Print this pageBryant Canyon/Fan and Rio Grande Fan Turbidite Systems: Shelf to Basin Modern Analogues for Productive Tertiary Mini-Basin Systems
John E. Damuth1, C. Hans Nelson2, and Hilary Clement Olson3
1Earth and Environmental Sciences, University of Texas at Arlington, Arlington, TX
2University of Granada, Granada, Spain
3Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX
The Western Ancestral Mississippi shelf-margin delta fed the Bryant Canyon/Fan Turbidite System primarily during the Marine Isotope Stage 6 glacial cycle. Multiple slope channels fed a chain of 15 fill and spill mini-basins with connecting canyons, and ultimately fed the Bryant Submarine Fan, which extends seaward from the Sigsbee Escarpment. The seismic facies of the Bryant mini-basins are similar to buried Miocene to Pleistocene mini-basins and consist of alternating ponded turbidites and mass-transport deposits covered by bypass channelized turbidites and thick wedges of muddy mass-transport deposits. The mini-basins are characterized by syntectonic activity, which typically begins midway through basin filling. The 400-km wide Bryant Submarine Fan consists of four channelized growth-stage units deposited in compensation cycles across the abyssal plain. Aggradational, leveed fan channels stack in the middle of each unit and end in separate distal lobes on the order of 30 km in length. Because scale, seismic facies and depositional style of the Bryant Canyon/Fan System are the same as those of productive Miocene canyon and fan systems in the Mississippi Canyon area, this system serves as an excellent analogue for these productive systems. In contrast to the Bryant System, the Rio Grande Fan was deposited on a continental-slope plateau in northwestern Gulf of Mexico and was fed by multiple slope canyons that provide coarse sediments to the fan via numerous distributary channels. These unleveed, incised channels, the seismic facies and the relatively steep fan gradient (1:250) suggest that the Rio Grande Fan is sand-rich and has a braided channel system. This fan appears to be an excellent modern analogue for plays such as the Wilcox and Frio.
AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas