Geology, geochronology, and geochemistry of Archean rocks in the Eqe Bay area, north-central Baffin Island, Canada: constraints on the depositional and tectonic history of the Mary River Group of northeastern Rae Province
Results of stratigraphic, UPb geochronological, and geochemical study are reported for rocks in a 2800 km 2 area along the southeastern margin of the Archean Rae Province on north-central Baffin Island. Archean rocks include a gneiss complex, two greenstone belts of the Mary River Group, and variou...
Published in: | Canadian Journal of Earth Sciences |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
2003
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Subjects: | |
Online Access: | http://dx.doi.org/10.1139/e03-028 http://www.nrcresearchpress.com/doi/pdf/10.1139/e03-028 |
Summary: | Results of stratigraphic, UPb geochronological, and geochemical study are reported for rocks in a 2800 km 2 area along the southeastern margin of the Archean Rae Province on north-central Baffin Island. Archean rocks include a gneiss complex, two greenstone belts of the Mary River Group, and various younger plutonic rocks. The 30002800 Ma gneiss complex contains intrusions of orthogneiss, dated at 27802770 Ma. Intermediate-felsic volcanism in overlying greenstone belts occurred at 27402725 Ma and was accompanied and outlasted by calc-alkaline plutonism (27302715 Ma). Peraluminous plutonism at ca. 2700 Ma, possibly associated with low- to medium-pressure metamorphism, represents the culmination of the Archean tectonic cycle. Dating of metamorphic zircon and titanite in Archean gneissic rocks indicates that overprinting, high-grade metamorphism in the northwest part of the area (footwall of the Isortoq fault zone) is Paleoproterozoic (ca. 1820 Ma). A weaker, somewhat older thermal disturbance (ca. 18501840 Ma with large errors) is recorded in the hanging wall of this zone. Additional tectonothermal events at ca. 15001400 Ma and ca. 700 Ma may, respectively, correlate with Mesoproterozoic faulting and emplacement of the Franklin dyke swarm. Unlike their age-correlative counterparts in the Mary River area and on the mainland to the southwest, the greenstone belts at Eqe Bay lack abundant orthoquartzite and komatiitic volcanic rocks: calc-alkaline volcanic rocks predominate, suggesting a fundamentally different tectonic environment. Striking similarities, both in lithology and age, to greenstone belts of the Minto block of the Superior Province raises the question of RaeSuperior correlation. |
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