黄河三角洲浅地层扰动的空间差异及其主控机制

Spatial variations in the disturbances of shallow strata and the controlling factors in the Huanghe (Yellow) River delta

  • 摘要: 现代黄河水下三角洲是油气开采、海底管道铺设等基础设施建设的重要地区,随着黄河经历多次改道,不同河口海域的泥沙供应、海洋动力以及人类活动等条件发生显著变化,黄河三角洲不同河口地区沉积演化出现明显差异,其地层结构的变化备受工程人员及研究学者的关注。本文基于2023年浅地层剖面数据,以整个现代黄河三角洲及其分区(刁口-神仙沟河口、现行河口、清水沟河口)为研究对象,研究黄河三角洲浅地层扰动空间分布特征,对比3个河口区浅地层扰动的差异性,结合不同河口区的泥沙供应、海洋动力等资料,揭示地层扰动差异性的主控机制。研究结果表明:(1)从典型地层扰动区的基本特征来看,黄河三角洲地区的扰动地层的总体分布呈现出随水深的增加而逐渐减少的规律。不同河口区扰动地层差异显著,其中刁口-神仙沟河口的扰动地层主要表现为数量多、埋藏深度浅的特征;清水沟河口的扰动地层以聚集分布、埋藏浅、发育规模大等为特征;而现行河口海域扰动地层以埋藏深、数量少为主要特征;(2)黄河三角洲不同区域的地层结构受入海泥沙和海洋动力等因素的影响,具有明显的空间差异性。波浪的高底剪切应力分布与地层扰动高密度区分布高度一致,波致底剪切应力是影响3个河口区域以及不同水深地层结构差异的主要动力因素,而入海泥沙供应则导致不同河口区扰动地层埋深有所差异。

     

    Abstract: The modern subaqueous delta of the Huanghe (Yellow) River is an important area for oil and gas exploitation, submarine pipeline construction, offshore wind farming, and other infrastructure developments. The Huanhe River has undergone multiple shifts in its deltaic river course, resulting in significant variations in sediment supply, ocean dynamics, and human activities in different river mouth areas. Based on the data from subbottom profiler and multibeam echo-sounder in 2022 and 2023, we investigated the spatial distribution of shallow-strata disturbances in the delta and its subordinate areas (the Diaokou-Shenxiangou river mouth, the modern river mouth, and the Qingshuigou river mouth). Differences in disturbances among the three areas were examined. The main controlling factors of the disturbances were revealed by combining data on sediment supply and ocean dynamics in different river mouth areas. Results show that (1) the shallow-strata structure of the delta exhibits significant spatial variability. The number of disturbed strata in the delta decreased with increasing water depth. The disturbances in various river mouth areas differed from each other significantly. The Diaokou-Shenxiangou river mouth is characterized by numerous disturbances in shallow burial depth. The Qingshuigou river mouth is characterized by disturbances in clustered distribution, shallow burial, and large development scale. The modern river mouth are characterized by deep burial and less disturbance. (2) The shallow-strata structure of different areas of the delta was significantly influenced by factors such as sediment input and ocean dynamics, exhibiting distinct spatial differences. The field of high bottom-shear stress of waves is highly consistent with the distribution of high-density stratigraphic disturbance, indicating that wave-induced bottom shear stress was the main dynamic factor affecting the differences in stratigraphic structure in the three subordinate estuarine areas at different water depths.

     

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