邓成龙+巩恩普+姜宝玉+王旭
摘要：建立了榆社盆地的高分辨率磁性地层年代学框架，厘定了高庄动物群和麻则沟动物群的准确年代，建立了中国陆相上新统高庄阶和麻则沟阶的高分辨率磁性地层年代学框架。高庄动物群和高庄阶的时代为早上新世，麻则沟动物群和麻则沟阶的时代为晚上新世。目前已对临夏盆地牛家村、丫沟、杨家山、后山和郭泥沟剖面等五个含有重要化石层位的剖面以约20 cm间距采集了古地磁定向手标本样品。结合岩石地层学、磁性地层学和生物年代学的制约，确定了下沙沟动物群的年代为2.2-1.7 Ma；将上新统/更新统界线确定于下沙沟剖面的底部。此外，结合研究组近年来在泥河湾盆地的其他磁性地层学定年结果，建立了泥河湾盆地哺乳动物群的年代序列。建立了大理盆地三营组的高分辨率磁性地层年代学框架，揭示出大理盆地记录了C4n.1r负极性时到C2n正极性时之间的沉积，其中三营植物群产于上新世地层中，从而准确厘定了三营植物群的年代。课题组建立了昭通盆地的高分辨率磁性地层年代学框架，揭示出昭通盆地记录了C3Br负极性时到C2An.1n正极性时之间的沉积，其中昭通古猿化石及其伴生哺乳动物群产于C3An.1n正极性时早期，年代为6.1 Ma。 此外，对辽西建昌玲珑塔大西山剖面含化石沉积层中的3 个凝灰岩样品进行了详细的SIMS 锆石U-Pb 定年， 获得了160.7±1.7， 159.5±2.3 和158.9±1.7 Ma 的年龄结果。 通过对义县组各个沉积层展开精细的研究，确定各沉积层的古环境特征，并对热河生物群开展古生物学研究，命名Microraptor一新种。对辽西四合屯早白垩世古湖泊边缘区和深水区的各种岩相的分布范围和厚度变化趋势进行调查，分析了各种岩相和相组合在时间和空间的分布规律，恢复了湖泊形成、演化和消亡规律，探讨了各种岩相和相组合中化石埋葬的方式，从而寻找有利于化石特异埋藏的环境。对富含珍稀动植物化石的、辽西四合屯早白垩世古湖泊演化的第二和第三阶段的沉积物进行了高分辨率、微米级的沉积微相分析，从而划分了6个微相。 通过有机碳同位素、碳酸盐碳氧同位素等地球化学手段在我国由南至北三个沉积盆地的地层中确定PETM事件的存在，并通过四醚膜类脂物（GDGTs）组分重建古温度等信息，进而恢复PETM时期我国陆地气候的空间格局和环境特征。本课题选取了内蒙古岱海地区全新世以来的湖泊沉积物DH99a钻孔，进行了黑碳的提取和碳同位素（δ13C）分析。 在揭西县灰寨、河源黄村和浏阳澄潭江发现了三条出露完整、化石丰富的新剖面。对这三条剖面以及宜章心田门剖面进行了详细的研究，初步建立了南岭地区晚三叠世-早侏罗世的岩石地层和生物地层的层序。
关键词：高分辨率磁性地层学；陆地生物群；古环境；古湖泊；古新世-始新世极热事件；沉积盆地
Chronology and sedimentary environment of terrestrial biota during the Mesozoic and Cenozoic
Abstract：High-resolution magnetostratigraphic investigations were conducted on a series of sedimentary basins and associated mammalian faunas. Results show that： The age of the sedimentary sequence in the Yushe Basin can be constrained to an interval from late Miocene to early Pleistocene. The Gaozhuang Fauna and the Mazegou Fauna have ages of Early Pliocene and Late Pliocene， respectively. The sedimentary profile in the Dali Basin spans from Chron C4n.1r to Chron C2n. The age can be constrained to an interval from late Miocene to early Pleistocene. The sedimentary profile in the Zhaotong Basin spans from Chron C3Br to Chron C2An.1n. The age of the sedimentary sequence in the basin can thus be constrained to an interval from late Miocene to late Pliocene. The hominoid fossil in the Zhaotong Basin has an age of ～6.1 Ma， the terminal Miocene. The Nihewan faunas can be placed between the Gauss–Matuyama geomagnetic reversal and the Matuyama–Brunhes geomagnetic reversal （2.58-0.78 Ma）， leading to a time range of ca. 2.6-0.8 Ma for the Nihewan mammalian faunas. The Pliocene–Pleistocene boundary is located in the lower part of the Xiashagou section. High-resolution paleomagnetic sampling has been conducted in the Linxia Basin， yielding more than 5000 samples at intervals of ～20 cm. The SIMS U-Pb zircon analyses of zircons derived from three tuff layers in Daxishan section in Linglongta yield （160.7±1.7）， （159.5±2.3） and （158.9±1.7） Ma， indicating that they were formed at early Late Jurassic. Sedimentary properties of the fossil-bearing deposits of Lake Sihetun （Yixian Formation， Lower Cretaceous） were investigated on a high-resolution， submillimetric scale. Lake evolution is subdivided into four phases， of which Phases 2 and 3 provided suitable conditions for excellent fossil preservation. Six microfacies are recognized within these two phases. Detailed geochemical analyses were carried out on three basin sequences along a north-south transect demonstrate the presence of the PETM. Carbon isotope ratio of black carbon was measured on the Daihai Lake sediment core with an objective to examine the effectiveness and sensitivity of the δ13C values of black carbon as a potential indicator of terrestrial environmental changes. Three well outcropped Mesozoic profiles rich in faunas at Huizhai， Huangcun and Chengtan were found. Lithostratigraphic and biostratigraphic sequences were established.
Keywords：High-resolution magnetic stratigraphy； terrestrial biota； paleoenvironments； paleolake； Paleocene-Eocene Thermal Maximum （PETM）； sedimentary basin
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