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Structural controls of Holocene reactivation of the Meers Fault, southwestern Oklahoma, from magnetic studies

Meridee Jones-Cecil
Structural controls of Holocene reactivation of the Meers Fault, southwestern Oklahoma, from magnetic studies
Geological Society of America Bulletin (January 1995) 107 (1): 98-112

Abstract

Holocene reactivation of the aseismic Meers fault in southwestern Oklahoma illustrates the limitation of using the historical seismic record for identifying hazardous faults in the central United States. The 26- to 37-km-long fault scarp is one of the few known scarps recording Holocene movement in the central and eastern United States. Two documented late Holocene slip events, each with about 2.5 m of net slip and estimated M (sub s) ranging from 6 3/4 to7 1/4, identify the Meers fault as a potentially hazardous fault. During Carboniferous and Early Permian tectonism, the Meers fault displaced rocks of sharply contrasting magnetic properties. Analysis of aeromagnetic data and twelve ground-magnetic profiles provides a detailed look at the fault within the magnetic basement. Because subsequent reactivation has been minor and of an opposite sense, the pronounced magnetic anomaly associated with the Meers fault reflects Paleozoic structures in the magnetic basement. The location of the Holocene fault scarp corresponds to the strong horizontal magnetic gradient caused by Paleozoic offset of magnetic basement, indicating that the Paleozoic fault controlled Holocene displacement. Two features apparent in both sets of magnetic data are splays of the Meers fault northwest of the Holocene scarp and dikelike bodies immediately south of the fault. Magnetic susceptibility measurements and rock magnetic data from unoriented core penetrating a dikelike body were incorporated into models of the ground-magnetic profiles. In most cases, secondary faults mapped or visible on low-sun-angle photographs correspond to faults modeled from magnetic data. This correlation shows that preexisting structures probably controlled secondary faulting. However, secondary faults at the southeastern end ofthe 26-km-long continuous fault scarp, previously interpreted fromlow-sun-angle photography, are not apparent in the magnetic data. Of importance to seismic hazard evaluation, the magnetic models show that the northwestern splays probably begin at the northwestern end of the reactivated segment and may indicate a persistent rupture propagation barrier to the west. In addition, the models show the dip of the Meers fault to be nearly vertical to about 0.5 km depth. This dip is consistent with the nearly straight fault trace, results of trenching studies, interpretation of shallow seismic-reflection data, and regional gravity and aeromagnetic models. In the present-day strike-slip regional stress field, the observed up-to-the-north Holocene displacement suggests that either the fault continues to dip steeply at depth or the regional stress field is approaching a normal-faulting stress regime. If the former is true, the scarcity of near-vertical faults with similar orientation within the area of the southern Oklahoma aulacogen implies that few are likely candidates for reactivation.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 107
Serial Issue: 1
Title: Structural controls of Holocene reactivation of the Meers Fault, southwestern Oklahoma, from magnetic studies
Affiliation: U. S. Geological Survey, Denver, CO, United States
Pages: 98-112
Published: 199501
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 50
Accession Number: 1995-018415
Categories: Quaternary geologyStructural geologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 9504
Illustration Description: illus. incl. sects., 2 tables, geol. sketch map
N34°40'00" - N35°00'00", W99°49'60" - W98°25'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199507
Program Name: USGSOPNon-USGS publications with USGS authors
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