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Tuesday, 30 June 2015

Re: [meteorite-list] Nastapoka Arc, Hudson Bay, Canada

Nastapoka Arc, Hudson Bay, Canada

Re: [meteorite-list] Changes In 14C and Impacts

In “Re: Changes in 14C and Impacts“
Sterling Webb wrote;

I can suggest another very ancient crater: the south-southeastern coast of Hudson Bay, above James Bay is a portion of a perfect circle and it has a nice cluster of islands at the geometric center of that circle like the remnants of central peaks. I've always thought that it could be what's left of a very, very ancient "astrobleme." 
The cluster of islands at the center of the Nastapoka Arc in Hudson Bay has at various times caught the attention of many a geologist, planetologist, and independent investigator and typically proved to be a major disappointment to many a stalker of extraterrestrial impact craters. They are the Beltcher Islands, which are an are an archipelago in Hudson Bay. Instead of consisting of older and highly brecciated and faulted strata that has been uplifted as part of a central uplift, they consist of younger, softer, tightly folded  Proterozoic metasedimentary and metavolcanic rocks that overlie the eroded surface of the older, harder, Archean gneisses that outcrop eastward of the Nastapoka Arc. This Arc closely follows the unconformable contact between Archean Superior province gneisses and westward dipping early Proterozoic Belcher Group. The Belcher Islands are the exposed part of the Circum Ungava Fold Belt, which underlies the eastern edge of Hudson Bay. The fold belt consists of continental margins and a seaway that has been curshed between between two Archean landmasses during the Trans-Hudson Orogeny.

Web pages:

Belcher Islands

Ricketts, B. D., and J. A. Donaldson, 1981,
Sedimentary History of the Belcher Group of
Hudson Bay. In Proterozoic Basins of Canada; Geological Survey of Canada, Paper 81-10,
p. 235-254

Hynes, A., 1991, The gravity field of eastern Hudson Bay: Evidence for a flextural origin
for the Hudson Bay (Nastapoka) Arc? Tectonics.
Volume 10, Issue 4, Pages 722–728, August 1991

Dietz, R.S., and J.P. Barringer (1973) Hudson
Bay Arc as an Astrobleme: a Negative Search.
Meteoritics. vol. 8, pp. 28–29.

Have you seen an Omar (Omarolluk erratic)?


Paul H.

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