摘要
贵州开阳地区是中国陡山沱期磷矿的主要产出地之一,含磷地层洋水组一直是国内外研究热点,但对其底板澄江组的研究严重不足,仅在地调中对其进行简单的地层描述和对比划分。通过对澄江组岩性、沉积序列、地球化学等分析,认为该组时代可能归属于陡山沱早期。沉积环境与前人认为冰湖相完全不同,早期以干热气候的近海湖相为主,在海侵的影响下逐渐过渡到海湾相,海侵后形成近滨相,之后逐渐从海滩相到浅海陆棚相,可能存在过碳酸盐台地相,最后暴露地表接受剥蚀。在澄江组晚期,就有磷质开始沉积,在砂岩中出现胶磷矿,说明成磷在陡山沱期前就开始,但大规模成磷作用发生在陡山沱期。
phosphorites of the Yangshui Formation are widespread in the Kaiyang？region of Guizhou Province,South China.However,the underlying Chengjiang Formation is poorly studied,with only preliminary stratigraphic description published in regional geological maps.In this study,we carried out a comprehensive lithostratigraphic,sedimentological,and geochemical analysis of the Chengjiang Formation.We conclude that the Chengjiang Formation is of early Doushantuoan in age.Contrary to previous interpretation that the Chengjiang Formation represents glaciolacustrine deposits,we argue that this unit represents depositional transition from coastal lacustrine environments in warm and dry climatic conditions,to restricted lagoonal facies upon transgression,to near-shore facies,beach facies,and shelf facies,with possible carbonate platform facies and termination with subaerial exposure.Phosphatic deposits occur in sandstone of the upper Chengjiang Formation,indicating that phosphogenesis began in early Doushantuoan age although large-scale phosphogensis occurred later in the Doushantuoan age.
出处
《地层学杂志》
CSCD
北大核心
2017年第4期437-444,共8页
Journal of Stratigraphy
关键词
岩石地层
资源地层
沉积特征
沉积环境
澄江组
陡山沱期
开阳
贵州
Lithostratigraphy
economic stratigraphy
sedimentary characteristics
depositional environment
Chengjiang Fm.
Doushantuo
Kaiyang
Guizhou
