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GEOREF RECORD

Processes of faulting in jointed rocks of Canyonlands National Park, Utah

Jason M. Moore and Richard A. Schultz
Processes of faulting in jointed rocks of Canyonlands National Park, Utah
Geological Society of America Bulletin (June 1999) 111 (6): 808-822

Abstract

Detailed studies of 11 segmented normal faults from five grabens in the Needles District of Canyonlands National Park, Utah, demonstrate key processes in the growth, linkage, and evolution of grabens. Field observations and stereophotogrammetry reveal a ubiquitous asymmetry in cross-sectional geometry, based on distinct map patterns of graben-bounding faults, rollover anticlines with attendant joint dilation, footwall uplift with joint closure, and spoon-shaped graben floors. Master and antithetic faults across Devils Lane and several other grabens are defined quantitatively by the displacement distributions along the faults. Two-dimensional shape parameters that characterize the displacement profiles indicate that inelastic processes such as changes in fault frictional strength influence strain accumulation along the faults. The degree of graben asymmetry increases systematically with distance from the Colorado River; greater symmetry is associated with locally greater age and/or strain of grabens nearer the river. Scatter in plots of maximum displacement vs. fault length was attributed previously to linkage of fault segments alone but is here shown to correlate additionally with distance from the Colorado River and, therefore, to spatial strain gradients within the graben array. Extensional strain across the fault array, accumulating at rates of perhaps 1.5 to 2 cm/yr or 10 (super -14) to 10 (super -13) s (super -1) , is accommodated at depth by salt flow and formation of reactive salt diapirs beneath the grabens and was probably initiated when the Colorado River had cut sufficiently deep into the section for active salt diapirism to commence.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 111
Serial Issue: 6
Title: Processes of faulting in jointed rocks of Canyonlands National Park, Utah
Affiliation: University of Nevada, Geomechanics-Rock Fracture Group, Reno, NV, United States
Pages: 808-822
Published: 199906
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Accession Number: 1999-037284
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
N38°00'00" - N38°30'00", W110°00'00" - W109°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199913
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