东秦岭松树沟超基性岩体“热”侵位时代新知  

New Data on the “Hot” Emplacement Age of Ultramafic Rocks from the Songshugou Area in the Eastern Qinling

作　　者：刘军锋[1] 孙勇[1] 

机构地区：[1]西北大学大陆动力学实验室

出　　处：《地质论评》2005年第2期189-192,共4页Geological Review

摘　　要：松树沟超镁铁质岩体位于秦岭商 -丹断裂以北 ,是该地区出露最大的超基性岩体 ,并以侵入方式与秦岭杂岩接触。该岩体主要由细粒纯橄榄岩、中粗粒纯橄榄岩和斜辉橄榄岩组成。利用 L A- ICPMS锆石 U- Pb法对采自该岩体北侧接触变质带的榴闪岩进行锆石定年 ,获得 2 0 6 Pb/ 2 38U变质年龄为 5 1 8± 1 9Ma。以上工作初步证实该岩体大致在 0 .5 2 Ga左右的构造热事件中侵位于秦岭杂岩中。Ultramafites in the Songshugou area to the north of the Shang-Dan fault is the largest one in the East Qinling area, and it is in contact with the Qinling Group as intrusions. The rockbody is composed mainly of fine-grained dunite, macrograined dunite and plagioclase pyroxene peridotite. Zircons from garnet amphibolites are dated by LA-ICPMS, and yielded a zircon U-Pb metamorphic age of 518±19 Ma. Garnet amphibolites in this study occur in a contact-metamorphic zone. The above study presents a preliminary understangding that the ultramafic intrusions were emplaced into the Qinling Group during the tectonic event at about 520 Ma.

关 键 词：超基性岩体 松树沟 侵位时代 东秦岭 秦岭杂岩 纯橄榄岩 接触变质带 ICPMS 构造热事件 超镁铁质 侵入方式 锆石定年 变质年龄 榴闪岩 

分 类 号：P588.1[天文地球—岩石学]