Sedimentary characteristics and model of gravity flows in the eocene Liushagang Formation in Weixi'nan depression, South China Sea
Sedimentary characteristics and model of gravity flows in the eocene Liushagang Formation in Weixi'nan depression, South China Sea
复制标题
南海涠西南凹陷始新统流沙港组沉积特征及重力流模式
DOI：
10.1016/j.petrol.2020.107082
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发表时间：
2020-07
影响因子：
--
通讯作者：
Yanqiong Zhao
中科院分区：
文献类型：
--
作者：
Yanpu Zhao;Hua Wang;Detian Yan;Ping Jiang;Si Chen;Jiaxiong Zhou;Jianghao Ma;Chunyu Qin;Jie He;Yanqiong Zhao
重力流在深海环境中已得到很好的研究，但在深湖环境中研究较少。为进一步认识断陷湖盆的沉积特征和重力流沉积过程，结合岩心、测井和三维地震资料，对南海威西南坳陷湖底扇进行了识别和研究。（1）分类：将重力流沉积划分为与滑塌侵位、富砾石泥石流、高密度浊流（可能转化为泥质泥石流）和低密度浊流有关的4种岩相组合。(2)近端与远端位置：岩相组合的定量分析表明，重力流沉积在湖底扇的近端以富砾石泥石流沉积和高密度浊积岩为主，而在盆地中心以低密度浊积岩为主。(3)主要触发因素（潮湿气候和/或斜坡崩塌）：活动构造的存在和潮湿气候有利于重力流的形成，重力流源于三角洲崩塌和/或洪水。(4)横向和纵向岩相分布：粗粒沉积物代表了不同类型重力流的频谱。在坡折带附近，滑塌通过液化和变形转化为富含砾石的泥石流。随着重力流向盆地推进，富含砾石的泥石流逐渐被周围的水稀释，并转化为高密度的浊流。当水流到达深盆平原时，由于粗颗粒不再处于悬浮状态，高密度浊流转变为低密度浊流。(5)替代机制：当水流侵蚀泥质基底/基底时，发生了涉及逆流转化的另一种机制。在某些情况下，高密度浊流转化为泥质泥石流，因为侵蚀轻物质成为向后方的浊流和抑制湍流分离。这种重力流沉积模式可用于研究区及类似断陷湖盆的油气勘探。
Gravity flows have been well investigated in deep-marine settings but less so in deep-lacustrine environments. To further understand the sedimentary characteristics and processes of gravity flows in a lacustrine rift basin, sublacustrine fans in the Weixi'nan Depression in the South China Sea were identified and studied by integrating core, well logging and 3D seismic data. Several aspects of gravity flow deposits were discussed in this study: (1) classification: seven lithofacies types were further grouped into four lithofacies assemblages/associations associated with emplacement by slumps, gravel-rich debris flows, high-density turbidity currents (which may transform into muddy debris flows) and low-density turbidity currents. (2) Proximal vs. distal position: the quantitative analysis of the lithofacies associations indicated that the gravity flow deposits are dominated by gravel-rich debris flow deposits and high-density turbidites in the proximal parts of the sublacustrine fans, whereas low-density turbidites dominate in the basin center. (3) Major triggers (humid climate and/or slope failures): the presence of active structures and a humid climate favored the formation of gravity flows, which originated from delta collapses and/or floods. (4) Lateral and vertical lithofacies distributions: the coarse-grained deposits represent a spectrum of different categories of gravity flows. In proximity to the slope break zone, slumps transformed into gravel-rich debris flows through liquefaction and deformation. As the gravity flows advanced toward the basin, the gravel-rich debris flows gradually became diluted with the surrounding water and transformed into high-density turbidity currents. When the flows reached the deep basin plain, the high-density turbidity currents transformed into low-density turbidity currents because the coarse grains could no longer remain in suspension. (5) An alternative mechanism: when the flows eroded the muddy substrate/basement, an alternative mechanism involving reverse-flow transformation occurred. In some cases, high-density turbidity currents transformed into muddy debris flows because the eroded light material became segregated toward the rear of the turbidity current and inhibited turbulence. This sedimentary model of gravity flows can be used for oil exploration in the study area and similar lacustrine rift basins.
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影响因子：
7.5
作者：
X. Pu;Lihong Zhou;Wenzhong Han;Changwei Chen;Xuanjun Yuan;Changmei Lin;Sa Liu;Guomeng Han;Wei Zhang-;Wenya Jiang
通讯作者：
X. Pu;Lihong Zhou;Wenzhong Han;Changwei Chen;Xuanjun Yuan;Changmei Lin;Sa Liu;Guomeng Han;Wei Zhang-;Wenya Jiang
重力流沉积物分类及其对非常规石油勘探的意义——以鄂尔多斯盆地南部三叠系延长组为例
影响因子：
3
作者：
Fan Aiping;Yang Renchao;van Loon A J;Yin Wei;Han Zuozhen;Zavala Carlos
通讯作者：
Zavala Carlos
适应带在控制地层结构变异和相分布中的相对作用：来自南海浮山凹陷的见解
影响因子：
4.2
作者：
Entao Liu;Hua Wang;Yuan Li;Nicole D. Leonard;Yuexing Feng;Songqi Pan;Cunyin Xia
通讯作者：
Cunyin Xia
影响因子：
5.8
作者：
Xuewei Zhang;C. Scholz;R. Hecky;D. Wood;H. Zal;C. Ebinger
通讯作者：
Xuewei Zhang;C. Scholz;R. Hecky;D. Wood;H. Zal;C. Ebinger
DOI：
10.1002/9781444303858.ch3
发表时间：
2009-04
期刊：
--
影响因子：
--
作者：
W. Nemec
通讯作者：
W. Nemec