摘要
湘川地区包括四川秀山、相西和湘中地区。该地区震－寒武系层状硅岩发育。硅岩有机碳含量较高，变化于０．０６～９．００％，平均１．５７％。有机碳与某些微量元素（Ｂａ、Ｚｎ、Ｒｂ、Ｃｏ、Ａｓ、Ｕ、Ｔｈ）的线性关系不明显；油浸显微镜下鉴定硅岩中的干酪根组成多为有机质碎片和微粒体，并显示微弱的各向异性。原始母质类型经恢复后基本为腐泥型，属于Ⅰ型无定型干酪根；在干酪根化学元素组成图上（ＶａｎＫｒｅｖｅｌａｎ图），均位于变生作用阶段区，表明有机质成熟度高；干酪酪根稳定碳同位素组成变化于－２９．３０～－３５．８４％。上述有机岩石学特征分析表明，生物及其降解产物－有机质对硅岩的形成具有不可忽视的贡献；硅岩形成过程中可能发生过“去杂质”作用；硅岩中的有机质成熟度较高；
The Xiangchuan region is referred to Shoushan County, Sichuan Province and the western and middle parts of Hunan Province where Sinian Cambrian bedded cherts are well developed. The organic carbon content in the chert samples is relatively high, ranging from 0.06 to 9.00% and averaging 1.91%. The linear positive relationship between organic carbon concentrations and some trace element contents is not clear. Microscopic studies of the kerogen from the chert samples show that the main components of the kerogen are organic fragments and microsome with weak anisotropy. The restoration results suggest that the primary mother materials basically belong to Type-Ⅰ amorphous kerogen. On the Van Krevelen diagram, all samples fall into the metagenesis field. Stable carbon isotopes of kerogen from the chert samples range from -29.30 to -35.84‰. Analysis of the features of organic petrology mentioned above suggests:1) that organisms and their degraded products contribute much to the formation of chert, 2) that in the formation of the chert a so called 'elimination of impurity matters' processes may probably take place; and 3) that the chert is formed in a shallow continental margin stagnant basin.
出处
《沉积学报》
CAS
CSCD
北大核心
1997年第1期54-59,共6页
Acta Sedimentologica Sinica
关键词
硅岩
有机岩石学
形成环境
湘川地区
震旦纪
chert organic petrology formation environment Xiangchuan region
