Topography, exhumation pathway, age uncertainties, and the interpretation of thermochronometer data

Katharine W. Huntington, Todd A. Ehlers, Kip Hodges, David M. Whipp

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

The relationship between thermochronometer age and structural elevation is commonly used to infer long-term exhumation histories. Previous studies suggest that inferred exhumation rates from the conventional (one-dimensional, 1-D) age-elevation approach are sensitive to topography and variations in exhumation rate and pathway. Here we evaluate the magnitude of these effects by (1) using a 3-D thermal-kinematic model of the central Nepalese Himalaya to predict age-elevation profiles for multiple thermochronometers as a function of exhumation rate and pathway (vertical, oblique, or thrust fault), and (2) calculating the probability that the true exhumation rate will be recovered from an age-elevation profile for sample uncertainties of different magnitudes. Results suggest that profiles oriented orthogonal to long-wavelength topography and the direction of lateral transport are relatively insensitive to their influence. For profiles oriented parallel to the transport direction, horizontal transport during exhumation partly counteracts topographic effects. The difference between model imposed and 1-D exhumation rates from the slope of a best fit line through an age-elevation plot is greatest when rocks are exhumed vertically and low-temperature thermochronometers are used. The magnitude of error in 1-D exhumation rate estimates varies dramatically as a function of sample uncertainty, particularly when exhumation is rapid. The nature of this variation can be used to design sampling strategies for which 1-D interpretations of age-elevation gradients are likely to be within error of the true exhumation rate. Alternatively, if sample uncertainties can be reduced, studies that combine thermal modeling with age-elevation data can potentially provide important constraints on thermal and kinematic fielos at depth.

Original languageEnglish (US)
Article numberTC4012
JournalTectonics
Volume26
Issue number4
DOIs
StatePublished - Aug 2007

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exhumation
Topography
topography
Kinematics
profiles
Rocks
Sampling
kinematics
Wavelength
datum (elevation)
Hot Temperature
Uncertainty
oblique fault
topographic effect
plots
sampling
Temperature
histories
thrust fault
rate

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Topography, exhumation pathway, age uncertainties, and the interpretation of thermochronometer data. / Huntington, Katharine W.; Ehlers, Todd A.; Hodges, Kip; Whipp, David M.

In: Tectonics, Vol. 26, No. 4, TC4012, 08.2007.

Research output: Contribution to journalArticle

Huntington, Katharine W. ; Ehlers, Todd A. ; Hodges, Kip ; Whipp, David M. / Topography, exhumation pathway, age uncertainties, and the interpretation of thermochronometer data. In: Tectonics. 2007 ; Vol. 26, No. 4.
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