Quaternary coral reefs of the Red Sea coast, Egypt: diagenetic sequence, isotopes and trace metals contamination
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ORIGINAL PAPER
Quaternary coral reefs of the Red Sea coast, Egypt: diagenetic sequence, isotopes and trace metals contamination Abdelbaset S. El-Sorogy & Hamdy Nour & Emad Essa & Mohamed Tawfik
Received: 9 September 2012 / Accepted: 11 December 2012 # Saudi Society for Geosciences 2012
Abstract This study focuses on the diagenetic sequence under marine and meteoric conditions as well as isotopes and trace metals contamination in Quseir and Gebel Zeit areas along the Egyptian Red Sea coast through a series of modern and fossil corals, Porites lutea and Favites pentagona. The diagenetic sequence begins with deposition of thin fringes of syntaxial aragonite and micritic high-magnesian calcite in the modern corals to completely altered Porites and partially altered Favites to low-magnesium calcite in the oldest Pleistocene unit. Average δ18O and δ13C values of Pleistocene corals in the two studied areas were lower than those of modern corals. Values of modern corals and lower fossil unit indicated coralline limestone, while those of middle and upper fossil units indicated fresh water influences. Average values of trace metals in modern corals were higher than those of Pleistocene counterpart except for Mn. Modern coral samples recorded enrichment in the average values of Pb, Zn, and Mn at Quseir area and enrichment in Co, Cu, and Ni at Gebel Zeit area. This may be attributed mostly to different tourist activities, landfill due to increase urbanization and nearby of Quseir area from the old phosphate harbor at El Hamrawin area, as well as oil exploration and production activities in the Gulf of Suez area. Also, results indicated that most samples of Porites have high concentration of trace metals than in Favites, especially in Cu, Zn, Mn, and Pb. A. S. El-Sorogy (*) Department of Geology and Geophysics, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia e-mail: [email protected] A. S. El-Sorogy : H. Nour : E. Essa : M. Tawfik Geology Department, Faculty of Science, Zagazig University, Zagazig, Egypt
This may due to high amounts of intergranular porosity and high total surface area of Porites in contrast to Favites. Keywords Diagenesis . Isotope analysis . Trace metals . Quaternary . Coral reefs . Red sea coast . Egypt
Introduction In their review on the geology of coral reefs in the Red Sea, Behairy et al. (1992) summarized the pressures affected coral reefs are increasing the human activities in the coastal areas, such as, urbanization, industrialization, and growing tourist industry as well as oil spills and untreated sewage from urban areas. Much of the extensive works on Quaternary reef sequences have been focused on their fossil record, trace and heavy metals, ecology, diagenetic features, and depositional history (James and Ginsburg 1979; Macintyre and Marshall 1988; ElSorogy 1997a, b; Bastidas and Garcia 1999; Abd El-Wahab and El-Sorogy 2003; Braithwaite and Montaggioni 2009; Gopinath et al. 2009; Kumar et al. 2010; El-Sorogy et al. 2012). Description of changes in Quaternary sequen
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