GEO 1111 Lecture Notes - Lecture 7: Closure Temperature, Geologic Time Scale, Radiocarbon Dating

• School: University of Ottawa
• Department: Geology
• Course: GEO 1111
• Professor: Robert Jack Cornett

Document Summary

Some minerals melt and other stay intact. Partial melting the mantle (ultra mafic): oceanic crust (mafic) Radiometric dating: uses half-life of radioactive isotopes, measuring parent vs. daughter isotope ratios, therefore, constrains time (like watching popcorn pop, kernels parent decrease and popcorn daughter increases)= Half life: the time it takes for half of the parent isotope to decay into daughter isotopes. Uranium used to date materials that are millions of year sold. Carbon used to date more recent materials. Below certain temp. , isotopes will no longer disuse in and out, and the minerals radiometric clock starts (closure temperature) Radiometric dating provides the time at which the rock crystallized, last cooled down below the closure temperature. Radiocarbon dating: wood or shells are most suitable, the 14c clock begins when the organism dies. Steps: collect sample, burn it to release co2, measure beta emissions from co2 in a steel-plated geiger, use known decay rate curve to obtain 14c age.