鄂西宣恩志留系细砂岩地球化学特征及物源构造环境分析

Analysis on Geochemical Characteristics and Provenance Tectonic Environment of Silurian Fine Sandstone in Xuan'en Region of the Western Hubei

鄂西宣恩志留系较为发育,自下而上可分为新滩组、罗惹坪组、纱帽组,为一套粉砂岩、细砂岩夹页岩的碎屑岩沉积。笔者在区域地质调查过程中,对鄂西宣恩地区新滩组、罗惹坪组、纱帽组内细砂岩(粉砂岩)进行了地球化学取样分析,显示碎屑岩母岩来自火山岛弧和稳定陆块。结合区内志留系沉积序列特征表明:鄂西早志留世阶段,中上扬子区为稳定陆块基底上发育而成的被动陆缘克拉通盆地。

Silurian strata in Xuan＇en region of the western Hubei is quite developed which can be divided into Xintan Formation, Luoreping Formation from bottom to top, Shamao Formation, and it is a sequence of clastic deposit with silt- stone, fine sandstone with intercalation of shale. During the regional geologic investigations, the authors analyzed the geo- chemical characteristics of fine sandstone in Silurian strata. Research results show that the parent rocks of clasolite come from volcanic arc and stable landmass. The Silurian sedimentary sequence characteristics indicate that the middle and upper Yangtze Region is passive margin cratonic basin which developes from stable landmass basement in Early Silurian.