桂东南云开地区变质杂岩锆石SHRIMP U-Pb年代学  

Zircon SHRIMP U-Pb geochronology of the Yunkai metamorphic complex in southeastern Guangxi, China

作　　者：覃小锋[1] 潘元明 李江[3] 李容森[3] 周府生[3] 胡贵昂[3] 钟锋运[3] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]Department of Geological Science University of Saskatchewan,Saskatoon,Saskatchewan,S7 N 5E2,Canada [3]广西区域地质调查研究院,广西桂林541003

出　　处：《地质通报》2006年第5期553-559,共7页Geological Bulletin of China

基　　金：中国地质调查局<1:25万玉林市幅(F49C002002)区域地质调查>项目成果。

摘　　要：对位于华夏古陆东南部的广西云开地区大面积出露的晚前寒武纪变质杂岩中的主体花岗质片麻岩、中深变质的天堂山岩群石榴辉石岩和中浅变质的云开岩群洋中脊型变质基性火山岩(斜长角闪岩)进行了高精度锆石SHRIMP U-Pb定年。获得天堂山岩群石榴辉石岩的形成年龄为1894Ma±17Ma和1847Ma±59Ma,表明其时代为古元古代;云开岩群洋中脊型变质基性火山岩(斜长角闪岩)的喷发年龄为1462Ma±28Ma,证明该地区存在中(-新)元古代的古洋壳残片;获得花岗质片麻岩的侵入年龄为906Ma±24Ma,应为1000Ma前后发生的全球性Grenville期(四堡期)造山作用的产物,并获得2702Ma±13Ma的继承碎屑锆石年龄,这是云开地区乃至华夏古陆目前获得的最古老年龄,证明华夏古陆曾存在新太古代陆壳物质。Highly precise zircon SHRIMP U-Pb dating was carried out on granitic gneiss in the Late Precambrian Yunkai metamorphic complex, garnet pyroxenite in the medium- and high-grade metamorphic Tiantangshan Group complex and mid-ocean ridge metabasic volcanic rocks （amphibohte） in the medium- and low-metamorphic Yunkai Group complex in the Yunkai area, Guangxi, southwestern Cathaysia. The data show the following ages： 1894±17 Ma and 1847±59 Ma for garnet pyroxenite of the Tiantangshan Group complex, indicating a Paleoproterozoic age; 1462±28 Ma for the metabasic volcanic rocks （amphiholite） of the Yunkai Group complex, indicating the presence of fragments of the Meso- and Neoproterozoic oceanic crust in the Yunkai area; 906±24 Ma for the granitic gneiss intrusion is, which should be the product of the global Grenville （Sibaoan） collisional orogeny occurring around 1000 Ma BP. In addition, an inherited detrital zircon age of 2702＋13 Ma was also obtained, which is the oldest age in the Yunkai area and even in Cathaysia, proving the presence of Neoarchean continental crustal material in Cathaysia.

关 键 词：云开变质杂岩 锆石SHRIMP U-PB年龄 华夏古陆 桂东南地区 

分 类 号：P588.3[天文地球—岩石学] P597.3[天文地球—地质学]