伦坡拉盆地渐新统丁青湖组油页岩特征及其地质意义

伦坡拉盆地丁青湖组油页岩呈北西-南东向断续分布，长约50 km，油页岩有18~22层，薄者0.10 m，厚者8.81 m，一般厚0.70~2.00 m。工业分析数据表明，油页岩属于高灰分、中低含油率、低发热量型。油页岩有机碳质量分数为2.40%~20.23%，平均值7.38%，丰度较高。干酪根镜检显示油页岩有机质类型为腐泥型（Ⅰ型），镜质体反射率（R_o）值为0.43%~0.71%，平均值为0.52%，说明油页岩有机质处于未成熟-低成熟阶段。油页岩样品检测出丰富的正构烷烃、类异戊二烯烷烃、萜烷化合物和甾烷化合物。饱和烃色谱/质谱特征表明伦坡拉油页岩有机母质来源以水生浮游植物为主。通过生物标志物特征及野外地质观察，揭示了油页岩形成于一定盐度的缺氧还原半深湖-深湖环境。湖盆内各种水生浮游植物、藻类等为油页岩的形成提供了主要的有机母质来源，稳定的构造条件和缺氧的环境有利于有机质的堆积和保存。

Characteristics of Oil Shale of Oligocene Dingqinghu Formation and Its Geological Significance,Lunpola Basin

Oil shale of Oligocene Dingqinghu Formation orientating in NW-SE with about 50 km in length is discontinuously distributed. There are 18 to 22 oil shale layers ranging from 0.70 m to 2.00 m in thickness, of which the thinnest layer is 0.10 m and the thickest layer is 8.81 m. The results of industrial analysis show that Lunpola oil shale is a kind of high content of ash, medium to low oil yield and low calorific value. Organic carbon content of oil shale ranges from 2.40% to 20.23% with an average of 7.38%, indicating a relatively high abundance. Microscopic observations indicate that organic matter of oil shale is a kind of sapropel type kerogen. Vitrinite reflectance of kerogen range from 0.43% to 0.71% with an average of 0.52%, indicating that organic matter of oil shale underwent a stage of immature to low maturation. Abundant biomarkers, including n-alkanes, isoprenoid, terpanes and steranes from oil shale have been detected by GC and GC-MS. GC-MS characteristics of saturated hydrocarbon show that organic matter is characterized by aquatic phytoplankton. The characteristics of biomarkers and field observation reveal that oil shale forms in low-salinity anoxic semideep-deep lake environment. Phytoplankton and algae in the lake provide main origin of organic matters for oil shale formation, and stable structure and anoxic environment are beneficial for the conservation of organic matters.