岩石矿物学杂志2018，Vol.37Issue(2)：197-210,14.
东昆仑祁漫塔格地区晚三叠世正长花岗岩岩石成因及构造意义
Petrogenesis and tectonic implications of the Late Triassic syenogranite in Qimantag area, East Kunlun Mountains
摘要
Abstract
The syenogranite in Qinghai Province is located on the east periphery of the Kendekeke deposit in the Qimantag area,East Kunlun Mountains.It consists of alkali feldspar (50％ ～ 60％),quartz (20％ ～ 30％),plagioclase (10％ ～20％),and biotite and hornblende (1％ ～5％).The results of LA-ICP-MS zircon U-Pb isotope dating reveal that the syenogranite was formed at 217.9 ± 1.7 Ma (MSWD =0.74,n =20),suggesting the Late Triassic and the same time as the metallogenic age of the iron-polymetallic deposit in Qimantag area.The syenogranite is characterized by high silicon (SiO2 =74.62％ ～ 75.28％),high alkali (K2O + Na2O =8.81％ ～8.95％),and fairly high ratio of FeOT/MgO (18.02 ～ 31.48).The trace element and REE compositions show the features of significant negative Eu anomalies (δEu =0.04 ～0.05),enrichment of Rb,Th,U,K,Ga,and depletion of Sr,Ba,Ta,P,Ti.The geochemical characteristics indicate that the syenogranite belongs to metaluminousweakly peraluminous A-type granite.The εHf(t) values of syenogranite vary from 2.0 to 12.4 with the two-stage model ages being tDM2 of 1 126 ～458 Ma.It is held that the source region of syenogranite probably had a mixture with the mantle and ancient crust,which provided abundant materials for the iron-polymetallic mineralization in this area.In the discrimination diagrams of A-type granite,the syenogranite falls into A2-type granites,which suggests that it was formed in an extensional tectonic regime after the orogenic process.All these characteristics display a transition of the Late Variscan-Indosinian orogenic cycle from the epi-orogenic stage to the extensional tectonic regime in Qimantag area in the late Triassic.关键词
地球化学/锆石U-Pb年代学/Hf同位素/A型花岗岩/祁漫塔格Key words
geochemistry/zircon U-Pb geochronology/Hf isotope/A-type granite/Qimantag分类
天文与地球科学引用本文复制引用
张明玉,丰成友,王辉,李大新,瞿泓滢,刘建楠,周建厚..东昆仑祁漫塔格地区晚三叠世正长花岗岩岩石成因及构造意义[J].岩石矿物学杂志,2018,37(2):197-210,14.基金项目
国土资源部公益性行业科研专项经费项目(201411025) （201411025）
中国地质调查局地质调查项目(1212011085528) （1212011085528）
中国地质调查局高层次地质人才培养计划(201309) （201309）
青年地质英才计划(201112) Special Scientific Research Fund of Ministry of Land and Resources (201411025) （201112）
Geological Survey Program from China Geological Survey (1212011085528) （1212011085528）
Program of High-level Geological Talents (201309) （201309）
Youth Geological Talents of China Geological Survey (201112) （201112）
