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闽江口外海域MIS 5和MIS 3的地震地层学特征和古环境
刘阿成,张杰,唐建忠
0
(上海东海海洋工程勘察设计研究院, 上海 200137;国家海洋局东海海洋环境调查勘察中心, 上海 200137;国家海洋局东海信息中心, 上海 200136)
摘要:
通过闽江口外海域进行的高分辨率浅地震剖面(拖筏)调查,揭示了MIS 6末期以来最大厚度约90 m的沉积地层。研究了MIS 5和MIS 3地震层序的反射波结构特征,基于地震相分析识别沉积地貌类型;结合深海氧同位素海平面变化曲线,阐述了两时期研究区的沉积环境、特殊地貌的分布和体系域阶段;最后简要探讨了海侵视强度(视高度)及其影响因素。在MIS 5,研究区主要为滨浅海环境,在MIS 5.3和MIS 5.1局部发育了赛江水下三角洲、潮流沙脊和滨海沙坝等沉积地貌;在初期和低海面亚期为陆相环境,发育了闽江和赛江河道,分别经南部和东北部向东入海(台湾海峡)。在MIS 3,研究区普遍为海水覆盖,以滨浅海环境为主,局部发育闽江水下三角洲叶瓣和潮流沙脊。MIS 5的海平面远高于MIS 3,但是典型地震剖面的研究表明,前者的海侵视强度(视高度)低于后者,推断这一现象主要与构造沉降有关,沉积物压缩也有一定的影响,这也可以解释南部海区MIS 5.2的古闽江河道要远低于当时海平面的现象。
关键词:  海洋地质学  MIS 5  MIS 3  闽江口  地震地层学  古环境  台湾海峡西部
DOI:10.3969/J.ISSN.2095-4972.2022.01.014
基金项目:我国近海海洋综合调查与评价专项资助项目(908-01-QC20号)
Characteristics of seismic stratigraphy and paleoenvironment during MIS 5 and MIS 3 off the Minjiang Estuary, Southeast China
LIU A’cheng,ZHANG Jie,TANG Jianzhong
(Shanghai East Sea Marine Engineering Survey and Design Institute, Shanghai 200137, China; East Sea Marine Environment Survey and Prospect Center of State Oceanic Administration, Shanghai 200137, China; East Sea Information Center of State Oceanic Administration, Shanghai 200136, China)
Abstract:
Highresolution shallow seismic surveys using boomer were carried out off the Minjiang Estuary. Depositional sequences since the end of MIS 6 were revealed with the maximum thickness of about 90 m. The reflection configurations of seismic sequences of MIS 5 and MIS 3 were studied and types of depositional morphology were identified based on seismic facies analysis. Combined with sea-level curves (SLC) of Marine Oxygen Isotope, sedimentary environments, special morphology and stages of system tracts were described. Finally, apparent intensity (apparent height) of transgressions and its affective factors were discussed. During MIS 5, the area studied was mainly an offshore-shallow sea environment where a subaqueous delta of Saijiang River (Jiaoxi Stream), tidal sand ridges and offshore bars were locally developed in MIS 5.3 and MIS 5.1. It was the land environments at its beginning and low sea-level stages, resulting in channels of Minjiang River and Saijiang River. During M3, the area was generally submerged under sea and dominated by offshore-shallow sea environments, a subaqueous delta lobe of Minjiang River and tidal sand ridges were locally developed. According to SLC, sea-level during MIS 5 was much higher than that of MIS 3, but typical seismic profiles show that the transgressive apparent intensity (apparent height) of the former was lower than the latter. It is inferred that this phenomenon was mainly related to tectonic subsidence and sediment compression to a certain extent as well, which may also explain why Minjiang River channels during MIS 5.2 in the southern area appeared much lower than the sea level at that time.
Key words:  marine geology  MIS 5  MIS 3  Minjiang Estuary  seismic stratigraphy  paleoenvironment  western Taiwan Strait

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