Introduction to Carbonate Facies, Depositional Environments, and Depositional Systems: Definition of Depositional Enviromnment

Introduction to Carbonate Environments, Facies, and Facies Tracts

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

Design Objectives

CONCEPT OF DEPOSITIONAL ENVIRONMENT

Reeckmann and Friedman (1982) defined depositional environment as “natural geographic entities in which sediment accumulates. They are characterized by sets of biological, physical, and chemical parameters. The interaction of these parameters produces different sediment types or facies. . . .”

Examples of depositional environments:

EXAMPLE 1. A platform-margin sand-shoal depositional environment is characterized by

(1) physical parameter: high-energy wave conditions;

(2) biological parameter: low biological activity because of the unstable shifting of sediment owing to waves and tides; and

(3) chemical conditions: common development of precipitated ooids.

Cat Cay platform-margin sand-shoal complex along the west margin of the Great Bahama Bank.

EXAMPLE 2. A platform-margin reef depositional environment is characterized by

(1) physical parameter: high-energy wave conditions,

(2) biological parameter: high biological activity because of abundant nutrients, and

(3) chemical conditions: common development of marine cements.

A well-developed platform-margin barrier reef offshore of southern Belize.