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Regional assessment of gravity-driven deformation offshore Namibia (West Africa)—Styles, distribution and controlling factors
Basin Research ( IF 2.8 ) Pub Date : 2022-07-16 , DOI: 10.1111/bre.12694 Nicola Scarselli 1 , Ken McClay 1, 2 , Chris Elders 3
Basin Research ( IF 2.8 ) Pub Date : 2022-07-16 , DOI: 10.1111/bre.12694 Nicola Scarselli 1 , Ken McClay 1, 2 , Chris Elders 3
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This paper presents a semi-quantitative analysis of gravity-driven deformation along the Namibian margin using extensive 2D depth converted seismic data. The geometries, internal characters and distribution of gravity-driven systems were investigated through regional and detailed seismic studies. The research shows that surficial slumps are typically ca. 50 m thick and are characterised by contorted seismic facies commonly occurring along the slopes of the margin. They commonly funnel and cluster within high relief areas such as canyons and pre-existing landslide scars. These contrast with coherent slides that are up to 2 km thick which extend laterally along the margin for tens to hundreds of kilometres. Slides preferentially occur in the proximal part of the margin and are constrained within the main margin depocenters. Here, high sedimentation rates and loading promote the generation of distinct, weak, overpressured layers that favour initiation of sliding of relatively coherent sediment masses. This research also shows that one-third of volume of the post-rift sediments on the Namibian margin were affected by slides and slumps. This demonstrates that gravity-driven deformation is a key geological process that can strongly modify the evolution of rifted passive margins.
中文翻译：
纳米比亚（西非）近海重力驱动变形的区域评估——类型、分布和控制因素
本文介绍了使用广泛的二维深度转换地震数据对纳米比亚边缘的重力驱动变形进行的半定量分析。通过区域和详细的地震研究，研究了重力驱动系统的几何形状、内部特征和分布。研究表明，地表坍塌通常是 ca。50 m 厚，其特征是扭曲的地震相通常沿着边缘的斜坡出现。它们通常汇集并聚集在高地势区域，例如峡谷和先前存在的滑坡疤痕。这些与厚达 2 公里的连贯滑坡形成鲜明对比，这些滑坡沿边缘横向延伸数十至数百公里。滑动优先发生在边缘的近端部分并且被限制在主要边缘沉积中心内。这里，高沉积速率和负荷促进了明显的、薄弱的、超压层的产生，这些层有利于相对连贯的沉积块开始滑动。这项研究还表明，纳米比亚边缘裂谷后沉积物体积的三分之一受到滑坡和坍塌的影响。这表明重力驱动变形是一个关键的地质过程，可以强烈改变裂谷被动边缘的演化。
更新日期：2022-07-16
中文翻译：
纳米比亚（西非）近海重力驱动变形的区域评估——类型、分布和控制因素
本文介绍了使用广泛的二维深度转换地震数据对纳米比亚边缘的重力驱动变形进行的半定量分析。通过区域和详细的地震研究，研究了重力驱动系统的几何形状、内部特征和分布。研究表明，地表坍塌通常是 ca。50 m 厚，其特征是扭曲的地震相通常沿着边缘的斜坡出现。它们通常汇集并聚集在高地势区域，例如峡谷和先前存在的滑坡疤痕。这些与厚达 2 公里的连贯滑坡形成鲜明对比，这些滑坡沿边缘横向延伸数十至数百公里。滑动优先发生在边缘的近端部分并且被限制在主要边缘沉积中心内。这里，高沉积速率和负荷促进了明显的、薄弱的、超压层的产生，这些层有利于相对连贯的沉积块开始滑动。这项研究还表明，纳米比亚边缘裂谷后沉积物体积的三分之一受到滑坡和坍塌的影响。这表明重力驱动变形是一个关键的地质过程，可以强烈改变裂谷被动边缘的演化。
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