【作者】 李顺；

【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， 2011， 硕士

【摘要】 “中国白垩纪大陆科学钻探-松科1井”是世界上第一口以陆相白垩纪地层为主的科学探井,聚焦我国东北松辽盆地。本论文即是基于其获取的连续、高分辨率的岩心资料,进行的介形类生物地层与古生态特征研究。本次研究通过对松科1井南孔1300余件岩心样品的处理挑选、超过10000枚化石的系统分析与鉴定,共识别出介形虫13属、80余种,根据化石分布组合及垂向上的变化特征,划分为15个化石组合带,建立松科1井南孔精细的介形类生物地层格架,并深入开展与前人化石带组合划分方案的对比研究。利用其良好的藻类和孢粉化石的资料,开展松科1井南孔不同微体化石门类间生物地层的对比研究。本文细致开展了松科1井南孔介形类古生态特征研究(统计化石丰度、简单分异度、双瓣壳/单瓣壳比值,计算复合分异度,描述化石保存特征,统计具瘤具刺类型和主要属分布等),系统分析和讨论松辽盆地晚白垩世早期湖泊水深、水动力条件、水体含氧量、水体盐度及古气候的演化。泉头组沉积期炎热半干旱气候条件下的曲流河或浅湖环境,水动力较强,水体富氧,盐度较低;青山口期湖泊大致经历:水体缺氧、半咸水的深湖环境→水体贫氧、微咸水的半深湖环境→含氧中等、盐度较低的浅湖环境的变化;水动力由弱渐强;古气候经历:温暖湿润→炎热干旱的变化。姚家期为温暖-炎热半干旱气候条件下的浅湖环境,水动力较强,水体含氧量较高,盐度较低。嫩江组一、二段沉积期为深湖-半深湖环境,水体缺氧,盐度较高,水动力低,古气候经历:温暖湿润→炎热半干旱的变化。尝试性地开展以介形类分异度为指标恢复古湖平面变化的研究。以松科1井南孔介形类复合分异度变化为基础,综合介形类新生种、绝灭种和简单分异度变化,半定量的恢复松辽盆地晚白垩世早期古湖平面的变化。推断其在青山口组二段中部和嫩江组一段上部至嫩江组二段沉积期呈现较高湖平面,较高的湖平面可能与较高的海平面存在直接的关系;由于松科1井相应层位化石保存较差的特征,认为本次研究中对青一段和嫩一段下部沉积期湖平面高度可能存在低估;而在泉头组、姚家组沉积期湖平面处于较低。更多还原

【Abstract】 “China Cretaceous Continental Scientific Drilling Project: SK-Ⅰ”(CCSD- SK-Ⅰ) which prompted by the concern among Chinese scientists over“Major Geological Events and Greenhouse Climate Change in the Cretaceous Earth Surface System”was the first scientific drilling of continental cretaceous strata all the world, and attracted all the global palaeontology and paleoenvironment scientists to focus on Songliao Basin, Northeast China. Basis on the 944.23m continuous, high-resolution drilling core, we study the biostratigraphy and palaeoecological characteristics of fossil ostracod from the south borehole.Basis on a detailed study of ostracod specimens, more than 80 species of 13 genera have been identified, and 15 fossil assemblages have been established, detailed ostracod biostratigraphic framework for CCSD-SK-Ⅰ(south) borehole has been established, and ostracod biostratigraphic correlations from Quantou Formation to Nenjiang Formation of Songliao Basin are discussed. Biostratigraphic relationships between ostracod, dinoflagellates and sporopollen has also been discussed.This paper carried out detailed study of palaeoecological characteristics of ostracod from the south borehole, including statistics fossil abundance, simple diversity, double valve shell/univalve shell ratio, complex diversity, describe characteristics of the fossil preservation, etc.). Basis on those detailed palaeoecological characteristics information, system analysis and discussion of palaeoenvironment (including water depth, salinity, hydrodynamic conditions, oxygen content, etc.) and palaeoclimate evolution in Songliao Basin has been taken.The available data of ostracod rangs for the Quantou Formation to Nenjiang Formation of Songliao Basin were examined and combined with new data from CCSD-SK-Ⅰ(south) borehole. A cumulative species diversity curve is presented for the ostracod of the Late Cretaceous of Songliao Basin. We consider that low diversity associated with a deeper water environment, high diversity corresponding with a lake-regressive trough on a long-term regressive. Basis on those data and curve, a model for lacustrine level change of Songliao Basin in early Late Cretadeous has been proposed.更多还原