东昆仑大水沟一带花岗岩体锆石年龄、岩石地球化学特征及地质意义  

Zircon age,petrogeochemical characteristics and geological significance of granite in Dashuigou area,East Kunlun

作　　者：邓红宾 李培龙 何文劲 杨鹏涛[1] 官云彬 DENG Hong-bin;LI Pei-long;HE Wen-jin;YANG Peng-tao;GUAN Yun-bin(Northwest Sichuan Geological Team,Sichuan Bureau of Geology and Mineral Exploration and Development,Mianyang 621000,China)

机构地区：[1]四川省地质矿产勘查开发局川西北地质队,四川绵阳621000

出　　处：《桂林理工大学学报》2021年第1期1-14,共14页Journal of Guilin University of Technology

基　　金：青海省地质勘查基金项目(青国土调勘[2014]573)。

摘　　要：东昆仑造山带大水沟一带花岗岩体位于东昆仑造山带中段,主要由正长花岗岩和少量的二长花岗岩组成。本文对该花岗岩体开展了锆石U-Pb年代学、主量元素、微量元素及矿质元素研究:正长花岗岩的锆石U-Pb年龄为395±3 Ma,属早泥盆世;主量元素组成上,正长花岗岩具高硅(SiO_(2)70.78%~75.14%)、富钾(Na_(2)O/K_(2)O=0.43~0.75)特点,二长花岗岩具高硅(SiO_(2)67.93%~70.41%)、主体富钠(Na_(2)O/K_(2)O=0.73~1.35)特点;两种岩性属弱过铝质(A/CNK=0.95~1.22)钙碱性-钾玄岩系列。微量元素显示轻稀土、高场强元素Zr、Hf、U、Th、Ce及大离子亲石元素K、Rb相对富集,亏损Ba、Sr、P和Eu;δEu=0.01~0.66,具典型的海鸥式REE分配模式,表现为同源岩浆演化且岩浆分异特征明显。花岗岩体具低Sr高Yb型特征,源区物质来源为壳-幔混合物质,整体显示为A_(2)型花岗岩,构造环境属造山型花岗岩。在实测剖面中获得正长花岗岩及二长花岗岩的10个成矿元素分析数据,与中国花岗岩、青海省主要成矿带及邻近成矿带平均元素丰度值进行对比,初步得到不同岩性、不同类型花岗岩富集的矿质元素为Y、Nb、Sb、Sn、Zn、Co等。与区域上已发现的成矿花岗岩体进行成因对比,认为研究区有较好的找矿前景,应引起足够的重视。The granitic body in the Dashuigou area of the east Kunlun orogenic belt is located in the middle part of the East Kunlun orogenic belt.Zircon U-Pb chronology,major elements,trace elements and mineral elements are studied in this paper.Zircon U-Pb age obtained from syenogranite is 395±3 Ma,belonging to early devonian.In terms of principal element composition,syenogranite is characterized by high silicon(70.78%-75.14%)and rich potassium(Na_(2)O/K_(2)O=0.43-0.75).The monzogranite is characterized by high silicon(67.93%-70.41%)and rich sodium(Na_(2)O/K_(2)O=0.73-1.35).The two lithologies are of weak superaluminite(A/CNK=0.95-1.22)calc-alkaline-potassium basalt series.Trace elements showed that light rare earth,high field intensity elements Zr,Hf,U,Th,Ce and large ionic lithic elements K and Rb were relatively enriched,and elements Ba,Sr,P and Eu were deficient.AsδEu=0.01-0.66,the REE distribution model is a typical seagull type,showing homologous magma evolution and obvious magma differentiation characteristics.The granitic mass is characterized by low Sr and high Yb type,and the source material is shell-mantle mixed material,which is generally shown as A_(2)type granite.The tectonic environment belongs to orogenic granite.The analysis data of 10 ore-forming elements of syenogranite and monzonitic granite are obtained from the measured sections,and compared with the average element abundances of granites in China,main metallogenic belts in Qinghai Province and adjacent metallogenic belts.The preliminary results show that the ore-forming elements enriched in different lithology and types of granites are Y,Nb,Sb,Sn,Zn,Co,etc.Compared with the metallogenic granite discovered in the region,it is considered that this is a good prospecting area and should be paid enough attention to.

关 键 词：花岗岩 锆石U-PB年代学 岩石地球化学 矿质元素 大水沟 东昆仑 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]