Seismic Reflection Imaging of
Impact-Induced Faulting and
Deformation at Upheaval Dome,
Canyonlands National Park, Utah
J. N. Louie, Z. Kanbur,
S. Chavez-Perez, and G. Plank
Seismological Lab (174),
University of Nevada, Reno
Seismic imaging techniques applied to a reflection survey
show two phases of faulting and deformation beneath
Upheaval Dome, Utah. Recent work suggests Upheaval Dome may
be the largest impact structure on the Colorado Plateau,
having a ring syncline ~3 km in diameter. To better
describe the impact deformation of a brittle layer above a
viscous layer, as exists at Upheaval Dome with the
underlying Paradox Salt, four institutions conducted a
NASA-funded seismic reflection survey in January 1995. We
obtained a 5 km section extending radially from the Dome's
central depression using a 320 kg weight-drop source and a
48-channel off-end receiver spread 0.5 km long. The data
show clear reflections as deep as 1.5 km. Imaging of the
reflection section with velocity filtering and 3-d prestack
Kirchhoff migration techniques reveals the geometries of
deformed stratigraphy from the surface to the top of the
Paradox Formation at 1.2 km depth. Stratigraphic
terminations and fault-plane images show the paths of
listric faults. We tie our sections to two well logs, one
in the ring syncline and one outside the zone of
deformation. Deformation appears in two phases with respect
to depth, with listric normal faults in the ring syncline
and the megablock zone confined to the part of the section
above the Hermosa Formation. Listric faults flatten and
sole into the clastic formations above the calcareous
layers of the Hermosa at 1.0 km depth. At the base of the
Hermosa, on the axis of the ring syncline, the Paradox has
forced the Hermosa 0.1 km up and broken it with thrust
faults. Post-impact relaxation of the crater form may have
driven this deeper uplift. These two modes of deformation,
driven from above and below, leave the upper Hermosa as the
least-deformed part of the structure.
- Upheaval Dome may be the eroded remnant of the largest meteor impact
to the Colorado Plateau.
- The structure has long been thought of as a salt dome, but may be a rare
terrestrial example of cratering above a deformable layer.
- Seismic profiling was needed to constrain the presence of any salt diapir,
and characterize deformation within and above the Paradox Formation.
- A 48-channel reflection survey collected 10 m station and 40 m source intervals
along a 5 km profile both transverse and radial to Upheaval Dome.
- Univ. of Utah's 700-lb hammer source provided hits for
the reflection survey, and for refraction records across the center
of Upheaval Dome by PASSCAL RefTeks (
reported here 2 years ago).
- Dip-filtered reflection records show clear returns as deep as
the base of the Paradox Fm. at 2.5 km.
- 3-D pre-stack Kirchhoff migration aided imaging of faults and
- Reflector depths in the pre-stack migrations tie very well to an
acoustic log from the Ring Syncline, and a gamma log away from the structure.
- Section 1 shows listric faulting of the Central Uplift, and little
deformation of the top of the Paradox salt.
- Section 2 shows the normal faulting outside the Ring Syncline,
thinning the stratigraphy above the Hermosa Fm. in agreement with
- Stratigraphic uplift observed in the center of Upheaval Dome cannot
arise from Paradox salt diapirism.
Radial listric faulting into a transient cavity provides the uplift.
- The top of the Paradox is deformed up to 100 m vertically, but
the top of the Hermosa appears undeformed.
- There is no evidence of any salt diapir below the center of Upheaval Dome.
- Deformation was driven from above by the impact, as shown by listric
faulting above the Hermosa Fm.
- Subsequent gravitational relaxation of the crater form fractured the
Hermosa below the Ring Syncline and allowed some salt flow in the Paradox.
- This project was funded by the NASA Planetary Geology Program, and is a
collaboration with Jeff Plescia and Ken Herkenhoff of the Jet
Propulsion Laboratory, and Brian Kriens of C.S.U. Dominguez Hills.
- Eugene Shoemaker originally recognized the impact origin of Upheaval Dome.
- The staff of Canyonlands National Park helped us to mitigate any environmental
impacts of the geophysical surveys.
- Jerry Schuster of the Univ. of Utah provided the 700 lb hammer source
as well as the 48-channel reflection recording system.
- The Incorporated Research Institutions for Seismology provided the PASSCAL
recorders, and allowed crucial participation in the field by Marcos Alvarez
of the Stanford Instrument Center.