赣西北上寒武统西阳山组碳酸盐岩岩石学特征及沉积环境分析

主要通过对修水县港口地区野外 1:5万地质填图而实测到的三条剖面 (沙墩上、岩背、洞下 )的详细研究,阐明西阳山组的岩石学及地层分布特征,进而分析得出本区西阳山组为深水碳酸盐台地斜坡环境沉积。鉴别出三个主要沉积相:环台地再沉积碎屑裙相、碳酸盐浊流沉积相和半远洋泥质沉积相。并在此基础上,又对本区西阳山组沉积过程的动态变化以及灰岩透镜体、扁豆体的成因作了初步分析,认为灰岩透镜体的成因是多源的,往往是多种作用共同作用的结果。另外,还发现西阳山组碳酸盐地层沉积旋回具有自相似和多重分形的特征。

Analyses of Petrology and Sedimentary Environment on Late-Cambrian Carbonate Rocks of the Xiyangshan Formation in NW Jiangxi, China

Based on studies of three geological transections (Shadunshang, Yanbei and Dongxia) from 1:50, 000 field mapp ing at Gangkou area, Jianxi, this paper addresses the petrological features and facies distribution of late-Cambrian carbonate rocks of Xiyangshan formation. Three main depositional facies of carbonate-ramp origin are identified, which are circum-platform redepositional clastic apron facies, carbonate turbidite facies and hemi-pelagic muddy facies. The dynamic variations of the depositional processes and the causes of carbonate lens are further analyzed.Carbonate lens observed in Xiyangshan formation are believed to be of multiple causes and may result from the combined action of several different mechanisms. In addition, cyclic carbonate sequences in this area are found to have self-similar and multifractal behaviors.