Late Paleozoic collision, delamination, short-lived magmatism, and rapid denudation in the Meguma Terrane (Nova Scotia, Canada): constraints from 40Ar/39Ar isotopic data
Por:
Keppie J.D., Dallmeyer R.D.
Publicada:
1 ene 1995
Resumen:
The Meguma Terrane consists of 8-15 km of early Paleozoic stratified rocks, deposited on a continental basement, that were deformed and metamorphosed during the late Paleozoic as a result of lithospheric plate collision. The oldest cleavage dates the onset of crustal thickening, which was followed by voluminous, but short-lived, Late Devonian granitic and minor mafic magmatism. 40Ar/39Ar plateau ages indicate that, at the present erosion level, most of the Meguma Terrane cooled through ~300°C by 368-360 Ma, slightly earlier than for the southwestern Meguma Terrane (ca. 345 Ma). Subsequent burial beneath ~6 km of Carboniferous sediments would not have been sufficient to completely rejuvenate older intracrystalline mica systems and result in the observed 40Ar/39Ar mica plateau ages between ca. 350 and 260 Ma. Such rejuvenation may have resulted from migration of hot fluids along shear zones derived from the lower crust and mantle, and from granitoid magma intruded at ca. 316 Ma. -from Authors
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