地质通报2013，Vol.32Issue(2)：318-326,9.
中蒙边界英巴地区元古宙杂岩的时代及其对南戈壁微陆块分布范围的限定
The age of the Proterozoic rocks in Yingba area in western Inner Mongolia:Constraints on the distribution of the South Gobi micro-continent in the Central Asian orogenic belt
摘要
Abstract
Micro-continents with Precambrian basement are developed in the Central Asian orogenic belt. In southern Mongolia, the Toto Shan and South Gobi miro-continents are characterized by Neoproterozoic magmatism. The South Gobi micro-continent might extend into China, as evidenced by the discovery of Neoproterozoic granitoid in Yagan area. However, the distribution of the South Gobi micro-continent is not well constrained in China. Regional geological data reveal that there are some Protero-zoic rocks in Yingba area of western Inner Mongolia. They are regarded as the relict blocks in and around the Yingba granitoid pluton and are mainly composed of gneiss, quartzite, mica and quartz schist and carbonate. In a Proterozoic block, the felsic gneiss composed of plagioclase, quartz and biotite gave complex U-Pb age results from the LA-ICP-MS zircon dating. The zircon cores with the igneous origin provided a wide range of207Pb/206Pb ages from 2.5Ga to 1.0Ga, while the igneous zircon mantles generated a weighted mean206Pb/238U age of 417.2Ma±3.5Ma, indicating an early Paleozoic tectonic event. In another block, the gneiss is crosscut by leucogranite veins, one of which gave a weighted mean206Pb/238UU age of 905.2Ma±6.1Ma. The age is close to the emplacement time (916Ma±16Ma) of Neoproterozoic gneissic granite pluton in Yagan. Therefore, the South Gobi micro-continent extended southward at least to the Yagan-Yingba area in China and were strongly modified and destroyed by the Phanerozoic tectonic-igneous activities.关键词
南戈壁微陆块/新元古代/锆石U-Pb定年/英巴地区/中蒙边界Key words
South Gobi micro-continent/ Neoproterozoic/ zircon U-Pb dating/ Yingba area/ Sino-Mongolian border分类
天文与地球科学引用本文复制引用
周印章,韩宝福,徐钊,任荣,苏犁..中蒙边界英巴地区元古宙杂岩的时代及其对南戈壁微陆块分布范围的限定[J].地质通报,2013,32(2):318-326,9.基金项目
国家重点基础研究发展计划(973计划)《兴蒙造山带构造叠合与大规模成矿作用》(编号:2013CB429806)、国家自然科学基金项目《华北克拉通中生代地壳减薄的机构变形机制、时限及动力学背景》(批准号:90714006)和中国地质调查局项目《兴蒙造山带花岗岩演化与成矿耦合关系综合研究》(编号:1212011085474)、《兴蒙造山带基本构造格局综合调查和研究》(编号:1212011085476)、《中国和亚洲不同造山带花岗岩年代学格架、岩浆序列及其与成矿关系的对比》(编号:1212010611803)和《中国北方增生造山过程、陆壳生长及其对找矿的作用》(编号:1212010611817) （973计划）
