关键词: 南天山, 库鲁克塔格, 花岗岩类, 构造演化, 闭合时间

Abstract:

Four typical granitoids exposed in east section of south Tianshan are chosen for this study. Geochemical analyses show that these intrusions are metaluminous to peraluminous high-K calc-alkaline series and relatively rich in LILEs of Rb, Ba, Th and U, poor in HFSEs of Nb, Ta, Zr, Hf. The chondrite-normalized REE diagrams show that these intrusions are rich in LREE and depleted in HREE with high fractionations of LREE and HREE and moderate negative Eu anomalies(δEu=0.52-0.96). Such similar geochemical and petrological characteristics and previous studies indicated that the granitoids formed during the continental collision stage. Correlation of diagenetic ages for high pressure metamorphic rocks, plutons, sedimentary formations and ophiolitic mélanges exposed in the east-west section of south Tianshan indicates  regional differences during late Paleozoic tectonic evolution process of south Tianshan which can be characterized by early Carboniferous collision on the eastern part and late Carboniferous collision on the western part, supporting that the closure time of the east section was earlier than the west section of the Paleo-south Tianshan ocean.

Key words: south Tianshan, Kuruktagh, granitoid, tectonic evolution, closure time