From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
Bureau Seminar, September 22, 2006
UAE Algal mats and lime muds: links to
Professor of Geological Sciences and Marine Science at the University of South Carolina
Whitings – Source of Black Gold?
Analysis of Holocene organic productivity data from Bahamian whitings demonstrates that as much as 25% of the 1.3 million metric tons precipitated each year is organic matter. Similarly Bahamian cores down to 1000m on the western slope of the platform preserve 1% TOC (up to 4%). This in turn suggests that these whitings-derived sediments may represent early stages of source rock formation.
It is proposed here that much of the hydrocarbons trapped in the Middle East were sourced from dispersed organic matter associated with whiting blooms of the geologic past. It has been shown recently that the contribution of cyanobacteria to oils is more than previously thought. The simple chemical composition and structure of cyanobacterial membranes liquefy at a threshold temperature. It has been argued that maturation does not require a time and temperature integral. Thus the low percentages of organic matter dispersed in the lime muds of the ancient Arabian Gulf section would be expected to generate a large volume of oil over a short time. This matches the published argument that a burst of oil generation would produce transient overpressures liberating oil by micro-fracturing and even long-range migration because of creation of fractures. This rapid accumulation of large volumes of oil in a short time would also provide the collective buoyancy necessary to drive large-scale migration. Thus it is possible that whitings of the modern Arabian Gulf are the key to the origin of the vast petroleum reserves found here.
References for this presentation
Collister, James, Robert Ehrlich, Frank Mango, and Glenn Johnson (2004), Modification of the petroleum system concept: Origins of alkanes and isoprenoids in crude oils AAPG Bulletin, v. 88, no. 5, p. 587–611