Abstract Old Crow tephra is the first extensive Pleistocene tephra unit to be documented in the northwestern part of North America. It has a calc-alkaline dacitic composition with abundant pyroxene, plagioclase, and Fe–Ti oxides, and minor hornblende, biotite, apatite, and zircon. Thin, clear, bubble-wall fragments are the dominant type of glass shard. This tephra can be recognized by its glass and phenocryst compositions, as determined by X-ray fluorescence, microprobe, and instrumental neutron activation techniques. It has an age between the limits of 60,000 and 120,000 yr, set by 14 C and fission-track measurements, respectively. Old Crow tephra has been recognized in the Koyukuk Basin and Fairbanks region of Alaska, and in the Old Crow Lowlands of the northern Yukon Territory, some 600 km to the east-northeast. The source vent is unknown, but these occurrences, considered in relation to the distant locations of potential Quaternary volcanic sources, demonstrate the widespread distribution of this tephra and underscore its importance as a regional stratigraphic marker.
Fifteen Japanese igneous reference rocks have been analyzed by X‐ray fluorescence spectrometry and instrumental neutron activation analysis for major and trace elements. Agreement between measured and accepted values is generally favourable with, however, several exceptions. Small systematic discrepancies are noted for MgO, Na2O, Sr, The, Eu, and Lu, which are likely the result of differences in calibration and/or analytical techniques. Zn generally shows poor agreement, suggesting that the rocks are not well characterized for this element.
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