Morphotectonic Evolution of Qaret El Sheikh Abdallah Depressions and Denuded Paleo-Karst in the White Desert, El Bahariya-Farafra Karst Territory, Egypt.

Abstract

HE Late Cretaceous-Early Eocene carbonate sequences of the White Desert of Egypt exhibit amazing complex paleo-humid karst landforms, so it was declared as a nature-protected area since 2002. Two karst depressions of El Sheikh Abdallah and the Crystal Mountain (Qaret El Sheikh Abdallah) are identified by detailed fieldwork and GIS morphometric analysis of the digital elevation model of the northern part of the White Desert. These depressions are verified as two separate karst uvalas between the major karst poljes of El Bahariya and Farafra karst territory with northeast alignment. The sea-level drops and uplifting phases of the carbonate sequences of the uvalas, associated with the major compressional events of the Syrian arc (Cretaceous-Paleogene) and Oligo-Miocene extensional tectonics in north Egypt caused the development of three major stratigraphic breaks (fossilized paleo-karst surfaces) of Late Cretaceous-Palaeocene, Palaeocene-Early Eocene, and post-Early Eocene (Oligocene-Miocene). Along these fossilized surfaces, paleokarst features and sediments are detected and described. El Sheikh Abdallah and the Crystal Mountain depressions (uvalas) are also dominated by exposed (surface) complex karst features such as unroofed caves, widened joints, sinkholes, collapse breccia's, and solution channels, together with sporadic remains of uncovered autochthonous and allochthones paleo-cave sediments. The recognized stratigraphic breaks and their paleokarst features and the subsequent surface denudation helped to propose a morphotectonic evolutionary model for the exposed karst landscape and the denuded karst features of El Sheikh Abdallah-Crystal Mountain uvalas.

Karst Heritage as a Tourist Attraction: a Case Study in the White Desert National Park, Western Desert, Egypt

“…The latter authors described the two depressions (QSA and CM) as uvalas, which are demarcated as large (in km scale) karst closed depressions with irregular plan form caused by enhanced erosion along major tectonic zones. Four karst facies forming speleothems, which include marine Khoman white chalk, clast-supported conglomerates, red soils, and bedded limestone/calcite strata, have been described at QSA and CM (Wanas et al 2009;El Aref et al 2021; Fig. 12A).…”

“…1D; El Aref, et al 1986;Halliday 2003). Several geoscientific researchers studied the karst rocks on the Bahariya-Farafra terrain (El Aref et al 1987;1999;Sokker 1991;Waltham 2001;Brook et al 2002;Halliday 2003;Kindermann et al 2006;Moustafa 2007;Wanas et al 2009;Abdel Tawab 2013;El Aref et al 2017a,b;Youssef et al 2017;El Aref et al 2021). Sixteen fields of karst landform in Bahariya-Farafra Oases have been recorded in WD, Egypt (Fig.…”

“…Moreover, the latter authors carried out an inventory and assessment of the selected geosites in these areas. Cretaceous-Eocene karstified carbonate successions interrupted by paleo-fossilized karst surfaces that are covered by Quaternary to Recent sediments forming exhumed karsts (e.g., sand dunes, playa deposits, salt lakes), occupy most lands of the Bahariya-Farafra terrain (Klimchouk and Ford 2000;El Aref et al 2021). Surficial duricrusts involving calcrete, silcrete, dolocrete, and ferrierite characterize the tops of the most karstified carbonate rocks (El Aref et al 2021).…”

“…Cretaceous-Eocene karstified carbonate successions interrupted by paleo-fossilized karst surfaces that are covered by Quaternary to Recent sediments forming exhumed karsts (e.g., sand dunes, playa deposits, salt lakes), occupy most lands of the Bahariya-Farafra terrain (Klimchouk and Ford 2000;El Aref et al 2021). Surficial duricrusts involving calcrete, silcrete, dolocrete, and ferrierite characterize the tops of the most karstified carbonate rocks (El Aref et al 2021). In the WD, enormous karstified carbonate platforms are documented, which are composed of limestone/chalk and shale/clay rhythmic beds in the time period from Upper Cretaceous/Palaeocene to Middle Miocene (Fig.…”

“…Its landforms refer to vast quantities of amazing and unique karst shafts/infillings, displaying diverse karst features (e.g., dolines/sinkholes, unroofed karst hills, and numerous remnants of degraded caves) (Figs. 12 and 13), along with clastic sediments and red soils formed by solution/erosion during karst uplifting, degradation, and rejuvenation processes (Embabi 2018;El Aref et al 2021). Unroofed/collapsed karst hills can be defined as subsoil karsts that are depicted by several different cave patterns during tectonic uplift with the removal of their cover by erosion (Field 1999).…”