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Re: A Look At The Age of The Earth.
Dear Frank et. al.,
I found an updated article improving upon Patterson's work of forty
years ago covering the large amount of work in the area of lead isotopes
over more recent years. The age accuracy has improved to one more
decimal point. It's likewise published in Geochimica - Vol. 59, No. 8.
pp. 1445-1456, 1995. It's called The Age of the Earth and I'll give a
brief synopsis for those who can't get a hold of it: it determines the
age of formation of Allende refractory inclusions as early as
4566(+2/-1) m.y. with the accretion of chondritic bodies 3 m.y. later
and partial melting and magmatic eruptions of planetary bodies such as
the Earth occurring 5 m.y. later still. During the next 200 m.y. further
differentiation took place. The age of the Earth is based on the period
of core formation and atmosphere outgassing and is about .1 b.y. younger
than the primitive meteorites, or about 4.46 b.y. old measured from the
time of atmosphere retention when the Earth was a large Venus-sized
object. Estimates put the moon's formation at 4.50 b.y. ago, at a time
before Earth's core was completely formed.
I hope this was as interesting to you all as it is to me. Hope also to
see some of you in Tucson.
David
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