地质学报2017，Vol.91Issue(6)：1208-1226,19.
中天山东段天湖花岗岩岩石学、地球化学及其成因
Petrology, Geochemical Characteristics and Genesis of the Tianhu Pluton in the East Section of the Middle Tianshan Mountains
赵宏刚 1苏锐 1梁积伟 2王驹 1金远新 1欧光习 1姜晓辉1
作者信息
- 1. 中核集团高放废物地质处置重点实验室,核工业北京地质研究院,北京,100029
- 2. 长安大学地球科学与资源学院,西安,710054
- 折叠
摘要
Abstract
The Tianhu granite pluton consists of six intrusive rocks,which can be divided into three lithofacies units but belong to one superunit.The round-shaped plutonic body was the product of three intrusive actitites of the same magma.Zircon LA-ICP-MS U-Pb dating result shows that the Tianhu pluton intruded in early Triassic between 241Ma and 243Ma and the product of early Indosinian period.Zircon in-situ Hf isotopic composition analysis yields the εHf(t) and tDM2 values of 2.6～5.5 and two-stage mode age of 941 ～1435Ma for the Tianhu pluton,suggesting that the magma originated from depleted mantle-derived juvenile crustal rock.Geochemically,the pluton is characterized by the high content of SiO2 (69.14％ ～ 76.62％),and high K2O+Na2O value(7.39％～8.83％),low contents of Ti,Ca,Fe and Mg,with the ratios of (K2O+Na2O)/Al2O3varying between 0.69 and 0.82,and the ratios of A/CNK between 0.95 and 1.04.All these features indicate that the pluton belongs to calc-alkaline granite.The pluton is also rich in LILE(K,Rb),HFSE(Ba,Th)and depleted in Ta,Nb,Ce,Hf,Zr,Sm,Y and Yb.Chondritenormalized REE distribution pattern of the Tianhu pluton displays right skewed shapes,distinct fractionation between LREE and HREE,with slightly negative Eu anomalies (δEu =0.24 ～0.78).Petrological and geochemical studies of the Tianhu pluton indicate that the pluton resulted from mantle magma underpalting and intraplating induced partial melting of the Meso-neoproterozoic new-born lower crust.Magma intrusion was driven by northward subduction of the Tethys Ocean from late Hercynian to early Indosinian and subsequently intense intra-continental extension in the eastern Tianshan Mountains.关键词
花岗岩/地球化学/印支期/天湖/中天山Key words
Granite/Geochemistry/Indosinian/Tianhu/Middle Tianshan Mountains引用本文复制引用
赵宏刚,苏锐,梁积伟,王驹,金远新,欧光习,姜晓辉..中天山东段天湖花岗岩岩石学、地球化学及其成因[J].地质学报,2017,91(6):1208-1226,19.
