Increasing long-wavelength relief across the southeastern flank of the Sierra Nevada, California

Richard A Bennett, N. P. Fay, S. Hreinsdóttir, C. Chase, George Zandt

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

A high degree of correlation between present-day relative rock uplift measured using continuous GPS geodesy and spatially averaged surface elevations suggests that long-wavelength topographic relief is presently increasing along the southeastern flank of the Sierra Nevada range and within an adjacent portion of the northern Basin and Range province. Current estimates for erosion rate are an order of magnitude smaller than the relative rates determined by geodesy. Thus, although the uplift serves to enhance long-wavelength relief, it cannot be explained entirely as an isostatic response to erosion. If uplift rates have been constant through time, the duration over which the uplift could have been active (<1.6 Myrs) is shorter than expected based on our current understanding of the geodynamic history of the region. One possible explanation for the observed present-day uplift pattern is that it represents an ongoing isostatic response to gradual reduction of the equivalent elastic thickness (EET) of the lithosphere under temporally constant loads. Another explanation is that the loads currently supporting the high elevations of the southern Sierra are evolving with time. According to either hypothesis, vertical surface motions may have slowly accelerated since ~mid-Pliocene time. Several possible mechanisms for progressive reduction of EET may be attributable to thermo-mechanical disequilibrium that began with the removal of an ultramafic root from the Sierran batholith during late Miocene or early Pliocene time. Specific mechanisms for ongoing enhancement of loads are less obvious. Based on these results, we suggest that dense networks of long-running continuous GPS stations around the world currently represent an underutilized resource for studies of orogenesis and upper mantle processes.

Original languageEnglish (US)
Pages (from-to)255-264
Number of pages10
JournalEarth and Planetary Science Letters
Volume287
Issue number1-2
DOIs
StatePublished - Sep 30 2009

Fingerprint

Geodesy
Global positioning system
Erosion
relief
uplift
Geodynamics
wavelength
Wavelength
geodesy
wavelengths
erosion
Rocks
Pliocene
GPS
geodynamics
mantle process
lithosphere
time constant
resources
batholith

Keywords

  • geodesy
  • GPS
  • orogenesis
  • rock uplift
  • Sierra Nevada
  • tectonics

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Increasing long-wavelength relief across the southeastern flank of the Sierra Nevada, California. / Bennett, Richard A; Fay, N. P.; Hreinsdóttir, S.; Chase, C.; Zandt, George.

In: Earth and Planetary Science Letters, Vol. 287, No. 1-2, 30.09.2009, p. 255-264.

Research output: Contribution to journalArticle

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