Paraburdoo Spherule Layer (Hamersley Basin, Western Australia): Distal Ejecta From A Fourth Large Impact Near The Archean-proterozoic Boundary

Title:
Paraburdoo Spherule Layer (Hamersley Basin, Western Australia): Distal Ejecta From A Fourth Large Impact Near The Archean-proterozoic Boundary
Authors:
Hassler, Scott W.; Simonson, Bruce M.; Sumner, Dawn Y.; Bodin, Louis
Abstract:
We report the discovery of the Paraburdoo spherule layer, which consists entirely of replaced impact-produced melt spherules. It is distal ejecta from a large impact close to the Archean-Proterozoic boundary in the Hamersley Basin of Western Australia. The spherule layer occurs in the Paraburdoo Member of the Wittenoom Formation and was deposited ca. 2.57 Ga (date via U-Pb age interpolation) in a deep shelf environment. The layer consists of microkrystites rich in plagioclase and ferromagnesian crystals, replaced by K-feldspar and a phlogopite-like sheet silicate, respectively. The skeletal textures indicate rapid cooling of a melt with mafic to ultramafic composition and suggest oceanic target rocks. The Paraburdoo spherule layer is 2 cm thick, normally graded, and was probably deposited by suspension settling, as there is no evidence of reworking; it is strikingly similar to the Reivilo spherule layer in the Griqualand West Basin (South Africa), appears to provide a third impact-related high-resolution stratigraphic correlation between these two basins, and points to a high frequency of large impacts around the Archean-Proterozoic boundary.
Citation:
Hassler, Scott W., Bruce M. Simonson, Dawn Y. Sumner, and Louis Bodin. 2011. "Paraburdoo Spherule Layer (Hamersley Basin, Western Australia): Distal Ejecta From A Fourth Large Impact Near The Archean-proterozoic Boundary." Geology 39(4): 307-310.
Publisher:
Geological Society of America
DATE ISSUED:
2011-04
Department:
Geology
Type:
article
PUBLISHED VERSION:
10.1130/G31526.1
PERMANENT LINK:
http://hdl.handle.net/11282/310059

Full metadata record

DC FieldValue Language
dc.contributor.authorHassler, Scott W.en_US
dc.contributor.authorSimonson, Bruce M.en_US
dc.contributor.authorSumner, Dawn Y.en_US
dc.contributor.authorBodin, Louisen_US
dc.date.accessioned2013-12-23T16:24:21Zen
dc.date.available2013-12-23T16:24:21Zen
dc.date.issued2011-04en
dc.identifier.citationHassler, Scott W., Bruce M. Simonson, Dawn Y. Sumner, and Louis Bodin. 2011. "Paraburdoo Spherule Layer (Hamersley Basin, Western Australia): Distal Ejecta From A Fourth Large Impact Near The Archean-proterozoic Boundary." Geology 39(4): 307-310.en_US
dc.identifier.issn0091-7613en_US
dc.identifier.urihttp://hdl.handle.net/11282/310059en
dc.description.abstractWe report the discovery of the Paraburdoo spherule layer, which consists entirely of replaced impact-produced melt spherules. It is distal ejecta from a large impact close to the Archean-Proterozoic boundary in the Hamersley Basin of Western Australia. The spherule layer occurs in the Paraburdoo Member of the Wittenoom Formation and was deposited ca. 2.57 Ga (date via U-Pb age interpolation) in a deep shelf environment. The layer consists of microkrystites rich in plagioclase and ferromagnesian crystals, replaced by K-feldspar and a phlogopite-like sheet silicate, respectively. The skeletal textures indicate rapid cooling of a melt with mafic to ultramafic composition and suggest oceanic target rocks. The Paraburdoo spherule layer is 2 cm thick, normally graded, and was probably deposited by suspension settling, as there is no evidence of reworking; it is strikingly similar to the Reivilo spherule layer in the Griqualand West Basin (South Africa), appears to provide a third impact-related high-resolution stratigraphic correlation between these two basins, and points to a high frequency of large impacts around the Archean-Proterozoic boundary.en_US
dc.publisherGeological Society of Americaen_US
dc.identifier.doi10.1130/G31526.1en
dc.subject.departmentGeologyen_US
dc.titleParaburdoo Spherule Layer (Hamersley Basin, Western Australia): Distal Ejecta From A Fourth Large Impact Near The Archean-proterozoic Boundaryen_US
dc.typearticleen_US
dc.identifier.journalGeologyen_US
dc.subject.keywordSouth Africaen_US
dc.subject.keywordIron formationen_US
dc.subject.keywordDynamic crystallizationen_US
dc.subject.keywordWittenoom Formationen_US
dc.subject.keywordConstraintsen_US
dc.subject.keywordMorphologyen_US
dc.identifier.volume39en_US
dc.identifier.issue4en_US
dc.identifier.startpage307en_US
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