LA-ICP-MS Zircon U-Pb Dating, Geochemistry of the Mishuling Intrusion in Western Qinling and Their Tectonic Significance
详细信息
- 责任者：Li Zuochen (Key Laboratory of Western China’s Mineral Resources and Geological Engineering ; Ministry of Education ; Faculty of Earth Sciences and Resources ; Chang’an University ; Xi’an 710054 ; China) ; Pei Xianzhi
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(8)
- 关键词：花岗岩 ; granite ; 铀—铅计时 ; U-Pb dating ; 秦岭 ; Qinling Mountains
- 页码：p.2617-2634
- 图表：15 illus., 2 tables, 122 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
An EW trending Indosinian granitoide belt distributes near the Mianlue Suture Zone in the southern margin of the Qinling Orogenic Belt. The Mishuling intrution is one of the Indosinian granitoids located in the western Qingling and north to the Mianlue Suture Zone. This article studies the LA-ICP-MS zircon U-Pb ages and geochemistry characteristics of the Mishuling biotite quartz monzonite and monzodiorite enclaves. The results show that the crystallization age of the Mishuling biotite quartz monzonite is 214. 5 ± 1. 6Ma(MSWD = 0. 24). The A/CNK ratios of the Mishuling biotite quartz monzonite and monzodiorite enclaves range from 0. 64 to 0. 97,indicating that the granitoids are metaluminous rocks. The ∑REE of the granitoides are 197. 3 × 10-6 ～ 246. 6 × 10-6. The REE patterns show rightward incline and moderate negative Eu anomaly. The trace element geochemistry is characterized evidently by negative anomaly of Ta,Nb,P,Ti,Ba,Sr,etc. and positive anomaly of Rb,U,La,Zr,Hf,Nd,Y,etc. The host rock biotite quartz monzonite and enclaves monzodiorite are I-type granitoids,which may originate from a single magma. The magma was formed by partial melting of basic rocks. The Mishuling intrusions are post-orogenic granitoids which were formed in a transitional tectonic setting from syn-(compressional setting) to post-collision (extensional setting). They were products formed by partial melting of thicken lower crust resulting from the collision between the North China plate and Yangtze plate.