Effects of igneous bodies on modification of modern slope morphology: Insights from the continental slope offshore Dongsha Islands, South China Sea
Effects of igneous bodies on modification of modern slope morphology: Insights from the continental slope offshore Dongsha Islands, South China Sea
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火成体对现代斜坡形态改造的影响：来自南海东沙群岛近海大陆坡的见解
DOI：
10.1007/s13131-019-1357-y
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发表时间：
2019
影响因子：
1.4
通讯作者：
Yanpu Zhao
中科院分区：
文献类型：
--
作者：
Chao Liang;Xinong Xie;Hua Wang;Guangjian Zhong;Entao Liu;Ming Sun;Hai Yi;Chunyu Qin;Haiyang Cao;Jie He;Yanpu Zhao
通过对大量地震剖面形态参数的统计分析，以及对水深约500 ~ 3100 m的东沙群岛东南陆坡的高分辨率地震研究，揭示了由于火成岩体的侵入和相关的沉积作用而导致的形态特征的变化。大陆坡分为三种类型：（1）有多个火成岩体的崎岖陡坡（第1类），（2）有单个火成岩体的相对平缓的斜坡（第2类），（3）没有火成岩体的平缓斜坡（第3类）。这些火成岩体形成于南海海底后扩张过程中，常具有高正地震振幅和形状复杂的混沌反射特征。第一类火成岩体将斜坡分隔成两个或两个以上的上部次凹和一个下部主凹，其中次凹和主凹可同时被沿斜坡底流搬运的沉积物充填。而第二类火成岩体只是将斜坡分隔为上次凹和下主凹，只有在上次凹被充填后，沉积物才能被输送到下主凹。第三类代表一个正常的斜坡，具有共同的斜坡变形。研究区的现代斜坡地貌是由于火成岩体的侵入和相关的沉积过程而引起的大陆坡调整的结果。三种现代斜坡形态的差异反映了不同的沉积条件和斜坡形态的调整。
A statistical analysis for the morphological parameters extracted from numerous seismic profiles, and a highresolution seismic study of the southeastern slope of the Dongsha Islands (South China Sea) with water depth between approximately 500 and 3 100 m, has revealed the variation of morphological features due to the intrusion of igneous bodies and associated sedimentary processes. Three types of the continental slope are distinguished: (1) a rough and steep slope with multiple igneous bodies (Type 1), (2) a relatively smooth and gentle slope with the single igneous body (Type 2), and (3) a smooth and gentle slope without igneous bodies (Type 3). These igneous bodies, formed in the post-seafloor spreading of the South China Sea, are often characterized by high positive seismic amplitudes, and chaotic reflections with complex shapes. The igneous bodies in Type 1 separated the slope into two or more upper sub-sags and a lower main-sag, in which the sub-sags and main-sag could be filled with sediments transported by alongslope bottom currents at the same time. Whereas, the igneous body in Type 2 just separated the slope into an upper sub-sag and a lower main-sag, in which the sediments could be transported into the lower main-sag only after the upper sub-sag has been filled up. Type 3 represents a normal slope with common clinoform progradation. The modern slope morphologies in the study area are the results of adjustments of the continental slope due to the intrusion of igneous bodies and associated sedimentary processes. The distinctions among three types of modern slope morphologies indicate different depositional conditions and adjustments of slope morphologies.