地质通报2012，Vol.31Issue(9)：1482-1495,14.
西秦岭天水地区流水沟岩浆杂岩LA-ICP-MS锆石U-Pb测年和岩石地球化学特征
LA-ICP-MS zircon U-Pb dating and geochemical characteristics of the Liushuigou igneous complex, Tianshui area, West Qinling Mountains
摘要
Abstract
The Liushuigou igneous complex distributed in the northern margin of the West Qinling Mountains consists of metagabbro, metagabbro-diorite and metadiorite. In order to determine the structural properties and discuss the process of tectonic evolution, the authors carried out the LA-ICP-MS zricon U-Pb dating as well as major and trace elements analysis. The results show that the zircon is of magmatic origin, and the age of the igneous complex is 548.7±1.8Ma (MSWD=0.56). The Liushuigou igneous complex is characterized by a wide range of SiO2 (52.47%-66,95%), low TiO2, low ALK, a wider range of Mg#, and a positive correlation between oxide and SiO2 in variation diagrams. The REE patterns are flat, the ratios of LREE/HREE range from 1.14 to 2.60, LREE and HREE show low fractionation, and 8Eu values are between 0.65 and 1.90, mostly assuming negative anomalies, In the trace element spidergrams, there exist the enrichment of such LILEs as Cs, Sr, Th and U and depletion of Rb and K and such HFSEs as Nb, P, Ti and Y, the ratios of Ti/Y, Th/Yb, Th/Nb and Hf/Th are 113-253, 0.23-2.85, 0.09-1.00 and 0.41-2.97, respectively, suggesting that the igneous complex was formed in an island-arc setting. The Liushuigou igneous complex might indicate that there existed a " Pan-African orogeny" tecto no thermal event in the Central Orogenic System. The results obtained by the authors provide evidence for the tectonic evolution of the Central Orogenic System in Late Neoproterozic and Early Paleozoic period.关键词
西秦岭北缘/岩浆杂岩/LA-ICP-MS锆石U-Pb测年/中央造山系/泛非造山运动Key words
northern marigin of West Qinling Mountains/igneous complex/LA-ICP-MS zircon U-Pb dating/Central Orogenic System/ Pan-African orogeny分类
天文与地球科学引用本文复制引用
高景民,陈有炘,裴先治,李佐臣,李瑞保,裴磊,魏方辉,吴树宽,刘成军,王银川..西秦岭天水地区流水沟岩浆杂岩LA-ICP-MS锆石U-Pb测年和岩石地球化学特征[J].地质通报,2012,31(9):1482-1495,14.基金项目
国家自然科学基金项目《西秦岭北缘变形构造解析及其祁连-秦岭构造交接关系研究》(批准号:40972136)、中央高校基本科业务费专项资金项目《中央造山系(中西段)关键构造部位复合造山作用研究》(编号:CHD2011TD020)和中国地质调查局地质调查项目《1:25万天水市幅区域地质调查(修测)》(编号:200013000154) （批准号:40972136）
