A Modern Analog Model for Shallow-water Tropical Carbonate Reservoir Systems in the Rock Record that Developed Under Adverse Photic Zone Conditions, Puerto Rico
Current carbonate models applied to the rock record are heavily influenced by studies of modern tropical systems, such as the Bahamas, which consist mostly of photozoan coral reef systems that develop in clear, warm water photic zone conditions. These models have biased interpretations of tropical carbonate systems in the rock record.
Although research on heterozoan-dominated systems has accelerated over the last two decades, we still lack understanding of controls on facies types and distribution, stratigraphic architecture, and reservoir character. The understanding of heterozoan-dominated systems in low-latitude tropical regions is especially lacking. They are increasingly being recognized in areas that are affected by excess nutrients and turbid water. In addition, some of these systems can contain abundant photozoans that are able to tolerate higher nutrients, more turbidity and reduced temperatures. To better understand these types of shallow-water tropical carbonate systems developed in the ancient, it is important to study modern analogs to develop models. Puerto Rico is chosen for study because it shows variable development of photozoan and heterozoan biota in shallow-water photic zone environments around the island as a result of natural and human-induced variations in nutrients, turbidity, water chemistry, energy and water temperature.
An initial phase of study is targeted at assimilating and mapping data already collected on the different types of heterozoan and photozoan biotic and non-biotic components and sediment, and to also relate those distributions to areas of land runoff, and oceanographic conditions for which data are available (e.g., water temperature, energy, currents, water chemistry). Those data will be used to identify areas for more targeted studies to further document, sample (e.g., to determine organic content, turbidity, and water chemistry), and map out component and sediment distributions and to determine the controls on development.
Overall goals of the study are to provide better understanding of the conditions affecting the coastal areas around Puerto Rico, and specifically map out and link differing carbonate system development (photozoan, heterozoan, or combination of both) around the island with the major factors responsible for the variability to develop predictive models that can be applied to the rock record.
