PRECAMBRIAN METAMORPHIC AND TECTONIC EVOLUTION OF NORTHERN BAFFIN ISLAND, NUNAVUT, CANADA

G. D. Jackson; R. G. Berman

doi:10.2113/gscanmin.38.2.399

Geology, U – Pb, and Pb – Pb geochronology of the Lake Harbour area, southern Baffin Island: implications for the Paleoproterozoic tectonic evolution of northeastern Laurentia

Canadian Journal of Earth Sciences ◽

10.1139/e17-012 ◽

1997 ◽

Vol 34 (2) ◽

pp. 140-155 ◽

Cited By ~ 33

Author(s):

David J. Scott

Keyword(s):

Tectonic Evolution ◽

Baffin Island ◽

Thrust Belt ◽

Tonalitic Gneiss ◽

Harbour Area

Geological and geochronological results of an investigation of the Paleoproterozoic siliciclastic and carbonate supracrustal rocks of the Lake Harbour Group (LHG) and surrounding tonalitic gneisses on southern Baffin Island are presented. Conventional U – Pb geochronology of monazite from rocks of the LHG suggest that penetrative deformation of these rocks occurred prior to, or during, peak metamorphic conditions at ca. 1845 –1840 Ma. Conventional U – Pb zircon results indicate that much of the tonalitic gneiss ranges in age from [Formula: see text] to 1827[Formula: see text]. The tonalitic gneisses and Lake Harbour Group units were tectonically imbricated by ca. 1805 Ma, and are part of a southwest-verging thrust belt interpreted from regional considerations to represent the northern continuation of the Ungava Orogen. The present results indicate that current tectonic models for the evolution of northeastern Laurentia that involve a dominantly Archean southeastern Rae province require revision. It is proposed that much of the metaigneous material that lies between the Archean Superior and Nain cratons represents a composite subduction-related domain.

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U–Pb geochronology of detrital zircons in metasedimentary rocks from southern Baffin Island: implications for the Paleoproterozoic tectonic evolution of Northeastern Laurentia

Canadian Journal of Earth Sciences ◽

10.1139/e01-093 ◽

2002 ◽

Vol 39 (5) ◽

pp. 611-623 ◽

Cited By ~ 17

Author(s):

David J Scott ◽

Richard A Stern ◽

Marc R St-Onge ◽

Sarah M McMullen

Keyword(s):

Detrital Zircon ◽

Tectonic Evolution ◽

Source Region ◽

Detrital Zircons ◽

Structural Level ◽

Baffin Island ◽

Ion Microprobe ◽

Metasedimentary Rocks ◽

Structural Levels ◽

Superior Craton

A geochronological investigation of metasedimentary rocks from southern Baffin Island using the Geological Survey of Canada SHRIMP II (sensitive high-resolution ion microprobe) has characterized the ages of detrital zircon populations to determine their provenance, bracket timing of deposition, and distinguish potentially distinct sequences of rocks. Four lithologically and structurally distinct metasedimentary packages have been identified; each appears to have been derived from a different source region. In the structurally lowest package, all analysed zircons are Archean, and > 90% have ages between 2.83 and 2.63 Ga; these rocks are interpreted as the northernmost exposures of the Paleoproterozoic Povungnituk Group of the Cape Smith Belt, northern Quebec, with detritus derived from the Superior craton. Occupying the intermediate structural levels, the most abundant supracrustal rocks on southern Baffin Island are siliciclastic and carbonate units of the Lake Harbour Group, and the Tasiuyak paragneiss. Five samples show a dominantly Paleoproterozoic signature (2.21.9 Ga), with only rare Archean zircons; the provenance of this detritus is uncertain. In the distinct package of feldspathic quartzite and pelite that stratigraphically overlies the Lake Harbour Group, all of the analysed detrital grains are Archean, ~80% are > 2.83 Ga, with a small proportion of the grains in excess of 3.0 Ga; all of this material is thought to be derived from the Archean craton exposed on the Hall Peninsula east of the study area. Finally, at the highest structural level, a sample associated with the Hall Peninsula orthogneisses contains zircons with prominent modes at 2.92, 2.82, and 2.77 Ga, consistent with derivation from the surrounding orthogneisses.

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