Permeability of the continental crust: Dynamic variations inferred from seismicity and metamorphism

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The variation of permeability with depth can be probed indirectly by various means, including hydrologic models that use geothermal data as constraints and the progress of metamorphic reactions driven by fluid flow. Geothermal and metamorphic data combine to indicate that mean permeability (k) of tectonically active continental crust decreases with depth (z) according to log k ≈ −14–3.2 log z, where k is in m2 and z in km. Other independently derived, crustal‐scale kz relations are generally similar to this power‐law curve. Yet there is also substantial evidence for local‐to‐regional‐scale, transient, permeability‐generation events that entail permeabilities much higher than these mean kz relations would suggest. Compilation of such data yields a fit to these elevated, transient values of log k ≈ −11.5–3.2 log z, suggesting a functional form similar to that of tectonically active crust, but shifted to higher permeability at a given depth. In addition, it seems possible that, in the absence of active prograde metamorphism, permeability in the deeper crust will decay toward values below the mean kz curves. Several lines of evidence suggest geologically rapid (years to 103 years) decay of high‐permeability transients toward background values. Crustal‐scale kzcurves may reflect a dynamic competition between permeability creation by processes such as fluid sourcing and rock failure, and permeability destruction by processes such as compaction, hydrothermal alteration, and retrograde metamorphism.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Permeability of the continental crust: Dynamic variations inferred from seismicity and metamorphism
Series title Geofluids
DOI 10.1111/j.1468-8123.2010.00278.x
Volume 10
Issue 1-2
Year Published 2010
Language English
Publisher Wiley
Contributing office(s) Volcano Science Center
Description 13 p.
First page 193
Last page 205
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