Publication Type:

Journal Article

Authors:

Smith, T. E.; Harris, M. J.; Huang, C. H.; Holm, P. E.

Source:

Canadian Journal of Earth SciencesCanadian Journal of Earth Sciences, National Research Council of Canada, Ottawa, ON, Canada, Volume 38, Number 7, p.1037-1057 (2001)

ISBN:

0008-4077

Keywords:

acidic composition, back-arc basins, basalts, basins, Canada, Canadian Shield, Central Metasedimentary Belt, chemical composition, concentration, crust, eastern canada, gabbros, genesis, geochemistry, Grenville Province, igneous rocks, mafic composition, metals, mid-ocean ridge basalts, mineral composition, North America, Ontario, plutonic rocks, rare earths, siliceous composition, Trace elements, volcanic rocks

Abstract:

Two bimodal mafic-silicic suites of igneous rocks, the Sharbot Lake volcanic rocks and the Lavant Igneous Complex, are identified geochemically in the Sharbot Lake domain of the Central Metasedimentary Belt in Ontario, and their genesis and thermotectonic environment are evaluated. The Sharbot Lake volcanic rocks comprise a series of basalts characterized by light rare-earth element (LREE) depletion and relatively high concentrations of Sigma Fe (sub 2) O (sub 3) , TiO (sub 2) , MnO, V, and Y, together with rhyolites and silicic pyroclastic rocks. They are intruded by rocks of the Lavant Igneous Complex, which comprises tholeiitic gabbros characterized by LREE enrichment and low concentrations of Sigma Fe (sub 2) O (sub 3) , TiO (sub 2) , MnO, V, and Y, and granitoid rocks. The trace element signatures of the mafic rocks of the Sharbot Lake volcanic sequences are most like those of back-arc tholeiitic basalts, and those of the Lavant Igneous Complex are comparable to those of low-K tholeiitic basalt suites. The trace element signatures of the silicic rocks associated with both suites are typical of those formed by crustal melting. Volcanic sequences with trace-element signatures very similar to those of the Sharbot Lake suites have been previously described in the Belmont and Grimsthorpe domains of the Central Metasedimentary Belt, suggesting that the three domains all belong to the Bancroft - Elzevir - Mazinaw - Sharbot Lake superterrane. The lithological, structural, and igneous characteristics of this superterrane suggest that it represents part of a complex back-arc basin underlain by areas of rifted and attenuated continental crust and oceanic crust.

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>2001-073866<br/>Sharbot Lake Domain