湖北宜昌九龙湾剖面震旦系陡山沱组盖帽碳酸盐岩微相研究

The microfacies of the cap carbonate from the Sinian Doushantuo Formation at the Jiulongwan section,Yichang,Hubei

盖帽碳酸盐岩是沉积于新元古代冰碛岩之上的微晶碳酸盐岩沉积。在华南地区,以陡山沱组底部碳酸盐岩为代表。笔者通过对湖北宜昌九龙湾剖面震旦系陡山沱组盖帽碳酸盐岩微相研究,认为陡山沱组盖帽碳酸盐岩是稳定的灰泥球粒微晶灰岩经过后期不同程度的重结晶作用形成。原岩缺乏可靠的冷泉碳酸盐岩的微相特征,从碳酸盐岩微相角度上并不支持其甲烷渗漏成因,同时微相类型表明九龙湾剖面陡山沱组沉积是一种台地前斜坡沉积。

Cap carbonates are rnicrocrystalline carbonate sequences overlying the Neoproterozoic glacial rock, which are represented, in South China, by the basal carbonates of the Doushantuo Forma- tion. Based on the microfacies studies of the cap carbonates from the Sinian Doushantuo Formation at Jiu- longwan section of Yichang, Hubei, we consider the cap carbonates are stable mud peloidal limestone and recrystallized in varying degrees after the deposition. No convincing evidence for cold-seep carbonates has been found in our study. Mierofacies data indicate that the cap carbonates in Yichang may have been deposited in the inner ramp environment.