Age determinations of the rocks of the batholiths of Baja and southern California, Sierra Nevada, Idaho, and the Coast Range of Washington, British Columbia, and Alaska
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Geology topics
Publications and source records attributed to David Gottfried.
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A direct comparison of helium and radiogenic lead in nonmetamict zircon crystals has indicated a 25 per cent discrepancy between these radiogenic constituents. It appears that the amount of helium is only three-quarters of the amount that should be present according to the content of radiogenic lead. Approximately the same proportion was found in zircon having a wide range in age, activity, and total alpha irradiation, and in large pegmatite zircon crystals, as well as in microscopic crystals from igneous rocks.
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