39 x 1011 yr1 t age in ma this is an equation of the

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: e Sr in these sulphides was derived from leaching of underlying basement do you think that these rocks were mantle ­ or crustally ­derived? Explain. Rb-Sr Isotopes: Basic Equations and Terminology Rb Sr Decay Equation and Isochron Age Calculations Rb ­Sr system is based on the decay of 87Rb to 87Sr from the following equation: (87Sr/86Sr)m = (87Sr/86Sr)o + (87Rb/86Sr)m(e t 1) (1) where: (87Sr/86Sr)m = measured 87Sr/86Sr ratio of the sample (87Sr/86Sr)o = initial 87Sr/86Srratio of the sample (or source) when the rock formed (87Rb/86Sr)m = measured 87Rb/86Sr ratio of the sample λ = decay constant (1.39 x 10 ­11 yr ­1) t = age in Ma. This is an equation of the form y = mx + b, by obtaining the slope of this line we can calculate the age of the sample/rock by using: m = e t –1 (2) and rearranging this we have: t = ln(m+1) / λ (3) Since we are often dealing with multiple datapoints for an isochron we must calculate the “least squares” regression line for the multi...
View Full Document

This document was uploaded on 03/06/2014 for the course ES 4211 at Memorial University.

Ask a homework question - tutors are online