We present a series of three-dimensional numerical models investigating the effects of metamorphic strengthening and weakening on the geodynamic evolution of convergent orogens that are constrained by observations from an exposed mid-crustal section in the New England Appalachians. The natural mid-crustal section records evidence for spatially and temporally variable mid-crustal strength as a function of metamorphic grade during prograde polymetamorphism. Our models address changes in strain rate partitioning and topographic uplift as a function of strengthening/weakening in the middle crust, as well as the resultant changes in deformation kinematics and potential exhumation patterns of high-grade metamorphic rock. Results suggest that strengthening leads to strain rate partitioning around the zone and suppressed topographic uplift rates whereas weakening leads to strain rate partitioning into the zone and enhanced topographic uplift rates. Deformation kinematics recorded in the orogen are also affected by strengthening/weakening, with complete reversals in shear sense occurring as a function of strengthening/weakening without changes in plate boundary kinematics.
Groome, Wesley G.; Koons, Peter O.; and Johnson, Scott E., "Metamorphism, Transient Mid-Crustal Rheology, Strain Localization and the Exhumation of High-Grade Metamorphic Rocks" (2008). Earth Science Faculty Scholarship. 61.
Groome, WG, Koons, PO, and Johnson, SE, 2008, Metamorphism, Transient Mid-Crustal Rheology, Strain Localization and the Exhumation of High-Grade Metamorphic Rocks: Tectonics, v. 27, TC1001. To view the published open abstract, go to http://dx.doi.org and enter the DOI.
© Copyright 2008 American Geophysical Union
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