9: Analytical data from 40K-40Ar age determinations * Ages preceded by = are minimum ages based on thin-section observations of groundmass glass a or minor alteration. B. RAD, radiogenic. C Sample believed to be from older volcanic flows underlying the Spurr volcanic complex. Constants: ?e+?'e=0.581x10^-10/year, ?ß=4.962x10^-10/year, 40K/Ktotal=1.167x10^-4 mol/mol *

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10: Whole-rock chemical data and modal analyses * Major elements are normalized to 100 anhydrous, original LOI and totals are reported. Sample prefixes are PUM, air-fall pumices from the 1953 eruption; CP, Crater Peak; PCP, proto-Crater Peak; PF, pyroclastic fan; SP, Mt. Spurr; AF, ash flows; AMS, ancestral Mt. Spurr; sample locations are shown on Fig. 2. CP, PCP-A, PCP-B, and AMS samples are in relative stratigraphic order, with youngest samples at the top of each group *

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11: Typical compositions of minerals from within SVC lavas * FeOm is total measured iron as FeO. Pyroxene recalculation scheme from Lindsley (19983). NONQ is total nonquadrilateral components. Spinel recalculation scheme from Perfit (1977). YFe, YCr, and YAl are proportions of trivalent Fe, Cr, and Al among all trivalent ions. Amphibole recalculation assumes total cations minus (Ca+Na+K) is less than 13, Si+tetrahedral Al equals 8, and Fe species are determined by charge balance. *

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12: Results of least-squares, major-element modelling

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13: Distribution coefficients used in trace-element modelling. * Y distribution coefficients are assumed to be those of medium-heavy rare earth elements *

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14: Mean composition of SVC lavas and potential crustal contaminants.

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15: Isotopic composition of SVC lavas

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