Examples of Shelf to Basin Modern Turbidite System Depositional Patterns in the Gulf of Mexico: Potential Analogues for Subsurface Petroleum Systems

C. H. Nelson¹, John E. Damuth², Hilary C. Olson³, David C. Twichell⁴, and Carlota Escutia^5
1University of Granada, Spain and University of Texas at Arlington, Arlington,, TX
²University of Texas at Arlington, Arlington, TX
³Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX
⁴U.S. Geological Survey, Woods Hole, MA
⁵Instituto Andaluz de Ciencias de la Tierra, University of Granada, Granada, Spain

A variety of depositional patterns have been observed in modern turbidite systems of the northern Gulf of Mexico continental margin. Our study utilizes high-resolution seismic profiling, side-scan sonar, swath bathymetry and cores. Bryant Canyon mini-basins exhibit patterns of: 1) MTD’s consisting of wedges of chaotic mud and sheets of chaotic mud and sand, 2) incised, ponded and perched turbidites, and 3) bypass channelized facies. Modern submarine fans exhibit three typical distributary channel patterns: braided channel system (Rio Grande Fan), single un-bifurcated channel with distal lobe (Bryant Fan), and multiple bifurcated and splayed channels (Mississippi Fan). The multiple canyons that provide coarse-grained sediment from adjacent mountain sources result in the braided channel pattern in the surface and subsurface of the sand-rich Rio Grande Fan. The more sandy Western Ancestral Mississippi shelf margin delta and the mini-basin pathway of Bryant Canyon, which traps mud, have caused single aggrading channels that extend 200 km across the sand/mud-rich Bryant Fan to feed single distal depositional lobes of ~ 30 km in length. The muddy Mississippi River source of the late Pleistocene has resulted in multiple mid-fan channel bifurcations and outer fan channel splays in distal lobes of the mud-rich Mississippi Fan. Splays and distal lobes are composed of half MTD and half turbidite deposits in contrast to the predominantly turbidite deposits in Rio Grande and Bryant Fans. These depositional patterns and seismic facies suggest that: 1) similar mini-basin depositional patterns are common in modern and subsurface systems across the northern Gulf of Mexico slope, 2) the Rio Grande patterns may be analogues for some Paleogene subsurface systems, and 3) the Bryant mini-basin and fan patterns provide analogues for the Miocene systems in the Mississippi Canyon area.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas