地质论评2017，Vol.63Issue(5)：1193-1208,16.DOI:10.16509/j.georeview.2017.05.006
扬子板块西缘石棉安顺场新元古代钾长花岗岩地球化学特征及其地质意义
Geochemical Characteristics and Geological Significance of the Neoproterozoic K-feldspar Granites from the Anshunchang, Shimian Area, Western Yangtze Block
摘要
Abstract
Objectives:Neoproterozoic magmatic rocks are widespread in western margin of the Yangtze block,Petrogenesis of the Neoproterozoic granitic rocks has potential significance to the tectonic evolution of supercontinent Rodinia.Methods:In this paper,we present zircon U-Pb age,and whole-rock major and trace elements,Sr—Nd isotopic compositions of the K-feldspar granites from the Anshunchang,Shimian county.Results:K-feldspar granites zircon U-Pb result show that the crystallization age of 777.3 ± 4.8Ma (MSWD =0.23,2σ),which belongs to Neproterozoic granites.The results indicate that the K-feldspar granites are peraluminous,high-K calc-alkaline S-type granites,with SiO2content ranging from 72.64％ to 76.27％,A/CNK =1.06 ～ 1.24,K2O/Na2O =1.40 ～ 2.22,σ =2.08 ～2.74.The granites are enriched in LREE and depleted in Nb and Ta,with significant negative Eu anomalies (δEu =018 ～ 0.23).The εNd (t) vary from 0.5 to 3.3 (average value =2.1),and TDM =1.19 ～ 1.61Ga,suggesting Neoproterozoic crust source region.The K-feldspar granites have [n (206 Pb)/n (204 Pb)]i =15.4103 ～ 17.2707,[n (207 Pb)/n (204 Pb)]i =15.4265 ～ 15.5479,and [n (208 Pb)/n (204 Pb)]i =33.3518 ～ 35.8641,respectively.Conclusion:In combination with geochemistry,isotopic signatures and the regional geology in the western of the Yangtze block,we argued that K-feldspar granites from the Anshunchang are peraluminous,high-K calcalkaline S-type granites,these K-feldspar granites were derived from partial melting of the pelite in middle—lower crust.They were formed in an compressive tectonic setting.关键词
钾长花岗岩/锆石U-Pb年龄/地球化学/Sr—Nd—Pb同位素/Rodinia超大陆Key words
K-feldspar granites/zircon U-Pb age/geochemistry/Sr—Nd—Pb isotopic/supercontinent Rodinia引用本文复制引用
朱毓,赖绍聪,赵少伟,张泽中,秦江锋..扬子板块西缘石棉安顺场新元古代钾长花岗岩地球化学特征及其地质意义[J].地质论评,2017,63(5):1193-1208,16.基金项目
本文为国家自然科学基金资助项目(批准号:41372067,41102037)和国家自然科学基金委创新群体项目(批准号:41421002)的成果.Financial support for this study was jointly provided by National Natural Science Foundation of China(Grant No.41372067,41102037)and National Natural Science Foundation Innovation Group (Grant No.41421002). （批准号:41372067,41102037）
