摘要
湘黔地区的奥陶纪红花园期及宝塔期在三都、吉首、桃源一线酉北为碳酸盐台地沉积。红花园期水体相对较浅，自西北而东南可划分为开阔台地相、台地滩相、台地边缘生物礁相、盆地边缘相；宝塔期水体较深，成为湮没了的台地。通过对红花园期和宝塔期碳酸盐稳定碳、氧同位素研究结果表明，其组成与环境的盐度、水体深度、水温及氧化－还原条件相关。随着含盐度的增加，碳氧同位素值也增大。水体变深，还原程度增强，则碳氧同位素值随之减小。
The Honghuayuanian and Baotaian (Ordovician) strata in the Hunan-Guizhou region are represented by the carbonate platform deposits in the Sandu-Jishou-Taoyuan zone.The sea water was relatively shallow during the Honghuayuanian,and the strata deposited during this period may be divided,from northwest to southeast,into the open platform factes,platform shoal factes,platform-margin organic reef factes and peribasinal factes. Till the Baotaian,the sea water became relatively deep,and the platform was drowned during this period. The stable carbon and oxygen isotopic data of the Honghuayuanian and Baotaian carbonate rocks indicate that the isotopic compositions are related to the salinity,depth and temperature of the sea water,and reduction-oxidation conditions. The carbon and oxygen isotopic values are a function of salinity. As the reduction-oxidation degrees increase with increasing water depth,the carbon and oxygen isotopic values decrease.
关键词
碳氧同位素
古环境
湘黔地区
奥陶纪
carbon and oxygen isotopes
palaeoenvironment
Hunan-Guizhou region
Ordovician
