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Quantification of Factors That Influence Carbonate Platform Growth and Demise Using Forward Sediment Modelling

Hughes, Tina 1; Simo, Toni 1
1 URC, ExxonMobil, Houston, TX.

Within Southeast Asia, Tertiary carbonate platforms exist as a variety of scales and styles; some initiate as singular mound features which coalesce to form large-scale amalgamated features with others being more aggradational or progradational in nature. Efforts directed at understanding the relative influence of processes on the growth and demise of carbonate platforms has the potential to assist in carbonate exploration.

It is widely accepted that many factors influence the growth and ultimate demise of carbonate platforms. These factors include tectonism, sea level amplitude and frequency, carbonate productivity, climate and sea water chemistry, which vary laterally in the modern environment and temporally in the ancient. CARB3D+ is a forward sediment modelling program, developed at the University of Bristol, which can be used to quantify changes form many of these parameters in an attempt to de-convolve the impact of these processes on carbonate platform growth and demise. The controls investigated using sensitivity analyses are tectonic subsidence and sea level amplitude, both of which influence the accommodation space, production rate and maximum production depth, as a function of the health of the carbonate system and capacity of the biota to calcify and finally surface dissolution rate has also been investigated in relation to climate. The analysis reveals that surface dissolution rate has a subtle impact on carbonate growth at low subsidence rates, due to greater periods of exposure and dissolution, however, this impact diminishes with increasing subsidence. Carbonate production depth becomes increasingly important for carbonate growth with increasing sea level amplitude. At low sea level amplitudes, the rate of accommodation change is subtle and the platform is able to keep up with slow increases in accommodation. However with increasing rates of accommodation, the water on the platform rapidly becomes deeper and in situ carbonate production ceases with shallow production depths. Sensitivity analysis can enhance our understanding of the interactions between various parameters that influence carbonate platform growth and therefore, could be beneficial for exploration in data-poor areas.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009