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For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.By comparing fossils of different primate species, scientists can examine how features changed and how primates evolved through time.These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.The XFe [= Fe3 /(Al Fe3 )] value of the secondary epidote ranges from 0.27 to 0.39.Epidote inclusions in plagioclase and interstitial grains contain less Fe3 (XFe = 0.08–0.29), Fe3 -poor epidote with XFe Fe value of 0.01–0.07 occurs only as inclusions in plagioclase, and usually has thin lamella-like layers of Fe3 -poor epidote with XFe = 0.09–0.14.

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Epidote occurs as inclusions in plagioclase, as interstitial phase in the matrix, and as secondary phase in chlorite pseudomorphs after biotite, and in saussuritized plagioclase.A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved.However, by itself a fossil has little meaning unless it is placed within some context.Abstract CHIME (chemical Th-U-total Pb isochron method) ages were determined for monazite from gneisses and granitoids of the Ryoke belt in the Iwakuni area.The CHIME monazite ages are 99.6 ± 2.4, 98.9 ± 2.1 and 98.2 ± 5.7 Ma for the Ryoke gneiss, 90.7 ± 2.2, 89.7 ± 2.0 and 89.3 ± 2.2 Ma for the Tajiri Granite, 91.0 ± 3.2, 90.6 ± 3.2 and 89.9 ± 3.2 Ma for the Namera Granite, 89.3 ±3.3 and 88.6 ± 5.6 Ma for a small stock at Shimizu, and 87.3 ± 1.6 and 86.6 ± 2.1 Ma for the post-tectonic Shimokuhara Granite.Xenotime has the properties of an ideal U–Pb chronometer, containing elevated levels of U (generally 1000 ppm) and very low concentrations of initial common Pb.In addition, it has an exceptional ability to remain closed to element mobility during later thermal events, and commonly yields concordant and precise dates.Xenotime (YPO) is an isotopically robust chronometer, which is increasingly being recognized as a trace constituent in siliciclastic sedimentary rocks.It may start to grow during early diagenesis, typically forming syntaxial outgrowths on detrital zircon grains.Recent advances in the field of geochronology have led to a greater understanding of the scale and duration of geological processes.It is currently possible to date igneous and metamorphic rocks by a variety of radiometric methods to within a million years, but establishing the depositional age of sedimentary rocks has remained exceedingly difficult.

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