Chronology, Geochemical Characteristics and Geological Significance of the Duweituwei Granite in Western Tiekelike of Xinjing

The Duweituwei granite exposed in western Tiekelike area of the southern Tarim Basin of Xinjiang intrudes into biotite monzo-gneiss of Heluositan terrain (Pt₁H), and contacts by fault withthe Kulangnagu(Pt₂K) terrain and west Datong granite. Besides, the east of the granite is unconformably covered by Bochatetage group (Jxbc). Geochemical analysis shows that the granite has high SiO₂, Al₂O₃, K₂O content but relatively low CaO, P₂O₅,TiO₂ and MgO content.The ratios of A/CNK vary from 1.37 to 1.43, and CIPWcorundum molecule is larger than 1%, suggesting its type of high-K calc-alkaline peraluminous syn-collision granite. The chondrite-normalized REE patterns show that the granite is rich in LREE but depleted in HREE, with high fractionations between LREE and HREE and moderate negative Eu anomalies (δEu is 0.59 to 0.82). In addition, the granite is relatively rich in such LILEs as Rb, Ba, Th and K, but poor in such HFSES as Nb, Ta and Ti in the primitive mantle-normalized trace elements patterns. Zircon LA-ICP-MS dating yielded the age of (1 909±47)Ma, implying that the magmatic crystallization epoch of the granite is late Paleoproterozoic.Comprehensive analysis suggests that the rock mass is formed in the late orogenic collision environment relevant to the formation of thickened crust induced crustal remelting. It is therefore speculated that the strong intracontinental orogenic activityin western Kunlun orogenic belt should have begun in the Paleoproterozoic.Combined with the zircon record of hornblende plagioclase gneiss in Heluositan rock group(Pt₁H), it is inferred that the Columbia supercontinent events occurred in the Tarim block during 2 000 to 1 800Ma.