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SAMPLE INFO : 8
Sample ID:8
Station ID:8
Latitude:51.9531
Longitude:178.5356
Datum:NAD83
Sample Type 1:Lava
Field Lithology:Dacite
Text Description:
Low-silica dacite of Little Sitkin dacite. Color: dark gray (N 3). Texture: hypocrystalline, porphyritic with prominent feldspar phenocrysts as much as 6 mm long. Plagioclase, 20-25 percent, ranges from An36 to An62 in individual zoned phenocrysts and between different crystals; average composition is about An50; graphic fritting texture and two-fluid inclusions present in centers or selected zones of some feldspar crystals. Clinopyroxene, 6 percent, appears as reaction rims on some orthopyroxene, 5 percent, and olivine, 1 percent. Accessory: magnetite, 1-2 percent. Groundmass is clear brown glass choked with plagioclase (average composition, An43) and acicular orthopyroxene(?) microlites. Index of refraction of an artificial glass of the powdered rock is greater than 1.540.

References:
Geology of Little Sitkin Island, Alaska

GEOCHEM DATA
StationIDLatitudeLongitudeGeologistDateVisitedVolcanoEruptionLocation 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
851.9531178.5356Snyder, G. L.Little SitkinLittle Sitkin dacite from crater flow of West Cove member 1 mile south of crater lakeLow-silica dacite of Little Sitkin dacite. Color: dark gray (N 3). Texture: hypocrystalline, porphyritic with prominent feldspar phenocrysts as much as 6 mm long. Plagioclase, 20-25 percent, ranges from An36 to An62 in individual zoned phenocrysts and between different crystals; average composition is about An50; graphic fritting texture and two-fluid inclusions present in centers or selected zones of some feldspar crystals. Clinopyroxene, 6 percent, appears as reaction rims on some orthopyroxene, 5 percent, and olivine, 1 percent. Accessory: magnetite, 1-2 percent. Groundmass is clear brown glass choked with plagioclase (average composition, An43) and acicular orthopyroxene(?) microlites. Index of refraction of an artificial glass of the powdered rock is greater than 1.540.8Whole Rock 60.11 0.77 16.84 6.81 0.15 3.08 6.91 3.5 1.46 0.15 99.95424NN2.254.77H2OM=0.05; H2OP=0.17; CO2=0NN 28.3 280 7.1 745XRFK V=1.21, M=NN, R=745;

SAMPLE LOCATION

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Page modified: July 14, 2014 13:37
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