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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Physiographic Controls on Submarine Fan
Development within Depositional Sequences
By
BP Upstream Technology Group
501 WestLake Park Blvd.
Houston, Texas, 77079
Depositional sequences with distinct depositional relief can
occur on the craton and continental shelf, as well
as along
the continental margin. This depositional topography can
occur along
sequence
boundaries (erosional), within sequences
(constructional), or as abandoned (relict) physiography.
Detailed
analysis
of the depositional topography associated with
sequences deposited in a variety of tectonic settings reveals that
neither the presence of depositional relief or proximity to the
continental margin explains basin-floor fan development within
sequences. However, in the data sets studied the magnitude of
the depositional relief along
sequence
boundaries can be used to
explain and predict basin-floor (low-stand) fan development
within sequences.
Integration of published seismic, well
-
log
, and outcrop data
from the Cretaceous and Tertiary of the U.S. Gulf and Atlantic
coasts, offshore Australia, Norway, Russia, as
well
as the Triassic
through Tertiary of the Alaskan North Slope, suggests that three
distinct types of depositional sequences (Low-, Moderate-, and
High-relief) can be defined. Low-relief sequences lack clinoform
development. These sequences typically have slopes of less than
0.5 of a degree and depositional relief of less than 50 meters
(150') along
sequence
boundaries. Low-relief sequences, which
are common in cratonic basins, lack basin-floor low-stand fans.
Moderate-relief sequences display distinct clinoform development,
have slopes of 0.5 to 3 degrees, and display depositional
relief of less than 150 meters (500') along
sequence
boundaries.
These Moderate-relief sequences are common in foreland basins
and on continental shelves. Moderate-relief sequences also lack
low-stand fans. High-relief sequences display slopes of 2-5
degrees and depositional relief greater than 150 meters (500')
along
sequence
boundaries. These High-relief sequences typically
occur along the continental margins, but can occur in foreland
and rift basins. High-relief sequences contain low-stand fans.
These observed relationships suggest that there is a Critical Shelf Break that controls slope stability or failure during relative sea-level falls. In basins where the depositional relief is less than the Critical Shelf Break, progradation continues during relative sea-level falls. The resulting Low- to moderate-relief sequences lack basin-floor (low-stand) fans. In basins where the depositional relief is greater than the Critical Shelf Break, slumping, canyon formation, fluvial capture, and sediment bypass occur during relative sea level falls. The resulting High-relief sequences contain basin-floor (low-stand) fans. In the data sets studied, it appears that the Critical (Erosional) Shelf Break occurs with erosional depositional relief of 150-180 meters (500-600') in clastic systems.
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