柴达木盆地新生界生物地层年代研究

THE BIOSTRATIGRAPHIC AND CHRONOLOGICAL RESEARCH OF CENOZOIC IN THE QAIDAM BASIN,NORTHWEST CHINA

柴达木盆地新生代地层广泛分布,富含油气资源。长期以来,各组时代归属存在较大争议。本文以介形类、孢粉和轮藻微体化石为基础,重新探讨了柴达木盆地新生界各组的地质年代归属:路乐河组为古新世—始新世中期;下干柴沟组沉积时代主体为始新世中晚期,渐新世早期也有部分沉积;上干柴沟组为渐新世早期—中新世早期;下油砂山组为中新世早—中期;上油砂山组为中新世中—晚期;狮子沟组为中新世晚期—上新世晚期;七个泉组为更新世早—中期。柴达木盆地新生界各组地质年代的确定对盆地内油气勘探工作具有重要意义。

The Cenozoic strata of Qaidam basin, Northwest China is widely distributed, and rich in hydrocarbon resources. Over a long time,the age assignment of each formation has been heatedly disputed. On the basis of ostracods, pollen and charophytes analyses, we revised the age of each formation of the Cenozoic in the Qaidam basin. The age assignment of the Lulehe Formation is Paleocene--Middle Eocene. The Lower Ganchaigou Formation is of the middle-late Eocene to Early Oligocene. Upper Ganchaigou Formation is of the Early Oligocene--Early Miocene. The Lower Youshashan Formation is of the Early Miocene-Middle Miocene. The Upper Youshashan Formation is of the Middle-Late Miocene. The Shizigou Formation is of the Late Miocene-Late Pliocene. The Qigequan Formation is of the Early-Middle Pliocene. The determination of geological age is significant for the oil and gas exploration in the Qaidam basin.