Reconstruction of linear dunes from ancient aeolian successions using subsurface data: Permian Auk Formation, Central North Sea, UK
Reconstruction of linear dunes from ancient aeolian successions using subsurface data: Permian Auk Formation, Central North Sea, UK
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DOI：
10.1016/j.marpetgeo.2017.12.021
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发表时间：
2018-03
影响因子：
4.2
通讯作者：
B. Besly;Hollie G. Romain;N. Mountney
中科院分区：
文献类型：
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作者：
B. Besly;Hollie G. Romain;N. Mountney
对穿透英国北海中部二叠纪 Rotliegend 群主要风成 Auk 组的一系列测井和岩心进行了评估，以确定原始沙丘床形的形态和迁移行为的类型、整体沉积环境，并评估对储层非均质性的影响。这是通过对地下数据集的详细相分析以及通过将观察到的堆积沉积样式与类似的现代风成沙丘场进行比较来实现的。风沙床形态类型、形态、详细的迁徙行为和堆积表面的性质都得到了解释。对保存的交错层状组和伴组的相结构分析表明，通过大型线性地床形态的迁移和爬升，在干燥基质上堆积，这些线性地床形态具有低角度倾斜的下底座，厚度可达 15m。沙丘底座元素以风纹和改造的风纹地层为主，并且随着连续的河床形态以低角度相互迁移而被优先保留。代表床状背风坡上部堆积的颗粒流主导地层包较少见，并且往往主要保留在大型地层陪集的上部（～30m厚）。大型线性地床被干燥的沙丘间区域隔开。虽然沙粒运移的主要方向是沿着地床形态的拉长波峰，但横向运动的次要分量使得能够横向迁移并优先保存由床形迁移的较小倾斜分量引起的背风坡沉积物。在某些地方，该建筑记录了小型酒石沙丘沉积物的保存，这些沉积物要么位于沙丘间洼地内，要么叠加在大型线性地床形态的下侧。保存完好的风成相类型对储层质量具有主要控制作用。以前很少有研究记录古代连续的线性沙丘。这些发现是一个有价值的案例。
A series of well logs and cores penetrating the predominantly aeolian Auk Formation, Permian Rotliegend Group, Central North Sea, UK, have been evaluated to determine the morphology and style of migratory behaviour of the original dune bedforms, the overall depositional environment, and to assess implications for reservoir heterogeneity. This has been achieved by detailed facies analysis of subsurface datasets and by comparison of the observed sedimentary styles of accumulation to analogous modern aeolian dune fields. Aeolian bedform type, morphology, detailed migratory behaviour, and the nature of the accumulation surface have been interpreted. Analysis of the facies architecture of preserved cross-bedded sets and cosets indicates accumulation on a dry substrate via the migration and climb of large linear bedforms that possessed low-angle inclined lower plinths, up to 15 m thick. Dune plinth elements are dominated by wind-ripple and reworked wind-ripple strata, and were preferentially preserved as successive bedforms migrated over one another at low angles. Packages of grainflow-dominated strata representative of accumulation on the higher part of the bedform lee slope are less common and tend to be preserved mostly in the upper parts of large cosets of strata (∼30 m thick). Large linear bedforms were separated by dry interdune areas. Although the primary direction of sand transport was along the elongated crests of the bedforms, a secondary component of transverse motion enabled the lateral migration and preferential preservation of lee-slope deposits that arose from a minor oblique component of bedform migration. In places, the architecture records the preservation of small barchanoid dune deposits, either within interdune depressions or superimposed on the lower flanks of the large linear bedforms. The preserved aeolian facies types exert a primary control on reservoir quality. Few previous studies have documented linear dunes in ancient successions; these findings represent a valuable case example.