2 looking at these plots what do you notice about 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: 44Nd = 0.1100 DM 143Nd/144Nd = 0.513163 147Sm/144Nd = 0.2137 CHUR 143Nd/144Nd = 0.512638 147Sm/144Nd = 0.1967 Do the following: 1) Construct isotope evolution diagrams for: a) 143Nd/144Nd – t; and b) εNd ­ time plots in 100 Ma increments from 0 to 3500 Ma. 2) Looking at these plots what do you notice about the 143Nd/144Nd values of the crust and mantle relative to CHUR over time? What about the εNd values, what happens to these as we get closer to the present? 3) What do you think happened in the earth at ~2.9 ­2.7 Ga? 4) Given your knowledge of the geochemistry of MORB from Labs #3 and 4, and given the isotope evolution diagrams you have constructed. Predict what the εNd of modern N ­MORB should be. 5) What about granitic rocks presently forming in volcanoes in the Andes, what type of εNd signatures would you expect them to have? Part 3. Sm Nd Isotope Geochemistry of Ancient Rocks II You will find in the table below Sm ­Nd data for two groups of scheelite from Au ­ veins in the Murutau Au deposit in Uzbekistan (Kempe et al., 2001). 147Sm/144Nd 143Nd/144Nd Sample Scheelite Vein Set 1 MT3773 0.2261 0.512273 MT3776 0.13869 0.512075 MT3778 0.13477 0.512053 MT3779 0.18236 0.512165 MT4 0.08616 0.511958 Scheelite Vein Set 2 MT1 0.21832 0.512193 MT1A 0.22011 0.512196 MT2 0.23516 0.51221 MT3423 0.18189 0.512135 MT76 ­276 0.15699 0.512089 MR876 0.1541 0.512062 MT ­7 MT ­3710 KM80 ­532 0.16914 0.30084 0.24755 0.512093 0.512343 0.512222 1) Plot and calculate isochron ages and initial 143Nd/144Nd ratios for the two generations of...
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