青藏高原沱沱河盆地渐新世湖相叠层石:韵律纹层记录的古气候条件  

Oligocene lacustrine stromatolites in the Tuotuohe basin,Qinghai-Tibet Plateau:paleoclimate conditions recorded by the rhythmic laminations

作　　者：惠博[1] 伊海生[1] 时志强[1] 夏国清[1] 武向峰[1] 陈三运[1] 

机构地区：[1]成都理工大学沉积地质研究院,四川成都610059

出　　处：《地质通报》2010年第1期62-69,共8页Geological Bulletin of China

基　　金：国家自然科学基金项目(编号:40872082);教育部博士点基金项目(编号:20060616005)联合资助

摘　　要：沱沱河盆地通天河剖面渐新世雅西措群发现一套产于湖泛过程中的柱状叠层石。通过对叠层石纹层形态和显微组构的研究,发现这些叠层石具有典型的富藻纹层和富屑纹层交替的显微结构特征,发育三级生长节律,纹层对之间渐变接触,纹层带之间间断明显。采用激光微区取样的方法,针对4块样品的8个纹层对,系统采集了16对碳氧同位素数据,结果是富藻纹层同位素值整体上均高于富屑纹层,正相关性明显。这表明富藻纹层生长时期气候炎热湿润,富屑纹层生长时期相对寒冷干燥。认为湖相叠层石生长受周期性气候变化的控制,其韵律纹层记录了丰富的古气候信息。A group of lacustrine stromatelites growing in the process of the flooding lake is discovered in the Oligocene Yaxicuo Group of Tongtianhe section,Tuotuohe Basin. The shape patterns and microstructure of stromatolite laminations show the rhythm demonstrated by microbial micrite layers（dark layers） and grain-rich layers（light layers）,three-level growth rhythm,gradational contact relation in the middle of the couplet while abrupt in the lamina growth bands. 16 pairs of carbon and oxygen isotopic data are collected systematically from 8 couplets of 4 samples. The value in microbial micrite layers are on the whole higher than in grain-rich layers,showing positive correlation. It＇s showed that the climate was hot and wet in the growth period of dark layers,while colder and drier in the growth period of light layers. The lacustrine stromatelites are controlled by periodic climate change,which preserve plentiful paleoclimate informations.

关 键 词：湖相叠层石 韵律纹层 碳氧同位素 古气候 渐新世雅西措群 沱沱河盆地 

分 类 号：P534.61[天文地球—古生物学与地层学] Q914.82[天文地球—地质学]