Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt
Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt
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DOI：
10.1016/j.sedgeo.2006.05.010
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发表时间：
2006-08-01
影响因子：
2.8
通讯作者：
Wanas, H. A.
中科院分区：
文献类型：
--
作者：
Catuneanu, O.;Khalifa, M. A.;Wanas, H. A.
下Cenomanian Bahariya组对应于在相对低速的正可容纳条件（3-6 My期间< 200 in）下在大陆架环境中形成的二级沉积层序。基准面上升的总体趋势被三次基准面下降打断，导致三级层序界面的形成。这些边界是由陆上不整合面（取代或不年轻的海侵波裂谷面），并细分Bahariya组分为四个三级沉积层序。Bahariya组的层序地层格架的建设是基于横向和纵向的变化之间的陆棚，潮下带，海岸和河流相，以及对它们分开的接触的性质。内部（三级）层序边界与下切谷有关，这解释了（1）下切谷充填沉积厚度的显著横向变化，（2）在特定区域缺乏三级高位甚至海侵体系域，以及（3）在相对短的距离内可能发生横向的突然相变。在每个层序中，低水位、海侵和高水位体系域的概念被用来解释观察到的横向和纵向相变化。并有助于确定13个阶段的基准面变化的历史，标志着巴哈利亚绿洲地区的演变在早期赛诺曼。(c)2006 Elsevier B. V.保留所有权利。
The Lower Cenomanian Bahariya Formation corresponds to a second-order depositional sequence that formed within a continental shelf setting under relatively low-rate conditions of positive accommodation (< 200 in during 3-6 My). This overall trend of base-level rise was interrupted by three episodes of base-level fall that resulted in the formation of third-order sequence boundaries. These boundaries are represented by subaerial unconformities (replaced or not by younger transgressive wave ravinement surfaces), and subdivide the Bahariya Formation into four third-order depositional sequences.The construction of the sequence stratigraphic framework of the Bahariya Formation is based on the lateral and vertical changes between shelf, subtidal, coastal and fluvial facies, as well as on the nature of contacts that separate them. The internal (third-order) sequence boundaries are associated with incised valleys, which explain (1) significant lateral changes in the thickness of incised valley fill deposits, (2) the absence of third-order highstand and even transgressive systems tracts in particular areas, and (3) the abrupt facies shifts that may occur laterally over relatively short distances. Within each sequence, the concepts of lowstand, transgressive and highstand systems tracts are used to explain the observed lateral and vertical facies variability.This case study demonstrates the usefulness of sequence stratigraphic analysis in understanding the architecture and stacking patterns of the preserved rock record, and helps to identify 13 stages in the history of base-level changes that marked the evolution of the Bahariya Oasis region during the Early Cenomanian. (c) 2006 Elsevier B.V. All rights reserved.