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Age constraints for Paleoproterozoic glaciation in the Lake Superior Region: Detrital zircon and hydrothermal xenotime ages for the Chocolay Group, Marquette Range Supergroup

Canadian Journal of Earth Sciences

By:
, , and
DOI: 10.1139/E06-010

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Abstract

A geochronological study of the Chocolay Group at the base of the Paleoproterozoic Marquette Range Supergroup in Michigan, Lake Superior Region, is attempted for the first time, Age data from detrital zircon grains and hydrothermal xenotime from the basal glaciogenic formation, the Enchantment Lake Formation, and the stratigraphically higher Sturgeon Quartzite and its equivalent, the Sunday Quartzite, provide maximum and minimum age constraints for the Chocolay Group. The youngest detrital zircon population in the Enchantment Lake Formation is 2317 ?? 6 Ma; in the Sturgeon Quartzite, it is 2306 ?? 9 Ma, and in the Sunday Quartzite, it is 2647 ?? 5 Ma. The oldest hydrothermal xenotime age in the Enchantment Lake Formation is 2133 ?? 11 Ma; in the Sturgeon Quartzite, it is 2115 ?? 5 Ma, and in the Sunday Quartzite, it is 2207 ?? 5 Ma. The radiometric age data in this study implies the depositional age of the Chocolay Group is constrained to ???2.3-2.2 Ga, which proves its correlation with part of the Huronian Supergroup in the Lake Huron Region, Ontario, and reveals the unconformity that separates the Chocolay Group from the overlying Menominee Group is up to 325 million years in duration. The source(s) of the ??? 2.3 Ga detrital zircon populations in the Enchantment Lake Formation and Sturgeon Quartzite remains an enigma because no known rock units of this age are known in the Michigan area. It is speculated that once widespread volcano-sedimentary cover sequences in Michigan were removed or concealed prior to Chocolay Group deposition. The hydrothermal xenotime ages probably reflect basinal hydrothermal fluid flow associated with the period of extension involving rifting and major dyke formation, that affected the North American provinces between 2.2 and 2.1 Ga. ?? 2006 NRC Canada.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Age constraints for Paleoproterozoic glaciation in the Lake Superior Region: Detrital zircon and hydrothermal xenotime ages for the Chocolay Group, Marquette Range Supergroup
Series title:
Canadian Journal of Earth Sciences
DOI:
10.1139/E06-010
Volume
43
Issue:
5
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Journal of Earth Sciences
First page:
571
Last page:
591