8/10/2019 5142 Facies

1/20

Sedimentation and StratigraphyGeology 5142

Dr. Thieme

Lecture 11: Facies and

Environments of Deposition

8/10/2019 5142 Facies

2/20

Facies

Sedimentary rocks or rockcharacteristics which indicate a

particular depositional environment

8/10/2019 5142 Facies

3/20

Walther's Law

The vertical succession of facies in astratigraphic column through timecorresponds to a lateral migration of those

facies over space (also referred to as-

8/10/2019 5142 Facies

4/20

Facies

Different sediments accumulate adjacentto one another at the same time

Sediment facies (lithofacies) differ in

those characteristics which indicate thedepositional environment

physical (i.e. sedimentological) chemical (salinity, pH, etc...)

The changes between adjacent lithofacies

tend to be gradual

8/10/2019 5142 Facies

5/20

Lithofacies

Lithofacies descriptions should include

sedimentary structures

dimensions (particularly thickness)

biogenic content (ooids, peloids, shells,

plant remains, etc... ) and its physicalcondition

composition (minerals, rocks, other sedparticles)

grain size

8/10/2019 5142 Facies

6/20

Biofacies, Ichnofacies

Facies may also be identified anddescribed based upon:

the latter are most likely to directly

coincide with the lithofacies identified

Trace fossils present in the rock

(ichnofacies)

Fauna and/or flora present at the timeand place of deposition (biofacies)

8/10/2019 5142 Facies

7/20

Facies Models

general enough to indicate depositionalenvironment, but

specific enough to be applied in theinterpretation of stratigraphic sections

typically combine lithofacies, ichnofacies,

and biofacies (where applicable) often define a lithofacies association

channel lag / overbank / buried soil are all

associated with "meandering stream" facies

8/10/2019 5142 Facies

8/20

8/10/2019 5142 Facies

9/20

Transgression (Onlap)

8/10/2019 5142 Facies

10/20

Regression (Offlap)

8/10/2019 5142 Facies

11/20

Depositional Environment

A geographic setting where sedimentis accumulating

Determines the nature of thesediments that accumulate (grain

size, grain shape, etc.)

8/10/2019 5142 Facies

12/20

8/10/2019 5142 Facies

13/20

8/10/2019 5142 Facies

14/20

Sedimentary Environments

Transitional (shoreline) Tidal flats

Lagoons Deltas

8/10/2019 5142 Facies

15/20

Transitional (Shoreline) Environments

Sedimentary structures tell us where we are on

the transect from mean high water across theshoreface to offshore depositional environments

8/10/2019 5142 Facies

16/20

8/10/2019 5142 Facies

17/20

Calcite Compensation Depth (CCD)

8/10/2019 5142 Facies

18/20

8/10/2019 5142 Facies

19/20

Photic Zone -Photosynthesis bymarine plants andalgae in the upper

part of the watercolumn providesfood for organismsthat build shells and

skeletons depositedin limestones on thesea floor.

8/10/2019 5142 Facies

20/20