Facies Analysis And Depositional Models Of The Surface Carbonate Succession In Abu Roash Area, North Western Desert, Egypt  

Abstract Category: Science
Course / Degree: Doctor of Philosophy in Science
Institution / University: Geology Department, Beni-Suef University, Egypt
Published in: 2010

Thesis Abstract / Summary:

The present study deals with the stratigraphy, the petrography, the facies analysis and the depositional models of the exposed carbonate succession in the Abu Roash area, north Western Desert of Egypt.

In the Abu Roash area, the sedimentary succession ranges in age from the Late Cretaceous to the Quaternary but is punctuated by several unconformity surfaces. The work focuses on the Santonian to the Upper Eocene rock units: the Khoman Chalk (Santonian-Middle Maastrichtian), the Giran El-Ful quarry beds (Paleocene-Early Eocene), the Sidr El-Khamis patch coral reef (Paleocene), the Mokattam and the Observatory formations (Middle Eocene) and the Wadi Hof Formation (Late Eocene). The Khoman Chalk comprises eight carbonate lithofacies. The Paleocene Giran El-Ful quarry beds and the Sidr El-Khamis patch coral reef consist of six carbonate lithofacies, while the Early Eocene beds and the Middle Eocene formations (Mokattam and Observatory) contain twelve carbonate lithofacies. The Wadi Hof Formation is composed of six carbonate lithofacies and four clastic lithofacies. The recognized lithofacies were deposited in variable depositional settings ranging from marine to marginal-marine grading locally to subaerial setting.

Thirty-five microfacies were recognized in the studied rock units. They are carbonates except five types are clastics that form the siliciclastic beds of the Upper Eocene Wadi Hof Formation. The carbonate microfacies were differentiated into twenty-one limestone and nine dolostone microfacies types.

The depositional model of each rock unit was deduced from the facies hierarchy of the obtained lithofacies. The facies sequence of the Santonian-Middle Maastrichtian Khoman Chalk is characterized by pelagic rhythmic bedding pattern in form of scouring upward cycles. The pelagic lithofacies were deposited in open-marine environments (middle to outer shelf) characterized by normal salinity, well oxygenated water, open circulation, moderate water depth and normal bottom conditions commonly below fair-weather wave base, but within the reach of extreme storm waves.
Some of the Khoman Chalk pelagic lithofacies were preferentially dolomitized. The dolostones and the hosted chalk are forming together several shoaling upward cycles. The geochemical characteristics of the studied dolostones including Oxygen and Carbon stable isotopes indicate marine environment for the Upper Cretaceous dolostones in the Abu Roash area. The dolomites are suggested to be formed by organogenic dolomitization at the sediment-water interface in marginal marine settings.

The facies sequence of the Paleocene rock succession at the Giran El-Ful quarry face consists of condensed pelagic lithofacies that was deposited on the inherited paleo-highs. The condensed pelagic lithofacies is overlain and eroded by calcirudites, which were moved downward onto the continental slope in form of debris flow channels. Remnants of small patch coral reefs are recognized indicating local growth on continental margin during the Late Paleocene.
The facies sequence of the Lower Eocene Giran El-Ful quarry beds and the Middle Eocene Mokattam and Observatory formations show that lithofacies are vertically arranged in shoaling upward cycles in a subtidal setting dominating in the middle to outer shelf. The association was resulted from repeated lateral shifting of the back-bank/ restricted lagoon, skeletal bank/ shoal and the fore-bank/ deep marine belts.

The facies hierarchy of the Upper Eocene Wadi Hof Formation infers shoaling of the depositional accommodation shifting to marginal-marine and subaerial settings.

Thesis Keywords/Search Tags:
Facies, Dolomite, Carbonates, Clastics, Microfacies, K/T boundary, Abu Roash

This Thesis Abstract may be cited as follows:

Badawy, H.S.M., 2010: Facies Analysis And Depositional Models Of The Surface Carbonate Succession In Abu Roash Area, North Western Desert, Egypt. PhD Thesis, Faculty of Science, Beni-Suef University, p 5.  

Thesis Images:
Science - Facies Analysis And Depositional Models Of The Surface Carbonate Succession In Abu Roash Area, North Western Desert, Egypt Arch Structure Related to Syrian Arc System in Gabal Abu Roash
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Submission Details: Thesis Abstract submitted by Hanan Badawy from Egypt on 09-Oct-2015 01:37.
Abstract has been viewed 2355 times (since 7 Mar 2010).

Hanan Badawy Contact Details: Email: h.s.badawy2000@gmail.com

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