About This Item
Share This Item
Abstract
Gulf Coast Association of Geological Societies Transactions
Volume 54 (2004)
EXTENDED ABSTRACT: Relation Between
Holocene and Tertiary Normal Faults: A Comparison of Shallow Seismic and
Gravity Data with Deep Well Data Across the Baton Rouge Fault System, Northern
Gulf of Mexico Coast, Louisiana, USA
Lorenzo, Juan,1 Cazes, Carrie,1 Westbrook,
Clay,1 Lowrie, Allen,2 and Van Heerden, Ivor3
ABSTRACT
The Tepetate-Baton Rouge fault system traverses Louisiana
from west (Tepetate system) to east (Baton Rouge system), and continues east
and south of the Pearl River. This fault system is part of a larger, regional,
down-to-the-basin fault system along the northern Gulf of Mexico that extends
into eastern Mexico (Murray, 1961). Within our study area (Fig.
1) productive
hydrocarbon accumulations occur principally south of the Baton Rouge fault-line
scarp in deep (~5-10,000 feet) rollover structures, downthrown to the fault.
Immediately to the north of the fault there are no equivalent structural
traps. Shallow (<1000 ft) hydrogeology studies suggest that fluids can
migrate across the fault zone.
Extensive, but unpublished well data from oil and gas exploration
has generally suggested the existence of E-W striking subsurface growth fault
trends but correlation with much lesser studied near-surface faults is lacking.
By comparison, the location of shallow (< 1500 ft) growth faults, their
geophysical characterization and the natural moderators that control their
rates of movement in the southern Gulf Coast region are poorly known. We
show for the first time that fault-line scarps are parallel to subsurface
growth fault traces that are mapped within productive hydrocarbon intervals.
At depth, this fault system exhibits late Eocene to Oligocene synextensional
growth strata. Maps of surface, fault-line scarps (Durham, 1964; McCulloh,
1991 and 1996) indicate reactivation of these growth faults during at least
the Quaternary. New laser altimetry data (www.atlas.lsu.edu) (Fig.
1) helps
verify and modify prior interpretation of fault-line scarp locations.
Overlapping normal fault segments along the central Baton
Rouge fault system, in Livingston Parish, may develop ramps that serve to
divert local stream flow from a general N-S direction into a more NW-SE direction.
We use new, high-resolution gravity data (+/- .01 milligal), digital elevation
models (LiDAR, +/- 1 ft; Light Detection and Ranging), and borehole data
(<100 ft depth), to investigate the effects of ramp evolution on sediment
history. Associated shallow (<300 ft) sedimentary bodies can be discerned
in gravity models. Gravity data reveals there is no consistent spatial relation
between the northern limits of Bouguer gravity anomalies and location of
the fault-line scarp. However, gravity anomalies are probably associated
with denser (sand) elongated units oriented parallel-to-subparallel to the
strike of the fault-line scarp and within the overlap zone. Interpreted sand
bodies increase in width (~500-3,000 ft) and thickness (~150-250 ft) toward
the east where the fault offset and accommodation, created by the rollover
are expected to be larger. A fault zone ~300 ft-wide extends from the northern
fault-line scarp southward, as interpreted from high-resolution (~100-350
Hz), seismic data. Together with forced folds and late-stage multiple fracture
directions that are expected from competent rock models of overlapping normal
fault zones (Peacock and Sanderson, 1991), a complex sediment distribution
pattern is predicted.
Pay-Per-View Purchase Options
The article is available through a document delivery service. Explain these Purchase Options.
Watermarked PDF Document: $14 |
Watermarked Document A Watermarked Document is branded with the name of the original licensed customer to discourage unauthorized users from sharing the document outside the user's organization. The PDF is no longer restricted to one machine, but can be circulated to others in the same company or department. A Watermarked Document also can be printed for hard copy distribution internally but is not authorized for outside distribution nor posting on the internet. Users will not be able to cut-and-paste text or images from one document to another.
|
Open PDF Document: $24 |
Open Document An Open Document is a fully functional PDF that can be circulated (a digital copy or hard-copy printed documents) outside the purchasing organization. Purchase of an Open Document does NOT constitute license for republication in any form, nor does it allow web posting without prior written permission from AAPG/Datapages ([email protected]).
|
GIS Map Publishing Program