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Can footwall unloading explain late Cenozoic uplift of the Sierra Nevada crest?

International Geology Review

By:
and
DOI: 10.1080/00206810903059156

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Abstract

Globally, normal-fault displacement bends and warps rift flanks upwards, as adjoining basins drop downwards. Perhaps the most evident manifestations are the flanks of the East African Rift, which cuts across the otherwise minimally deformed continent. Flank uplift was explained by Vening Meinesz (1950, Institut Royal Colonial Belge, Bulletin des Seances, v. 21, p. 539-552), who recognized that isostasy should cause uplift of a normal-faulted footwall and subsidence of its hanging wall. Uplift occurs because slip on a dipping normal fault creates a broader root of less-dense material beneath the footwall, and a narrowed one beneath the hanging wall. In this paper, we investigate the potential influence of this process on the latest stages of Sierra Nevada uplift. Through theoretical calculations and 3D finite element modelling, we find that cumulative slip of about 4km on range-front faults would have produced about 1.3km peak isostatic uplift at the ridge crest. Numerical models suggest that the zone of uplift is narrow, with the width controlled by bending resistance of the seismogenic crust. We conclude that footwall unloading cannot account for the entire elevation of the Sierran crest above sea level, but if range-front faulting initiated in an already elevated plateau like the adjacent Basin and Range Province, then a hybrid model of pre-existing regional uplift and localized footwall unloading can account for the older and newer uplift phases suggested by the geologic record.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Can footwall unloading explain late Cenozoic uplift of the Sierra Nevada crest?
Series title:
International Geology Review
DOI:
10.1080/00206810903059156
Volume
51
Issue:
9-11
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
International Geology Review
First page:
986
Last page:
993