2007 GSA Denver Annual Meeting (28-31 October 2007)
Paper No. 118-13Main Menu
Presentation Time: 1:30 PM-5:30 PM

CARBONATE CEMENTS AND HYDROGEOLOGY OF THE AL-UKAIR COASTLINES, SOUTHERN SHORELINES OF THE ARABIAN GULF: A SCANNING ELECTRON MICROSCOPIC STUDY

HUSSAIN, Mahbub, Tybrin Corporation, Edwards Airforce Base, California, Los Angeles, CA 93524-6630, mahbub.hussain.ctr@edwards.af.mil, AL-SHAIBANI, Abdulaziz M., Earth Sciences, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi Arabia, shaibani@kfupm.edu.sa, and KHANDAKER, Nazrul I., Natural Sciences Department, Geology Discipline, York College of CUNY, 94-20 Guy R. Brewer Blvd, Jamaica, NY 11451

The influence of water chemistry in carbonate cement mineralogy, more specifically, Mg/Ca ratio in crystal (polymorph) habit has been demonstrated by laboratory experiments. Bulk studies have indicated that calcite growth is inhibited through either step-blocking by Mg2+ adsorption and slow dehydration or enhanced mineral solubility associated with Mg2+ incorporation. Based on several studies, meteoric water, generally low in Mg/Ca ratio, would favor formation of equant crystals of calcite. On the other hand, marine waters marked by high Mg/Ca ratios would produce the elongate (c-axis) aragonite crystals. The southern shorelines of the Arabian Gulf stretching from the backdune/supratidal to the subtidal areas are characterized by systematic increase in the Mg/Ca ratio in pore-water. A scanning electron microscopic (SEM equipped with EDX) study of the carbonate sediments from Al-Ukair lagoon systems, south of Dammam, the capital of Eastern Province of Saudi Arabia, shows systematic variations in calcium carbonate mineralogy in response to the pore-water chemistry represented by different shoreline sub-environments. Considering the fact that the composition and crystal habit of the primary carbonate minerals have profound effects on the diagenetic evolution and reservoir quality of carbonate rocks and carbonate-cemented clastic rocks, if preserved in geologic records, such mineralogy should provide a better understanding of reservoirs deposited in similar settings.

2007 GSA Denver Annual Meeting (28-31 October 2007)
Session No. 118--Booth# 186
Involvement in Geological Research: Close Collaboration among the Faculty and Undergraduate and K-12 Students (Posters)
Colorado Convention Center: Exhibit Hall E/F
1:30 PM-5:30 PM, Monday, 29 October 2007

Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 328

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