【作者】 屈海英；

【导师】 万晓樵；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2014， 博士

【摘要】 松辽盆地是白垩纪亚洲古陆上面积最大的陆相淡水湖盆之一。盆地上部沉积岩系主要由碎屑岩组成，沉积物内包含了大量腹足类、双壳类、介形类、轮藻和孢粉等化石。通过对这些化石的研究，为我们还原晚白垩世温室效应在陆相的响应提供了可靠的保障。松科1井是世界上第一口陆相白垩纪科学钻井，其北孔获取了自嫩一段顶部至明水组的连续地层记录。本文以松科1井（北孔）岩心样品介形类化石的系统鉴定和统计分析为基础，共建立了5个介形类化石组合，自下而上分别为：（1）Cypridea gunsulinensis-Mongolocypris magna组合；（2） Cypridea liaukhenensis-Ilyocyprimorpha-Limnocypridea sunliaonensis-Periacanthella组合；（3）Strumosia inandita组合；（4） Talicypridea amoena-Metacypris kaitunensis-Ziziphocypris simakovi组合；（5） Ilyocypris组合，其中前4个介形类组合的时代大致为晚白垩世中期（Santonian）至晚白垩世晚期（Maastrichtian），而在明水组顶部发现的介形类Ilyocypris属在松辽盆地明水组中首次发现，其与轮藻化石Neochara和Grovesicahra属共生，它们均为古近纪繁盛的属，与大量晚白垩世的介形类特征分子和少量轮藻的孑遗分子共生，因此我们认为Ilyocypris bisculatasp. nov.的出现可能为古近纪开始的标志，但是在第5组合内共生有大量的晚白垩世的介形类化石，因此我们认为第5化石组合具有白垩纪-古近纪过渡色彩。根据介形虫碳氧同位素相关性的分析，我们得出：在四方台组和明水组沉积时期，松辽盆地整体上属于开放性湖盆，湖水可以外流；从四方台组到明水组二段中上部，碳氧同位素变化范围较小，基本维持在2‰左右，从下而上呈逐渐增大的趋势；到了明水组二段顶部335m附近，碳氧同位素同时出现较大负偏，与Ilyocypris出现层位相当，碳氧同位素组份在这一层位的变化及Ilyocypris的出现可能与K/Pg界线时期的环境演化有关。更多还原

【Abstract】 The Cretaceous biostratigraphy of the Songliao basin in Northeast China has beenwell suited for the petroleum investigation. Widespread deposits in the upper part ofthe basin are mainly composed of clastic sediments which contain abundant fossilsincluding gastropods, bivalves, ostracods, charophytes, spone and pollen amongothers. These well preserved fossils provide us valuable informations about pastclimate changes and biotic responses in a greenhouse environment. However, despitemuch research having been conducted in the basin, the Late Cretaceousbiostratigraphy and palaeoenvironment are still less understood. Here, we are trying toestablish a high-resolution biostratigraphy of the Late Cretaceous based on ostracodsfrom borehole SK1(n) in the Songliao basin, Northeast China. As part of the presentstudy,45species assigned to20genera have been recovered, with one new species(Ilyocypris bisulcata sp. nov.) and5ostracod assemblages: the Cyprideagunsulinensis-Mongolocypris magna assemblage; the Ilyocyprimorpha-Limnocypridea sunliaonensis-Periacanthella assemblage; the Strumosia inanditaassemblage; the Talicypridea amoena-Metacypris kaitunensis-Ziziphocyprissimakovi assemblage; and the Ilyocypris assemblage. Moreover, the zonal fossilIlyocypris bisulcata sp. nov. of Zone5is here described for the first time from theupper Mingshui Formation, and Paleocene charophyte genera including Neochara andGrovesicahra have been found to coexist with the Zone5fauna. The first appearanceof Ilyocypris bisulcata sp. nov. possibly marks the K/Pg boundary. The IlyocyprisAssemblage coexisting with Late Cretaceous elements, and therefore it is assigned tothe transition biota from latest Maastrichtian to the earliest Paleocene.Base on study of the oxygen and carbon isotopes, we suggest that the songliaoBasin was a relatively open lake during the deposition of Sifangtai and Mingshuiformations, and the values of oxygen and carbon gradually increased about2‰fromthe Sifangtai to the Mingshui Formation. Suddenly, the values delined around thedepth of335m where the Ilyocypris genus appeared, which might be correlated with the K/Pg boundary and caused by the environmental changes during the time.更多还原