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Putting it all together: Exhumation histories from a formal combination of heat flow and a suite of thermochronometers

Journal of Geophysical Research B: Solid Earth

By:
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DOI: 10.1029/2006JB004725

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Abstract

A suite of new techniques in thermochronometry allow analysis of the thermal history of a sample over a broad range of temperature sensitivities. New analysis tools must be developed that fully and formally integrate these techniques, allowing a single geologic interpretation of the rate and timing of exhumation and burial events consistent with all data. We integrate a thermal model of burial and exhumation, (U-Th)/He age modeling, and fission track age and length modeling. We then use a genetic algorithm to efficiently explore possible time-exhumation histories of a vertical sample profile (such as a borehole), simultaneously solving for exhumation and burial rates as well as changes in background heat flow. We formally combine all data in a rigorous statistical fashion. By parameterizing the model in terms of exhumation rather than time-temperature paths (as traditionally done in fission track modeling), we can ensure that exhumation histories result in a sedimentary basin whose thickness is consistent with the observed basin, a physically based constraint that eliminates otherwise acceptable thermal histories. We apply the technique to heat flow and thermochronometry data from the 2.1 -km-deep San Andreas Fault Observatory at Depth pilot hole near the San Andreas fault, California. We find that the site experienced <1 km of exhumation or burial since the onset of San Andreas fault activity ???30 Ma.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Putting it all together: Exhumation histories from a formal combination of heat flow and a suite of thermochronometers
Series title:
Journal of Geophysical Research B: Solid Earth
DOI:
10.1029/2006JB004725
Volume
112
Issue:
8
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article