Palynology and palynofacies of the Upper Cretaceous succession of the El-Noor-1X borehole, northwestern Egypt
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ORIGINAL PAPER
Palynology and palynofacies of the Upper Cretaceous succession of the El-Noor-1X borehole, northwestern Egypt Maher I. El-Soughier
Received: 9 September 2012 / Accepted: 11 December 2012 # Saudi Society for Geosciences 2013
Abstract Palynological and palynofacies analyses were carried out on some middle–upper Cretaceous samples from the El-Noor-1X borehole, northern Western Desert, Egypt. Palynological age has lead to a refinement of the original ages suggested by the drilling company. Upper Albian–Lower Cenomanian, Upper Cenomanian, and Turonian–Coniacian were recognized. The palaeoenvironment was interpreted on the basis of the ecological preferences of the palynomorphs. It was fluctuating between marginal to inner-middle shelf environment. Distribution of araucaroid pollen and xerophytes suggests that arid or semi-arid paleclimate prevailed during the deposition of the studied sediments. A warm tropical palaeoclimate is suggested on the basis of abundance of hygrophilous plants. Based on the recovered palynological organic matter, two palynofacies were recognized: palynofacies A for the Bahariya Formation, which suggests kerogen type III, and palynofacies B for the upper Bahariya and Abu Roash Formations, which suggests kerogen type IX. Data gathered from the theoretically estimated vitrinite reflectances, which are based on spore/pollen coloration, and visual pterographic kerogen analysis are used to define the source rock potentialities of the studied sediments. Keywords Cretaceous . Palynostratigraphy . Palynofacies . Depositional environment . Western Desert . Egypt
Introduction The northern part of the Western Desert, where the El Noor1X borehole was drilled (Fig. 1), was covered by shallow M. I. El-Soughier (*) Faculty of Science, Geology Department, Aswan University, Aswan 81528, Egypt e-mail: [email protected]
seas during most of its geological history (Said 1990). The stratigraphic succession of northern Egypt encounters several carbonate–clastic alternations that together with the enclosed secondary transgressive–regressive cycles constitute one of the elements of the Mesozoic–early Tertiary petroleum system of the Western Desert (Sestini 1995). Geological data from the Mesozoic strata of northern Egypt have contributed to a better understanding of transgression/regression cycles in this part of the African continent. Regressive and transgressive episodes were seen from the Albian period, as represented by a regressive phase in which a large part of the Western Desert received fluvial sediments coming from eroding basement to the south. The major transgression, which occurred in the late Lower Cretaceous (Albian) and continued throughout the Upper Cretaceous, represented the widest transgressive phase of the Cretaceous over the Western Desert, and resulted in the deposition of a thick marine section. During the Cenomanian a marine transgression covered northwest Egypt, where fluvio-marine deposits were accumulated (i.e., Bahariya Formation). Cenomanian seems to have been deposi
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