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Submarine topographic control on distribution of supercritical-flow deposits in lobe and related environments, middle Eocene, Jaca Basin, Spanish Pyrenees
Journal of Sedimentary Research ( IF 2 ) Pub Date : 2020-10-06 , DOI: 10.2110/jsr.2020.59
Pauline H. Cornard 1 , Kevin T. Pickering 1
Affiliation  

Submarine lobe and related deposits are amongst the largest discrete sandbodies on Earth, and can be significant hydrocarbon reservoirs. In outcrop and core-based studies, tools such as analysis of bed-thickness and grain-size distributions have been used to improve the understanding of the composition and architecture of such sandbodies. Analysis of sediment-gravity-flow (SGF) processes have also proved to be a useful tool in understanding the evolution of submarine lobes. In this paper, based on outcrop studies of submarine lobe and related deposits in the middle Eocene Jaca Basin, Spanish Pyrenees, a revised interpretation of the depositional environments of the lobe and related deposits and a new model for their architectural evolution is presented. This model is based on an analysis of bed-thickness, grain-size distribution, and a qualitative and quantitative study of the distribution of supercritical-flow deposits (SFDs) in these environments. The interpretation of lobe and related environments is mainly based on sandstone content and the distribution of sedimentary facies. The main supercritical-flow sedimentary structures recognized in the Jaca Basin, are unstable and stable antidunes, upper plane beds and backset-laminated beds.This study demonstrates that seafloor topography, strongly controlled by both syndepositional tectonics and the accumulation of mass-transport complexes, likely exerted a significant influence on lobe architecture and the distribution of SFDs. Local increase in bed thickness, together with a progressive decrease in grain size and little variation in the proportion of SFDs in proximal-to-distal and axial-to-lateral directions, can be explained by: i) an increase in basin confinement of the distal part of the Jaca Basin due to tectonically induced narrowing, ii) enhanced local lateral confinement due, at least in part, to “carbonate megaturbidites” present in the distal part of the Jaca Basin and creating topography. Thus, basin confinement is introduced as a new parameter playing a role on flow criticality. There is a decreasing proportion of SFDs between the submarine channels and canyons of the Ainsa Basin and the submarine lobes of the Jaca Basin, the last basin being the focus of this paper. This confirms previous studies showing that channel confinement and slope gradient likely played an important role in flow criticality.

中文翻译:

海底地形对超临界流沉积物在波及相关环境,中始新世,哈卡盆地,西班牙比利牛斯山脉的分布

海底波瓣和相关沉积物是地球上最大的离散砂体之一,可以是重要的油气藏。在基于露头和岩心的研究中,已使用诸如分析床厚和粒度分布之类的工具来增进对此类沙体组成和构造的了解。沉积物重力流(SGF)过程的分析也被证明是了解海底裂片演变的有用工具。本文基于西班牙比利牛斯山脉始新世中部始新世中部海底叶和相关沉积物的露头研究,提出了对叶和相关沉积物沉积环境的修订解释,并提出了其构造演化的新模型。该模型基于床厚,晶粒尺寸分布,对这些环境中超临界流沉积物(SFD)的分布进行定性和定量研究。裂片及相关环境的解释主要基于砂岩含量和沉积相的分布。哈卡盆地公认的主要超临界流沉积结构是不稳定且稳定的反沙丘,上层床和逆层积层床。这项研究表明,海底地形受同沉积构造和大量输运复合物的强烈控制,可能对瓣结构和SFD的分布产生重大影响。床层厚度的局部增加,以及晶粒尺寸的逐渐减小,SFD的比例在近端到远端和轴向到侧面的变化很小,可以解释为:i)由于构造引起的变窄,哈卡盆地远端部分的盆地限制增加; ii)至少部分地由于该地区远端存在的“碳酸盐巨浊体”,增强了局部横向限制作用。哈卡盆地和创造地形。因此,盆地限制被引入作为对流量临界性起作用的新参数。在Ainsa盆地的海底河道和峡谷与Jaca盆地的海底裂谷之间,SFD的比例逐渐降低,最后一个盆地是本文的重点。这证实了先前的研究表明,通道限制和坡度梯度可能在流动临界中起重要作用。ii)至少部分归因于Jaca盆地远端存在的“碳酸盐巨浊体”并形成了地形,从而增强了局部侧向封闭性。因此,盆地限制被引入作为对流量临界性起作用的新参数。在Ainsa盆地的海底河道和峡谷与Jaca盆地的海底裂谷之间,SFD的比例逐渐降低,最后一个盆地是本文的重点。这证实了先前的研究表明,通道限制和坡度梯度可能在流动临界中起重要作用。ii)至少部分归因于Jaca盆地远端存在的“碳酸盐巨浊体”并形成了地形,从而增强了局部侧向封闭性。因此,盆地限制被引入作为对流量临界性起作用的新参数。在Ainsa盆地的海底河道和峡谷与Jaca盆地的海底裂谷之间,SFD的比例逐渐降低,最后一个盆地是本文的重点。这证实了先前的研究表明,通道限制和坡度梯度可能在流动临界中起重要作用。在Ainsa盆地的海底河道和峡谷与Jaca盆地的海底裂谷之间,SFD的比例逐渐降低,最后一个盆地是本文的重点。这证实了先前的研究表明,通道限制和坡度梯度可能在流动临界中起重要作用。在Ainsa盆地的海底河道和峡谷与Jaca盆地的海底裂谷之间,SFD的比例逐渐降低,最后一个盆地是本文的重点。这证实了先前的研究表明,通道限制和坡度梯度可能在流动临界中起重要作用。
更新日期:2020-11-25
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