Organic Petrology of the CambriarrSinian Chert from the Xiangchuan Region
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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；硅岩的形成环境可能属于浅水陆缘滞流盆地。Abstract: The Xiangchuan regionis referred to Shoushan County，Sichuan Province and the western and middle parts of Hunan Province where Sinian-Cambrian bedded cher is are w ell-dev eloped. T he orgyic car-bon 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 contentsis not clear. Microscopic studies of the kerogen from the chert samples show that the main componentsprobably take place; and 3) that the chert is formed in a shallow continertal-margin stagnant basin.results sug-gent that the primary mother materials basically belong to Type一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一29. 30 t0，一3 5. 84%.Analysis of thefeatures of organic petrology mentionedabove suggests 1)that organisms and their degraded products contribute much to the formation of chert, 2) that in the formation of the chert a scalled elimination of impurity matters”processes may
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Key words:
- chert /
- orgyic petrology /
- formation environment /
- Xiangchuan region
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