3671: Major-Element Composition (Weight Percent) of Glass in Sheep Creek Tephra at Occurrences in the Fairbanks Area, Alaska * Note. Major elements in glass determined on an ETEC energy dispersive microprobe operating at 20 keV accelerating voltage, 1–2 mm beam diameter, and 50–60 nAmp beam current. Standardization using mineral and glass standards. Mg, Mn, and Cl concentrations below detection limit. Analyses recalculated to 100% to remove effects of variable hydration. A-One standard deviation is given. See Figure 2 for location of sites. B-Total iron as FeO. C-H2O by difference. ‘‘n’’ is number of analyses. *

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3681: Major- and Trace-Element Composition of Glass Shards in Old Crow Tephra at Upper Eva Creek Locality, Fairbanks, Alaska (a) * (a) Microprobe operating conditions and other traits as specified in Table 1. Average MgO concentration is 0.27 +/- 0.06 wt.% but this oxide was not detected during analysis of UT828. H2O (by difference) for UT828 is 5.0 +/- 1.0 wt.%. Trace-element concentrations determined by INAA following the methods of Barnes and Gorton (1984). See Figure 6 for stratigraphic position of Old Crow tephra in relation to Sheep Creek tephra. *

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