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SAMPLE INFO : 46AC260
Sample ID:46AC260
Station ID:46AC260
Latitude:51.86
Longitude:-176.638
Datum:NAD83
Date Sampled:1946-01-01
Sample Type 1:Lava
Sample Type 2:Dome
Field Lithology:Andesite
 Text Description:
Andesite porphyry dome of Tertiary age. Zeto point basalt porphyry, from the Sand Hill Quarry, about half a mile north of the breakwater at the entrance to Sweeper Cove. Hornblende andesite porphyry. A medium light-gray (N7) porphyritic rock, about one-fourth phenocrysts. Phenocrysts are predominately plagioclase, ranging in size from 5 to 0.1 mm. The median composition of the plagioclase is about An55. Many of the phenocrysts show reverse zoning to a composition of about An73, succeeded by normal zoning to about An50. Hornblende is the commonest of the colored constituents; the prisms show outer rims of augite, which are due to reaction with the magma. The single large flake of biotite has a reaction rim of magnetite and is embedded in green hornblende. One round grain of quartz has the appearance of a xenocryst. The groundmass consists of plagioclase, averaging about An43, quartz, and orthoclase. Some calcite is in part interstitial to clear, unaltered plagioclase crystals of the groundmass, but has developed a reaction border of epidote against augite.

References:
A petrologic re-investigation of the Adak volcanic center, central Aleutian arc, Alaska
Magmatic differentiation in Tertiary and Quaternary volcanic rocks from Adak and Kanaga Islands, Aleutian Islands, Alaska

GEOCHEM DATA
StationIDLatitudeLongitudeGeologistDateVisitedAge InfoVolcanoEruptionLocation DescriptionText DescriptionSample IDSample Type 1Sample Type 2Final UnitMaterialSiO2TiO2Al2O3FeOTMnOMgOCaONa2OK2OP2O5Total-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
46AC26051.86-176.638Unknown, Unknown1946-01-01 Adak Island. Sand Hill Quarry, about half a mile north of the breakwater at the entrance to Sweeper CoveAndesite porphyry dome of Tertiary age. Zeto point basalt porphyry, from the Sand Hill Quarry, about half a mile north of the breakwater at the entrance to Sweeper Cove. Hornblende andesite porphyry. A medium light-gray (N7) porphyritic rock, about one-fourth phenocrysts. Phenocrysts are predominately plagioclase, ranging in size from 5 to 0.1 mm. The median composition of the plagioclase is about An55. Many of the phenocrysts show reverse zoning to a composition of about An73, succeeded by normal zoning to about An50. Hornblende is the commonest of the colored constituents; the prisms show outer rims of augite, which are due to reaction with the magma. The single large flake of biotite has a reaction rim of magnetite and is embedded in green hornblende. One round grain of quartz has the appearance of a xenocryst. The groundmass consists of plagioclase, averaging about An43, quartz, and orthoclase. Some calcite is in part interstitial to clear, unaltered plagioclase crystals of the groundmass, but has developed a reaction border of epidote against augite.46AC260LavaWhole-rock 59.16 0.4 16.87 6.14 0.16 2.54 7.37 3.54 1.18 0.36 99.881085NN3.932.57H2OP=0.88; H2OM=1.39NN 20 452 684 13.3 27.1 14.3 3.03 0.9 2.67 2.45 1.45 1.3 14.4 97 4 15 159 20 11 34 155DCP
46AC26051.86-176.638Unknown, Unknown1946-01-01 Adak Island. Sand Hill Quarry, about half a mile north of the breakwater at the entrance to Sweeper CoveAndesite porphyry dome of Tertiary age. Zeto point basalt porphyry, from the Sand Hill Quarry, about half a mile north of the breakwater at the entrance to Sweeper Cove. Hornblende andesite porphyry. A medium light-gray (N7) porphyritic rock, about one-fourth phenocrysts. Phenocrysts are predominately plagioclase, ranging in size from 5 to 0.1 mm. The median composition of the plagioclase is about An55. Many of the phenocrysts show reverse zoning to a composition of about An73, succeeded by normal zoning to about An50. Hornblende is the commonest of the colored constituents; the prisms show outer rims of augite, which are due to reaction with the magma. The single large flake of biotite has a reaction rim of magnetite and is embedded in green hornblende. One round grain of quartz has the appearance of a xenocryst. The groundmass consists of plagioclase, averaging about An43, quartz, and orthoclase. Some calcite is in part interstitial to clear, unaltered plagioclase crystals of the groundmass, but has developed a reaction border of epidote against augite.46AC260LavaWhole-rock H2OP=0.88; H2OM=1.39NN units are percent 0.03units are percent 0.1units are percent 0 units are percent 0.004 units are percent 0 0.01units are percent 0.001 0.001units are percent 0.0009units are percent 0.003 units are percent 0.0007units are percent 0units are percentunits are percent 0 1085SPEC

SAMPLE LOCATION

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