Geochemical and geochronological evidence was obtained from granitoids of the South Tianshan orogen and adjacent regions, which consist of three individual tectonic domains, the Kazakhstan–Yili plate, the Central Tianshan Terrane and the Tarim plate from north to south. The Central Tianshan Terrane is structurally bounded by the Early Paleozoic ‘Nikolaev Line–North Nalati Fault’ and Late Paleozoic ‘Atbashy–Inyl’chek–South Nalati–Qawabulak Fault’ zones against the Kazakhstan–Yili and Tarim plates, respectively. The meta-aluminous to weakly peraluminous granitic rocks, which are exposed along the Kekesu River and the Bikai River across the Central Tianshan Terrane, have a tholeiitic, calc-alkaline or high-potassium calc-alkaline composition (I-type). Geochemical trace element characteristics and the Y versus Rb–Nb or Y versus Nb discrimination diagrams favor a continental arc setting for these granitoid rocks. SHRIMP U–Pb and LA-ICP-MS U–Pb zircon age data indicate that the magmatism started at about 480 Ma, continued from 460 to 330 Ma and ended at about 275 Ma. The earlier magmatism (>470 Ma) is considered to be the result of a simultaneous southward and northward subduction of the Terskey Ocean beneath the northern margin of the Tarim plate and the Kazakhstan–Yili plate, respectively. The later magmatism (460–330 Ma) is related to the northward subduction of the South Tianshan Ocean beneath the southern margin of the Kazakhstan–Yili–Central Tianshan plate. The dataset presented here in conjunction with previously published data support a Late Paleozoic tectonic evolution of the South Tianshan orogen, not a Triassic one, as recently suggested by SHRIMP U–Pb zircon dating for eclogites.

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Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid rocks

Tectonics of the North Qilian orogen, NW China

Late Carboniferous collision between the Tarim and Kazakhstan-Yili terranes in the western segment of the South Tian Shan Orogen, Central Asia, and implications for the Northern Xinjiang, western China

Paleozoic Tian-Shan as a transitional region between the Rheic and Urals-Turkestan oceans

Geochemical and geochronological studies of granitoid rocks from the Western Tianshan Orogen: Implications for continental growth in the southwestern Central Asian Orogenic Belt

The Heiyingshan granite and the Laohutai granite plutons exposed in the Southwest Tianshan resemble A-type granites geochemically. Analysis shows that the both are ferron calc-alkalic peraluminous or ferron alkali-calcic peraluminous with a relatively high concentration of SiO2 (>70%), high alkali contents (Na2O + K2O = 7.14%-8.56%; K2O>N2O; A/CNK = 0.99-1.20), and pronounced negative anomales in Eu, Ba, Sr, P and Ti. A SHRIMP zircon U-Pb age of 285±4 Ma was obtained for the Heiyingshan hornblende biotite granite intrusion. The geochemical and age dating data reported in this paper indicate that these granites were formed during the post-collisional crustal extension of the Southwest Tianshan orogenic belt, in agreement with the published data for the granites in the South Tianshan.

Geochemistry and SHRIMP Zircon U-Pb Age of Post-Collisional Granites in the Southwest Tianshan Orogenic Belt of China: Examples from the Heiyingshan and Laohutai Plutons

There are three groups of pillow volcanics in the Dachadaban ophiolite. Group 1 is typical boninite, enriched in Si, Mg and depleted.in Ti, HREE and.HFSE; group 2 is the evolved boninite, slightly higher abundance of Ti, HREE, HFSE and.large variation of Mg' due to fractional crystallization; and group 3 is tholeiite with MORE : character. The existence of MORB and boninite indicates;hat the Dachadaban ophiolite was probably formed in island-arc and back-arc environments.

Geochemical characteristics and genesis of Dachadaban ophiolite in North Qilian area

The Ordovician Laohushan ophiolite, located in the eastern part of the North Qilian Mountains, is mainly composed of meta-peridotites, gabbros and basalts alternating with sediments. The sediments are mainly turbidites, including sandstones, siltstones, cherts etc. Major elements show that the basalts are subalkaline tholeiites and may be analogous to ocean-floor basalts. Except a few N-MORBs, most of the basalts are E-MORBs as indicated by incompatible element ratios such as (La/Ce)N, La/Sm, Ce/Zr, Zr/Y and Zr/Nb. Negative Nb anomaly is common but negative Zr, Hf and Ti anomalies are quite rare. Based on the geochemical characteristics, it is suggested that the Laohushan basalts were formed in a back-arc basin. eNd (t) of the basalts ranges between +3.0 and +8.9 and (87Sr/86Sr), ranges between 0.7030 and 0.7060, indicating a depleted mantle source which was mixed with more or less enriched mantle components. Furthermore, the petrography of the sandstones and geochemistry of the cherts suggest that the sediments were deposited near a continental margin.

Qian Qing

Papers

Geochemistry and SHRIMP Zircon U-Pb Age of Post-Collisional Granites in the Southwest Tianshan Orogenic Belt of China: Examples from the Heiyingshan and Laohutai Plutons

Geochemical characteristics and genesis of Dachadaban ophiolite in North Qilian area

Geochemical Characteristics and Tectonic Setting of the Laohushan Basalts, North Qilian Mountains