渤海莱州湾第四纪晚期有孔虫特征及沉积环境演化

发布时间：2018-12-14 22:45

【摘要】：渤海莱州湾地区处于海陆交互作用的过渡带地区,是全球气候变化和区域地质作用的敏感地带,沉积物的沉积速度较快,可以将不断变化的海陆作用和气候变革等环境信息记载下来。论文以渤海莱州湾西南岸GK138孔、GK111孔、GK95孔、GK59孔GK74孔、GK79和GK89钻孔等7 口岩心样品为研究对象,分析各个钻孔有孔虫的组成及垂向分布特征,探讨有孔虫种类分布、共生组合特征及地质环境意义,结合测年资料和聚类结果对钻孔进行沉积单元划分和分析其沉积环境,并进一步讨论第四纪晚期以来的沉积环境演化。研究区7 口钻孔样品中总共鉴定出有孔虫16属35种,以原生底栖有孔虫为优势种,优势种主要有:Ammonia beccarii,Ammonia annectens,Ammonia takanabensis, Ammonia convexus, Ammonia sobrina, Elphidium limpidum ,Elphidium advenum, Elphidium excavatum, Astrononion italicum 等。通过钻孔的沉积单元分析揭示不同期次的海侵过程,发现每次海侵过程中海相地层的顶、底板高程和厚度存在不同程度的差异,其中GK138孔、GK111孔、GK95孔、GK59孔和GK79可以揭示出3套海相地层,GK74揭示出2套海相地层以及GK89揭示1套海相地层,通过地层对比发现三次海侵分别发育于中更新世末期、晚更新世和全新世期间。通过与全球海平面升降曲线相对比发现3套海相沉积地层从早到晚划分于MIS7、MIS5和MIS1期间的高海平面阶段。与渤海沿岸地域许多钻孔的交叉比较发现研究区海侵期间沉积地层分布较连续,因而具有很好的可对比性。不同海相地层顶、底地层的高度和厚度的差别揭示了区内发生过不同期次、不同强度的构造运动。
[Abstract]:The Laizhou Bay area of the Bohai Sea is located in the transitional zone of ocean-land interaction, which is sensitive to global climate change and regional geological processes. Environmental information such as changing land and sea processes and climate change can be documented. In this paper, seven core samples from GK138, GK111, GK95, GK59, GK79 and GK89 boreholes in the southwestern coast of Laizhou Bay, Bohai Sea, are studied. The foraminifera composition and vertical distribution of each borehole are analyzed, and the distribution of foraminifera species is discussed. The characteristics of symbiotic assemblage and the significance of geological environment, combined with the dating data and clustering results, are used to divide the sedimentary units and analyze the sedimentary environment of the boreholes, and the evolution of the sedimentary environment since the late Quaternary is further discussed. A total of 16 genera and 35 species of foraminifera were identified from 7 borehole samples in the study area, with primary benthic foraminifera as the dominant species. The dominant species were: Ammonia beccarii,Ammonia annectens,Ammonia takanabensis, Ammonia convexus, Ammonia sobrina, Elphidium limpidum, Elphidium advenum, Elphidium excavatum, Astrononion italicum et al. The sediment unit analysis of the borehole reveals the transgression process in different periods. It is found that there are differences in the elevation and thickness of the top, bottom plate of the marine strata during each transgression, including the GK138 hole, the GK111 hole, the GK95 hole. GK59 pore and GK79 reveal 3 sets of marine strata, GK74 reveal 2 sets of marine strata and GK89 reveal 1 set of marine strata. Through stratigraphic correlation, it is found that three transgressions developed in the late Middle Pleistocene, late Pleistocene and Holocene respectively. By comparing with the global sea level rise and fall curve, it is found that three sets of marine sedimentary strata are divided into high sea level stages during MIS7,MIS5 and MIS1 from early to late. The cross-comparison with many boreholes along the coast of the Bohai Sea shows that the distribution of sedimentary strata in the study area during transgression is relatively continuous, so it has a good contrast. The difference of the height and thickness of the top and bottom strata of different marine strata reveals that there have been tectonic movements of different periods and different strength in the area.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P534.63;P512.2

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