南海北部中—深层环流格局下海山-阶地-峡谷沉积效应

Depositional mode for the seamount-terrace-canyon sedimentary combination under the impacts of intermediate and deep circulation dynamics in the northern margin of the South China Sea

作为研究水-岩界面物质能量交换的天然实验室,南海北缘陆坡区具有复杂的地形地貌(如凸起海山、平坦阶地、下凹峡谷等),并发育不同类型的深水沉积体系(包括重力流滑移滑塌、浊流和底流沉积等)。基于高分辨率海底地形、地震反射资料,海水温盐深(CTD)观测资料,以及已发表的海洋沉积学及物理海洋数值模拟结果,本文针对南海北缘代表型陆坡区开展中—深层环流格局下海山-阶地-峡谷沉积效应分析。发现了尖峰陆坡区侵蚀型-海山型(环槽-丘状漂积体)和席状/无沉积型底流阶地的沉积组合,以及一统陆坡区海山相关底流沉积(环槽-丘状漂积体)-席状/无沉积型底流阶地-黏附型漂积体-陡坡滑塌/峡谷体系的沉积组合;揭示了这些典型深水沉积组合与南海中—深层环流动力格局的耦合关系。该成果对于深入了解深水沉积过程对中-深层动力格局的响应及其对于大陆边缘形态的塑造具有较好的启示意义。

As a natural laboratory for studying energy and material exchange at water-rock interfaces,the northern slope area of the South China Sea possesses complex geomorphology,such as uplifted seamounts,flat terraces,and depressed canyons.It also develops various types of deep-water depositional systems,including gravity flow slides/slumps,turbidity currents,and contouritic deposits.Based on high-resolution bathymetry and seismic reflection data,CTD data,as well as published results from marine sedimentology and physical oceanic numerical simulations,this study focuses on analyzing the seamount-terrace-canyon sedimentary combination under intermediate and deep circulation bottom currents on the South China Sea northern margins.This study identifies the seamount-related moat-drift systems,the erosional/sheeted-nondepositional/seamount related contourite terraces,the plastered drifts,as well as the steep slopes with slides/slumps and canyons.This research reveals the coupling relationship between these deep-water sedimentary combinations and the hydrodynamic patterns among the intermediate and deep circulations.The findings obtained have significant implications for further understanding of the response of deep-water depositional processes to intermediate and deep circulation hydrodynamics and their impact on shaping continental margin morphology.