摘要
中国阿尔泰山位于西伯利亚板块南缘,其内发育较为频繁的古生代侵入岩浆活动,为研究中亚造山带地壳增生的理想窗口。本文通过对北阿尔泰地区西段契巴罗依北基性岩体的岩相学、锆石LA-ICP-MS U-Pb测年及岩石地球化学数据进行研究,探讨该岩体就位的大地构造背景和成因机制,为研究区域构造演化提供了新资料。契巴罗依北基性岩体包括细粒辉长岩、角闪辉长岩、角闪苏长岩、细粒苏长岩等不同岩相,本次获得角闪辉长岩锆石U-Pb年龄为470.6±4.3Ma,首次确认在北阿尔泰造山带发育中奥陶世基性侵入岩。根据区域岩浆岩年代学及地质特征,结合契巴罗依北基性岩体岩石地球化学数据分析,认为该期基性岩浆可能形成于大陆板块边缘的弧后伸展环境,源于早古生代古亚洲洋向北俯冲。
Objectives： Since the precambrian period in Altay, there have been many tectonic -- magmatic events, and formed large areas of granite. These granite bodies are believed to be mainly formed in late Paleozoie. Recently, some early Paleozoic and Mesozoic granite bodies were found. However, the study on the tectonic background and genetic mechanism of mafic intrusion in the region is weak. In this paper, we studied on the newly discovered mafic intrusion body systematically, the new evidence will be provided for the tectonic--magmatic activity of Altay in early Paleozoic.
Methods： Based on detailed observations of Qibaroi mafic intrusion in western of Ahay mountains, we have studied the petrology, geochemistry and chronology of Qibaroi rock. The geological implications of Qibaroi mafic intrusion was discussed.
Results ： The Qibaroi marie intrusion including fine-grained gabbro, hornblende gabbro, hornblende norite and fine-grained norite, the zircon U-Pb age of hornblende gabbro is 470.6＋4.3Ma,which was identified the Middle Ordovician mafic intrusive rocks in the North Altay orogenic region for the first time. In the diagrams of SiO2- （Na2O ＋ K2O） and SiO2-K2O, it is shown as a calcium alkaline rock series, the sample contains relatively low high field strength elements （HFSE）, Nb has a slight loss, and has the characteristics of light rare earth enrichment, it is shown that Qibaroi Marie Intrusion is influenced by the crust and has the characteristics of subduction. According to regional magmatic geochronology and geological characteristics, combined with the geochemical data of the Qibaroi marie intrusion rocks, it is believed that the mafic magma may be formed in the back arc extension environment on the margin of continental plate, formed in the the paleo Asian Ocean northward subduction, the separation of plate from deep mantle leads to the interaction between asthenosphere mantle and overlying metasomatic mantle, and it is intruded into the weak zone.
Conclusions： The Qibaroi marie i
出处
《地质论评》
CAS
CSCD
北大核心
2018年第1期247-259,共13页
Geological Review
基金
新疆区域地质调查片区总结与服务产品开发(编号:DD20160345-04)
新疆阿尔泰成矿带喀纳斯和东准地区地质矿产调查项目(编号:DD20160006)的成果~~
