L04_11_Sept_Age_Earth_Timescales

Daughter nuclides in the mineral to determine the age

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Unformatted text preview: tains’ the daughter isotope 3)  Measure the amount of parent and daughter nuclides in the mineral to determine the age iniKal mineral: only parent nuclides mineral later in Kme: some of the parents have decayed into daughters 5 Radiometric DaKng of Minerals The basic idea: 1)  Choose a mineral that incorporates a parent radioisotope, but not it’s daughter isotope 2)  The mineral must be such that it ‘retains’ the daughter isotope 3)  Measure the amount of parent and daughter nuclides in the mineral to determine the age iniKal mineral: only parent nuclides mineral later in Kme: some of the parents have decayed into daughters mineral sKll later in Kme: more parents have decayed into daughters 6 Rates of Decay We observe the following very simple phenomenon: the more of a radioacKve substance is present, the more frequently radioacKve decay occurs: The rate of decay is proporKonal to the amount of radioacKve isotope a small amount of radioacKve substance a large amount of radioacKve substance very few decay events per unit Kme many decay events per unit Kme 7 Rates of Decay dN = kN (equation 1) dt Nt t ∫ dN = N ln Nt = −kt N0 N0 Nt = e− kt N0 **Note: you...
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This document was uploaded on 03/26/2014 for the course GEC AS.270.103 at Johns Hopkins.

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