--> --> Abstract: Variations and Consistencies of Depositional Patterns within one Sequence Across Three Structural Elements: Vicksburg Formation, Texas, by Janet M. Combes; #90914(2000)

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Janet M. Combes1
(1) consultant, Houston, TX

Abstract: Variations and consistencies of depositional patterns within one sequence across three structural elements: Vicksburg Formation, Texas

Regional correlation of the Vicksburg Formation across the Gulf Coastal Plain of Texas demonstrates effects of interaction between sediment influx and contemporaneous faulting within one eustatic sequence in the Early Oligocene. The depositional patterns developed in the lowstand, transgression and highstand systems tracks are present across Texas, but there are distinct variations of the patterns within each of 3 structural entities of the Texas coast. Within the Rio Grande Embayment, lowstand and transgressive deposition was intricately involved with synchronous “glide plane” growth fault episodes. Extremely thick sections of lowstand and transgressive deltaic and other paralic deposits form the prolific Vicksburg reservoirs of South Texas. Highstand deltas of the Rio Grande Embayment, also petroleum reservoirs, were affected by later Vicksburg growth faulting. Across the San Marcos Arch region of the central Texas coast, numerous smaller fields produce from Vicksburg deltaic depocenters. These deltas generally formed on the shelf landward of the growth faulted shelf margin; however, distal delta front sands and shales contributed to the progradation of the shelf margin. The deltas in the Houston Embayment built out to the shelf margin during both lowstand and highstand and fed sand-rich flows onto the upper slope where the coarser sediments frequently accumulated as slope-basin fill. Fields in the Houston Embayment produce from the deltaic section and from slope-basin sands. Knowledge of the Vicksburg depositional systems and their characteristics with the embayments and across the arch is vital in both production and exploration efforts.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana