摘要
本文以草海两个钻孔剖面的孢粉资料为佐证,讨论了该区晚上新世晚期以来不同气候条件下形成的沉积物中,CaCO_3等作古气候指示剂的可能性。研究表明:在大陆湖盆沉积区与溶蚀区(物源区)相距不远、沉积区没有远源物质加入的情况下,寒冷气候时期,沉积盆地的堆积物中CaCO_3的含量较高;而温暖气候时期沉积物中的CaCO_3含量较低。
Since Teihert (1958) and Chave (1967) pointed out that some places where a lot of shallow water sediments contained over 50% carbonate were located in some higher latitude areas, a few scholars have observed that both cold water carbonate and warm water carbonate exist in the world, especially in some higher latitude areas , and this fact has clarified a wrong idea, which is popular among some geologists , that all carbonate rocks can be explained by the ' temperate climate' model. But in China, there is hardly any report about cold water carbonate sediments of lakes.
According to the sporepollens taken from two drilled hole sections of the Late Cenozoic strata in Caohai, Guizhou, this paper discusses a possibility that the CaCO3 abundance,etc. of sediments is used as a palaeoclimate indicator. The research indicates that in the sediments of Late Cenozoic in Caohai the CaCO3 abundance, etc. is st-rickly controlled by the climate environments of different ages, i.e., in the sediments formed in the temperate-cool or cold climate age, the content of CaCO3 and CaO is higher; in the sediments formed in the temperate-warm toward cool or temperate climate environment, the content of CaCO3 and CaO is moderate; in the sediments for-med in the temperate-warm climate condition, the content of CaCO3 and CaO is low-er, Thus, it can be concluded that the abundant Caohai carbonate sediments of Late Cenozoic belong to a cold water type.
This paper also deals with the geological, geographical and geochemical condi -tions under which the cold water carbonate sediments were formed in Caohai area and the forming mechanism. The Caohai Basin is located in a land watershed zone, with carbonate rocks widely developed in its base layer, the basin sedimentary area not far from the corrional area, no far resource materials added to the sediments, the sedi -mentary basin medium containing the pH ( 7 - 8 ) value suitable for CaCO3 deposi -tion. It is in such special environment that the cold water carbonate sediments of Caohai area were formed.
出处
《贵州地质》
1989年第4期347-356,共10页
Guizhou Geology
