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A Cryogenian chronology; two long-lasting synchronous Neoproterozoic glaciations

Alan D. Rooney, Justin V. Strauss, Alan D. Brandon and Francis A. Macdonald
A Cryogenian chronology; two long-lasting synchronous Neoproterozoic glaciations
Geology (Boulder) (March 2015) 43 (5): 459-462

Abstract

The snowball Earth hypothesis predicts globally synchronous glaciations that persisted on a multimillion-year time scale. Geochronological tests of this hypothesis have been limited by a dearth of reliable age constraints bracketing these events on multiple cratons. Here we present four new Re-Os geochronology age constraints on Sturtian (717-660 Ma) and Marinoan (635 Ma termination) glacial deposits from three different paleocontinents. A 752.7 + or - 5.5 Ma age from the base of the Callison Lake Formation in Yukon, Canada, confirms nonglacial sedimentation on the western margin of Laurentia between ca. 753 and 717 Ma. Coupled with a new 727.3 + or - 4.9 Ma age directly below the glacigenic deposits of the Grand Conglomerate on the Congo craton (Africa), these data refute the notion of a global ca. 740 Ma Kaigas glaciation. A 659.0 + or - 4.5 Ma age directly above the Maikhan-Uul diamictite in Mongolia confirms previous constraints on a long duration for the 717-660 Ma Sturtian glacial epoch and a relatively short nonglacial interlude. In addition, we provide the first direct radiometric age constraint for the termination of the Marinoan glaciation in Laurentia with an age of 632.3 + or - 5.9 Ma from the basal Sheepbed Formation of northwest Canada, which is identical, within uncertainty, to U-Pb zircon ages from China, Australia, and Namibia. Together, these data unite Re-Os and U-Pb geochronological constraints and provide a refined temporal framework for Cryogenian Earth history.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 43
Serial Issue: 5
Title: A Cryogenian chronology; two long-lasting synchronous Neoproterozoic glaciations
Affiliation: Harvard University, Department of Earth and Planetary Sciences, Cambridge, MA, United States
Pages: 459-462
Published: 20150327
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 34
Accession Number: 2015-039979
Categories: StratigraphyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2015157
Illustration Description: illus. incl. strat. cols.
N42°00'00" - N84°00'00", W141°00'00" - W52°00'00"
N42°00'00" - N52°00'00", E87°00'00" - E120°00'00"
S17°00'00" - S08°00'00", E22°00'00" - E33°30'00"
Secondary Affiliation: University of Houston, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, 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: 201519
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