都庞岭-九嶷山地区早元古代地壳存在证据  

The proofs of existing earth crust's double foundation in the area of Duoponglin-Jiuyan mountainous

作　　者：彭学军[1] 刘耀荣[2] 李泽泓[2] 郑基俭[2] 马爱军[2] 

机构地区：[1]中国地质大学,武汉430074 [2]湖南地质调查研究院,湖南湘潭411100

出　　处：《华南地质与矿产》2005年第4期18-22,共5页Geology and Mineral Resources of South China

基　　金：中国地质调查局1:25万道县幅区域地质调查项目(200113000012)

摘　　要：都庞岭-九嶷山地区出露的南华纪至第四纪地层最大厚度累加为18.5km,物探推测的地壳厚度为32～40km,两者相减尚应有13.5～18.5km厚的硅铝质地壳物质;地表基性-超基性火山岩中已发现有年龄值为1141～2707Ma的片麻岩、麻粒岩、辉长岩、尖晶石二辉橄榄岩、片岩等沉积岩和岩浆岩变质结晶岩类;源岩主要属地壳成分的花岗岩,钕同位素T2dm值为1790～1380Ma;花岗岩内磨圆状残留锆石SHRIMP法年龄值912～2669Ma.推测南华系-奥陶系仅属上地壳基底,南华系之下还存在元古代甚至太古代的变质结晶基底.The strata＇s thickness from Cryogenian Period to Quaternary Period is 18.5km in the area of Duoponglin-Jiuyan Mountainous; the physical exploration＇s data related that the earth crust＇s thickness is 32-40km. Therefore, under the Cryogenian System, exists salic material which thickness is about 13.5-18.5km. In the terrestrial basic-ultrabasic volcanic rock, exists metamorphous-crystalline rock whose ages between 1141Ma and 2707Ma such as gneiss, granulite, gabbro, spinel lherzolite and schist. The values of Nd isotope t2DM of granite whose source rock belonged to earth crust are between 1790Ma and 1380Ma. SHIMP ages of Zircong porphyroclast in granite are between 912 Ma and 2699Ma. So we propose a conclusion that from the Cryogenian System to Ordovician System is only the upper foundation of the earth crust, under the Cryogenian System exists the under foundation consisted of the metamorphous-crystalline rock which belong to the Proterozoic PR Eonothem even the Neoarchean Erathem.

关 键 词：基底 南华系-奥陶系 元古界 

分 类 号：P534.3[天文地球—古生物学与地层学]