Localization of listric faults at thrust fault ramps beneath the Great Salt Lake Basin, Utah: Evidence from seismic imaging and finite element modeling

Gopal K. Mohapatra, Roy A Johnson

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Reflection seismic data from the Great Salt Lake Basin, Utah, show that the major basin-bounding normal faults decrease in dip from ∼60° at the surface to ∼10°-20° at depths as shallow as 4-6 km. This rapid decrease in fault dip at depths shallower than the brittle-ductile transition zone in the Basin and Range Province suggests an explanation other than a gradual change of rheology and stress orientations with depth. Using a dense grid of seismic data, gravity data, borehole data, and published geologic information from islands in the lake, we constrain the position of the Sevier age Willard thrust and a footwall imbricate and show their reactivation as normal faults during Tertiary extension. In the absence of surface geologic information, we use available subsurface information from the lake to draw an analogy with the Ogden duplex in the Wasatch Front, where Cenozoic normal faulting was superimposed on an earlier Sevier age thrust regime to give rise to listric normal faults. Our interpretations are consistent with finite element modeling results, which demonstrate that extensional slip on preexisting thrust ramps leads to the formation of energetically favored synthetic normal faults, some of which may merge with the thrust ramp and obtain listric geometries. Further slip on these listric faults gives rise to secondary synthetic and antithetic faults resulting in hanging wall grabens.

Original languageEnglish (US)
Pages (from-to)10047-10063
Number of pages17
JournalJournal of Geophysical Research: Space Physics
Volume103
Issue number5
StatePublished - May 10 1998

Fingerprint

Great Salt Lake (UT)
listric fault
saline lake
thrust fault
ramps
Catchments
thrust
normal fault
Lakes
Salts
Imaging techniques
lakes
modeling
dip
Faulting
seismic data
slip
Information use
Boreholes
ductile-brittle transition

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

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abstract = "Reflection seismic data from the Great Salt Lake Basin, Utah, show that the major basin-bounding normal faults decrease in dip from ∼60° at the surface to ∼10°-20° at depths as shallow as 4-6 km. This rapid decrease in fault dip at depths shallower than the brittle-ductile transition zone in the Basin and Range Province suggests an explanation other than a gradual change of rheology and stress orientations with depth. Using a dense grid of seismic data, gravity data, borehole data, and published geologic information from islands in the lake, we constrain the position of the Sevier age Willard thrust and a footwall imbricate and show their reactivation as normal faults during Tertiary extension. In the absence of surface geologic information, we use available subsurface information from the lake to draw an analogy with the Ogden duplex in the Wasatch Front, where Cenozoic normal faulting was superimposed on an earlier Sevier age thrust regime to give rise to listric normal faults. Our interpretations are consistent with finite element modeling results, which demonstrate that extensional slip on preexisting thrust ramps leads to the formation of energetically favored synthetic normal faults, some of which may merge with the thrust ramp and obtain listric geometries. Further slip on these listric faults gives rise to secondary synthetic and antithetic faults resulting in hanging wall grabens.",
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AB - Reflection seismic data from the Great Salt Lake Basin, Utah, show that the major basin-bounding normal faults decrease in dip from ∼60° at the surface to ∼10°-20° at depths as shallow as 4-6 km. This rapid decrease in fault dip at depths shallower than the brittle-ductile transition zone in the Basin and Range Province suggests an explanation other than a gradual change of rheology and stress orientations with depth. Using a dense grid of seismic data, gravity data, borehole data, and published geologic information from islands in the lake, we constrain the position of the Sevier age Willard thrust and a footwall imbricate and show their reactivation as normal faults during Tertiary extension. In the absence of surface geologic information, we use available subsurface information from the lake to draw an analogy with the Ogden duplex in the Wasatch Front, where Cenozoic normal faulting was superimposed on an earlier Sevier age thrust regime to give rise to listric normal faults. Our interpretations are consistent with finite element modeling results, which demonstrate that extensional slip on preexisting thrust ramps leads to the formation of energetically favored synthetic normal faults, some of which may merge with the thrust ramp and obtain listric geometries. Further slip on these listric faults gives rise to secondary synthetic and antithetic faults resulting in hanging wall grabens.

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