EARTH221 Lecture Notes - Lecture 8: Molybdenite, Geochronology, Radiogenic Nuclide
26 Aug 2016
School
Department
Course
Professor
Document Summary
Long lived for ages older than a couple of million of years: law of radioactive decay. The rate of decay of a radioactive isotope is proportional to the number of atoms present n. Geochronology equation: d, radiogenic: daughter that is produced vs radioactive decay (parent decay, good for any geological material that takes up only the parent and none of the daughter at the time the material formed. Molybdenite takes up parent re 187 but not daughter os 187 when it crystallizes. Zircon takes up parent 238 and u 235 but not daughter pb isotopes when crystallized. So when a zircon is formed, it contains only the uranium and no lead. Over time when decay occurs within the mineral then the date when the mineral was crystallized can be found. During time of crystallization only parent present in ores, each sample will have different concentrations of the parent material.
