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huelsenbeck14slides - Principle of superposition A typical...

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A typical rock formation Relative dating: some principles to follow... 1 Principle of superposition 2 Principle of original horizontality 3 Principle of lateral continuity 4 Principle of cross-cutting relationships 5 Principle of inclusions 6 Huelsenbeck Lecture 14 Slides page 1 of 11
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Principles of unconformities (missing time) 7 Radiometric Age Dating Uses unstable isotopes of naturally occurring elements. The isotopes decay: they change into different elements or different isotopes of the same element. The rate of decay is known (has been measured in the laboratory) for a variety of isotopes. When igneous rocks form, there is 100% parent and 0% daughter isotopes in the rock. The ratio of the parent and daughter isotopes can be measured using a mass spectrometer. 8 9 Method Parent isotope Daughter isotope Half life Dating range Rubidium- strontium Rb-87 Sr-87 47 by 10m-4.6b Uranium-lead U-238 Pb-206 4.5 by 10m-4.6b Uranium-lead U-235 Pb-207 71.3 my 10m-4.6b Thorium-lead Th-232 Pb-208 14.1 by 10m-4.6b Potassium-argon K-40 Ar-40 1.3 by .1m-4.6b Carbon-14 C-14 N-14 5730 y 100-100,000 10 1999 GEOLOGIC TIME SCALE CENOZOIC MESOZOIC PALEOZOIC AGE (Ma) EPOCH AGE PICKS (Ma) MAGNETIC POLARITY PERIOD HIST. ANOM. CHRON. 5 10 15 20 25 30 35 40 45 50 55 60 65 QUATER- NARY PLEISTOCENE MIOCENE OLIGOCENE TRIASSIC JURASSIC CRETACEOUS PERMIAN DEVONIAN ORDOVICIAN SILURIAN MISSISSIPPIAN PENNSYLVANIAN CAMBRIAN* CARBONIFEROUS EOCENE PALEOCENE PLIOCENE PIACENZIAN L 0.01 1.8 3.6 5.3 7.1 11.2 14.8 16.4 20.5 23.8 28.5 33.7 37.0 41.3 49.0 54.8 57.9 61.0 65.0 E L E L M E L M E E L ZANCLEAN MESSINIAN TORTONIAN SERRAVALLIAN LANGHIAN BURDIGALIAN AQUITANIAN CHATTIAN RUPELIAN PRIABONIAN BARTONIAN LUTETIAN YPRESIAN DANIAN THANETIAN SELANDIAN CALABRIAN HOLOCENE TERTIARY PALEOGENE NEOGENE 1 C1 C2 C2A C3 C3A C4 C4A C6 C6A C6B C6C C7 C8 C9 C10 C11 C12 C13 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C7A C5 C5A C5B C5C C5D C5E 2 2A 3 3A 4 4A 5 5B 5A
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