Calcareous nannofossil biostratigraphy of the marine Oligocene and Miocene succession in some wells in Northern Egypt
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ORIGINAL PAPER
Calcareous nannofossil biostratigraphy of the marine Oligocene and Miocene succession in some wells in Northern Egypt Mahmoud Faris 1 & Hassan El Sheikh 2 & Fatma Shaker 2
Received: 6 July 2015 / Accepted: 28 March 2016 # Saudi Society for Geosciences 2016
Abstract Twelve calcareous nannofossil biozones of Late Oligocene-Late Miocene in Northern Egypt were defined and correlated with their corresponding biozones in Egypt and other parts of the world. These are arranged from the top to base as Zone NN12, Zone NN11, Zone NN10, Zone NN8, Zone NN7, Zone NN6 Zone NN5, NN4, Zone NN3, Zone NN2 Zone NP25 and Zone NP24. In the present study (Boughaz-1 Well), the Late Miocene unconformably overlies the Middle Miocene. This unconformity surface is recognized by the missing of calcareous nannofossil zones NN7 to NN9. While, in North Sinai (Malha-1 Well), the Early/Middle Miocene boundary cannot be recognized, where the Middle Miocene unconformably overlies the topmost Oligocene, and it is defined by the missing calcareous nannofossil zones NN1 to NN4. Keywords Calcareous nannofossil . Oligocene . Miocene wells . Northern Egypt
Introduction In comparison to the widespread distribution of Paleocene to Eocene rocks in the Levant and the Middle East, Oligocene
* Fatma Shaker [email protected]; [email protected] 1
Department of Geology, Faculty of Science, Tanta University, Tanta, Egypt
2
Department of Geology, Faculty of Science, Benha University, Benha 13518, Egypt
strata are recorded from only a few outcrops of restricted extent. Within the Mediterranean coast and the Red Sea/Gulf of Suez regions, Oligocene exposures are patchy in occurrence. This is due to erosion, as a consequence of tectonically induced uplift, enhanced by a major mid-Oligocene global sea-level fall (Haq et al., 1988; Haq and Al-Qahtani, 2005). The Miocene succession in Egypt represents about 12 % of the total land surface (Ball 1952). Lying unconformably on the older rocks, they extend from near Cairo westwards across the northern part of the Western Desert into Libya. They are forming a plateau rising gradually to south and reaching height over 200 m. Also, they occur in hills to the east of Cairo, as well as, along both sides of the Gulf of Suez and near the Red Sea coast in both Egypt and Sudan (El-Heiny 1979). Several biostratigraphical studies have been done on this succession, (e.g. El Heiny and Martini 1981; Arafa 1982, 1991; El Heiny and Morsi 1992; El Sheikh 1995; Marzouk 1998; Sadek 2000, 2001; Mandur 2003; Marzouk and Soliman 2004; Abu Shama 2007; Faris et al. 2007, 2009; Soliman et al. 2012; Boukhary et al. 2012; Samir 2013; Hewaidy et al. 2014). This study aims (1) to investigate the distribution of the calcareous nannofossils and establish biostratigraphic zonation for the subsurface Oligo-Miocene rocks in five wells (Boughaz-1, El-Temsah-2, San El-Hagar-1, Bardawil-1, and Malha-1) and (2) to discuss some Neogene Stage boundaries.
Location and material A total of 138 subsurface ditch samples were co
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