三江地区两类古陆成分的铅同位素组成——Ⅰ.碳酸盐岩类  

Pb ISOTOPIC COMPOSITIONS OF TWO TYPES OF PALEO_CONTINENTS IN SANJIANG REGION:Ⅰ. CARBONATE ROCKS

作　　者：徐启东[1] 夏林[1] 

机构地区：[1]中国地质大学资源学院

出　　处：《地球科学（中国地质大学学报）》1999年第3期274-277,共4页Earth Science-Journal of China University of Geosciences

基　　金：国土资源部"九五"科技攻关项目

摘　　要：根据铅同位素组成，西南三江地区前中生代的碳酸盐岩可分成具高放射性和低放射性成因铅同位素特征的两种类型，其数值范围和样品的空间分布都可分别与已知的冈瓦纳和劳亚古陆群的铅同位素组成对比．运用不同古陆群显示的块体铅同位素组成差异作为标志，判别兰坪盆地中以灰岩和细碎屑岩组成的上三叠统可能不是中生代兰坪盆地的沉积产物。Pb isotope data confirm that the Pre_Mesozoic carbonate rocks in Sanjiang region, Southwestern China can be divided into two types: highly radiogenic Pb isotope and lowly radiogenic Pb isotope. The numerical range of the Pb isotopic composition and the spatial distribution of the two types of samples can be correlated with those of Gondwana and Laurasia continents. Therefore, the difference in Pb isotopic composition between the Gondwana_like and Laurasia_like continental segments may be used to determine that the Upper Triassic strata composed of limestone and fine detrital rocks in the Lanping basin did not result from the sediments in the Mesozoic Lanping basin, but from structural slivers transported through the thrust and nappe from the Gondwana continent groups in the west of the Lanping basin in the early Cenozoic.

关 键 词：冈瓦纳古陆 铅同位素 古陆成分 碳酸盐岩 

分 类 号：P597[天文地球—地球化学] P588.245[天文地球—地质学]