Upper Miocene to Quaternary unidirectionally migrating deep-water channels in the Pearl River Mouth Basin, northern South China Sea
Upper Miocene to Quaternary unidirectionally migrating deep-water channels in the Pearl River Mouth Basin, northern South China Sea
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DOI：
10.1306/07121211159
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发表时间：
2013-02
期刊：
影响因子：
3.5
通讯作者：
C. Gong;Yingmin Wang;Weilin Zhu;Weiguo Li;Qiang Xu
中科院分区：
文献类型：
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作者：
C. Gong;Yingmin Wang;Weilin Zhu;Weiguo Li;Qiang Xu
珠江口盆地白云凹陷发现了一系列短而陡的单向迁移深水河道，这些河道通常没有堤坝，并逐渐向东北迁移。目前的研究利用三维地震和井数据，记录了它们的形态、内部结构和沉积历史，并讨论了这些河道内底部水流改造砂的分布和沉积控制。单向迁移的深水河道由不同的河道复合体组（CCS）组成，总体上短而陡，其东北岸壁总体上比西南岸更陡。在每个 CCS 内，下部的底部水流改造砂向上分级为泥质滑坡和泥石流沉积物，最后形成页岩披覆层。 CCS发展的三个阶段被认为是：（1）早期低位切入阶段，在此期间，强烈的重力和/或浊度流与北太平洋中间水（NPIW-BC）相对较弱的沿坡底流形成了基底侵蚀边界表面和有限的底流-再造砂； (2) 低水位横向运移和主动充填阶段晚期，CCS逐渐加宽，并逐渐向东北方向运移，其特征是强烈的NPIW-BCs对重力流和/或浊流沉积物的改造，CCS主要被底流改造砂和有限的滑塌和泥石流沉积物充填； (3)海侵废弃阶段，其特征是重力流和/或浊度流终止，CCS被海相页岩广泛覆盖。这三个阶段随着时间的推移不断重复，导致单向迁移的深水河道的产生。底部水流改造砂的分布在空间和时间上都有所变化。在空间上，这些砂粒主要沿着单向运移的深水河道的轴线聚集，并优先沉积到河道运移的一侧。从时间上看，这些砂粒主要在低位横向运移晚期和主动充填阶段聚集。底流改造砂是在重力和/或浊流与NPIW-BCs沿坡底流的共同作用下发育的。其他因素，包括相对海平面波动、沉积物供应和斜坡构造，也影响了这些沙子的形成和分布。所提出的底部水流改造砂的分布模式对于预测与底部水流相关的河道中储层的出现和分布具有实际意义。
A series of short and steep unidirectionally migrating deep-water channels, which are typically without levees and migrate progressively northeastward, are identified in the Baiyun depression, Pearl River Mouth Basin. Using three-dimensional seismic and well data, the current study documents their morphology, internal architecture, and depositional history, and discusses the distribution and depositional controls on the bottom current–reworked sands within these channels. Unidirectionally migrating deep-water channels consist of different channel-complex sets (CCSs) that are, overall, short and steep, and their northeastern walls are, overall, steeper than their southwestern counterparts. Within each CCS, bottom current–reworked sands in the lower part grade upward into muddy slumps and debris-flow deposits and, finally, into shale drapes. Three stages of CCSs development are recognized: (1) the early lowstand incision stage, during which intense gravity and/or turbidity flows versus relatively weak along-slope bottom currents of the North Pacific intermediate water (NPIW-BCs) resulted in basal erosional bounding surfaces and limited bottom current–reworked sands; (2) the late lowstand lateral-migration and active-fill stage, with gradual CCS widening and progressively northeastward migration, characterized by reworking of gravity- and/or turbidity-flow deposits by vigorous NPIW-BCs and the CCSs being mainly filled by bottom current–reworked sands and limited slumps and debris-flow deposits; and (3) the transgression abandonment stage, characterized by the termination of the gravity and/or turbidity flows and the CCSs being widely draped by marine shales. These three stages repeated through time, leading to the generation of unidirectionally migrating deep-water channels. The distribution of the bottom current–reworked sands varies both spatially and temporally. Spatially, these sands mainly accumulate along the axis of the unidirectionally migrating deep-water channels and are preferentially deposited to the side toward which the channels migrated. Temporally, these sands mainly accumulated during the late lowstand lateral-migration and active-fill stage. The bottom current–reworked sands developed under the combined action of gravity and/or turbidity flows and along-slope bottom currents of NPIW-BCs. Other factors, including relative sea level fluctuations, sediment supply, and slope configurations, also affected the formation and distribution of these sands. The proposed distribution pattern of the bottom current–reworked sands has practical implications for predicting reservoir occurrence and distribution in bottom current–related channels.