Quote:
Originally Posted by sjastro
Thanks that would be very interesting.
I read the the oldest rock found is from WA.
Regards
Steven
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Not quite. The Jack Hill Formation contains the oldest dated minerals on Earth - zircons of about 4 billion years. The rocks themselves are alluvial deposits which have undergone several metamorphic events. So there was an igneous rock somewhere that was weathered and eroded. The zircons were washed into a sedimentary basin. The sediment was buried and lithified. Later it was folded and metamorphised several times. Despite all this the zircons remained a chemically closed system and so can be dated radiometrically.
What we have from Greenland are whole rocks which have remained unaltered for over 3.7 billion years.