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Paleozoic-aged brine and authigenic helium preserved in an Ordovician shale aquiclude

I. D. Clark, T. Al, M. Jensen, L. Kennell, M. Mazurek, R. Mohapatra and K. G. Raven
Paleozoic-aged brine and authigenic helium preserved in an Ordovician shale aquiclude
Geology (Boulder) (July 2013) 41 (9): 951-954


Consideration of the geosphere for isolation of nuclear waste has generated substantial interest in the origin, age, and movement of fluids and gases in low-permeability rock formations. Here, we present profiles of isotopes, solutes, and helium in porewaters recovered from 860 m of Cambrian to Devonian strata on the eastern flank of the Michigan Basin. Of particular interest is a 240-m-thick, halite-mineralized, Ordovician shale and carbonate aquiclude, which hosts Br (super -) -enriched, post-dolomitic brine (5.8 molal Cl) originating as evaporated Silurian seawater. Authigenic helium that has been accumulating in the aquiclude for more than 260 m.y. is found to be isolated from underlying allochthonous, (super 3) He-enriched helium that originated from the rifted base of the Michigan Basin and the Canadian Shield. The Paleozoic age and immobility of the pore fluids in this Ordovician aquiclude considerably strengthen the safety case for deep geological repositories, but also provide new insights into the origin of deep crustal brines and opportunities for research on other components of a preserved Paleozoic porewater system.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 9
Title: Paleozoic-aged brine and authigenic helium preserved in an Ordovician shale aquiclude
Affiliation: University of Ottawa, Department of Earth Sciences, Ottawa. ON, Canada
Pages: 951-954
Published: 20130711
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Accession Number: 2013-061455
Categories: Isotope geochemistryStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013267
Illustration Description: illus. incl. sect., sketch map
N44°10'00" - N44°12'00", W81°37'60" - W81°37'60"
Secondary Affiliation: University of New Brunswick, CAN, CanadaNuclear Waste Management Organization, CAN, CanadaUniversity of Bern, CHE, SwitzerlandGeofirma Engineering, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201337
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