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Home Q & A Board Science-Related Homework Help Geography and Earth Sciences
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Victoria79 Victoria79
wrote...
4 years ago
half life of 235U 207Pb = 704 million years with a decay life of 9.8485x10-10
half life of 238U 206 Pb= 4.46 billion years with a decay constant of 1.55125x10-10

Ratio:    206Pb/238U           207Pb/235U

zircon 1 :  0.732                       32.25

What is the age of the rock. More zircon ratios continue below...I just need help working through one and I can probably do the rest. I've spent hours on this and it's just not making sense to me.
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wrote...
#1
Educator
4 years ago
λ238 = 1.55125 ×10-10a-1 (t1∕2 = 4.468 gigayears or 1,000,000,000)

λ235 = 9.8485 ×10-10a-1 (t1∕2 = 703.8 million years)

For this, you'll need to know the U-Pb system

I found a tutorial here: https://www.ucl.ac.uk/~ucfbpve/geotopes/indexch5.html
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