Gaia Travan , Virginie Gaullier , Jacques Déverchère , Bruno C. Vendeville
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引用次数: 0
Abstract
Convergence between African and European plates generates compressional strain, primarily concentrated along the northern African margin. This is testified on the Algerian margin by numerous earthquakes (e.g. Bougrine et al., 2019) and by the presence of active folds and thrusts. Multi-channel seismic reflection profiles from the MARADJA I survey reveal north-verging thrusts rooted below the Messinian units, and the geometries of the Messinian salt structures. This study examines the characteristics of salt tectonics offshore Algiers and Dellys, focusing on the effect of the positive structural inversion of the former passive margin on geometries, timing, and mechanisms of salt deformation. The interpretation of seismic reflection and multi-beam bathymetric data of the MARADJA I survey, along with its comparison with analogue models, allowed us to reconstruct the salt tectonics processes on the margin and to identify the predominant role of a plateau uplift on salt deformation. Early and ubiquitous salt deformation by downbuilding was followed by a major phase of plateau uplift (end of Messinian Crisis), leading to westward gravity gliding and a slowdown of the salt deformation above the plateau. Km-tall salt structures were developed and thick minibasins deposited. Salt tectonics is nowadays active only where the relationship between salt and overburden thickness is favorable.
非洲板块和欧洲板块的汇聚产生了压缩应变,主要集中在非洲北部边缘。阿尔及利亚边缘的多次地震(如 Bougrine 等人,2019 年)以及活跃褶皱和推力的存在都证明了这一点。MARADJA I 勘探的多道地震反射剖面显示了扎根于梅西尼亚单元之下的北向推力,以及梅西尼亚盐构造的几何形状。本研究探讨了阿尔及尔和德利斯近海盐构造的特点,重点是前被动边缘的正构造反转对盐变形的几何形状、时间和机制的影响。通过对 MARADJA I 勘测的地震反射和多波束测深数据的解释,以及与模拟模型的比较,我们得以重建该边缘的盐构造过程,并确定高原隆起对盐变形的主要作用。早期普遍存在的下沉式盐变形之后是一个重要的高原隆升阶段(梅西尼亚危机末期),导致重力向西滑动,高原上方的盐变形减缓。千米高的盐构造被开发出来,并沉积了厚厚的小盆地。如今,只有在盐和覆盖层厚度之间的关系有利的地方,盐构造才会活跃。
期刊介绍:
The Journal of Structural Geology publishes process-oriented investigations about structural geology using appropriate combinations of analog and digital field data, seismic reflection data, satellite-derived data, geometric analysis, kinematic analysis, laboratory experiments, computer visualizations, and analogue or numerical modelling on all scales. Contributions are encouraged to draw perspectives from rheology, rock mechanics, geophysics,metamorphism, sedimentology, petroleum geology, economic geology, geodynamics, planetary geology, tectonics and neotectonics to provide a more powerful understanding of deformation processes and systems. Given the visual nature of the discipline, supplementary materials that portray the data and analysis in 3-D or quasi 3-D manners, including the use of videos, and/or graphical abstracts can significantly strengthen the impact of contributions.