Characterization of the Campanian-Maastrichtian Sudr Chalk, Gabal El Bruk, North Sinai, Egypt

Hatem Hassan,Mohamed Abouelresh

doi:10.21608/jpme.2018.37460

Abstract

The Campanaian – Maastrichtian Sudr Chalk of Gabal El Bruk subdivided into two members, the lower Markha and the upper Abu Zemina members. Nine biostratigraphic zones (CF13-CF2) have been identified from the planktonic foraminiferal content. The qualitative and semi-quantitative analysis of the foraminiferal parameters revealed the predominance of Midway type fauna over the Velasco type fauna in the Campanian indicating that the Sudr Chalk was deposited on the continental shelf. The benthonic fauna show an intermediate value between Velasco-type fauna and Midway type fauna indicating an increase in water depth from the continental shelf during the Campanian to lower slope during the Maastrichtian time. Two microfacies associations have been identified from the petrographic analysis of the Sudr Chalk in the study area. Foraminiferal micrite (wackstone) and fossiliferous mudstone (mudstone) revealing the deepening upward from Markha to Abu zenima member.The study area was affected by both sea level fluctuations as well as tectonic instability due to the Syrian arc system from Middle Campanian upward. The total organic carbon (TOC) ranges between 0 to 3.8 %. This variation is controlled by lithology, faunal content, sedimentation rate as well as depositional environmental conditions. There are three intervals of maximum TOC within the studied Sudr Chalk which indicates a fair to good source rock (CF2, CF5+CF6 and CF12).

Highlights

The Upper Cretaceous sea level encroachment over North Sinai was marked by shallow marine to basin sediments
Numerous papers in the literature have dealt with the Sudr Chalk in many aspects among them, 12-20.Cherif et al [21] suggested continuous open marine sedimentation prevailed from the Late Campanian to the Late Maastrichtian based upon the foraminiferal content, and Shahin [22] assigned a middle neritic environment to the Sudr Chalk
The term velasco-type "fauna" (VF) was suggested by Berggren and Aubert (1975) for a lower continental slope and abyssal plain fauna, which counterpart the Midway-Type "fauna" (MF) typically represent the continental shelf .According to distribution models of microfauna and semiquantitative analysis (% of Planktics (Pl %) and Pl./b ratio) of the foraminiferal assemblages (Fig. 6).The following is a detailed discussion of the paleoecological interpretation and the depositional environments of the studied Sudr Chalk based upon foraminiferal data

Summary

Introduction

The Upper Cretaceous sea level encroachment over North Sinai was marked by shallow marine to basin sediments. Among these sediments is the Sudr Chalk which deposited generally within deep marine conditions due to the presence of synclines formed as a result of the Syrian-arc system of Krenkel [1]. It is represented by persisting facies almost all over North Sinai such as chalk, chalky limestone or even argillaceous limestone. It attains a total thickness of 50.8m as investigated through two profiles 1 and 2, Fig. 1

Materials and Methods

Depositional Environment and Paleobathymetry

Markha Member

Findings

Hydrocarbon Potential