39AR-40AR AGE OF THE IBITIRA EUCRITE AND CONSTRAINTS ON THE TIME OF PYROXENE EQUILIBRATION

dc.contributor.author	Bogard D.D.
dc.contributor.author	Garrison D.H.
dc.date.accessioned	2020-11-26T05:24:47Z
dc.date.available	2020-11-26T05:24:47Z
dc.date.issued	1995
dc.identifier	https://elibrary.ru/item.asp?id=661604
dc.identifier.citation	Geochimica et Cosmochimica Acta, 1995, , 20, 4317-4322
dc.identifier.issn	0016-7037
dc.identifier.uri	https://repository.geologyscience.ru/handle/123456789/19585
dc.description.abstract	We determined a 39Ar-40Ar age of 4.495 +/- 0.015 Ga for the unbrecciated Ibitira eucrite. This age ranks among the oldest 39Ar-40Ar ages for eucrites and suggests that Ibitira escaped the widespread impact resetting of K-Ar ages ?4.1-3.5 Ga ago indicated by other HED meteorites. Ibitira exhibits a relatively high degree of chemical equilibration of its pyroxene caused by prolonged annealing. This equilibration must have occurred subsequent to the reported 207Pb-206Pb formation age for Ibitira of 4.556-4.560 Ga, but prior to its determined Ar-Ar age. If pyroxene equilibration occurred during burial at significant depths or in a large impact deposit, then the Ar-Ar age may date this event.
dc.title	39AR-40AR AGE OF THE IBITIRA EUCRITE AND CONSTRAINTS ON THE TIME OF PYROXENE EQUILIBRATION
dc.type	Статья

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