Search Results (18)

The Upper Carboniferous strata in the eastern Qaidam Basin, comprising several hundred meters of thick, mixed clastic–carbonate successions that have been little reported or explained, provide an excellent geological record of paleoenvironmental and paleo-sea level changes during the Late Carboniferous icehouse period. This tropical carbonate–clastic system offers critical constraints for correlating equatorial sea level responses with high-latitude glacial cycles during the Late Paleozoic Ice Age. Based on detailed outcrop observations and interpretations, five facies assemblages, including fluvial channel, tide-dominated estuary, wave-dominated shoreface, tide-influenced delta, and carbonate-dominated marine, have been identified and organized into cyclical stacking patterns. Correspondingly, four third-order sequences were recognized, each composed of lowstand, transgressive, and highstand system tracts (LST, TST, and HST). LST is generally dominated by fluvial channels as a result of river juvenation when the sea level falls. The TST is characterized by tide-dominated estuaries, followed by retrogradational, carbonated-dominated marine deposits formed during a period of sea level rise. The HST is dominated by aggradational marine deposits, wave-dominated shoreface environments, or tide-influenced deltas, caused by subsequent sea level falls and increased debris supply. The sequence stratigraphic evolution and geochemical records, based on carbon and oxygen isotopes and trace elements, suggest that during the Late Carboniferous period, the eastern Qaidam Basin experienced at least four significant sea level fluctuation events, and an overall long-term sea level rise. These were primarily driven by the Gondwana glacio-eustasy and regionally ascribed to the Paleo-Tethys Ocean expansion induced by the late Hercynian movement. Assessing the history of glacio-eustasy-driven sea level changes in the eastern Qaidam Basin is useful for predicting the distribution and evolution of mixed cyclic succession in and around the Tibetan Plateau. Full article

The southwestern region of China is tectonically situated within the Tethyan tectonic domain, with the eastern part comprising the Upper Yangtze Block, while the western orogenic belt forms the main part of the Tibetan Plateau. This belt was formed by the subduction of the Paleo-Tethys Ocean and subsequent arc-continent collision, and was later further modified by the India-Asia collision, resulting in complex geological structures such as the Hengduan Mountains. The lithostratigraphy in this region can be divided into six independent units. In terms of mineralization, the area encompasses two first-order metallogenic domains: the Tethyan-Himalayan and the Circum-Pacific. This study synthesizes extensive previous research to systematically investigate representative rare earth element (REE) deposits (e.g., Muchuan and Maoniuping in Sichuan; the Xinhua deposit in Guizhou; the Lincang deposit in Yunnan). Through comparative analysis of regional tectonic-metallogenic settings, we demonstrate that REE distribution in Southwest China is fundamentally controlled by Tethyan tectonic evolution: sedimentary-weathered types dominate in the east, while orogenic magmatism-related types prevail in the west. These findings reveal critical metallogenic patterns, establishing a foundation for cross-regional resource assessment and exploration targeting. The region hosts 32 identified REE occurrences, predominantly light REE (LREE)-enriched, genetically classified as endogenic, exogenic, and metamorphic deposit types. Metallogenic epochs include Precambrian, Paleozoic, and Mesozoic-Cenozoic periods, with the latter being most REE-relevant. Six prospective exploration areas are delineated: Mianning-Dechang, Weining-Zhijin, Long’an, Simao Adebo, Shuiqiao, and the eastern Yunnan-western Guizhou sedimentary-type district. Notably, the discovery of paleo-weathering crust-sedimentary-clay type REE deposits in eastern Yunnan-western Guizhou significantly expands regional exploration potential, opening new avenues for future resource development. Full article

Located in the eastern Paleo-Tethys Ocean and near the equator, carbonate sedimentation widely developed in the Sichuan Basin in the Permian Guadalupian period. Although the growth and decline of carbonate particles are closely related to the surrounding sedimentary environment, the relationships between the grain composition and distribution of the northwest Sichuan Basin and the sedimentary environment are not clear. This study explored the particle type, particle content, and sedimentary structure of 300 thin sections from 19 wells and seven field profiles of the Guadalupian period in the northwest Sichuan Basin, identified seven microfacies and four microfacies associations, analyzed the sedimentary environment, and established a sedimentary evolution model. The results show that there was a warm-water Dasycladaceae-dominated and foraminifera-dominated open platform developed in the early Roadian era in the research area. As the climate cooled during the late Roadian era, the warm-water carbonate sedimentary environment was replaced by a cold-water bryozoan-dominated and echinoid-dominated marginal sedimentary environment. As the climate continued to cool and the sea level dropped, the platform margin grain beach sediment underwent further development in the early Wordian era. In the late Wordian era stage, the sedimentary environment was influenced by the Dongwu movement, resulting in sea level changes and acidification caused by hydrothermal activities, which reduced the degree of grain beach development. During the Capitanian era, the climate became warmer due to the eruption of the ELIP. The uplift caused by the Dongwu movement resulted in a relative shallowing of the platform margin region, and hence, the grain beach sediment only developed in the southwest, while the northeast was dominated by deepwater basin sediments. The sudden transition from a warm-water, autotroph-dominated carbonate open platform to a cold-water, heterozoan-dominated carbonate platform margin resulted from a combination of tectonic movements, rapid sea level changes, and sedimentary environment changes during the Guadalupian era. Full article

Large volumes of Early Mesozoic intermediate to basic igneous rocks related to the evolution of the Paleo-Tethys Ocean are exposed in the East Kunlun Orogenic Belt (EKOB). The petrography, geochemistry, and results of zircon U-Pb dating of Defusheng intermediate to basic rocks from the eastern segment of the EKOB are presented in this report. Zircon U–Pb dating of the intermediate to basic rocks yields ages of 239–245 Ma (Middle Triassic). Defusheng intermediate to basic rocks have low TiO₂ contents (0.80–1.47 wt.%) and widely varying MgO (3.14–6.08 wt.%), and are enriched in large ion lithophile elements and light rare earth elements, having a geochemical composition similar to that of island arc basalts. The variation diagrams of major elements indicate that the Defusheng intermediate to basic rocks underwent fractional clinopyroxene and olivine crystallization. Depletion of the high-field-strength elements Nb, Ta, and Ti may have been caused by the mantle wedge having been infiltrated by fluids derived from the subducted slab. The Defusheng intermediate to basic rocks represent magmatic records of the Early Mesozoic oceanic crust subduction in Eastern Kunlun. This indicates that the final closure of the Paleo-Tethyan Ocean and the beginning of collisional orogeny occurred after the Middle Triassic. Full article

Precise determination of the tectonothermal events at the Qinling–Qilian junction is significant for understanding the tectonic evolution of the eastern branch of the Paleo-Tethys. The Banpo pluton outcrops in the northern margin of the North Qinling were chosen as the research subject and their formation and tectonic environment were investigated using zircon U-Pb age and geochemical compositions. The weighted average values of ²⁰⁶Pb/²³⁸U ages of samples from three sites of the Banpo pluton corresponded to 213.4 ± 2.1 Ma (MSWD = 0.56), 213.0 ± 1.6 Ma (MSWD = 0.92), and 216.3 ± 2.3 Ma (MSWD = 2.0). All the samples are rich in light rare earth elements, exhibiting a seagull-type right-leaning partitioning curve, with obviously negative Eu anomalies. In addition, based on the regional geological data, it can be concluded that the Banpo pluton was formed during the transition period from a post-Orogenic environment to an anorogenic environment. The results indicated the final stage of the Triassic orogeny and the closure phase of the Paleo-Tethys. Also, it shows closure of the Paleo-Tethys-Mianxian-Lueyang Ocean by the Late Triassic period as well as the completion of the collision between the North China and Yangtze Blocks along the Qinling Orogenic Belt. Full article

The eastern Qaidam Basin (EQB), along with its surrounding orogenic belts, witnessed complicated tectonic movements in the period from the late Paleozoic to the early Mesozoic. As strategic succeeding strata, the Carboniferous strata (CST) in the EQB have gradually become a research hotspot in recent years. However, the question of how tectonism controlled the tempo-spatial evolution of the CST has yet to be studied. To resolve these issues, we collated statistics related to unconformities, seismic interpretation, and basin modeling in this study. The results show that the structure of the CST was mostly controlled by NNE-striking faults, namely the Zongjia and Ainan Fault, in the period from the Carboniferous to the Triassic time. During the Carboniferous time, the sedimentation of the CST was controlled by medium-high angle potential normal faults. The CST experienced two stages of tectonic subsidence and subsequent burial: the highest average subsidence and burial rate of 45 m/Ma and 12 m/Ma occurred at 340~285 Ma, decreasing to 15 m/Ma and 7.5 m/Ma between 305 Ma and 250 Ma. However, the maximum burial (~5500 m) took place at ~250 Ma. From the end of the late Permian to the late Triassic (254~195 Ma), the overall exhumation rate of the CST has averaged 38.71 m/Ma, and 75 m/Ma in the southern margin of the Huobuxun Depression. The CST near the piedmont margins of the EQB suffered essential denudation at 254~195 Ma, resulting in small amounts of the residual CST. In these areas, the CST were deformed with a steepening dip during this time and were characterized by the combinations of syncline-anticlinal asymmetric folds with the high-angle interlimb. These findings indicated that the tempo-spatial evolution of the CST was possibly influenced by the sedimentary and tectonic transition, and was a combined response to Paleo-Tethys Ocean subduction, and arc-continental collisions since the late Paleozoic to early Mesozoic periods. Full article

Adakites are magmatic rocks with specific geochemical characteristics and specific dynamics that provide important clues to understanding the magmatic-tectonic evolution of orogenic belts. We studied the Early Triassic Nanpo adakitic pluton of the Luang Prabang-Loei tectonic belt in the Eastern Tethys domain (Laos Sarakan) using detailed petrological, zircon U-Pb chronological, whole-rock geochemical, and zircon Lu-Hf isotope studies to constrain their petrogenesis. The rocks are predominantly diorites and granodiorites with Early Triassic zircon U-Pb emplacement ages ranging from 247.9 ± 1.0 to 249.0 ± 2.4 Ma. Moderate SiO₂ (56.26–65.95 wt%) and Na₂O (3.24–5.00 wt%) contents, with Na₂O/K₂O values between 1.76 and 2.51 and A/CNK values between 0.81 and 0.94, indicate that the rocks belong to the metaluminous calc-alkaline rock series. The high Sr content (590–918 ppm), low Y (6.30–11.89 ppm) and Yb (1.99–3.44 ppm) contents, intermediate Mg# (42–50) values, and high Sr/Y and (La/Yb) _N ratios (Sr/Y = 24–41, (La/Yb) _N = 6.84–13.8) are typical for adakites. Zircon Hf isotope analysis shows a significant variation in the εHf(t) values (6.7–12.0), with a mean value of 9.4 and a T_DM2 of 512–845 Ma. Geochemical evidence indicates that the Nanpo adakitic rock was formed by the partial melting of the thickened lower crust in the plate-breaking environment and has an important contribution to the underplated mantle-derived magma. We propose that the Early Triassic adakites in the Luang Prabang-Loei tectonic belt formed during the transition from subduction to a continental collision, and the mixing of crust- and mantle-derived magmas is the main mechanism for the growth of continental crust in the Paleo-Tethys orogenic belt of southeastern Asia. Full article

The rhyolites which are widely exposed to the northern margin of the East Kunlun orogenic belt were chosen as a research object to discern the post-orogenic tectonic evolution of the East Kunlun orogenic belt and reconstruct the post-collision orogenic processes of the Buqingshan- A’nyemaqen Ocean. We researched zircon U-Pb ages and geochemistry characteristics of the Late Triassic rhyolites in the eastern segment of the East Kunlun Orogenic Belt in the northern Tibetan Plateau. Zircon U-Pb dating yields coeval ages of 200.4 ± 1.4 Ma and 202.8 ± 1.2 Ma for the Keri rhyolites of the East Kunlun Orogenic Belt, indicating that the volcanic rocks were formed in the Late Triassic Rhaetian–Early Jurassic Hettangian. The Keri rhyolite is a product of the late magmatism of the Elashan Formation volcanic rocks. The rhyolites include rhyolitic brecciated tuff lavas and rhyolitic tuff lavas. The rhyolites are peraluminous and are high-K calc-alkaline, with high contents of SiO₂, K₂O, TFe₂O₃, and low P₂O₅ contents. The A/CNK ratios range from 0.97 to 1.09, indicating that the rhyolites are metaluminous to weakly peraluminous. The chondrite-normalized rare earth element (REE) distribution shows a significant negative Eu anomaly and low total REE concentrations. All samples are depleted in high field strength elements (HFSEs, e.g., Eu, Sr, Ti, and P), heavy rare earth elements (HREEs), and enriched in large ion lithophile elements (LILEs, e.g., Rb, Zr, Nd, Th, and U) and light rare earth elements (LREEs). The Keri rhyolite has the characteristics of A₁-type magmatic rock, formed in an anorogenic environment after the closure of the Paleo-Tethys Ocean, and was the product of late magmatism in the Elashan Formation volcanic rocks. Full article

The Heihaibei gold deposit is located in the Eastern Kunlun Orogen in Northwest China. The gold mineralization here occurs predominantly in quartz veins within faulted granite zones. The sulfide mineral assemblage is dominated by pyrite and arsenopyrite, with minor chalcopyrite, galena, sphalerite, tetrahedrite, and micro-native gold. Weak alterations in Heihaibei granites include silicification and sericitization, with minor chloritization and carbonatization. The measured δD_H2O and δ¹⁸O_quartz values of quartz in auriferous quartz veins range from −104.2‰ to −81.1‰ and +9.2‰ to +13.9‰, respectively. The δ³⁴S values of sulfides in auriferous quartz veins range from +7.60‰ to +8.65‰, and the lead isotope compositions of sulfides in ores range from 18.7219 to 19.0007 for ²⁰⁶Pb/²⁰⁴Pb, 15.6959 to 15.7062 for ²⁰⁷Pb/²⁰⁴Pb, and 37.7359 to 38.8055 for ²⁰⁸Pb/²⁰⁴Pb. The Pb isotope compositions of potassic feldspars from Heihaibei granites vary from 18.3532 to 19.4864 for ²⁰⁶Pb/²⁰⁴Pb, 15.6475 to 15.6812 for ²⁰⁷Pb/²⁰⁴Pb, and 37.1750 to 38.4598 for ²⁰⁸Pb/²⁰⁴Pb. Collectively, the isotope (H, O, S, and Pb) geochemistry suggests that the ore-forming fluid was a special metamorphic water evolved from the deep slab-derived fluids, and the sulfur and lead were predominantly sourced from such metamorphic fluids, and from the deep parts of the Heihaibei granites. Therefore, the Heihaibei gold deposit can be classified as an orogenic gold deposit, which is closely associated with the subduction of the Paleo-Tethys oceanic plate, and even the final closure of this ocean by the Later Triassic. Full article

Numerous Indosinian granitoids occur in the East Kunlun Orogen (EKO). The Indosinian was a key transitional period associated with the evolution of the Paleo-Tethys Ocean. Here, we study the relationship between the petrogenesis of the granitoids and the regional tectonic setting based on a comprehensive analysis of the petrology, geochronology, and geochemistry of typical granitoids in the eastern part of the EKO. The Indosinian granitoid compositions are dominated by quartz diorites, granodiorites, monzogranites, porphyritic monzogranites, and syenogranites. Early Indosinian granitoids are large, granitic batholiths, while the middle and late Indosinian granitoids are smaller in size. From the early Indosinian to late Indosinian, the granitoids show a transition from a medium-K calc-alkaline to high-K calc-alkaline composition. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) and depleted in high-field-strength elements (HFSEs), especially for the Helegangxilikete and the Kekeealong plutons. The late Indosinian granitoids have relatively low Y and Yb contents, high Sr contents, and high La/Yb and Sr/Y ratios, which suggests adakitic affinity. The zircon saturation temperatures of the early Indosinian syenogranite and the Keri syenogranite are above 800 °C. The zircon saturation temperatures of other Indosinian granites (average 749 °C) are lower than those of the biotite and amphibole partial melting experiment. In the early Indosinian (255–240 Ma), numerous granitoids were the products of the partial melting of the juvenile lower crust by mafic magma underplating. This underplating is geodynamically related to the continuous subduction of a branch of Paleo-Tethys Ocean, with slab break-off, rapid upwelling, and mantle decompression. In the middle Indosinian (240–230 Ma), the compression that accompanied the continent–continent collision was not conducive to fluid activity, and hence, the formation of magma could be attributed to dehydration partial melting of muscovite, biotite, or amphibole. In the late Indosinian (230–200 Ma), the delamination of thickened crust would provide heat and channels for fluid migration, leading to a flare-up of the magmas. The composition and petrogenesis of the Indosinian granitoids in the eastern EKO are the result of processes associated with the subduction, collisional, and post-collisional stages, during the evolution of the Paleo-Tethys Ocean. Full article

The East Kunlun Orogenic Belt is located in the western part of the Central Orogenic Belt of China, with a large number of Triassic igneous rocks parallel to the Paleo-Tethys ophiolite belt, which provides a large amount of geological information for the tectonic evolution of the Paleo-Tethys Ocean. The granitoids studied in this paper are located in the Ela Mountain area in the eastern part of the East Kunlun Orogenic Belt. Zircon U-Pb dating results show that these different types of granitoids were crystallized in the Triassic. The 247.5 Ma porphyritic granites from Zairiri (ZRR) displayed calc-alkaline I-type granite affinities, with the zircon ε_Hf(t) values being mainly positive (−0.5 to + 3.8, T_DM2 of 1309–1031 Ma), indicating that they are derived from the partial melting of the juvenile crust and mixed with ancient crustal components. The 236.8 Ma Henqionggou (HQG) granodiorites and 237.5 Ma Daheba (DHB) granodiorites are high-K calc-alkaline I-type granite, and both have mafic microgranular enclaves (MMEs), showing higher and more varied Mg^# (39.73–62.73), combined with their negative Hf isotopes (ε_Hf(t) = −2.6 to −1.6, T_DM2 = 1430–1369 Ma), suggesting that their primary magmas were the products of partial melting of the Mesoproterozoic lower crust that mixed with mantle-derived rocks. The 236.4 Ma DHB porphyritic diorites showed characteristics of high-K calc-alkaline I-type granitoids, with moderate SiO₂ contents, medium Mg^# values (40.41–40.65), with the Hf isotopes (ε_Hf(t) = −2.9 to −0.5; T_DM2 = 1451–1298 Ma) indistinguishably relative to contemporaneous host granodiorites and MMEs. The petrographic and geochemical characteristics indicate that the porphyritic diorites are the product of well-mixed magma derived from the Mesoproterozoic lower crust and lithospheric mantle. Based on the results of this paper and previous data, the chronology framework of Late Permian–Triassic magmatic rocks in the eastern part of the East Kunlun Orogenic Belt was constructed, and the magmatic activities in this area were divided into three peak periods, with each peak representing an extensional event in a particular tectonic setting, for example, P1 (slab roll-back in subduction period; 254–246 Ma), P2 (slab break-off in transition period of subduction and collision; 244–232 Ma), P3 (delamination after collision; 230–218 Ma). Full article

The Ailaoshan orogenic belt, located in the SE margin of the Qinghai–Tibet Plateau, is an important Paleo-Tethys suture zone in the eastern margin of the Sanjiang Tethys tectonic domain. The areas of Mojiang and Zhenyuan, located in the middle part of the Ailaoshan orogenic belt, are the key parts of the Ailaoshan Paleo-Tethys Ocean closure and collision orogeny. The rhyolites outcropped in the Mojiang area, and the granite porphyries outcropped in Zhenyuan area, are systematically studied for petrology, isotope geochemistry and geochronology. The Zircon U-Pb geochronology of rhyolites and granite porphyries give weighted average ages of 253.4 ± 4.2 Ma and 253.3 ± 2.0 Ma, respectively, both of which were formed in the late Permian period. The rhyolites belong to potassic calc-alkaline to subalkaline series. The patterns of the rare earth elements (REE) show a right-inclined seagull-type distribution, and the trace elements plot is right-inclined. The granite porphyries are high potassic calc-alkaline to subalkaline. The REE patterns show a right-inclined distribution, and the trace elements plot is right-inclined, which is consistent with the typical patterns observed in the crust. The peraluminous, highly differentiated and high ASI values suggest that rhyolites and granite porphyries are S-type granites. The zircon εHf(t) of the rhyolites range from −7.22 to −0.72, and two-stage Hf zircon model ages are (T_DM^C) 1771–2352 Ma, indicating that the magma source area is mainly crust-derived. The zircon εHf(t) of the granite porphyries range from −0.97 to 4.08, and two-stage Hf zircon model ages are (T_DM^C) 1336–1795 Ma, indicating that the magma is derived from a depleted mantle source and the partial melting of ancient crustal materials. The rhyolites and granite porphyries were possibly formed in the syn-collisional tectonic setting during the late Permian, and their ages limited the time of the final closure of the Ailaoshan Ocean and the initiation of collisional orogeny. Full article

The Jinshajiang–Ailaoshan–Song Ma orogenic belt (JASB), as a vital segment of the eastern Paleo-Tethyan tectonic zone, is one of the most important zones in which to study the Paleo-Tethyan tectonic evolution. We have undertaken an integrated geochronological, petrological, and geochemical study of mafic rocks from the JASB to reveal the subduction and closure processes of the eastern Paleo-Tethyan Ocean during the Permian to Triassic. In conjunction with previous magmatic and metamorphic records in the JASB, three important tectonic stages are identified: (1) Early Permian to Early Triassic (ca. 288–248 Ma). Most of the Early Permian to Early Triassic mafic rocks have normal mid-ocean ridge basalt (N-MORB)- or enriched MORB (E-MORB)-like rare earth elements (REE) and trace element-normalized patterns with positive εNd(t) and εHf(t) values and negative Nb and Ta anomalies. Their La/Nb ratios and εNd(t) values show that approximately 3%–15% of slab-derived fluid accounts for the generation of these rocks. These characteristics suggest that the mafic rocks formed in an arc/back-arc basin setting at this stage. Additionally, the Early Permian mafic rocks are mainly exposed in the Jomda–Weixi–Yaxuanqiao–Truong Son magmatic rock belt (JYTB) on the western side of the JASB, indicating that the westward subduction of the Jinshajiang–Ailaoshan–Song Ma Paleo-Tethys Ocean (JASO) began in the Early Permian. Middle Permian mafic rocks are exposed in the Ailaoshan-Day Nui Con Voi metamorphic complex belt and the JYTB on both sides of the JASB. We propose that the bipolar subduction of the JASO occurred in the Middle Permian and ended in the Early Triassic. (2) Middle Triassic (ca. 248–237 Ma). The mafic rocks at this stage have LREE- and LILE-enriched patterns, negative Nb and Ta anomalies and negative εNd(t) values. Their variable εHf(t), εNd(t) values and La/Nb ratios show that these mafic rocks were highly affected by crustal material (ca. 16%). Considering the Middle Triassic high-pressure (HP) metamorphism and massive Al-enriched felsic magmatism in the JASB, these rocks may have formed in a collisional setting between the South China Block (SCB) and the North Qiangtang–Simao–Indochina Block (QSIB) during the Middle Triassic. (3) Late Triassic (ca. 235–202 Ma). The mafic rocks at this stage have negative εNd(t) and εHf(t) values and show terrestrial array characteristics. The εNd(t) values and La/Nb ratios show that approximately 30% of crustal components account for the generation of these rocks. Combined with the contemporaneous bimodal magma and metamorphism during the Late Triassic, we suggest that these rocks may have formed in a postcollisional extensional setting associated with magma diapir. Full article

The Sanjiang Indosinian orogen, located in the eastern part of the Paleo-Tethys tectonic domain, is a critical region to study the Paleo-Tethyan Ocean evolution. Middle Permian–Late Triassic magmatic rocks are widespread in the Deqin–Weixi–Madeng area of southwestern (SW) Sanjiang Indosinian orogen, yet their petrogenesis and tectonic setting remain disputed. In this study, LA-ICP-MS zircon U-Pb age and Hf isotopes, and whole-rock elemental and Sr-Nd isotope geochemistry of Madeng dacite were studied. The Madeng dacite was dated at ca. 241.7 and 243.4 Ma. The samples had high Al₂O₃ (12.91 to 14.39 wt.%) but low MgO (0.62 to 1.76 wt.%) contents, and were alkali-rich (Na₂O + K₂O = 6.97 to 8.66 wt.%) with A/CNK > 1.1, strongly resembling peraluminous S-type granites. The rocks were enriched in Rb, K, Th, U and LREE, but depleted in Ba, Sr, Nb, Ta, P and Ti, and showed obvious negative Eu anomalies, suggesting fractionation of Ti-bearing minerals (e.g., rutile and ilmenite) and plagioclase. The dacite had an initial ⁸⁷Sr/⁸⁶Sr value of 0.705698 to 0.710277, and negative ε_Nd(t) (−11.28 to −10.64) and ε_Hf(t) (−13.99 to −8.60), indicating a continental meta-sedimentary source. Their average Nb/Ta (12.24) and Th/U (4.65) were also consistent with continental crust. According to the lithological assemblage and geochemical features, we propose that the Deqin–Weixi–Madeng area intermediate-felsic magmatism was generated in a subduction-related tectonic setting. Full article

The eastern Tiklik belt is mainly composed of meta-sedimentary rocks of the Ailiankate and Sailajiazitage Groups that were previously interpreted as Palaeoproterozoic, Mesoproterozic and Neoproterozoic stratigraphic units, which are part of the Tarim Precambrian basement. Our new detrital (U-Pb) zircon ages yield a dominant single peak with a major range between ca. 700 Ma and 800 Ma for meta-sedimentary rocks from both the Ailiankate and Sailajiazitage Groups, which demonstrates that they were mainly derived from an independent Neoproterozoic terrane. There are several ages of 444–659 Ma, of which, the youngest has an age of 444 ± 6 Ma, indicating that the time of deposition of the meta-sedimentary rocks could have been in the Early Silurian. The porphyritic granite sample has a weighted mean crystallization age of 442 ± 2 Ma. The adakite-like geochemical characteristics of the porphytitic granite suggest derivation from the melting of the oceanic slab and formation in a subduction, arc-related tectonic setting. After integration with relevant published data, our work suggests that the Ailiankate and Sailajiazitage Groups belong to a tectonic mosaic that contains Middle Neoproterozoic extensional and Paleozoic accretionary and collisional complexes, rather than the Paleoproterozoic or Mesoproterozoic basement, as previously regarded. We propose a new tectonic model for the eastern Tiklik belt that started with a Middle Neoproterozoic extension and ended with Paleozoic continuous accretion and collision in a Paleo-Tethys archipelago, which contributed to the considerable continental growth of the southern Tarim Block. Full article