Seismic Stratigraphy – identifying the seismic sequence Objectives for the Day Seismic Stratigraphy – identifying the seismic sequence Describing the seismic sequence Basic seismic sequence identification exercise Tom Wilson, Department of Geology and Geography

Seismic Stratigraphy Seismic stratigraphy allows us to gain more accurate insights into sediment succession. Facies association rather than lithostratigraphy forms the basic architectural element. In the fluvial system we are interpreting at Stratton, the reflection events and the entire Frio interval represents a collection depositional environments including not only the channel sands (B48, C36, F11, etc.) but levee, overbank, flood sand sheets, … These intervals are simultaneously deposited and the reflection events do not represent lithologically distinct sedimentary packages. These genetically related packages of sediment are often separated by unconformities of one sort or another, and the identification of these unconformities in the seismic section forms the basis of seismic stratigraphy.

Sequence identification is based on Boundary Relationships Mitchum et al. (1976)

.. and internal configuration: parallel to sub parallel and prograding clinoforms

Seismic Sequence Characterization b. c. d.

Sequence mapping

Identifying Seismic Sequences Mitchum et al. (1976)

Chronostratigraphic Representations Generalized stratigraphic section of a sequence The depositional sequence - Genetically related strata bounded above and below by unconformities or correlative conformaties Generalized chronostratigraphic section of a sequence Mitchum et al. (1976)

Stratigraphic Sequences / Log Correlation Mitchum et al. (1976)

Sequence Deposition During Sea Level Rise Shoreline position during sea level rise is tied to terrigenous influx Vail et al. (1976)

Gradual vs Rapid Fall Mitchum and Vail . (1976)

Relative Sea Level Change Sea level variations appear throughout the range of temporal scales Vail et al. (1976)

Island Platform, Deep Water, Southern Bahamas

Baltimore Canyon, East Coast, US

National Petroleum Reserve, Alaska

Central Atlantic Shelf, near the Baltimore Canyon

to do's to be updated …