南海北部不同背景下深水斜坡沉积体系特征及其演化模式
发布时间：2019-01-29 06:02
【摘要】：深水斜坡沉积是深水沉积理论的主要组成部分之一,开展深水斜坡沉积研究工作具有重要的科学理论意义和实际应用价值。本文利用地震沉积学的方法对南海北部深水斜坡沉积体系进行了系统的研究和分析。首先,根据深水斜坡不同的物源供给背景将深水斜坡划分为陆架斜坡、台缘斜坡和火山斜坡。其次,根据深水斜坡与其它地貌单元的空间分布关系,将其进一步划分为不同的阶次。最后,分别对不同背景下的深水斜坡体系沉积特征和演化模式分别进行了系统的研究。结果表明,陆架斜坡具有多阶次性,表现为阶梯式沉积物输送模式。一阶陆架斜坡之上发育峡谷群体系和蠕变皱痕群体系,二阶陆架斜坡主要发育单条大型海底峡谷体系。不同阶次的斜坡侵蚀性表现出相似的先变强后变弱的特点,导致沉积物在不同阶次斜坡上部以沉积物过路为主,下部以沉积为主。上一阶次斜坡的下部沉积物聚集区是下一阶次斜坡沉积物的主要供给区,这是一种典型的阶梯式搬运过程。陆架斜坡的多阶次性与阶梯式沉积模式是由构造基底格局和沉积物输入共同决定的,并受到海平面变化的影响。陆架斜坡的阶梯式沉积模式首次揭示了陆架斜坡沉积过程的宏观分布规律,不仅具有重要的科学意义,而且对深水油气勘探和海底工程建设具有重要的指导意义。本文揭示了碳酸盐台地台缘沉积过程和斜坡沉积体系沉积模式。台缘存在四种混合沉积机制,即原位混合、间断混合、相缘混合以及与火山活动相关的混合。在流花碳酸盐台地台缘斜坡发育大型水道体系,水道充填沉积以灰岩和泥岩组成的交互层为主,表现出间断混合沉积的特征。进一步研究表明水道混合沉积旋回受控于海平面变化,水道碳酸盐岩充填发生在台地生产力较高的高位期。西沙海域现代岛礁碳酸盐台地台缘斜坡发育由“冲沟群-滑坡凹槽-(等深流)水道-大型峡谷”组成的沉积物输送网体系,将浅水岛礁碳酸盐台地与深海盆地连接起来。该输送体系是台缘源汇过程中最为核心的输送路径,其揭示了台缘斜坡存在复杂的由碳酸盐岩碎屑组成的面状浊流、块体流、底流及其线状浊流等沉积物输送方式。台前斜坡沉积物输送过程揭示了岛礁台前蕴含着频发的沉积地质灾害,这对于岛礁建设决策具有一定的理论参考价值。此外,通过分析火山周缘层序地层,揭示了火山周缘斜坡沉积过程异于正常盆地沉积,主要原因是火山活动改变了原有的源汇体系、可容纳空间以及水动力环境。根据岩石学特征和地震相分析,建立了火山周缘沉积演化模式,对火山周缘沉积历史划分为前火山丘阶段、同火山喷发阶段、间火山喷发阶段、后火山丘阶段等演化阶段。该研究还揭示了火山作用大大改变了原有的盆地充填过程,这对盆地演化以及油气成藏具有重要的影响。火山丘及其周缘斜坡层序演化模式具有重要的沉积学意义和实际应用价值。
[Abstract]:The deep-water slope deposition is one of the main components of the deep-water sedimentary theory, and it is of great theoretical and practical value to carry out the research of deep-water slope deposition. This paper studies and analyzes the deep-water slope deposition system in the north of the South China Sea by means of the method of seismic sedimentology. First, the deep-water slope is divided into a shelf slope, a stage edge slope, and a volcanic slope according to the different source supply background of the deep water slope. Secondly, according to the spatial distribution of the deep-water slope and other geomorphic units, it is further divided into different order times. Finally, the sedimentary characteristics and the evolution model of the deep-water slope system under different background are studied respectively. The results show that the slope of the continental shelf is of multi-order and is represented as a step-type sediment transport mode. The system of the canyon group and the creep-creping group system are developed on the slope of a step-order continental shelf, and the second-order shelf slope mainly develops a single large-scale submarine canyon system. The slope erosion of different order times shows the characteristics of similar first and weak first, leading to the sediment passing mainly at the upper part of the lower slope of the different order, and the lower part is dominated by the deposition. The lower sediment accumulation region of the next-order secondary slope is the main supply area of the next-order secondary-slope sediment, which is a typical step-by-step process. The multi-order and step-step sedimentary mode of the shelf slope is determined by the structure base pattern and the sediment input, and is affected by the sea level change. The step-step sedimentary model of the shelf slope is the first time to reveal the macro-distribution of the sedimentary process of the continental shelf, which not only has important scientific significance, but also has important guiding significance to the deep-water oil and gas exploration and the submarine engineering construction. The deposition process of the carbonate platform and the deposition mode of the slope deposition system are described in this paper. There are four mixed deposition mechanisms at the edge of the stage, namely, in-situ mixing, intermittent mixing, phase-edge mixing, and mixing associated with volcanic activity. A large-scale water channel system is developed on the slope of the platform edge of the flow-flower-carbonate platform, and the filling and deposition of the water channel is dominated by the interaction layer composed of the limestone and the mudstone, and the characteristics of the discontinuous mixed deposition are shown. Further research shows that the mixed sedimentary cycle of the water channel is controlled by the sea level change, and the carbonate filling of the water channel takes place in the high-order period with high platform productivity. The sediment transport network system, which is composed of the 鈥済ully group-landslide groove-(deep-flow) water channel-large-scale canyon鈥，
本文编号：2417717
[Abstract]:The deep-water slope deposition is one of the main components of the deep-water sedimentary theory, and it is of great theoretical and practical value to carry out the research of deep-water slope deposition. This paper studies and analyzes the deep-water slope deposition system in the north of the South China Sea by means of the method of seismic sedimentology. First, the deep-water slope is divided into a shelf slope, a stage edge slope, and a volcanic slope according to the different source supply background of the deep water slope. Secondly, according to the spatial distribution of the deep-water slope and other geomorphic units, it is further divided into different order times. Finally, the sedimentary characteristics and the evolution model of the deep-water slope system under different background are studied respectively. The results show that the slope of the continental shelf is of multi-order and is represented as a step-type sediment transport mode. The system of the canyon group and the creep-creping group system are developed on the slope of a step-order continental shelf, and the second-order shelf slope mainly develops a single large-scale submarine canyon system. The slope erosion of different order times shows the characteristics of similar first and weak first, leading to the sediment passing mainly at the upper part of the lower slope of the different order, and the lower part is dominated by the deposition. The lower sediment accumulation region of the next-order secondary slope is the main supply area of the next-order secondary-slope sediment, which is a typical step-by-step process. The multi-order and step-step sedimentary mode of the shelf slope is determined by the structure base pattern and the sediment input, and is affected by the sea level change. The step-step sedimentary model of the shelf slope is the first time to reveal the macro-distribution of the sedimentary process of the continental shelf, which not only has important scientific significance, but also has important guiding significance to the deep-water oil and gas exploration and the submarine engineering construction. The deposition process of the carbonate platform and the deposition mode of the slope deposition system are described in this paper. There are four mixed deposition mechanisms at the edge of the stage, namely, in-situ mixing, intermittent mixing, phase-edge mixing, and mixing associated with volcanic activity. A large-scale water channel system is developed on the slope of the platform edge of the flow-flower-carbonate platform, and the filling and deposition of the water channel is dominated by the interaction layer composed of the limestone and the mudstone, and the characteristics of the discontinuous mixed deposition are shown. Further research shows that the mixed sedimentary cycle of the water channel is controlled by the sea level change, and the carbonate filling of the water channel takes place in the high-order period with high platform productivity. The sediment transport network system, which is composed of the 鈥済ully group-landslide groove-(deep-flow) water channel-large-scale canyon鈥，
本文编号：2417717
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