山西中奥陶世石膏岩的成因类型及生成环境

山西中奥陶世石膏岩的沉积受到机械沉积作用的影响。区内九种石膏岩分别是不同水深条件下的沉积及交代产物,并可归纳为浪基面下洼地、浅水、滩岛潮坪等三种沉积环境。在空间上,它们彼此依存、转换并连为一体形成一个巨大的浅水蒸发岩沉积。

THE GENETIC TYPE AND FORMATIONAL ENVIRONMENT OF GYPSUM IN THE MIDDLE ORDOVICIAN PERIOD, SHANXI PROVINCE

Investigating the middle ordovician gypsum deposit in Shanxi province the author has found a lot of evidences illustrating that the mechanical deposition of gypsum took place under hydrodynamic conditions. The theory of detrital origin is also applicable to the formation of gypsum sediment in that area. These are 9 kinds of gypsums,namely: (l)laminated argillaceous gypsum-dolomitic gypsum, (2)nodular gypsum, (3) laminated gypsum, (4)stromatolithic gypsum, (5)oblate rudaceous gypsum,(6) oolitic gypsum, (7) psammitic and ( or ) clastic gypsum, (8) striped gypsum, (9) massive gypsum. They are sedimentary and replacement products which have been formed under the conditions at different depths of the shallow sea. These are tyree types of environments which caused these gypsum deposits, that is, (1) depression environment at depth below the wave base, (2) the shallow water environment, (3) the tidal-flat environment which was transitional in the form of island-bank. These three environments were interdependent and interchanging, and eventually united to be a whole body in the form of vast evaporite sedimentation in theshallow sea.