A Brief Introduction to Sequence Stratigraphy

The Sea Level Record

Highstand Deltas of the East Texas shelf

Main Surfaces 1. Sequence Boundary 2. Maximum Flooding Surface 3. Transgressive Surface

Systems Tracts

Seismic and Chronostratigraphy (Oxygen isotope stratigraphic analysis and biostratigraphic analysis used to relate surfaces and the systems tracts they bound to sea level curve)

Contrasts in Stratigraphic Architecture ( West Florida Margin (Steep, ramp-like profile, low subsidence, bedload -dominated rivers) 1. Sandy, late highstand deltas dominate 2. No lowstand delta/fan 3. Extensive transgressive sheet sand Western Louisiana/Brazos/Lagniappe Margins (Broad, low-gradient margins, moderate subsidence, high sediment supply rivers) 1. Dominance of late highstand deltas 2. Sands in channels and mouth bars 3. No lowstand fans East Texas-Trinity/Sabine Margin ( Broad, low-gradient margin fed by rivers with moderate sediment supply) 1. Re-incision of valleys results in significant shelf bypass and fan nourishment East Texas-Colorado Margin (Broad, low-gradient margin, moderate sediment supply) 1. Sands occur in late highstand, lowstand and transgressive deltas and in lowstand slope fans Central Texas Margin (Steep, ramp-like margin with moderate subsidence, rivers with low sediment yields) 1. Sands mostly confined to highstand and consist of strike-oriented shoreface deposits. 2. No lowstand deltas or fans South Texas (Rio-Grande) Margin (Broad, low-gradient margin with moderate subsidence) 1. Extensive, sandy highstand, lowstand and transgressive deltas and lowstand slope fan