闽江口外海域全新统地震地层学特征和沉积作用  

Characteristics of seismic stratigraphy and sedimentation of the Holocene off the Minjiang River Estuary,Southeast China

作　　者：刘阿成 张杰[1,2] 唐建忠 Liu Acheng;Zhang Jie;Tang Jianzhong(Shanghai East Sea Marine Engineering Survey and Design Institute,Shanghai 200137,China;East Sea Marine Environment Survey and Prospect Center,State Oceanic Administration,Shanghai 200137,China;East Sea Information Center,State Oceanic Administration,Shanghai 200136,China)

机构地区：[1]上海东海海洋工程勘察设计研究院,上海200137 [2]国家海洋局东海海洋环境调查勘察中心,上海200137 [3]国家海洋局东海信息中心,上海200136

出　　处：《海洋学报》2020年第11期49-61,共13页

基　　金：我国近海浅地层剖面和侧扫声纳调查研究项目(908-01-QC20)。

摘　　要：本文采用高分辨率单道浅地震剖面资料研究闽江口外海域的全新统沉积作用。研究区的全新统底面为MIS 2期侵蚀面,局部为古河道,深度一般在现海面下约30~60 m,最深约65 m;近岸浅,外海深,局部受古河道的下切影响呈条带状负地形。全新统由早全新世晚期以来的海相沉积层(U1)和早全新世河流湖沼相沉积层(U2)组成,前者包括滨浅海平行地震相和河口滨岸前积地震相,根据其反射波向陆上超和向海下超底界面,结合沉积物厚度分布特征,可以判断主要的沉积物来源和运移趋势。全新统沉积层厚度一般为10~20 m,最厚约38 m,位于古河道区,但是在马祖列岛和白犬列岛之间海区缺失。海相全新统沉积层的厚度为数米至20 m,最厚约25 m,位于研究区东南部(海坛岛东侧)。自全新世海侵以来,沉积物主要来源于3部分:台湾海峡来沙为研究区南部海区提供了沉积物;闽江悬沙扩散沉积物覆盖研究区北部海区,主要沿NE方向至外海,在河口向南呈舌状,现代沉积中心位于河口北部,厚度大于15 m;浙闽沿岸流来沙对研究区东北部海区的沉积物有影响。沉积环境划分为台湾海峡源沉积区、闽江源沉积区、东北部混合沉积区和马祖-白犬沉积缺失区,平均沉积速率分别约为0.8 mm/a、1.0 mm/a、1.1 mm/a和0 mm/a。马祖-白犬沉积缺失区主要因为沉积物受沿岛环流的控制。High-resolution single channel shallow-seismic profiles were used to analyze the Holocene sedimentation off the Minjiang River Estuary. The base surface of the Holocene is an erosional surface of MIS 2, locally paleo-river channels. Its depth is usually between 30 m and 60 m with the maximum of 65 m below present sea level.Generally, the surface is shallower near the shore and deeper toward the open sea, locally showing strips of negative topography due to paleo-river channels. The Holocene consists of marine depositional unit(U1) formed after late Early Holocene and fluvial-lacustrine-swamp depositional unit(U2) of early Holocene. The former unit is in turn composed of offshore-shallow sea parallel seismic facies and estuary-inshore clinoform seismic facies. Their landward onlap and seaward downlap against base surfaces are indicative, combined with distribution characteristics of sediment thickness, of major sediment sources and their transport tendency. The thickness of the all Holocene sediment is usually between 10 m and 20 m, with the maximum of 38 m in paleo-river channel areas, but absent in the area between Mazu Archipalegos and Baiquan Archipalegos. The marine Holocene is a few meters to 20 m, with the maximum of some 25 m in the southeastern area(east of the Haitan Island). Since the Holocene transgressive, there were three main sediment sources. Sediments from the Taiwan Strait in south covered the southern part of the study area. Minjiang River-delivered suspended sediments deposited in the northern area, mainly toward NE to the open sea with a southerly tongue-branch near the mouth. Its modern depocenter located in the northern estuary, indicated by a thickness of more than 15 m of mud. The northeastern part of the area was affected by suspended sediments from Zhejiang-Fujian Costal Current. Four sedimentary zones are distinguished. They are sedimentary zone of Taiwan Strait source, sedimentary zone of Minjiang River source, northeastern mixture zone and nonsedimentation zone between Mazu Archipaleg

关 键 词：地震地层学 沉积作用 全新统 闽江口外 台湾海峡 

分 类 号：P539.1[天文地球—古生物学与地层学]