3) The Permian in the Western Qinling exhibit multi-provenance supply, dominated by the North Qinling Orogenic Belt and the North China Craton basement, with local contributions from the North Qilian Orogenic Belt. Significant regional variations in provenance contributions were identified. This study further constrains the closure of the Shangdan Ocean to pre-Late Permian. It reveals that the Western Qinling was situated in a back-arc rift basin setting during the Late Paleozoic. Key sedimentary evidence is provided for understanding the tectonic evolution of the Paleo-Tethys Ocean and the collision between the North China and Yangtze cratons.