西藏南部江孜地区床得组大洋红层有孔虫生物地层

发布时间：2018-04-01 09:40

本文选题：西藏南部　切入点：江孜　出处：《中国地质大学(北京)》2015年硕士论文

【摘要】：白垩纪海相地层在我国出露较少,仅见于西藏、新疆及台湾等地区,其中在西藏南部地区保存完整并有良好露头可供研究,因而该地区成为众多地质学家们探究白垩纪海相地层的理想场所。白垩纪大洋红层(Cretaceous oceanic red beds)通常被认为是深水环境中的沉积物被氧化后在原地堆积的产物。大洋红层沉积的出现代表当时的海洋具有氧化能力,使海洋中的有机碳发生氧化反应,产生大量CO2,从而影响全球的碳循环以及气候环境。对大洋红层进行研究可进一步探讨红层沉积时期古海洋和古地理的环境变化,探究环境变化机制,对未来气候和环境的变化具有指示意义。江孜地区的大洋红层沉积指示该地区在白垩纪时期总体上处于一种水体相对较深的大陆斜坡-大洋盆地沉积环境。大洋红层中常见的微体化石主要包含有孔虫、放射虫以及少量的介形虫,通过研究这些微体化石,可以厘定地层时代,为重建古地理、古环境以及探究古气候提供重要的科学依据。本文针对大洋红层保存良好的江孜床得西剖面,对其开展浮游有孔虫生物地层学的研究,通过鉴定浮游有孔虫属种,进行化石带的划分,从而推断大洋红层地层的时代。论文针对江孜床得西白垩纪地层(主要是床得组)剖面中所含的浮游有孔虫化石进行系统的研究和鉴定,最终结果为10属37种,根据有孔虫的组合特征划分出3个浮游有孔虫化石带:①Globotruncana ventricosa带,②Radotruncana calcarata带,③Globotruncanella havanensis带。鉴于床得西剖面中浮游有孔虫组合的特征,将该剖面的时代厘定为坎潘期-马斯特里赫特期。其中,红层沉积为剖面一段,时间被定为早坎潘晚期-早马斯特里赫特期,总体上属于坎潘期。
[Abstract]:The Cretaceous marine strata in China outcrops, found only in Tibet, Xinjiang and Taiwan and other regions, including in the southern region of Tibet to preserve the integrity and good outcrop for study, so this area is an ideal place for many geologists study the Cretaceous marine strata of Cretaceous oceanic red beds. Ji (Cretaceous oceanic red beds) is usually that is a product of sediment in deep water is oxidized in situ accumulation. CORBs deposition time on behalf of ocean with oxidation, the organic carbon in the ocean oxidation reaction occurs to produce large quantity of CO2, thus affecting the global carbon cycle and climate. The oceanic red beds were studied for further research changes of paleo ocean and paleogeographic environment during the deposition of the red layer, to explore the mechanisms of environmental changes, is the indication of future climate and environmental changes in Jiangzi ocean red. The indicator layer deposition area in the Cretaceous period, generally in a relatively deep water continental slope - ocean basin sedimentary environment. Fossils of common oceanic red beds mainly contains foraminifera, radiolaria and a small amount of ostracods, by studying these microfossils, to determine stratigraphic age, for the reconstruction of ancient geography, ancient environment and to explore the ancient climate provide an important scientific basis. This paper Jiangzi bed oceanic red beds is well preserved in the west section, the planktonic foraminiferal biostratigraphy research, through the identification of planktonic foraminiferal species, divide the fossil zone, thus infer oceanic red layer. According to the Jiangzi times to the west of the Cretaceous strata (bed the bed is mainly to study group) and identification system contained in the profile of planktonic foraminiferal fossils, the final result is 10 genera and 37 species, according to the foraminiferal assemblages Divided into 3 planktonic foraminiferal zones: Globotruncana ventricosa belt, the Radotruncana calcarata band, Globotruncanella havanensis band. In view of the characteristics of planktonic foraminifera in the West combined bed profile, the profile of the age for the Campanian Maastricht period. Among them, for a red layer deposition profile, time is late Early Campanian early Maastricht period, generally belong to the Campanian.

【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】：2015
【分类号】：Q915

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