Premium
Metamorphism, transient mid‐crustal rheology, strain localization and the exhumation of high‐grade metamorphic rocks
Author(s) -
Groome Wesley G.,
Koons Peter O.,
Johnson Scott E.
Publication year - 2008
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2006tc001992
Subject(s) - geology , metamorphic rock , metamorphism , shear zone , crust , strain rate , seismology , petrology , deformation (meteorology) , kinematics , shear (geology) , tectonics , geochemistry , oceanography , materials science , physics , classical mechanics , metallurgy
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.