Depositional environments and facies development of the Cenomanian–Turonian Galala and Maghra el Hadida formations of the Southern Galala Plateau (Upper Cretaceous, Eastern Desert, Egypt)
Depositional environments and facies development of the Cenomanian–Turonian Galala and Maghra el Hadida formations of the Southern Galala Plateau (Upper Cretaceous, Eastern Desert, Egypt)
复制标题
南加拉拉高原（埃及东部沙漠上白垩统）塞诺曼阶-土伦阶加拉拉组和马格拉哈迪达组的沉积环境和相发育
作者：
M. Wilmsen;Emad Nagm
埃及Wadi Araba（东部沙漠北部）南部Galala高原盖拉拉组和Maghra el Hadida组是热带古纬度新特提斯洋南缘晚白垩世早期海侵后发育的海相沉积体系。对这些层序进行岩相、生物相和微相分析，发现存在22种相类型（其中6种与Galala组有关，而Maghra el Hadida组有16种）。加拉拉组沉积于完全海相泻湖环境中，是对晚塞诺曼尼亚中期至早期海侵的响应。Galala组丰富的悬浮物和沉积物取食大型底栖动物表明中至富营养化（即绿水）条件。盖诺曼—turonian Maghra el Hadida组上段沉积相类型表明沉积在同斜的碳酸盐岩斜坡上，亚环境为深潮下盆地—潮间带后斜坡。与（相对）海平面变化相关的沉积环境主要和快速变化发生在晚塞诺曼世中期、早中Turonian边界段、中Turonian中期和中晚Turonian边界段。
The Cenomanian–Turonian (Upper Cretaceous) Galala and Maghra el Hadida formations of the Southern Galala Plateau in Wadi Araba (northern Eastern Desert, Egypt) represent marine depositional systems developing in response to the early Late Cretaceous transgression at the southern margin of the Neotethyan Ocean in tropical paleolatitudes. A facies analysis (litho-, bio- and microfacies) of these successions shows the presence of 22 facies types (FTs, six are related to the Galala Formation, while the Maghra el Hadida Formation is represented by 16 FTs). The Galala Formation was deposited in a fully marine lagoonal environment developing in response to a latest Middle to early Late Cenomanian transgression. The rich suspension- and deposit-feeding macrobenthos of the Galala Formation indicate meso- to eutrophic (i.e., green water) conditions. The facies types of the uppermost Cenomanian–Turonian Maghra el Hadida Formation suggest deposition on a homoclinal carbonate ramp with sub-environments ranging from deep-subtidal basin to intertidal back-ramp. Major and rapid shifts in depositional environments, related to (relative) sea-level changes, occurred in the mid-Late Cenomanian, the Early–Middle Turonian boundary interval, the middle part of the Middle Turonian and the Middle–Late Turonian boundary interval.