Sedimentology and architecture of the Douglas Creek terminal splay, Lake Eyre, central Australia
Sedimentology and architecture of the Douglas Creek terminal splay, Lake Eyre, central Australia
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DOI：
10.1111/j.1365-3091.2008.00974.x
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发表时间：
2008-12
期刊：
影响因子：
3.5
通讯作者：
J. Fisher;C. Krapf;S. Lang;G. Nichols;T. Payenberg
中科院分区：
文献类型：
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作者：
J. Fisher;C. Krapf;S. Lang;G. Nichols;T. Payenberg
道格拉斯溪终端岔道位于澳大利亚中部艾尔湖北岸西岸，面积约 4 平方公里，从分流河道终点到岔道边缘的下游系统长度为 2·5 公里。两条分流河道为两个沉积物叶提供水源，这两个沉积物叶合并形成终端张角。已确定了三个主要相组合，将溪流末端细分为分流河道、近端和远端张开部分。近端扇形沉积物的特点是基于侵蚀的、相对较厚（> 100 毫米）、粗到中度砂层堆积，通常显示槽形和平面交错层理，而远端扇形沉积物的特点是薄（通常< 50 毫米）、由非常细的砂、粉砂和粘土组成的块状床层。扇状沉积学的变化被解释为反映了从河道扩散到干湖床上时减速的面状洪水从以床质为主的沉积转变为以悬浮质为主的沉积的转变。还注意到近端到远端的张开过渡区，其中两个相组合的沉积物横向和垂直地相互交错。在规模、几何形状和相组合方面，Douglas Creek 终端扇形区与经常被引用的位于北部 70 公里处的 Neales 终端扇形区有很大不同。建议这些结构差异反映了排放量、输入沉积物分布和植被覆盖程度的变化。了解终端扇形结构的变化对于类似地下石油系统的建模具有非常重要的意义，目前该系统依赖于很少的现代类似物。
Douglas Creek terminal splay, sited on the western shoreline of Lake Eyre North, central Australia, covers a surface area of approximately 4 km2 with a down‐system length of 2·5 km from the distributary channels terminus to the splay fringe. Two distributary channels feed two sediment lobes which have amalgamated to form the terminal splay. Three primary facies associations have been identified sub‐dividing the creek terminus into distributary channel, proximal and distal splay sections. Proximal splay sediments are characterized by erosionally based, relatively thick (> 100 mm), stacked sheets of coarse to medium sand which commonly display trough and planar cross‐bedding, whereas the distal splay is characterized by thin (generally < 50 mm) massive beds of very fine sand, silt and clay. The change in splay sedimentology is interpreted as reflecting the transition from bedload‐dominated deposition to suspended load‐dominated deposition from decelerating sheetfloods as they spread out from the channel onto the dry lake bed. A proximal to distal splay transition zone is also noted where deposits of both facies associations interfinger laterally and vertically. In scale, geometry and facies associations, the Douglas Creek terminal splay is very different to the often cited Neales terminal splay complex located 70 km to the north. It is suggested that these architectural differences reflect variations in discharge volume, input sediment distribution and the degree of vegetation cover. Understanding the variation in terminal splay architecture has very significant implications for the modelling of analogous subsurface petroleum systems, which at present relies on few modern‐day analogues.