12 Neotectonics and Magmatism in Death Valley and Southwestern Basin and Range II

Monday, 4 April 2016
1:30 PM - 5:30 PM
Meeting Room 200 C

ENIGMATIC WALKER LANE DEXTRAL-SHEAR ACCOMMODATION: PALEOMAGNETICALLY-DETERMINED VERTICAL-AXIS ROTATION OF CRUSTAL BLOCKS BETWEEN THE CENTRAL WALKER LANE AND SIERRA NEVADA FRONTAL FAULT SYSTEM

Paper number: 12-1
Program: Theme Sessions
Time: 1:30 PM – 1:50 PM

Authors

Abstract

Located west of dextral fault systems of the central Walker Lane and east of the Sierra Nevada frontal-fault system is a region of north-striking normal faults and asymmetric basins, where geodetic studies define ~5 mm/yr of northwest-directed dextral strain. As this region is devoid of major strike-slip fault systems, how this strain is accommodated is poorly understood. To elucidate the long-term tectonic development of this region, paleomagnetic data from late Oligocene ash-flow tuffs are used to determine magnitudes of vertical-axis rotation of crustal blocks, as a potential mechanism for accommodation of dextral shear.

Paleomagnetic directions collected from multiple locations across the region define domains of vertical-axis rotation of varying magnitudes. Preliminary paleomagnetic data have identified low/no rotations within translating blocks of the central Walker Lane (Walker Lake domain), statistically-significant magnitudes of ~20-30° clockwise vertical-axis rotation west of central Walker Lane dextral faults, and ~30-60° of clockwise rotation to the northwest in the northern Walker Lane (Carson domain). Boundaries between these domains, although potentially gradational, are relatively discrete and support a distinction of domains by style of faulting. Future work will focus on collecting additional paleomagnetic data within domains, better defining domain boundaries, and address the timing and rates of vertical-axis rotation through the sampling of Miocene-Pliocene volcanics. This paleomagnetic data set will be compared with ongoing and complementary studies of subsurface basin geometry and recent fault-slip motions to ultimately understand the tectonic development of this enigmatic part of the Walker Lane.

Geological Society of America Abstracts with Programs. Vol. 48, No. 4

doi: 10.1130/abs/2016CD-274435

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