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(super 40) Ar- (super 39) Ar ages for detrital white mica in Meguma Terrane, Nova Scotia, Canada; implications for provenance of the Goldenville and Halifax Groups

P. H. Reynolds, C. E. White, Sandra M. Barr and C. M. Muir
(super 40) Ar- (super 39) Ar ages for detrital white mica in Meguma Terrane, Nova Scotia, Canada; implications for provenance of the Goldenville and Halifax Groups
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (July 2012) 49 (7): 781-795

Abstract

Single-grain (super 40) Ar/ (super 39) Ar ages are reported for detrital white mica, along with conventional step-heating data for whole rocks, from low-grade metasandstone samples from the Goldenville, Halifax, and Rockville Notch groups in the Meguma terrane of southern Nova Scotia. The majority (166) of single grains from 11 samples yielded ages between ca. 615 and 350 Ma, and the remaining 12 grains yielded ages between ca. 1900 and 870 Ma. The late Neoproterozoic-Paleozoic age distributions are consistent with derivation of sediments from the rapidly uplifted flanks of an active rift, where partial to complete resetting of white mica ages occurred at ca. 520-500 Ma, preceding sediment deposition. The ca. 615 Ma ages may be relics of the original detrital white mica that existed in the source rocks prior to the rifting event. Ages from the Upper Silurian White Rock Formation appear to reflect this same ca. 520-500 Ma event, suggesting that sediments in the White Rock Formation were recycled from the Goldenville and Halifax groups. The older Precambrian ages are inferred to represent white mica in the source region, likely Amazonia. The whole-rock age spectra are discordant, with pronounced age gradients and no well-defined age plateaus. Initial gas released from five of the samples at low laboratory extraction temperatures (ca. 450-500 degrees C) yielded ages of ca. 260-300 Ma, not seen in the single-grain data, whereas gas released at the highest extraction temperatures yielded ages in the range ca. 510-530 Ma, possibly reflecting the principal result obtained from the single-grain data.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 49
Serial Issue: 7
Title: (super 40) Ar- (super 39) Ar ages for detrital white mica in Meguma Terrane, Nova Scotia, Canada; implications for provenance of the Goldenville and Halifax Groups
Affiliation: Dalhousie University, Department of Earth Sciences, Halifax, NS, Canada
Pages: 781-795
Published: 201207
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 55
Accession Number: 2012-094270
Categories: Geochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Accessed on August 23, 2012
Illustration Description: illus. incl. strat. col., 1 table, geol. sketch map
Source Medium: WWW
N43°00'00" - N46°00'00", W66°30'00" - W61°00'00"
Secondary Affiliation: Nova Scotia Department of Natural Resources, CAN, CanadaAcadia University, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 201249
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