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SAMPLE INFO : 87-ARh-15e
Sample ID:87-ARh-15e
Station ID:87-ARh-15e
Latitude:62.1518
Longitude:-144.2604
Datum:NAD83
Date Sampled:1987-00-00
Sample Type 1:Lava
Sample Type 2:Flow
Field Lithology:Andesite
Sample Unit:Qwa
Text Description:
Mount Wrangell two-pyroxene andesite flows (Pleistocene). Extensive, medium- to dark-gray, thin to thick (5-30 m) flows that generally exhibit oxidized and slightly scoriaceous tops and bottoms. In places, unit contains lenses of light-colored silicic airfall tuff. Rock is conspicuously porphyritic, containing phenocrysts of plagioclase (10-24%, 1-10mm), hypersthene (1-8%, 0.5-3 mm), augite (trace to 3%, 1-4 mm), and olivine (trace), in intersertal to pilotaxitic groundmass of plagioclase, mafic minerals, and brown glass. Hypersthene is invariably the dominant phenocrystic pyroxene. * * * Plagioclase from two samples (locs. 6, 9, table 1) yielded K-Ar ages of 0.60+/-0.02 and 0.51 +/-0.02 M, respectively. Most likely source is summit region of Wrangell volcano, but unit may also include flows from Wrangell flank eruptions or from older Chetaslina eruptive center 5 km south of quadrangle, especially in area of Chichokna and Chetaslina Glaciers. * * * Maximum thickness probably more than 400 m.

References:
Geologic map of the Gulkana A-1 Quadrangle, south-central Alaska

GEOCHEM DATA
StationIDLatitudeLongitudeGeologistDateVisitedAge InfoVolcanoEruptionLocation DescriptionText DescriptionSample IDMaterialSiO2TiO2Al2O3FeOTMnOMgOCaONa2OK2OP2O5Total-majorsREF majorsMETH majorsFe2O3/Fe203T origFeO/FeOT origVolatiles csvMETH volatilesCsRbBaSrLaCePrNdSmEuGdTbDyHoErTmYbLuYZrNbHfTaPbThUScVCrFeCoNiCuZnGaMoAsNaKRef trace1METH trace1RbBaSrLaCeNdSmEuGdDyErYbLuYZrNbPbThUScTiVCrNiCuZnGaRef trace2METH trace2Light csvHalogen csvother major csvother lile csvother ree csvother hfse csvother hpe csvother tm csvother misc csv
87-ARh-15e62.1518-144.2604Richter, D. H.1987-00-00 WrangellMount Wrangell rocks within Gulkana A-1 quadrangle. Latitude and longitude derived from paper map.Mount Wrangell two-pyroxene andesite flows (Pleistocene). Extensive, medium- to dark-gray, thin to thick (5-30 m) flows that generally exhibit oxidized and slightly scoriaceous tops and bottoms. In places, unit contains lenses of light-colored silicic airfall tuff. Rock is conspicuously porphyritic, containing phenocrysts of plagioclase (10-24%, 1-10mm), hypersthene (1-8%, 0.5-3 mm), augite (trace to 3%, 1-4 mm), and olivine (trace), in intersertal to pilotaxitic groundmass of plagioclase, mafic minerals, and brown glass. Hypersthene is invariably the dominant phenocrystic pyroxene. * * * Plagioclase from two samples (locs. 6, 9, table 1) yielded K-Ar ages of 0.60+/-0.02 and 0.51 +/-0.02 M, respectively. Most likely source is summit region of Wrangell volcano, but unit may also include flows from Wrangell flank eruptions or from older Chetaslina eruptive center 5 km south of quadrangle, especially in area of Chichokna and Chetaslina Glaciers. * * * Maximum thickness probably more than 400 m.87-ARh-15eWhole Rock 59.5 0.94 16.7 5.6 0.09 3.98 6.47 3.74 1.74 0.26 100.022262NN1.414.33H2OP=0.85; H2OM=0.12; CO2=0.01RAPIDA

SAMPLE LOCATION

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