During the previous highstand, the Colorado and Brazos rivers constructed extensive deltas on the continental shelf. During the early highstand (Stage 5)as sea level gradually fell, these deltas prograded seaward in search of accommodation space. Platform borings indicate that the Brazos delta is strongly mud-dominated, whereas the Colorado delta contained sands, but the size and distribution of these sand bodies is poorly constrained due to a paucity of platform borings in the western portion of the study area. During the late highstand (Stage 3) both rivers constructed more lobate, fluvial-dominated deltas with radiating distributary channels and associated sandy mouth bars. The reasons for the shift from more muddy Brazos delta facies to more sandy facies between the early and late highstands is currently under investigation. Ongoing research should also lead to maps of the mouth bar sand bodies. For a more detailed discussion see Abdulah et al (2004).

Seismic Example

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