南黄海盆地中部第四纪地震层序与地层学

发布时间：2018-01-09 18:25

本文关键词：南黄海盆地中部第四纪地震层序与地层学　出处：《中国海洋大学》2014年博士论文　论文类型：学位论文

更多相关文章： 第四纪 地震地层学 大陆架 南黄海

【摘要】：黄海是一个半封闭的陆架浅海，内外营力共同作用使得其沉积物质中蕴藏着丰富的陆地、海洋及其相互作用的信息：长江和黄河两条大河以及其它中小河流带来了充沛的陆源物质供应，构造运动导致的盆地沉降为沉积体的发育提供了可观的可容空间，全球气候冷暖旋回导致了海平面频繁而剧烈波动以及复杂的海洋动力系统。因此黄海地区是为研究第四纪环境变化的良好靶区。本研究基于南黄海盆地中部高分辨率地震剖面数据，结合岩芯的年代地层划分，采用地震地层学、层序地层学、沉积地层学等多种方法，揭示南黄海盆地中部第四纪地层的时空发育规律，重建南黄海盆地中部与构造运动和海平面变化等因素相适应的第四纪沉积地层演化模式。本研究通过分析地震反射结构及其接触关系，共识别出14个主要的地震反射界面，并以此划分出13个主要的地震地层单元SU1~SU13。使用相关岩芯的年代数据对地震地层进行年代标定，由此确定了上述13个地震单元为1.95MaB.P.以来形成的。研究区内的第四纪地层呈现海陆交互沉积的特点，并且整体上继承了上新统的“南北厚中间薄”沉积分布格局。研究区内第四系（Q）的平均厚度为91.2m，其中，下更新统（Q1）平均厚度为11.8m，中更新统（Q2）平均厚度为38.1m，上更新统（Q3）平均厚度为34.9m，全新统（Q4）地层平均厚度为5.7m。海平面周期性升降是造成区域内地层海陆交互沉积模式的关键因素，由此造成的一系列不整合界面组成了南黄海盆地第四纪沉积地层的骨架。海平面升降的幅度和周期在一定的范围内影响了海相地层发育的规模：在900ka B.P.以前海平面高频低振幅波动时期，区域内发育了小规模的滨海及近海相沉积地层；在128ka B.P.以后海平面低频高振幅波动时期，发育大规模的浅海相沉积地层；而在900~128ka B.P.期间，海相地层发育则没有对应较高的海平面水平和较长的高海面持续时间，这种地层发育与海平面水平相背离的现象应该与构造运动有关。构造运动及其继承性的影响因素控制了晚更新世以前区域内地层在空间上的发育和分布模式。浙闽-岭南隆起带在晚更新世以前一直都是海水入侵黄海的主要障碍。南黄海中部隆起带在晚更新以前表现出了继承性的抬升作用，这种相对抬升于中更新世缓和并于晚更新世初终止，导致南黄海盆地中部地层晚更新世以前发育和分布呈现“南北厚中间薄”的模式，而晚更新世以后，地层的发育和分布已经不再受中部隆起带的束缚。河流物质是研究区沉积地层最主要的物质来源，河流输入的物质对研究区MIS1、MIS3和MIS5的海相沉积地层的贡献分别为65.9%、55.9%和69.0%，其中黄河是研究区所有入海河流中物质贡献最大者，另外海洋动力侵蚀、改造和再分配的海床物质也是研究区主要的物质来源。海洋动力是影响沉积物改造、搬运、沉积等环节的关键因素，，其作用在晚更新世以来的两次高海平面时期得以显现。研究区海相地层SU1~SU13沉积速率分别为54.6、46.8、30.2、6.6、9.2、3.5和5.1cm/ka，可见海相地层沉积速率自晚更新世起上升了一个数量级，这种现象不但与青藏高原隆升和MIS5e时期特殊的暖热导致的物源区侵蚀和河流输沙量激增有关，而且与稳定的高海面导致的海洋动力系统对物质的输送和分配能力增强有关。影响南黄海盆地中部沉积地层发育和演化的主要因素是海平面变化和构造运动，而河流物质供应和海洋动力环境等因素也起着重要的作用。控制地层发育和演化的主导因素在晚更新世伊始发生转变：晚更新世以前构造运动及其继承性的影响是控制和约束研究区地层发育的主导因素，而晚更新世以后海平面的波动、河流物质供应以及海洋动力环境的共同作用则成为主导的控制因素。
[Abstract]:The Yellow Sea is the 1.5 shelf closed, the joint action of internal and external force so that the deposited material is rich in land, sea and the interaction of information: the Yangtze River and the Yellow River river two rivers and other small rivers brought abundant terrigenous material supply, providing substantial accommodation to the subsidence of the basin is tectonic movement sedimentary development, global climate changes cycle caused ocean power system of sea level frequent fluctuations and complex. Therefore the Yellow Sea area is a good target for Quaternary environmental research changes. This research is based on the middle of the South Yellow Sea basin high-resolution seismic data, combined with the stratigraphic division of the core, using seismic stratigraphy, sequence stratigraphy. The sedimentary stratigraphy and other methods, reveals the middle Quaternary strata of South Yellow Sea basin development law, reconstruction of the South Yellow Sea Basin in the Department The Quaternary sedimentary stratigraphic evolution model adapted to the tectonic movement and the sea level change.
Through the analysis of the seismic reflection structure and contact relationship, identified 14 main seismic reflection interface, and the division of seismic stratigraphic age calibration data in 13 main seismic stratigraphic unit SU1~SU13. associated with the use of the core, so as to determine the 13 seismic units for 1.95MaB.P. since the formation of the characteristics of the study. Within the area of Quaternary strata showed paralic deposition, and inherited the Pliocene "north south middle thick thin sedimentary patterns. In the research area of Quaternary (Q) the average thickness is 91.2m, the lower Pleistocene (Q1) the average thickness is 11.8M, the Middle Pleistocene (Q2) average thickness for 38.1m, the upper Pleistocene (Q3) the average thickness is 34.9m, the average thickness of the Holocene (Q4) formation is 5.7m.
The sea level fluctuation is the key factors in regional strata paralic depositional model, resulting in a series of unconformity interface composed of Quaternary sedimentary strata in the South Yellow Sea basin skeleton. The period and amplitude of sea-level change affects the marine strata size in a certain range in 900ka B.P. before the sea level low frequency the amplitude of fluctuation period, regional development of the coastal and offshore small-scale sedimentary strata; in 128ka B.P. after the sea level low frequency and high amplitude fluctuation period, the development of large-scale shallow sea facies sedimentary strata; and during the 900~ 128ka B.P., the high sea marine strata does not correspond to a high sea level and longer duration. The formation and development of sea level phase deviation should be related to tectonic movement.
Influence of tectonic movement and inherited factors before control of the late Pleistocene stratum in the space of the regional development and distribution pattern. The Zhejiang Fujian south of the Five Ridges uplift in the late Pleistocene has been a main obstacle to seawater intrusion in the Yellow Sea. The central uplift of the uplift of the inheritance table in the late update before this relative uplift in Middle Pleistocene and late Pleistocene to early termination of relaxation, resulting in middle of the South Yellow Sea basin formation before late Pleistocene development and distribution show "north south middle thick thin" model, and the late Pleistocene, development and distribution of strata is no longer affected by the shackles of the central uplift belt.
The river is the main material sources of sedimentary strata in the study area, MIS1 river input material to the study area, marine sedimentary strata MIS3 and MIS5 contributions were 65.9%, 55.9% and 69%, of which the Yellow River is the study area all substances in rivers of the greatest contribution, the other offshore ocean power erosion, main source of material transformation the material is also on the seabed and redistribution area. Ocean power is the effects of sediment transport, transformation, key factors and other aspects of the role of deposition, to appear in the two high sea level period since late Pleistocene. The deposition rate of marine strata SU1~SU13 were 54.6,46.8,30.2,6.6,9.2,3.5 and 5.1cm/ka, the deposition rate of marine strata visible up a number of since late Pleistocene, this phenomenon not only with the Qinghai Tibet Plateau special rise and MIS5e period of warm heat causes provenance of erosion and sediment discharge The surge is related, and it is related to the enhancement of the transport and distribution of material to the marine power system resulting from a stable high sea level.
The main factors affecting the development and evolution of the Central South Yellow Sea basin sedimentary formation is the sea level change and tectonic movement, and river material supply and marine dynamic environment and other factors also play an important role. The main factor controlling the development and evolution of the late Pleistocene strata in the beginning of changes: Late Pleistocene tectonic movement and its influence before inheritance is the leading factors of strata control and constraint of the study area, and after the late Pleistocene sea-level fluctuations, river material supply and ocean dynamic environment interaction has become the dominant controlling factor.

【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P736.22;P539.1

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