塔里木盆地西部阿克彻依剖面晚白垩世介形虫生物地层

发布时间：2018-10-18 06:56

【摘要】：阿克彻依地区是塔里木盆地西部最早接受海侵的沉积区之一。前人对本剖面做过较多研究,获得良好基础,但对地层归属存有不同意见。阿克彻依剖面晚白垩世地层中含有丰富的海相介形类化石,本次工作在晚白垩世库克拜组地层中发现数量丰富的海相介形类化石。经鉴定共发现介形类化石11属17种。根据介形类化石的分布规律,建立了3个介形类组合带,自下而上为:Ovocytheridea bashibu lakeensis Ovocytheridea akedaoensis Cytherella cf.anteromarginata组合带、Ovocyt heridea Procytherura sp.1组合带和Ovocytheridea akedaoensis Pontocyprella proc eraformis Haplocytheridea sp.2组合带。本次工作在库克拜组下段新发现了具有时代意义的化石,据此深入研究,对前人地层学研究结果进行补充完善,进一步厘定了地质年代。通过与世界上其它地区相关层位介形类化石组合的对比,得出上述各组合的时代分别为Cenomanian晚期 Turonian早期、Turonian中期和Turonian晚期 Santonian晚期。由此分析库克拜组的地质时限为Cenomanian中期 Santonian晚期。在此基础上,结合其它门类生物地层(有孔虫、钙质超微化石、双壳类)及前人对本区晚白垩世地质时代的研究结果,确定阿克彻依剖面晚白垩世库克拜组的地质时限应为Cenomanian早中期 Santonian晚期(库克拜组下段的地质时限应为Cenomanian早中期;中段的地质时限应为Cenomanian晚期—Turonian早期;上段的地质时限应为Turonian中期 Santonian晚期)。乌依塔格组及依格孜牙组的地质时限应为Campanian期—Maastrichtian期。
[Abstract]:Akcheit area is one of the earliest transgressive sedimentary areas in the west of Tarim Basin. Previous researches on this section have obtained a good foundation, but there are different opinions on stratigraphic attribution. There are abundant marine ostracods in the late Cretaceous strata of the Akcheir section, and abundant marine ostracods were found in the late Cretaceous Kukkba formation. A total of 17 species belonging to 11 genera were identified. According to the distribution of ostracoda fossils, three ostracod assemblages have been established, from the bottom up to the: Ovocytheridea bashibu lakeensis Ovocytheridea akedaoensis Cytherella cf.anteromarginata assemblage, Ovocyt heridea Procytherura sp.1 and Ovocytheridea akedaoensis Pontocyprella proc eraformis Haplocytheridea sp.2 assemblages. In this work, new fossils of epochal significance have been discovered in the lower member of Kukba formation, based on which further studies have been carried out to supplement and perfect the results of previous stratigraphic studies and to further determine the geological age. Based on the comparison with the related stratigraphic ostracoda assemblages in other regions of the world, it is concluded that the ages of these assemblages are early Turonian in the late Cenomanian, late Santonian in the middle Turonian and late Santonian in the late Turonian. The geological time limit of the Kukba formation is the late stage of Santonian in the middle of Cenomanian. On this basis, combined with other biostratigraphy (foraminifera, calcareous ultrafossils, bivalves) and previous studies of the late Cretaceous geological age in this area, It is determined that the geological time limit of the late Cretaceous Kukkba formation in the Akcheir section should be the early and middle Cenomanian and the late Santonian, the geological time of the lower member of the Cookby formation should be the early and middle Cenomanian, the geological time of the middle segment should be the late Cenomanian to the early Turonian; The geological time limit of the upper member should be the middle period of Turonian and the late period of Santonian. The geological time limit of Wuytagge formation and Yigezi formation should be Campanian-Maastrichtian.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q915;P534.53

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