Soft-sediment deformation structures of tide origin: A case study from the late Miocene Tafna Basin (NW Algeria)

IF 1.2 4区地球科学 Q2 Earth and Planetary Sciences

Proceedings of the Geologists Association Pub Date : 2024-12-18 DOI:10.1016/j.pgeola.2024.12.001

Mostapha Benzina , Abdelmalik Draoui , Hakim Hebib , Małgorzata Pisarska-Jamroży

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引用次数: 0

Abstract

Typical liquefaction-induced soft-sediment deformation structures were recognised in the Neogene-age tide-dominated estuarine sedimentary succession Bled El Trayfa in the Tafna basin (NW Algeria). Although NW Algeria was tectonically active during late Neogene, we suggest that another trigger mechanism that is not related to earthquakes is responsible for the liquefaction phenomenon and the development of soft-sediment deformation structures in the area. The sedimentary succession called the Bled El Trayfa exhibits tidal rhythmites, heterolithic beddings, bi-directional cross-laminae, and tidal bore couplets deposited in tidal flats within the intertidal environment. A tidal bore, defined as upstream-propagating hydraulic jumps associated with the flood tide in estuarine rivers, is proposed as the main trigger mechanism responsible for the liquefaction phenomenon and the development of soft-sediment deformation structures. This suggestion was made on a set of observed arguments: firstly, the presence of draping massive sand underlain by erosional surfaces indicating scouring by upstream-propagating bores, followed by a very rapid deposition in a tide-dominated estuarine from the intertidal environment and secondly, the formation of distinctive (typical) soft-sediment deformation structures, characterised by convoluted and folded structure like flow rolls along with associated dewatering structures. Alongside flow rolls as typical and dominant soft-sediment deformation structures, the succession also includes load casts, recumbent folds, water-escape structures, convolute laminations, ball-and-pillow structures, and flame structures. Even though the relationship between the tidal bore and sediment deformation structures has been proved in some current researches, the Bled El Trayfa succession was considered among the rare areas where this relationship was identified as the origin of SSDSs in ancient rock record.

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潮源软沉积变形构造——以晚中新世Tafna盆地为例

在阿尔及利亚西北部塔夫纳盆地新近系以潮汐为主导的河口沉积序列Bled El Trayfa中发现了典型的液化软沉积变形构造。尽管阿尔及利亚西北部晚新近纪构造活动活跃，但我们认为该地区的液化现象和软沉积变形构造的发育有另一种与地震无关的触发机制。该沉积序列显示潮间带环境中潮滩上的潮节律岩、异质层理、双向交叉纹层和潮孔对联沉积。潮涌是指河口河流中与涨潮相关的上游传播的水力跳跃，它是液化现象和软沉积变形结构形成的主要触发机制。这一建议是基于一系列观察到的论点提出的：首先，在侵蚀表面下存在着大量的覆盖砂，表明上游传播钻孔的冲刷，其次是潮间带环境中潮汐主导的河口的快速沉积，其次，形成了独特的（典型的）软沉积变形结构，其特征是像流卷一样的卷曲和折叠结构以及相关的脱水结构。除了以流卷为典型和主导的软沉积变形构造外，还包括荷载浇筑、平卧褶皱、泄水构造、卷曲层状构造、球枕构造和火焰构造。尽管目前已有一些研究证实了潮涌与沉积物变形构造之间的关系，但在古岩石记录中，这种关系被确定为ssds起源的罕见地区被认为是Bled El Trayfa演替。

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来源期刊

Proceedings of the Geologists Association 地学-地质学

CiteScore

2.70

自引率

8.30%

发文量

审稿时长

6-12 weeks

期刊介绍： The Proceedings of the Geologists'' Association is an international geoscience journal that was founded in 1859 and publishes research and review papers on all aspects of Earth Science. In particular, papers will focus on the geology of northwestern Europe and the Mediterranean, including both the onshore and offshore record. Following a long tradition, the PGA will focus on: i) a range of article types (see below) on topics of wide relevance to Earth Sciences ii) papers on aspects of Earth Science that have societal relevance including geoconservation and Earth management, iii) papers on palaeoenvironments and palaeontology of the Mesozoic and Cenozoic, iv) papers on aspects of Quaternary geology and climate change, and v) papers on the history of geology with particular reference to individuals that have shaped the subject. These topics will also steer the content of the themes of the Special Issues that are published in the PGA.