摘要
秦岭造山带是中朝克拉通华北板块和扬子克拉通板块结合区域。其基底组成为广大地质学家所关注。笔者报道了秦岭造山带中部陕西省商南县湘河地区楼房沟古变质结晶岩片斜长角闪岩-浅粒岩和黑云二长石英片岩的SHRIMP锆石U-Pb年龄数据,讨论了其地质意义。斜长角闪岩-浅粒岩为同一岩浆连续分异变质火山岩,锆石Pb严重丢失,207Pb/206Pb年龄≥(2488±8)Ma。年龄值与已获得的Sm-Nd等时年龄值在误差范围内一致。黑云二长石英片岩为副变质岩,锆石U-Pb年龄(978±13)Ma。秦岭造山带中部老于太古宇岩片(块)的发现表明,秦岭造山带下部可能存在过太古宙结晶基底。
The Qinling orogenic belt is the junction between the North China plate of the Sino-Korean craton and the Yangtze cratonic plate and its basement arouses attention of many geologists. This paper reports the zircon SHRIMP U-Pb age data for the Loufanggou metamorphic crystalline rock sheet amphibolite-leptite and biotite- bearing monzonitic quartz schist in the Xianghe area, Shangnan, Shaanxi, in the central part of the Qinling orogenic belt and discusses their geological significance. Arnphibolite-leptite is meta-volcanic rocks resulting from continuous differentiation of the same magma. Zircon Pb loss is serious and the ^207Pb/^206Pb age is ≥2488±8 Ma. This age is consistent with the available Sm-Nd isochron age with the error limits. Biotite-bearing monzonitic quartz schist is parametamorphite with a zircon U-Pb age of 978±13 Ma. The discovery of an Archean sheet （block） in the central part of the Qinling orogenic bek suggests that the Archean crystalline basement may have existed in the lower part of the Qinling orogenic bek.
出处
《中国地质》
CAS
CSCD
2005年第4期579-587,共9页
Geology in China
基金
国家自然科学基金项目(40072071)资助
关键词
同位素年代学
变质岩
秦岭造山带
isotope chronology
metamorphic rock
Qinling orogenic belt
