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The Chinese Southwest Tianshan Orogenic Belt is located along the boundary between the Central Asian Orogenic Belt (CAOB) and the Tarim Block (TB), NW China. It records the convergence of the Tarim Block and the Middle Tianshan, and is, therefore, a crucial region for understanding the Eurasia continental growth and evolution. The Wulagen (geographical name) metasedimentary rocks of the Wuqia area (mainly metamorphic sandstones and mica schists) form one of the metamorphic terranes in the Southwestern Tianshan Orogenic Belt. The geochronology of these rocks is poorly known, which hampers our understanding of the tectonic evolution of the belt. We analyzed 517 zircon grains for detrital zircon U–Pb dating and 93 zircon grains for in situ Lu–Hf isotopic compositions from the Wulagen metasedimentary rocks. The analyzed zircon grains yield Neoarchean to late Paleozoic U–Pb ages with major age peaks at ~2543 Ma, 1814 Ma, 830 Ma, 460 Ma, and the youngest cluster of zircon (magmatogene) ages is 395 Ma. The zircon U–Pb data show that the late Paleozoic (Early Devonian) is the maximum depositional age of the Wulagen metasedimentary rocks, rather than the previously considered Precambrian period. The zircons with Paleozoic ages yield εHf(t) values of −22.0 to +11.3 and two-stage model ages (TDM2) of 3.95 to 1.30 Ga, suggesting that the parental magmas were formed from partial melting of pre-existing crustal rocks. Our zircon U–Pb geochronology and Hf isotopic data indicate the major source regions for the Wulagen metasedimentary rocks was the Kyrgyzstan North Tianshan. The zircon age population of 600–400 Ma (peak at ~460 Ma) has negative εHf(t) values (−15.0 to −0.6) and Mesoproterozoic two-stage model ages, suggesting that the early Paleozoic magmatism resulted mainly from the melting of ancient crust, which played an important role in crustal evolution in the southern CAOB. [ABSTRACT FROM AUTHOR]

The Baleigong granites, located in the western part of the southwestern Tianshan Orogen (Kokshanyan region, China), records late Paleozoic magmatism during the late stages of convergence between the Tarim Block and the Central Tianshan Arc Terrane. We performed a detailed geochronological and geochemical study of the Baleigong granites to better constrain the nature of collisional processes in the Southwest Tianshan Orogen. The LA‐ICP‐MS U‐Pb zircon isotopic analyses indicate that magmatism commenced in the early Permian (∼282 Ma). The granite samples, which are characterized by high contents of SiO2 (67.68–69.77 wt%) and Al2O3 (13.93–14.76 wt%), are alkali‐rich and Mg‐poor, corresponding to the high‐K calc‐alkaline series. The aluminum saturation index (A/CNK) ranges from 0.93 to 1.02, indicating a metaluminous to slightly peraluminous composition. Trace element geochemistry shows depletions in Nb, Ta, and Ti, a moderately negative Eu anomaly (δEu=0.40–0.56), enrichment in LREE, and depletion in HREE ((La/Yb)N=7.46–11.78). These geochemical signatures are characteristic of an I‐type granite generated from partial melting of a magmatic arc. The I‐type nature of the Baleigong granites is also supported by the main mafic minerals being Fe‐rich calcic hornblende and biotite. We suggest that the high‐K, calc‐alkaline I‐type granitic magmatism was generated by partial melting of the continental crust, possibly triggered by underplating by basaltic magma. These conditions were likely achieved in a collisional tectonic setting, thus supporting the suggestion that closure of the South Tianshan Ocean was completed prior to the Permian and was followed (in the late Paleozoic) by collision between the Tarim Block and the Central Tianshan Arc Terrane. [ABSTRACT FROM AUTHOR]

The Mesozoic to Cenozoic mountain uplift, exhumation, and deformation of the SW Tianshan Mountains (Kyrgyzstan and Northwest China) offer an important window to understand the intra-continental rejuvenation mechanism of the Central Asian Orogenic Belt (CAOB), as response to the far-field effects of the India-Asia collision. This article presents new observation and data for the planation surface and sedimentation and deformation features of the regional intermountain basins to rebuild the orogenic history in Mesozoic to Cenozoic. Three planation surfaces were recognized by field observation, showing that the mountain may have experienced lengthy erosion since the end Cretaceous, and a continuous planation surface may have formed at the Eocene to Oligocene. The filling sequences and deformation character revealed that the orogenic disintegrate and intermountain basin formation likely began in the end of Oligocene. Subsequently, the uniform planation surface in Western Tianshan may have begun to disintegrate, leading to the basin-and-range landform formation. Folds and nappes in the Cenozoic basins, large-scale thrusting of Palaeozoic rocks over Cenozoic sediments at the basin margin associated with the rapid mountain uplift may have occurred at the end of Early Pleistocene, suggesting a tectonic inversion. The Mesozoic-Cenozoic Tianshan uplift and deformation were likely induced by the collision/accretion along the southern margin of Eurasia. Both the northward propagation of the Parmir syntaxis to the SW Tianshan and the oblique dextral faulting of the Talas-Fergana fault have likely played an important role on the formation and deformation of the Cenozoic basins in the SW Tianshan. [ABSTRACT FROM AUTHOR]

The Atebayue Sb deposit is hosted in the Silurian clastics in the South Tianshan Orogen in Kyrgyzstan. The Sb ores appear as veins/veinlets and disseminations, with stibnite being the main ore mineral. Gangue minerals comprise quartz, calcite, and clay minerals. The quartz at Atebayue only contains aqueous fluid inclusions with low homogenization temperature (215–336 °C) and salinity (3.4–6.9 wt.% NaCl equiv.), supporting an epizonogenic hydrothermal origin. The minimum trapping pressures estimated from the NaCl─H2O inclusions are 9–14 MPa, suggesting that the Sb mineralization mainly occurred at a depth of 0.9–1.4 km. Sulphur isotopes (δ34S = −0.4 to 6.2‰) suggest that the host rocks within the Silurian system to be a significant source of ore metals. The ores contain average 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of 18.112, 15.547, and 38.064, respectively, and 2‐stage model ages of 337–381 Ma, indicating the ores were likely sourced from the Paleozoic strata. Integrating the data obtained from the studies including ore geology, fluid inclusion, and S─Pb isotope geochemistry, we conclude that that the Atebayue Sb deposit is best classified as epizonogenic type formed by the Tarim–Kazakhstan continent–continent collision. [ABSTRACT FROM AUTHOR]

Paleo-altitude reconstructions using oxygen isotopes provide past surface elevation data that can constrain the topographic evolution of mountain belts. This paper presents oxygen and carbon stable isotopic compositions of gastropod fossils, carbonate cements, and shelly sandstones in the Anjihai and Shawan formations located in the Sikeshu drainage basin, northern Tianshan, western China. Correlations between the stable isotopic compositions and lithofacies suggest that the Sikeshu drainage basin was mainly an open hydrological depositional environment. Based on the oxygen isotopic compositions of the gastropod fossils and petrographic examination, the δ13C and δ18O values have not been reset by late-stage diagenesis. Paleo-altitudes were reconstructed using the corrected paleo-surface water δ18O psw values recovered from gastropod fossils, carbonate cements, and shelly sandstones. An empirical formula was developed to calculate the paleo-latitudes when the Anjihai and Shawan formations were deposited. The paleo-altitude of the Sikeshu drainage basin had attained an elevation exceeding 2000 m by 28 Ma, similar to the present-day elevation in this area. This conclusion contributes to our understanding of the extent of surface uplift in the Cenozoic of Tianshan and the climatic differences on either side of Tianshan during the Cenozoic. Unlabelled Image • This study is the first in Tianshan to provide quantitative evidence for uplift and exhumation. • δ18O date of gastropod fossil analyzed in situ by NanoSIMS rule out diagnetic reset. • Paleoelevation of the north of Tianshan have exceeded 2000 m at least before 28 Ma. [ABSTRACT FROM AUTHOR]

• A "porphyroclast" system occurred in the Tuwu area in the late Early Permian. • The dextral shear event within the Kangguer Shear Zone was initiated at ca. 278 Ma. • The event provides constraints to the intracontinental convergence of the East Tianshan. The Kangguer Shear Zone, located in the East Tianshan, is one of the key faults for understanding the final amalgamation processes of the southwestern margin of the Central Asian Orogenic Belt. Magmatism was active in the Tuwu area of the Kangguer Shear Zone during the late Early Permian. LA–ICP–MS U–Pb dating analyses of the magmatic zircons from three monzogranite plutons, a felsic dyke, and a diorite dyke show ages of 286.9±0.78, 282.8±0.62, 281.7±0.89, 278.0±0.61, and 278.1±1.2 Ma, respectively. Detailed field and microscopic observations reveal that these intrusions form a "porphyroclast" system, and this area has undergone ductile dextral strike-slip deformation, with foliations dipping steeply to the south and subhorizontal stretching lineations trending to the east. Further structural analysis indicates that the three monzogranite plutons intruded into the Kangguer Shear Zone and cooled into rigid bodies before regional dextral strike-slip deformation, which limited the deformation that occurred after 282 Ma. The felsic dykes exhibit synkinematic characteristics, and the diorite dyke may have intruded before or at the same time as dextral strike-slip deformation, implying that regional dextral shear was initiated at ca. 278 Ma. These data, combined with previous studies, suggest that the initiation of dextral shear in the Kangguer Shear Zone occurred after the closure of the Kangguer Ocean and was the result of regional nearly N–S compression caused by the convergence of the Tarim Craton and plates north of the Kangguer Shear Zone. [ABSTRACT FROM AUTHOR]

Model for the tectonic evolution of the SCTSZ within the Kawabulake area, showing the SCTSZ within the Kawabulake area was involved in two ductile deformation events (three stages) during the late Paleozoic. The D1 event (400–290 Ma) was caused by the clockwise rotation of the Tarim Craton and the oblique subduction of the South Tianshan Ocean crust beneath the CTB. The early stage of D2 (ca. 290 Ma) was associated with the oblique collision between the Tarim Craton and the CTB. The late stage of D2 (276–270Ma) records the convergence of the Tarim Craton and plates north of the CTB. 1 represents Kangguer–Huangshan Shear Zone that occurs along the North Tianshan Ocean; 2 represents North Central Tianshan Shear Zone that separates the CTB and the North Tianshan Belt; 3 represents SCTSZ that separates the CTB and the South Tianshan Belt; 4 represents Xingeer Shear Zone that separates the Tarim Craton and the South Tianshan Belt; CTB is the abbreviation for Central Tianshan Block; YB is the abbreviation for Yili Block; KO is the abbreviation for Kazakhstan Orocline; SCTSZ is the abbreviation for South Central Tianshan Shear Zone. [Display omitted] • The Kawabulake Shear Zone records two events of ductile deformation (D1 and D2). • The timing of D1 deformation is constrained in the range of 400–290 Ma. • The early stage of D2 and the late stage of D2 occurred at ca. 290 and 276–270 Ma, respectively. • The deformation events provide constraints to the amalgamation of the SW CAOB. The South Central Tianshan Shear Zone occurs along the southern margin of the Central Tianshan Block (CTB), NW China. This shear zone contains important information about the history of the amalgamation of various plates in the southwestern margin of the Central Asian Orogenic Belt. This study focuses on the deformation of the South Central Tianshan Shear Zone within the Kawabulake area in East Tianshan and provides insights into the late Paleozoic tectonic history of this region. Field observations indicate that the shear zone records at least two ductile deformation events (D1 and D2), where D1 is a sinistral strike-slip deformation event and D2 is dextral strike-slip. The shear zone contains four giant tectonic lenses that were formed during the D2 event. Microstructures and quartz crystallographic preferred orientation patterns indicate that D1 and D2 both occurred under low temperature conditions. We constrained the timing of deformation using mica 40Ar/39Ar and zircon U–Pb approaches. The timing of D1 deformation is constrained in the range of 400–290 Ma and the early and late stages of D2 deformation occurred at ca. 290 and 276–270 Ma, respectively. Regional comparisons indicate that D1 resulted from the clockwise rotation of the Tarim Craton and the oblique subduction of the South Tianshan Ocean crust beneath the CTB, the early stage of D2 was the result of the oblique collision between the Tarim Craton and the CTB, and the late stage of D2 records the convergence of the Tarim Craton and plates north of the CTB. [ABSTRACT FROM AUTHOR]