苏州地区更新世以来地层对比及古地理环境分析

发布时间：2018-03-05 12:02

本文选题：地层对比　切入点：古地理　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：苏州地区地处苏南-沪西的中心地带,位于太湖和长江三角洲南翼后缘之间,占据有重要的地理位置;在地质构造方面,本区位于我国东部大构造单元—下扬子准地台区下扬子断块内,南与浙西地块相接,苏州地区第四系埋深大致为150m-200m。通过前人的研究大致了解到整个长江三角洲地区的地层格架的特点,苏州地区从属于长江三角洲的地层格架,因此本区地层厚度分布特点是:全新统到更新统上部整个地区地层厚度无明显变化,更新统中部到更新统下部底界地层东厚西薄。除此之外,在苏州地区发现70%的钻孔分布有埋藏在不同深度的硬质粘土,前人已验证浅层硬粘土可作为划分全新统与更新统上部的分界线,对于深层硬粘土是否可作为地层划分的标志尚未见报道,是本文讨论的问题之一。本论文主要参考苏州地区23个钻孔及标准孔的代表性年代地层数据,借助控制性钻孔BK1、BK2孢粉图谱推测某一深度范围内孢粉曲线预测的古气候,结合苏州地区岩性地层划分方案,收集了包括常州、上海在内的10个代表性钻孔对苏南——沪西地区的第四纪地层格架进行划分,得出跨区地层格架东厚西薄的特点,修改并验证了前人的部分地层划分结构:参考苏州联合钻孔、SK03孔及长三角整体地层划分对比图将西部钻孔BK2、东部钻孔BK1的更新统上、中、部的界线统一下移3-8m,底界与前人划定方法一致,同时也证明了苏州地区的过渡性特点及地层格架划分的合理性。此外,根据浅层硬质粘土的研究方法参考控制性钻孔测年数据借助孢粉曲线探讨深层硬质粘土作为更新世上部与中部、中部与下部标志层的可能性与可靠性,通过研究发现,分布在3m左右的黄褐色硬质粘土、90m左右的蓝灰色硬质粘土及120m左右的灰绿色硬质粘土可以作为全新世与更新世,更新世上部与中部及中部与下部的分界线。划分本区地层可适当的参考硬质粘土的埋藏位置。最终通过硬质粘土的研究论证本区地层格架划分的合理性。
[Abstract]:Suzhou is located in the center of Sunan-West Shanghai, between Taihu Lake and the rear edge of the southern wing of the Yangtze River Delta, occupying an important geographical position. This area is located in the lower Yangtze fault block of the lower Yangtze quasi platform area, which is a large tectonic unit in the east of China, and is connected with the western Zhejiang block in the south. The burial depth of Quaternary system in Suzhou area is approximately 150m-200m.The characteristics of stratigraphic framework in the whole Yangtze River Delta region are roughly understood by previous studies, and the Suzhou area is subordinate to the stratigraphic framework of the Yangtze River Delta region. Therefore, the characteristics of stratigraphic thickness distribution in this area are as follows: there is no obvious change in the stratigraphic thickness of the whole area from the Holocene to the upper part of the Pleistocene, and the strata from the central part of the Pleistocene to the lower bottom of the Pleistocene are. In Suzhou, 70% of the boreholes were found to have hard clay buried at different depths. It has been proved that the shallow hard clay can be used as the dividing line between the upper part of the Holocene and the Pleistocene. Whether deep hard clay can be used as a sign of stratigraphic division is one of the problems discussed in this paper. This paper mainly refers to the representative chronostratigraphic data of 23 boreholes and standard holes in Suzhou area. The paleoclimate predicted by the sporopollen curve in a certain depth range was estimated by the sporopollen map of BK1 and BK2, and the paleoclimate, including Changzhou, was collected in combination with the lithostratigraphic classification scheme in Suzhou area. Ten representative boreholes in Shanghai have divided the Quaternary stratigraphic framework from southern Jiangsu to western Shanghai, and obtained the characteristics of the cross-area stratigraphic framework, which is thick, thick and thin in the east and west. Modification and verification of some stratigraphic division structure of predecessors: referring to Suzhou combined drilling hole SK03 hole and the whole stratigraphic division and correlation map of Yangtze River Delta, the upper and middle Pleistocene series of BK1 in the western borehole BK2 and the eastern borehole, The boundary line of the part is uniformly shifted from 3 to 8 m, and the bottom boundary is consistent with the previous methods. It also proves the transitional characteristics of Suzhou area and the rationality of stratigraphic framework division. According to the research method of shallow hard clay, the possibility and reliability of deep hard clay as the renewal of the world part and the middle part and the middle part and the lower part of the earth are discussed with the aid of sporopollen curve according to the controlled borehole dating data. The yellow-brown hard clay about 90m and the gray-green hard clay about 120m can be used as Holocene and Pleistocene. The dividing line between the middle part of the world and the middle part and the middle part and the lower part is renewed. The stratigraphic division of this area can refer to the buried location of hard clay appropriately. Finally, the rationality of stratigraphic framework division in this area is proved through the study of hard clay.
【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】：P534.631

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