Introduction to Carbonate Facies, Depositional Environments, and Depositional Systems: Facies Tracts

Introduction to Carbonate Environments, Facies, and Facies Tracts

Robert G. Loucks, Charles Kerans, and Xavier Janson
Bureau of Economic Geology

Design Objectives

FACIES TRACTS PATTERNS

Facies tracts are distributed across a platform or ramp in response to physical, biological, and chemical processes. Distinct facies tract patterns form depending on the distribution and intensity of the processes. An example of a facies tract pattern across a modern leeward platform is presented below. Please note that “facies” is a concept for rocks, but in this section we apply it to modern environments in order to teach the concept.

At top: Photograph from space showing the area from Cat Cay platform margin on the left to Andros Island on the right. The facies tracts are labeled. Place cursor over photo to see a facies tract map showing the facies tracts of the platform. The alignment of the facies tracts across the platform produces a predictable pattern based on the processes affecting the platform. Projected below: a simplified topographic cross section across the platform showing the facies tracts.