An Ensimatic Island Arc and Ocean Closure in the Grenville Province of Southeastern Ontario, Canada

R. L. Brown, J. F. Chappell, J. M. Moore Jr., P. H. Thompson


Within the Grenville Province of Southeastern Ontario geological data may be interpreted in the light of plate tectonic theory. An early cycle involving subduction of oceanic lithosphere, generation of an island arc complex together with partial melting of the down-going slab to produce calc-alkalic volcanism and granodioritic
intrusions, was followed by a second cycle during which the island arc was uplifted, eroded and covered by miogeoclinal sediments. Subsequently the miogeocline was deformed presumably during continental collision. The evolution from early island arc phase to ocean closure and consolidation took approximately 250 m.y.

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