Contribution to Book
Fault architecture, linkage and internal structure—field examples from the Iron Wash fault zone, central Utah,
The San Rafael Swell and Henry Mountains Basin—Geologic Centerpiece of Utah
(2013)
Abstract
The northeast-striking Iron Wash fault zone is part of a complex deformation zone that extends
approximately 25 km through the San Rafael Swell in central Utah. This fault zone consists of multiple
fault segments that likely formed during the Neogene. The fault terminates in the San Rafael
monocline, which is characterized by Mesozoic and Paleozoic rocks deformed by Laramide compressional
tectonics and subsequently Neogene extensional tectonics related to uplift and extension of the
Colorado Plateau.
Field mapping and observations are used to characterize the geometry, kinematics, and architecture
of the Iron Wash fault zone with observations covering structural overprinting, fault-zone
architecture, and fault propagation and linkage structures. Data and observations demonstrate that
overall fault zone thickness commonly increases with structural complexity, particularly in areas of
structural intersection, fault relay zones, fault-related folding, and fault tips. Analysis of the internal
fault architecture of relay zones and fault lenses reveals that a higher density of small-faults (meters of
slip) and denser fracturing are present in relay zones than in areas with a single, discrete fault strand.
Asymmetrical fault propagation folds (monoclines) have amplitudes of up to ~20 m and generally
parallel the strike of the fault. These folds become increasingly complex in areas of fault relays and
lenses. Field analog studies such as this contribute to our understanding of fault linkage and propagation
mechanisms, development of fault damage zones and lens-structures, and the sealing nature of
faults related to migration of fluids in the subsurface.
Keywords
- Fault zone,
- utah
Disciplines
Publication Date
2013
Editor
Morris, T.H., and Ressetar, R.
Publisher
Utah Geological Association
Citation Information
Richey, D.J., and Evans, J.P., 2013, Fault architecture, linkage
and internal structure—field examples from the Iron Wash fault
zone, central Utah, in Morris, T.H., and Ressetar, R., editors,
The San Rafael Swell and Henry Mountains Basin—Geologic
Centerpiece of Utah: Utah Geological Association Publication
42, p. 91-112.
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