Have distal impact ejecta changed through geologic time?

Title:
Have distal impact ejecta changed through geologic time?
Authors:
Simonson, Bruce M.; Harnik, Paul
Abstract:
Sand-size spherules of former silicate melt have been identified in ~10 thin Early Archean to Paleoproterozoic layers that appear to be reworked ejecta from large impacts. Melt spherules are common in Phanerozoic layers of distal impact ejecta, but the aggregate thickness of spherules in early Precambrian layers is generally 10 to 100 times greater, and they display textures rarely seen in Phanerozoic spherules. These contrasts suggest secular variations in the nature of both impactors and target materials, such as a progressive decrease in the size of impactors and a progressive increase in the fraction of Earth's surface covered by continental crust.
Citation:
Simonson, B., and P. Harnik. 2000. "Have distal impact ejecta changed through geologic time?" Geology, 28(11): 975-978.
Publisher:
Geological Society of America
DATE ISSUED:
2000
Department:
Geology
Type:
article
PUBLISHED VERSION:
10.1130/0091-7613(2000)28<975:HDIECT>2.0.CO;2
PERMANENT LINK:
http://hdl.handle.net/11282/309591

Full metadata record

DC FieldValue Language
dc.contributor.authorSimonson, Bruce M.en_US
dc.contributor.authorHarnik, Paulen_US
dc.date.accessioned2013-12-23T16:12:53Z-
dc.date.available2013-12-23T16:12:53Z-
dc.date.issued2000en
dc.identifier.citationSimonson, B., and P. Harnik. 2000. "Have distal impact ejecta changed through geologic time?" Geology, 28(11): 975-978.en_US
dc.identifier.issn0091-7613en_US
dc.identifier.urihttp://hdl.handle.net/11282/309591-
dc.description.abstractSand-size spherules of former silicate melt have been identified in ~10 thin Early Archean to Paleoproterozoic layers that appear to be reworked ejecta from large impacts. Melt spherules are common in Phanerozoic layers of distal impact ejecta, but the aggregate thickness of spherules in early Precambrian layers is generally 10 to 100 times greater, and they display textures rarely seen in Phanerozoic spherules. These contrasts suggest secular variations in the nature of both impactors and target materials, such as a progressive decrease in the size of impactors and a progressive increase in the fraction of Earth's surface covered by continental crust.en_US
dc.language.isoen_USen_US
dc.publisherGeological Society of Americaen_US
dc.identifier.doi10.1130/0091-7613(2000)28<975:HDIECT>2.0.CO;2-
dc.subject.departmentGeologyen_US
dc.titleHave distal impact ejecta changed through geologic time?en_US
dc.typearticleen_US
dc.identifier.journalGeologyen_US
dc.subject.keywordImpactsen_US
dc.subject.keywordSpherulesen_US
dc.subject.keywordEjectaen_US
dc.subject.keywordPrecambrianen_US
dc.subject.keywordSecular variationsen_US
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