N. Jb. Geol. Paläont. Abh. 270/2 (2013), 129–149 Article Stuttgart, November 2013 Cambrian ichnofossils from northeastern Egypt Olaf Elicki, Mohamed Abdel Ghany Khalifa, and Sherif Mohamed Farouk With 5 figures and 1 table Abstract: New finds of ichnofossils from the Cambrian Araba Formation are described from the Eastern Desert and Sinai Peninsula (northeastern Egypt), and recent knowledge on Cambrian ichno- fossils from these regions is summarized. Five ichno-assemblages from Sinai Peninsula and two from the Eastern Desert represent ichnocoenoses of low diversity, dominated by arthropod and vermiform traces. The assemblages are attributed to the Cruziana and Skolithos ichnofacies realms of a tidally influenced, marginal marine to probably freshwater affected depositional area. Based on the oc- currence of Cruziana salomonis (Seilacher, 1990) and Rusophycus burjensis hofmann, mángano, elicki & Shinaq, 2012, an early Middle Cambrian age (basal stage 5 of series 3) can be deduced. The Cambrian ichnofauna of northeastern Egypt points to close palaeogeographic affinity with the Jordan Rift Valley (southern Dead Sea and northern Wadi Araba). In contrast to this latter area, the sedimentological character of the northeastern Egyptian Cambrian succession indicates a somewhat more proximal position on the northern Gondwana shelf relative to that interpreted from depositional conditions documented for the Jordanian Cambrian in the central to southern Wadi Araba. Key words: Cambrian, Palaeozoic, Araba Formation, ichnofossils, Egypt, Eastern Desert, Sinai Pe- ninsula. 1. Introduction 2011, and below). The Cambrian sediments of Egypt are represented exclusively by siliciclastic rocks, so the Egypt represents an area that is not only important impetus of investigations was not only on their strati- due to its renowned cultural history and iconic land- graphic context, but also on characterisation of the marks, but also for its geological endowment. Mineral depositional facies for which the included ichnofossils and hydrocarbon resources, as well as water manage- have a particular potential. ment play a crucial role in the region (Said 1990). Ichnological data – and palaeontological infor- Knowledge of the geology of Egypt – and also of its mation in general – are rather rare for the Cambrian Cambrian succession which is of particular interest succession of Egypt (klitzSch 1990a). Seilacher here – mainly results from extensive geological map- (1990) reported some ichnofossils from the Eastern ping activities and hydrogeological and hydrocarbon Desert about 30 km south of the fossiliferous localities exploration during the last few decades (klitzSch et documented herein, and some further material from al. 1984; klitzSch1986; Said 1990; tawadroS 2001, the Umm Bogma area of southwestern Sinai Penin- 2012). Regarding the earliest Palaeozoic rocks it was sula (Tab. 1, Fig. 1). Further palaeontological infor- not until the 1980s that a Cambrian age was confirmed mation was provided by andrawiS et al. (1983) and in specific cases by palaeontological data (see wanaS el dakkak (1988), who mentioned the occurrence of ©2013 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany www.schweizerbart.de DOI: 10.1127/0077-7749/2013/0358 0077-7749/2013/0358 $ 5.25 eschweizerbart_xxx 130 O. Elicki et al. Fig. 1. Regional geographic map (1a) and scheme of location of sections (1b, indicated in 1a by black rectangle) investigated in this study. For coordinates of ichnofossil sites see text. Modified from Mountain High Maps 2.1 (Digital Wisdom, 1996). eschweizerbart_xxx Cambrian ichnofossils from northeastern Egypt 131 Table 1. Ichnofossils reported from Cambrian successions of Egypt. klitzSch (1990a) and Present study Seilacher (1990) Eastern Sinai Eastern Sinai Desert Peninsula Desert Peninsula Rusphycus aegypticus (Seilacher, 1990) ••• Rusophycus burjensis hofmann, mángano, elicki & Shinaq, 2012 • • Cruziana salomonis (Seilacher, 1990) •• • Cruziana isp. • Diplichnites isp. • Dimorphichnus quadrifidus Seilacher, 1990 • Dimorphichnus cf. quadrifidusS eilacher, 1990 • Dimorphichnus cf. obliquus Seilacher, 1955 • Bergaueria sucta Seilacher, 1990 • ?Bergaueria isp. • Diplocraterion isp. • Arenicolites isp. • Teichichnus rectus Seilacher, 1955 • Skolithos isp. •• Palaeophycus tubularis hall, 1847 •• Planolites montanus richter, 1937 • Fucusopsis isp. • Helminthopsis tenuis kSiążkiewicz, 1968 • isp. indet. (?Dydimaulichnus, ?Archaeonassa) • biomat structures • brachiopods and single trilobites from two cored drill- This record must be considered dubious because nei- holes in the Western Desert that indicate a Cambrian ther klitzSch (1990a) nor two of the present authors age (possibly Middle Cambrian, G. geyer, Würzburg, (O.E and S.M.F. in 2010) were able to relocate either personal communication 2013). The same age is in- the type locality or any related lithofacies in the field, dicated by palynomorphs reported from the northern even though omara (1972) described both in detail. area of the Western Desert (gueinn & raSul 1986, Additionally, P.L. Brenckle (in keeley 1994) stated keeley 1989). According to klitzSch (1990a), a few that the ostensible archaeocyathan material of omara additional wells from northwestern Egypt have also (1972) probably represents Cretaceous/Palaeogene red intersected Cambrian sedimentary rocks, whereas ear- algae, and that Carboniferous strata lie directly on lier reports on the probable occurrence of Cambrian top of Proterozoic basement in the area considered by strata in southwestern Egypt were discounted by that omara (1972). Finally, F. deBrenne (personal commu- author. A report of archaeocyathans (a sponge group nication, 2013), one of the leading specialists on ar- almost exclusively restricted to the Early Cambrian) chaeocyaths, has clearly rejected the affiliation of the together with stromatolites from the Abu Durba area remains published by Omara to the Archaeocyatha). in southwestern Sinai was published by omara (1972). Summing up all these critical remarks by various au- If correct, this report would be surprising because ar- thors, the data and stratigraphic conclusions published chaeocyathans or favourable facies are not otherwise by omara (1972) must be dismissed. known from anywhere in the broader palaeogeograph- The objects of the present paper are to report new ic region (northeastern Africa, Middle East, Arabia). information on Cambrian ichnofossils from the East- eschweizerbart_xxx 132 O. Elicki et al. ern Desert and Sinai Peninsula of Egypt, to evaluate unconformable on basement, succeeded by the Araba their stratigraphic significance, and to extent know- Formation after a further unconformity (el-araBy & ledge of their palaeoecological and palaeogeographic aBdel-moteliB 1999). In western Sinai Peninsula and distribution. Field data were collected during two field in the Eastern Desert, the Taba Formation is missing trips (2009 and 2010) by the authors. The working area and the upper part of the Araba Formation rests direct- is located in the Eastern Desert (Wadi Mor, Somr el ly on basement rocks (Fig. 2A-B). The Araba Forma- Qaa, Jebel el Zeit) and on Sinai Peninsula (Wadi Sara- tion generally consists of fluviatile to shallow marine, bit el Khadem) (Fig. 1). cross-bedded sandstone, and minor conglomerates Illustrated specimens are housed in the collection of the (and a palaeosol) at its base and can be subdivided into Geological Institute of Freiberg University (archive number three major units: the lower unit consists of basal con- FG 630). glomerate and fluviatile, cross-bedded sandstone. The 2. Geological background middle unit is represented by shallow marine, dark red silt and fine sandstone (ichnofossil bearing unit, In Egypt, Proterozoic basement is mainly exposed in Fig. 2C-D). The upper unit is predominated by trough eastern Egypt as the Arabian-Nubian Shield and as cross-bedded sandstone. Altogether, the formation has small extensions of the older East Sahara Craton in the a thickness of up to 190 m. Detailed sedimentological southwest (klitzSch 1986; Schandelmeier et al. 1987; investigations of the Araba Formation in northeastern Said 1990). The region was mainly affected by the Egypt have been published by aBdel-wahaB et al. Pan-African Orogeny during formation of the Neopro- (1992) and khalifa et al. (2006). In the Eastern Des- terozoic Gondwana supercontinent, and by subsequent ert (Somr el Qaa), also fine-grained siliciclastic rocks extensional tectonics (Schandelmeier et al. 1987; Pet- (siltstone and shale) also occur (for details see tawad- terS 1991; Stern 1994; Boger & miller 2004; sum- roS 2012). mary in khalifa et al. 2006). Following amalgamation In contrast to the Cambrian, Egypt was a topo- of the Arabian-Nubian Shield and succeeding tecton- graphically positive area with no deposition during ics, several basins originated and subsequently filled nearly the whole of the Ordovician (klitzSch 1990a). during the Phanerozoic (e.g., klitzSch 1990b; keeley Sandstones were deposited only locally, in the very 1994; hawat 1997; guiraud 1999). southwest (Jebel Uweinat, klitzSch 1990a). Strati- Palaeozoic deposition commenced on the igne- graphic reports from petroleum companies and some ous and metamorphic basement, producing a distinct other reports on the occurrence of Ordovician strata erosional unconformity (Fig. 2A-B). Cambrian to Car- have been rejected by klitzSch (1990a) as represent- boniferous rocks are known from Sinai Peninsula, the ing rocks of either Cambrian or post-Ordovician