摘要
柴达木盆地西部干柴沟一带发育了大量湖相叠层石,主要存在于新近纪中新世地层中。柴西地区的叠层石形态各异,成因各具特点,而且部分叠层石与现代叠层石完全不同而是更类似于前寒武时期的对应物,根据国内外叠层石研究的最新成果和成因分类标准,柴西地区主要发育了骨架、凝集和细粒叠层石。对应于不同的分类标准其成因也各不相同,细粒叠层石的形成主要是通过微生物自身的钙化作用和生物膜上过饱和碳酸盐等物质以及微生物的引发的沉淀作用;凝集型叠层石的形成主要与原核生物和真核藻类共同发挥粘附作用有关;骨架型叠层石的形成主要是真核藻类等的钙化与原地碳酸盐的沉淀综合作用的结果。柴达木盆地频繁变化的湖相水体条件和周围的构造运动是叠层石形态多样,成因各异的主要外部和环境因素。对各类叠层石的深入细致研究将对沉积学和环境学的研究提供宝贵的现代对应物。
In western Qaidam basin, abundant Tertiary lacustrain stromatolites have been discovered recently in several kilometers Miocene strata from lower member of lower Ganchaigou Formation to lower Youshashan Formation in Ganchaigou area. The stromatolites, greatly variable in type and genesis, may partly reflect the Precambrian analogues and further be in contrast with the modern stromatolites, therefore it is of important significance for the international stromatolite research. According to the recent study and trend, the stromatolites in western Qaidam basin may be classified as skeleton, agglutinated and fine-grained types which also imply different genesis. The skeleton stromatolites is formed through microbially biological mineralization and calcification combined with in-situ precipitation; the agglutinated stromatolites are mainly related with binding and trapping performed by prokaryotic and eukaryotic algae together; and the fine-grained stroamtolites are mainly formed through biofilm calcification, over-saturated calcite precipitation on the biofilm and microbial chalk precipitation. Overall, the frequently fluctuated lacustrine conditions and the surrounding tectogenesis are mainly responsible for the greatly varied form, different genesis of stromatolites. The detailed discussion and study on Qaidam examples will offer valuable modern analogues in the research of sedimentology and environmental science.
出处
《西北地质》
CAS
CSCD
2005年第2期40-48,共9页
Northwestern Geology
基金
国家自然科学基金资助项目(编号40172073)
教育部博士点基金项目(编号20030425008)
中国石油天然气集团公司创新基金项目(编号2002F70108)
关键词
叠层石
成因
环境
柴达木盆地
中新世
Stromatolites
genesis
environment
Qaidam basin
Miocene