Facies and Facies Models

What is a facies? A sedimentary unit with consistent characteristics (lithology, grain size, texture, structures, etc.) that formed under specific depositional conditions. What are facies models? An idealized vertical succession of facies that would be expected from the migration of depositional environments within a particular setting (e.g., sandy braided river model, wave-dominated delta model).

Walther’s Law Rationale for interpreting vertical facies succession is based on Walther’s Law Vertical succession of facies represents migration of laterally adjacent depositional environments, unless there is evidence of erosion (unconformity)

Constructing a facies model: 1.Identify important surfaces (especially erosional)

Constructing a facies model: 2.Interpret facies using knowledge of sedimentary processes and modern environments

Constructing a facies model: 3.Determine characteristic vertical succession of facies