About This Item
- Full text of this item is not available.
- Abstract PDFAbstract PDF(no subscription required)
Share This Item
The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Predicting Structural
Trap
Geometries
in Overthrust Belts
![Previous Hit](/data/images/arrow_left.gif)
![Next Hit](/data/images/arrow_right.gif)
By
ARCO Exploration and
Production Technology, Plano, TX
Trap
-forming
structures in
overthrust belts are
commonly characterized
by structural
complexity and poor
seismic data quality.
Therefore, seismic
data is usually insufficient
to constrain
the location and size
of potential structural traps. Geologic and
geophysical data, when combined with
structural modeling and balanced cross
section techniques can improve structural
interpretations and thereby reduce
trap
risk
for prospective structures.
Predictive models for interpreting structural
styles must incorporate key geometric
and kinematic characteristics observed in
well-constrained surface and subsurface
structures. Mechanical contrasts of key
lithotectonic units play an important role in determining the
type and geometry of fold-fault
relationships, such as
fault
-bend,
fault
-propagation, and detachment folds.
Lithotectonic packages with strong competency
contrasts, such as thick carbonate
units encased within thin shale units, result
in
fault
-bend folds and duplexes. Examples
of this structural style are found in the
Sawtooth Range in Montana, the Canadian
Foothills and the Southern Appalachians.
Moderate to low competency contrasts,
such as interlayered, thin-bedded sandstones
characterized by high flexural slip
efficiency, result in
fault
-propagation folds.
Examples of these styles are found in the
Polish and Romanian Carpathians. Overthrust
belts characterized by relatively
competent packages overlying weak shales
or salt typically result in disharmonic,
detachment folds with related accommodation
faults. Examples of this style are found
in the Dinaride, Zagros, and Jura fold belts.
Delineation of deep anticlinal traps typically involves the extrapolation of surface
and near-surface geometries to deeper
horizons. Trap
risks are related to changes
in the geometry, location, and size of structures
with depth. The relationship between
the geometries of deep targets and near-surface
horizons are dependent on the
structural model, structural disconformities
or changes in structural style. Therefore, a
good understanding of the mechanical
stratigraphy and its influence on structural
geometry is critical in delineating poorly-imaged
traps.
End_of_Record - Last_Page 9---------------