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Pitchblende U–Pb isochron dating yields an uranium mineralization age of 106.4±2.9 Ma, which is younger than the age of the granite emplacement and thus considerably postdates the time of magma crystallization, but is close to the closure time of the K–Ar system in the biotite.
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We critically re-examined all radiometric evidence suggesting Holocene survival of Chinese Late Quaternary megafauna, and conducted new dating of mammal material from reportedly Holocene sites containing characteristically Late Pleistocene faunas.
Evidence for Holocene survival of any Chinese Late Pleistocene megafaunal species is weak or untenable.
Both of these “experiments” involved 7 heating steps where the temperature increased for each step and the gas released from each step was analysed.
The data for each of those 7 steps is represented by one of the 7 boxes on the diagram.
Oxygen isotope thermometry for both granites gives temperatures of 685 to 720, 555 to 580, 435 to 460 and 320 to 330 °C, for hornblende, magnetite, biotite and orthoclase respectively, when paired with quartz.
The systematic differences among the ages by the different techniques on the different minerals are used to reconstruct the cooling history of the granite.
First up, let’s look at an Age Spectrum: In the diagram below I have drawn 2 different age spectra.
The bottom, green spectrum is what we would expect to see if we had an ideal sample that has no excess-Ar, and the top, blue spectrum is what we might expect if the sample contained excess-Ar in fluid inclusions.
Radiometric dating of the quartz syenite yields a whole-rock Rb–Sr isochron age of 135.6±4.3 Ma, a zircon U–Pb isochron age of 132.9±2.2 Ma, and K–Ar ages of 126±2, 118±3 and 94±4 Ma for hornblende, biotite and orthoclase, respectively.Tags: Adult Dating, affair dating, sex dating