高校地质学报2018，Vol.24Issue(2)：147-159,13.DOI:10.16108/j.issn1006-7493.2017094
西准噶尔库什库都克石英闪长岩地球化学、年代学及地质意义
LA-ICP-MS Zircon U-Pb Geochronology and Geochemistry of the Kushenkuduke Quartz Diorite in Western Junggar and Its Tectonic Significance
摘要
Abstract
The Kushenkuduke quartz diorite is located in the Late Paleozoic intermediate-acidic magmatic rocks belt along Dalbute area in Western Junggar, Xinjiang. LA-ICP-MS zircon U-Pb dating yields an age of 305.3 ± 2.8 Ma(n=19, MSWD= 0.17)for the quartz diorite,indicating that it was generated during late stage of the Late Carboniferous(C2).The quartz diorite has a hypidiomorphic heterogranular texture and a massive structure,and consists mainly of plagioclase,quartz,amphibole,and biotite,etc.A small amount of quartz gabbro diorite with columnar pyroxene has also been observed in this pluton.The geochemical analyses show that the pluton is characterized by SiO2of 59.38％～63.37%,total alkali(Na2O+K2O)of 6.55%～7.51%,and Rittman index σ of 2.62～2.88,aluminum index A/CNK of 0.83～0.90,indicating a metaluminous composition.The quartz diorite is enriched in LREE,depleted in HREE(LREE/HREE=3.86～4.38,(La/Yb)N=2.99～3.66),with negative Eu anomalies(δEu=0.64～0.79).The trace elements are characterized by Ba, Nd, Zr, K, LREE enrichment, and Rb, Nb, Th, Sr, P, Ti, HREE depletion. All the features suggest a high K calcic-alkaline I-type granite. The quartz diorite was likely derived from metabasalt in the upper crust, and subsequently underwent the fractional crystallization of plagioclase,pyroxene,rutile,and apatite without amphibole.Based on comprehensive analysis of the genetic type of the quartz diorite and evolution of regional tectonic environment, we suggest that when the Junggar Ocean perpetually continued its deep subduction toward north from the early Late Carboniferous to the Early Permian, and the Kushenkuduke quartz diorite of the island-arc type was formed during this tectonic evolution.关键词
石英闪长岩/地球化学/晚石炭世/库什库都克/西准噶尔Key words
quartz diorite/geochemistry/Late Carboniferous/Kushenkuduke/Western Junggar分类
天文与地球科学引用本文复制引用
乔耿彪,赵寒森,陈隽璐,白建科,彭素霞,樊金生..西准噶尔库什库都克石英闪长岩地球化学、年代学及地质意义[J].高校地质学报,2018,24(2):147-159,13.基金项目
国家自然科学基金项目(41302051) （41302051）
中国地质调查局项目(DD20160006) （DD20160006）
陕西省科学技术研究发展计划项目(2014JM2-4037)联合资助 （2014JM2-4037）
