Late Cenozoic displacement transfer in the eastern Sylvania Mountain fault system and Lida Valley pull-apart basin, southwestern Nevada, based on three-dimensional gravity depth inversion and forward models

Abstract

The Sylvania Mountain fault system is a major left-oblique structure that extends east from the Furnace Creek-Fish Lake Valley fault in southwestern Nevada (USA). The system interacts with a series of north-northeast-striking structures that bound a rectilinear pull-apart basin, Lida Valley, and serve as part of a displacement transfer system relaying slip from the eastern California shear zone to the Walker Lane. On the basis of gravity analysis, the Lida Valley basin is internally dissected by a complex system of faults. The subsurface basin morphology differs from north to south. Major extensional faults localized displacement in the north and formed deep basins, but in the south, displacement was distributed on widely spaced structures with modest displacement. Localized extension in the north is separated from the southern domain of distributed deformation by a west-northwest oblique-slip fault. The subsurface geometry of the basin was determined from a gravity survey with measurements depth inverted in three dimensions. Geologic cross sections were constructed and their gravity signatures forward modeled for compatibility with observations. Projections of mapped faults together with structures determined from gravity modeling were combined to construct the subsurface geometry of the Lida Valley fault system and to evaluate a fault displacement budget. By conserving fault slip on the array of structures, restoration of the pre-Neogene basement to a reference datum indicates a cumulative vertical displacement of 2.3-2.5 km since the onset of basin formation. Vertical displacement estimates were used to compute the horizontal component of extension, which ranges from 1.3 to 1.4 km.