LI, Y. Y., and * IAN LERCHE, University of South Carolina, Columbia, SC; and M. A. PERLMUTTER, Texaco, Houston, TX

ABSTRACT: Global Cyclostratigraphy - A Model of Carbonate Growth Patterns

Cyclostratigraphy is the study of cyclic depositional patterns produced by climatic and tectonic processes (Perlmutter and Matthews, 1989). This paper describes a global scale quantitative cyclostratigraphic model which simulates carbonate growth patterns controlled by tectonic and climatic processes.

The model uses seven factors simulating the effects of physical and chemical environments on the deposition rates of carbonate accumulations. These factors are sea level change, the rate of basement subsidence, food supply (influence of nutrient), available sunlight, temperature, salinity, and dissolved oxygen. The factors are considered as functions of climatic and tectonic processes. The model also integrates Milankovitch induced, short-term, climatic changes with the long-term, tectonic evolution of basins to examine the potential carbonate accumulation patterns.

The two dimensional computer model results provided here show that: (1) carbonate growth patterns in different climates and under different tectonic processes can be modeled quantitatively; (2) carbonate production increases toward the equator (latitude decreasing) due to both the temperature and nutrition supply increasing in tropical belts, and production changes because of the tropical belt expansion or contraction in different climatic periods; (3) when matched with the turbidity, the model describes different carbonate accumulation patterns in different climatic patterns; (4) at either abnormally high or low salinity, carbonate accumulation rates decline sharply, and the salinity becomes normal away from the strand line; and (5) cyclic sea level changes cause a cyclic change of c rbonate accumulation.

A case study is presented from the Texas Upper Pennsylvanian. The simulation results indicate that carbonate growth patterns observed from field, well or seismic data are accurately modeled by the quantitative procedure given here.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.