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Sediment Characteristics and Microfacies Analysis of Jizan Supratidal Sabkha, Red Sea Coast, Saudi Arabia

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Sediment Characteristics and Microfacies Analysis of Jizan Supratidal Sabkha, Red Sea Coast, Saudi Arabia Arab J Geosci (2015) 8:9973–9992 DOI 10.1007/s12517-015-1852-1 ORIGINAL PAPER Sediment characteristics and microfacies analysis of Jizan supratidal sabkha, Red Sea coast, Saudi Arabia Mohammed H. Basyoni & Mahmoud A. Aref Received: 20 May 2014 /Accepted: 24 February 2015 /Published online: 30 April 2015 # Saudi Society for Geosciences 2015 Abstract Jizan sabkha extends along the southeastern coastal the brine surface and floor of saline pans, and the diagenetic plain of the Red Sea, Saudi Arabia, and is considered as one of formation of gypsum and anhydrite below the sediment sur- the main problems that has a negative impact on infrastructure face as intrasediment displacive, inclusive, and replacive of buildings. Field examination of the surface of the wet growth in the wet sandflat and mudflat areas. Recognition of sabkha area indicated the presence of sedimentary surface such structural and textural features of the evaporite sediments structures produced by physical forces such as adhesion rip- helps in solving engineering geological problems in Jizan area ples, tepee polygonal ridges, efflorescent halite pods, and and allowed also for interpreting the similar sabkha sediments structures produced by microbial activities such as petees in the rock record. and blisters. Microfacies analysis of the siliciclastic and evap- orite lithofacies types has been done for sediment samples Keywords Lenticular . Rosette gypsum . Nodular anhydrite . from the surface, trenches, and cores. The siliciclastic Basin zonation . Jizan sabkha . Saudi Arabia lithofacies type represents the host sediments in Jizan sabkha and consists of sand and mud. The evaporite lithofacies type is distinguished into three microfacies types of gypsum, anhy- drite, and halite. The gypsum microfacies types are represent- ed by diagenetic growth of individual lenticular, twinned len- Introduction ticular, twinned complex lenticular, rosettes, nodular, poikilotopic, porphyroblastic, alabastrine, and clastic gypsum. The coastal plain of the Red Sea of Saudi Arabia contains a The anhydrite microfacies types are represented by nodular series of isolated coastal lagoons, saline pans, and supratidal and enterolithic anhydrite. The halite microfacies types are sabkhas. The coastal lagoons have salinities slightly higher represented by primary rafts, cumulates, chevrons and cornets, than the Red Sea water, and their mineralogic composition, and diagenetic overgrowth and mosaic halite cement. The sediment textures, pollution, environmental characteristics, structural and textural characteristics of the evaporite sedi- and micro- and macro-faunal assemblages were studied by ments indicated the formation of primary halite crystals at Abou Ouf and El-Shater (1991), Al-Washmi (1999), Coakley and Rasul (2001), Al-Washmi (2003), Basaham et al. (2006), Abu-Zied et al. (2011), Abu-Zied and Bantan (2013), Rasul et al. (2013), and Basaham et al. (2014). The saline pans occur only south of Jeddah and were studied by M. H. Basyoni (*) : M. A. Aref Department of Petroleum Geology and Sedimentology, Faculty of Taj and Aref (2014, 2015a). The studies carried out on the Earth Sciences, King Abdulaziz University, Jeddah, Saudi Arabia supratidal sabkhas of the eastern Red Sea coast were con- e-mail: [email protected] cerned mainly with water and sediment chemistry (e.g., M. A. Aref Bahafzullah et al. 1993; Basyoni 1997; Serhan and Sabtan e-mail: [email protected] 1999; Sabtan et al. 1997; Sabtan and Shehata 2003; Banat et al. 2005; Basyoni and Aref 2014; Taj and Aref 2015b). M. A. Aref Geology Department, Faculty of Science, Cairo University, Several works were concerned with the sedimentology of the- Giza, Egypt se sabkhas (e.g., Basyoni 2004;Al-Washmietal.2005; 9974 Arab J Geosci (2015) 8:9973–9992 Gheith et al. 2005; Taj and Aref 2009, 2011; Basyoni and Aref Fig. 1 a Location map for Jizan area. b Geology of Jizan area (after 2007, 2009, 2010, 2011; Basyoni et al. 2008; Ginau et al. Blank et al. 1987). Note: the insert box is the studied area shown in (c). 2012; Aref and Taj 2013; Aref et al. 2014). Most studies c Surface lithology and location of the sediment samples and cores drilled in the studied Jizan sabkha. d Lithologic interpretation of the cores drilled carried out on Jizan sabkha were concerned with the engineer- in Jizan area ing geological problems of the sabkha soil (Dhowian et al. 1987; Dhowian 1990;Erol1989; Al-Shamrani and Dhowian to the heavy rainfall intensity which may happen during the 1997; Al-Mhaidib 2002; Youssef et al. 2012). However, none rainy storms, and the peak runoff flows from the East towards of these works tried to relate the behavior of the sabkha sed- West (Elsebaie et al. 2013). Abdelrahman (1997) found that iments to their mineralogy and sediment composition. the average temperature in Jizan area is 23 °C, the annual Therefore, the purposes of the present work are the examina- precipitation is 1.3 cm, and the average relative humidity tion of the sedimentary surface structures, microfacies analy- varies between 45 and 65 % in winter and 25 and 40 % in sis of the evaporite sediments, and distribution of the different summer. The annual mean rate of evaporation at Jizan is evaporitic basins in the sabkha area. The results of this paper 156 cm/year (Abdelrahman and Ahmad 1995). The prevailing may help in solving the problems of damage of the infrastruc- winds at Jizan blow from west during summer and southwest ture in the sabkha area and interpretation of the depositional during winter, with wind speeds ranging between 2 and setting and mechanism of formation of similar evaporite 50 km/h. These climatic data indicated the recharge of mete- sediments. oric water to the sabkha area during winter months and the deposition of evaporite minerals during summer months. Location and geologic setting of Jizan sabkha Jizan sabkha is located on the southeastern coastal plain Methods of study of the Red Sea of Saudi Arabia, between latitudes N 16° 44′ and N 16° 60′, and longitudes E 42° 32′ and E 42° 42′ The results achieved in this paper are based on the field (Fig. 1). The sabkha area occupies the lowest topographic works, trenches, cores, and thin sections. Ten-day field depression that gradually increases in height towards the trips were made to Jizan sabkha in August 2012 and east. Three topographic zones are defined in Jizan area, May 2013 for examining the surface features of the wet which run for approximately 1800 km parallel to each and dry parts of the sabkha. Several shallow trenches, up other in a NW-SE direction (Blank et al. 1987; Hussein to 150 cm in depth, that meet the water table have been and Loni 2011)(Fig.1b): (1) the dissected highland of excavatedinJizansabkha.Inthefieldwork,thesalinity, Hijaz-Asir Precambrian basement complex; (2) the central temperature, and pH values of the brines in the trenches plateau that slopes gently towards the Red Sea coast, dug in the sabkha were measured. The salinity was deter- which consists of the Cambro-Ordovician Wajid mined by hydrometer glasses taking into account the mea- Sandstone that rests unconformably on peneplained suring of standard sea water. The hydrometers measure Precambrian basement rocks (Powers et al. 1966); and the Mass % NaCl in the brine up to 25 %. The density (3) the Tihama coastal plain that forms a strip of land of the brine samples was measured by using two portable extending approximately 10 km to the foothills of the hydrometer glasses; the first measures density from 1.00 Red Sea escarpment. The coastal plain is covered with to 1.10 g/cm3 and the second measures density from 1.10 Quaternary aeolian sand, alluvial sand and gravel, loess, to 1.2 g/cm3. The pH value of the brine was measured in and flood plain silt deposits. Recent wet, sabkha sedi- the field by a portable pH meter. Seven PVC plastic tubes ments are widespread near the shore of the Red Sea have been drilled to a depth of 120 cm with a hammer to (Fig. 1c). The prominent elevated relief (up to 50 m in extract core samples (Fig. 1d). The evaporite sediments height) on the coastal plain is a salt dome at the old city were selected for preparation of thin sections from the of Jizan, which has an area of 4 km2 (Fig. 1c). surface, trenches, and cores in the sabkha area. The wet and loose sediment samples were dried in the oven and impregnated with epoxy resin. The thin sections were Climate prepared under dry cool condition using paraffin oil and epoxy cement in the laboratory of Cairo University. Jizan area has a subtropical desert climate, where several Petrographic examination and mineralogic identification ephemeral wadi systems drain to the shelf (Abdelrahman of 51 thin sections were investigated by Meiji polarizing and Ahmad 1995). Jizan city is characterized by rainfall microscope adapted with digital camera. The relative storms which vary in intensity and duration. The southern part abundance of the siliciclastic components in thin sections of the city is sometimes exposed to the risk of flash flood due was made in relation to a comparison chart. Arab J Geosci (2015) 8:9973–9992 9975 E 42° 30´ 25 E 42° 34´ E 42° 38´ E 42° 42´ 5 B Jizan 24 C A C Duba NORTH 23 N 16° 58´ EGYPT SUDI ARABIA SAUDI ARABIA 21 22 4 Jeddah RED SEA 20 RED 19 SUDAN SEA 3 Jizan 16 17 0 250 km 18 N 16° 54´ Y YEMEN Ji 15 26 6 14 7 13 Quaternary surficial deposits N 16° 50´ RED SEA Pleistocene basalt 11 12 Mesozoic & Paleozoic sedimentary rocks 10 Sediment sample Hijaz-Asir complex 7 Core location (JZ-7) 2 8 10 9 N 16° 46´ 7 Granite pluton Wet mudflat/sandflat 1 4 Al 6 Proterozoic rocks 3 5 0 3 km Dry sandflat 2 Salt dome 1 JZ-1 JZ-2 JZ-3 JZ-4 JZ-5 JZ-6 JZ-7 D Clastic gypsum Microbial filaments 10 cm Rosette gypsum Shell fragments Lenticular gypsum Poikilotopic gypsum Sand & mud layers 0 Mud Anhydrite nodules Sand Gypsum nodules 9976 Arab J Geosci (2015) 8:9973–9992 Discussion The cap rocks of the salt dome are gypsum, anhydrite, dolo- mite, shale, and sandstone layers (Fig.
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