湘中地区中奥陶统沉积岩的稀土元素地球化学  

REE Geochemistry of Sedimentary Rocks Middle Ordivician in Central Hunan Province

作　　者：蒋德和[1] 杨振强[1] 赵时久[1] 

机构地区：[1]湖北地矿部宜昌地质矿产研究所

出　　处：《沉积学报》1994年第1期106-111,共6页Acta Sedimentologica Sinica

摘　　要：湘中地区中奥陶统黑色岩系稀土元素地球化学特点为稀土丰度高轻稀土富集，重稀土亏损，无负Ｃｅ异常，Ｅｕ负异常明显并有高的∑ＬＲＥＥ／∑ＨＲＥＥ、Ｌａ／Ｙｂ、（Ｌａ／Ｙｂ）ｎ特征值等，是一种被动大陆边缘缺氧盆地的产物，其沉积物的稀土元素地球化学特点受沉积速率、搬运方式、物源供给等因素的影响。There is a suit fine grain black rocks, Middle Ordivician, in central Hunan province. including black shale, banded silt-shale, mudstone and siliceous shale (sillcalite) and so on. They were formed at slopebasin facies zone, and they have characters of REE geochemistry such as: high abundance of REE (ΣREE 271. 7ppm), high ratio of ΣLREE/ΣHREE, La/Yb, (La/Yb)n, Ce value, and low Eu value. The REE patterns are compared to sediments of passive contnental margin region. Because of affecting sub sedimentary environment, the sediments of background passive continental margin in the studied area are not only bigger Ce value, but also higher abundance of REE. Other sedimentary data demonstrated that they are products of anoxic environment at studied area, but they aren't appeared bagser Ce negative anomaly on the model curve of REE distribution. So Ce value cannot be take as indicator of anoxic environment. This paper discusses the tectonic background, the relationship Ce value between anoxic ement and manganese ordain, mudstone REE abundance and so on. It is made intelligible characteristics and distribution of REE anoxic down-warping basin of passive continental margin region.

关 键 词：中奥陶世 沉积岩 稀土族 地球化学 

分 类 号：P588.2[天文地球—岩石学]