Analysis of Holocene sedimentary seascape is focused on the Red Sea windward Al-Wajh platform margin, its central lagoon, and nearby isolated platforms based on data that include mapped ecological facies (habitats), water depths, grain sizes, and allochem types and abundances determined from thin sections. On this basis, a depositional model applicable to Red Sea Plio-Pleistocene and other ancient icehouse carbonate platforms is presented. The model highlights favorable reservoirs in analogous ancient systems to include coral crests and columnar framework habitats with primary porosity developed in boundstone lithologies and windward platform margins to contain considerable open pore space, including cavernous openings, of which not all should be anticipated to be occluded with marine cements and sediments. Meteoric diagenesis is expected to be minor as limited freshwater is available due to extreme aridity, but may play a role during glaciation.Most habitats have potential for secondary (enhanced) porosity resulting from dissolution of aragonite skeletons, particularly mollusk shells and calcareous coral (Scleractinia) endoskeletons. Central-lagoon habitats are expected to have the least favorable reservoir potential of environments considered because they are dominated by peloids. Central-lagoon sediment differs from other published localities, having higher peloid abundances, greater peloid distribution, and little or no association with Halimeda and quartz grains. Under the likely scenario that platform-interior sediments are completely bioturbated and comprise peloid-rich, grain-dominated fabrics, with many smaller peloids (most of them likely fecal pellets) at or near 4 μm in size (i.e., mud fraction), it is possible that grain size will control pore size once the considered deposits are lithified. If so, platform-interior sediments will lithify as mudstones, wackestones, or very fine-grained grainstones, an outcome which might otherwise be unexpected given the abundance of coarse peloid grains.The Al-Wajh platform is compared with 15 Holocene analogs and found to be unique with respect to rift-margin type, restricted-marine circulation, in having a lagoon with high peloid content, and lack of karst. In further comparison with ancient reservoir analogs, two greenhouse and four icehouse, it compares favorably to icehouse platforms deposited in rift basins with respect to mineralogy of deposition, meter-scale cycle thicknesses, and general peloid content and distribution. It provides a snapshot as to how an icehouse platform might have nucleated and attached along an active rift margin; it is a broadly applicable carbonate analog for the Red Sea Plio-Pleistocene and similar icehouse, rift basins.

中文翻译：

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红海全新世碳酸盐岩：沙特阿拉伯北部 Al-Wajh 附近的迎风平台边缘和泻湖

全新世沉积海景分析的重点是红海迎风 Al-Wajh 平台边缘、其中央泻湖和附近的孤立平台，其数据包括绘制的生态相（栖息地）、水深、颗粒大小以及确定的异体化学类型和丰度从薄片。在此基础上，提出了适用于红海上新—更新世等古冰库碳酸盐台地的沉积模型。该模型突出了类似古代系统中的有利储层，包括在边界岩和迎风平台边缘开发的具有原生孔隙度的珊瑚嵴和柱状格架栖息地，以包含相当大的开放孔隙空间，包括海绵状开口，预计其中并非所有的都应被海洋水泥和沉积物。由于极端干旱，可用淡水有限，因此预计流星成岩作用较小，但可能在冰川作用期间发挥作用。大多数栖息地都有可能因文石骨骼，特别是软体动物贝壳和钙质珊瑚（硬骨珊瑚）的溶解而产生次生（增强）孔隙度。 ) 内骨骼。预计中央泻湖栖息地具有最不利的环境储层潜力，因为它们以 peloids 为主。中央泻湖沉积物不同于其他已发表的地点，具有更高的珠粒丰度，更大的珠粒分布，并且与 Halimeda 和石英颗粒几乎没有或没有关联。在平台内部沉积物完全受到生物扰动并包含富含球状体、以谷物为主的织物的可能情况下，许多较小的颗粒（其中大部分可能是粪便颗粒）的大小（即泥浆部分）达到或接近 4 μm，一旦考虑的沉积物被岩化，颗粒大小可能会控制孔径大小。如果是这样，台地内部沉积物将石化为泥岩、碎屑岩或非常细粒的颗粒岩，考虑到丰富的粗粒状颗粒，这种结果可能是出乎意料的。 将 Al-Wajh 平台与 15 个全新世类似物进行比较，发现在裂谷边缘型、海洋环流受限、具有高珠粒含量和缺乏岩溶的泻湖方面具有独特性。进一步与古代水库类似物、两个温室和四个冰库相比，它在沉积矿物学、米级循环厚度、和一般 peloid 含量和分布。它提供了一个关于冰库平台如何沿活动裂谷边缘成核和附着的快照；它是一种广泛适用的碳酸盐类似物，适用于红海上新-更新世和类似的冰库、裂谷盆地。