Active Salt
Tectonics and Its Effect on the Internal Architecture and Connectivity Between Minibasins Near the Sigsbee Escarpment, Gulf of
Montoya, Patricia1, Michael R.
Hudec2 (1) Anadarko, The Woodlands, TX (2) Bureau of Economic
Geology, Jackson School of Geosciences, The University of Texas at Austin,
Austin, TX
Three key factors controlled the
evolution and distribution of sediment-transport systems in lower slope minibasins: the rise of interbasin
salt massifs (caused either by shortening or minibasin
subsidence), variations in sedimentation rate, and the construction of leveed-channel systems. These factors were combined to
create a new dynamic-salt fill-and-spill model. This model differs from
published upper-slope models in that it not only considers variations in
sedimentation rate, but also includes the effects of mobile salt surrounding
the minibasins. The model also examines
multidirectional connections between proximal and distal minibasins.
This presents four connection styles between nearby minibasins.
These four styles of connections are: 1. No connection, in which sediments are
not transported between adjacent minibasins. 2. Wide
connection, in which suspended fine-grained flows spill over the downdip edge proximal minibasins
as run-out clouds through wide source areas. 3. Narrow connection, in which
flows are transported from a proximal to distal minibasins
through narrow zones by channel systems. 4. Bypass connection, in which
high-energy flows erode across chains of minibasins.
In the study area, the analysis showed that minibasin
sedimentation was strongly cyclical, with periods of low sedimentation
associated with drapes above each interpreted sequence boundary. As a result,
cycles in connection style were also identified, with drape intervals largely
shutting down channels systems. Drape intervals were therefore associated with minibasin isolation while connectivity was typically
reestablished later within each sequence.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California