GEOL 100 Lecture Notes - Lecture 16: Radioactive Decay, Radiometric Dating, Geochronology
30 Mar 2019
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Document Summary
Fossils in a sequence of sedimentary rocks. Fossils are incorporated into rocks as they are deposited. Some species lived short time span so give narrow age range. Can use overlap of two fossils to constrain age range. Some rock sections can disappear from erosion. Many relative ages can be assigned actual dates. Based on radioactive decay of atoms in minerals. Decay proceeds at a known, fixed rate. Isotopes: same number of protons/electrons, different number of neutrons. Half-life: time it takes for half the parents isotope to decay to daughter isotope (an exponential function) Some daughters also decay creating a decay chain until a stable isotope is created. After one half-life, half the parent isotopes will turn into daughter isotopes. Half the parent atoms decayed to daughter atoms (time=half life) The age of a mineral determined by . Measuring the ratio of parent isotopes to daughter isotopes. Calculating the amount of time by using the t1/2.
