CAS ES 351 Lecture Notes - Lecture 15: Magnetostratigraphy, Geochemistry, Paleoclimatology
27 Feb 2019
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It decays by ejecting an electron from its nucleus. So the parent isotope decays and the daughter isotope accumulates. Radiometric dating: the parent decays at a fixed rate (half-life) which is the daughter isotope. Marine sediment and ice cores don"t have anything that radiometric datable. Biostratigraphy: tells us the age of sediment by dating the microfossils in the sediment. ~volcanic ash can be dated with radiometric dating in ice cores. ~constrain age in sedimentary sequence based on first and last appearance of microfossils of well-known age - index age (have a limited and well-known time frame in the sediment, and they are wide-spread in the ocean) Magnetostratigraphy: measures the natural remnant magnetization of rocks (igneous or sediments) to determine magnetic field orientation at time of ricks formation. ~the last time this happened was 870,000 years ago. ~of the sediments that fall to the seafloor, they contain iron-bearing minerals.
