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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Geomorphologic, Stratigraphic, and Seismic
Visualization Analysis of Deepwater Deposits
By
Veritas Exploration Services
Detailed seismic-geomorphologic, seismic-stratigraphic, and
seismic vizualization analyses of 3D seismic data offshore
Indonesia, Nigeria, and the Gulf of Mexico reveal the presence of
extensive turbidite and debrite deposits. Key depositional elements
include: turbidity
flow
leveed channels, channel overbank
sediment waves, frontal splays/distributary channel complexes,
and debris
flow
channels, lobes and sheets. These depositional
elements will be described and the mode of formation discussed
within the context of deepwater sedimentary process and interaction
with local bathymetry.
Turbidity
flow
channel widths range from 2 km to less than 200 m.
Sinuosity ranges from moderate to high, and channel meanders
are observed to migrate in a down-system direction. High-sinuosity
channels are associated with extensive sediment
wave development in proximal overbank settings, especially in
association with outer channel bends. The long axes of these
sediment waves are oriented normal to the inferred direction of
turbidity flows. These sediment waves reach heights of 20 m and spacing of 3 km.
Overbank thickness decreases systematically down-system. Near to where overbank
thickness can no longer be resolved seismically, high-sinuosity isolated
channels feed low-sinuosity distributary channel complexes/frontal splays. Low
sinuosity distributary channel complexes are expressed as lobate sheets, in excess of 5-10 km wide and potentially tens of
kilometers long. Notably, they appear to be characterized by
channelized
flow
all the way to the edges of these systems.
Debris deposits are in the form of low-sinuosity channel fill, narrow
elongate lobes, and sheets. These deposits are characterized
seismically by a contorted, chaotic seismic facies that commonly
overlies a striated/grooved pavement. These striations/grooves
can be up to tens of kilometers long, 15 m deep, and 25 m wide.
In areas where flows are unconfined, striation patterns suggest
that divergent
flow
is common. Within the constraints of the
seismic data coverage, the debris deposits extend as far basinward
as the turbidite deposits. Individual debris
units
reach
80 m in thickness.
Examples utilizing different visualization techniques will be presented. Other examples and techniques will also be shown by Veritas Exploration Services in the Vendor's Corner during the social hour.
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