GEOL 212 Lecture Notes - Lecture 57: Meteoroid, Meteorite Fall, Silt
27 Dec 2017
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Presolar grains: the ratios of 17o/16o and of 18o/16o from unambiguously genuine presolar grains shows substantial variation. Thus, if cais are presolar grains, we would expect them to show considerable variation in oxygen isotope ratios. Samples of cais from the allende meteorite plot along a clear fractionation line. (for comparison, samples of. Earth rocks tend to plot along the terrestrial fractionation line. that is different but represents the same process. ) Different meteorite types, likewise, plot along their own sloping lines. Cais of the allende meteorite are similar, plotting in a simple linear manner. Current estimages of the age of the solar system are 4. 5 billion years, but the oldest rocks on the earth are only 3. 6 billion years old. Rocks on earth surface are not as old as the earth, they are recycled rock materials. Rocks are broken down into sediment (gravel, sand, silt, clay). Sediment will turn into sedimentary rock over time. Older rocks are buried deeply under younger rocks.
