This laboratory has developed techniques for dating samples of low radiogenic argon content. Results of three principle lines of study utilizing these techniques will be reported. (1) Ages of a series of well classified glauconites from New Zealand ranging from the Cretaceous (55 million years) to the Miocene (20 million years). (2) Ages of two near surface igneous micas from Sutter Buttes, California, less than two million years in age. (3) Ages of a series of related plutonic igneous micas from the Sierra Nevada around 90 million years in age.

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