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Onset of slip partitioning under oblique convergence within scaled physical experiments

Michele L. Cooke, Kevin Toeneboehn and Jennifer L. Hatch
Onset of slip partitioning under oblique convergence within scaled physical experiments
Geosphere (Boulder, CO) (March 2020) 16 (3): 875-889

Abstract

Oblique convergent margins host slip-partitioned faults with simultaneously active strike-slip and reverse faults. Such systems defy energetic considerations that a single oblique-slip fault accommodates deformation more efficiently than multiple faults. To investigate the development of slip partitioning, we record deformation throughout scaled experiments of wet kaolin over a low-convergence (<30 degrees ), obliquely slipping basal dislocation. The presence of a precut vertical weakness in the wet kaolin impacts the morphology of faults but is not required for slip partitioning. The experiments reveal three styles of slip partitioning development delineated by the order of faulting and the extent of slip partitioning. Low-convergence angle experiments (5 degrees ) produce strike-slip faults prior to reverse faults. In moderate-convergence experiments (10 degrees -25 degrees ), the reverse fault forms prior to the strike-slip fault. Strike-slip faults develop either along existing weaknesses (precut or previous reverse-slip faults) or through the coalescence of new echelon cracks. The third style of local slip partitioning along two simultaneously active dipping faults is transient while global slip partitioning persists. The development of two active fault surfaces arises from changes in off-fault strain pattern after development of the first fault. With early strike-slip faults, off-fault contraction accumulates to produce a new reverse fault. Systems with early lobate reverse faults accommodate limited strike-slip and produce extension in the hanging wall, thereby promoting strike-slip faulting. The observation of persistent slip partitioning under a wide range of experimental conditions demonstrates why such systems are frequently observed in oblique convergence crustal margins around the world.


EISSN: 1553-040X
Serial Title: Geosphere (Boulder, CO)
Serial Volume: 16
Serial Issue: 3
Title: Onset of slip partitioning under oblique convergence within scaled physical experiments
Affiliation: University of Massachusetts-Amherst, Geosciences Department, Amherst, MA, United States
Pages: 875-889
Published: 20200310
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 69
Accession Number: 2020-028711
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, block diags.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202019
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