On the archean geologic history of eastern Hall Peninsula, Baffin Island, Nunavut, Canada
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Date
2017-12-22
Authors
From, Richard Eric
Journal Title
Journal ISSN
Volume Title
Publisher
Precambrian Research
Abstract
Eastern Hall Peninsula on southeastern Baffin Island, lies at the junction of a
complex Paleoproterozoic collision between the Rae craton, Meta Incognita
microcontinent and the North Atlantic craton from ca. 1.88 to 1.80 Ga. The original
configuration of these cratons is not well understood because eastern Hall Peninsula,
which lies at the triple junction between these plates, lacks detailed geoscience mapping
and geochemical data. Consequently, detailed mapping was conducted in eastern Hall
Peninsula and zircons separated from selected samples were analyzed for U-Pb and Lu-
Hf isotopes.
Magmatic zircons yielded U-Pb crystallization ages between ca. 2976 to 2720 Ma
and metamorphic zircons record tectonothermal disturbances between ca. 2740 to 2700
Ma, a period coinciding with metamorphism documented in adjacent crustal blocks.
Magmatic rocks older than ca. 2740 Ma yielded positive εHf(t) and consistent model ages
of ca. 3.1 to 3.0 Ga, indicating the time that protolith melt was extracted from the mantle.
The oldest, granodioritic crust crystallized at ca. 2976 Ma and was then reworked
periodically at ca. 2.93, 2.84-2.81 and 2.77-2.69 Ma, forming other rock units. Two rock
units younger than ca. 2740 Ma yielded negative εHf(t) model ages of ca. 3.4 and 3.3 Ga
respectively, indicating derivation from an older crustal source yet to be identified in
outcrop on Hall Peninsula.
Zircons from a suite of relatively undeformed magnetite-bearing granites yielded UPb
magmatic ages between ca. 2750 to 2612 Ma. Sm-Nd data from these granites outline
a spatial trend across eastern Hall Peninsula with negative εNd(t) in the west becoming
more positive εNd(t) to the east. This trend outlines an increase of crustal reworking and recycling in the west compared with more mantle-derived, juvenile crust towards the east, delineating a boundary between Paleoproterozoic rocks of Meta Incognita microcontinent and Archean rocks of eastern Hall Peninsula.
Synthesizing all data we propose a new regional correlation model that incorporates
previous models and other recent studies. This new model groups eastern Hall Peninsula,
southern Cumberland Peninsula and southern Aasiaat domain into a “core zone” that
shared a geologic history prior to 1.90 Ga and potentially prior to 2.75 Ga.
Description
Keywords
geology, metamorphic, Archean
Citation
From, R.E., Camacho, A., Pearson, D.G. and Luo, Y. 2017. U-Pb and Pb and Lu-Hf isotopes of the Archean orthogneiss complex on eastern Hall Peninsula, southern Baffin Island, Nunavut: identification of exotic Paleo- to Mesoarchean crust beneath eastern Hall Peninsula, southern Baffin Island, Nunavut. Precambrian Research.