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SAMPLE INFO : 54-Sn-270
Sample ID:54-Sn-270
Station ID:54-Sn-270
Latitude:53.88707
Longitude:-166.93202
Datum:NAD83
Date Sampled:1954-01-01
Sample Type 1:Countryrock
Sample Type 2:Plutonic
 Text Description:
Leuco albite quartz monzonite from an irregular aplitic body at the margin of the 3600 Mountain roof pendant, 0.7 mile southwest from the summit of the 3,600-foot peak for which the pendant is named. The texture is allotriomorphic-granular, locally subgraphic, locally pseudoperthitic. The specimen contains 94-98 percent felsic minerals: 20-24 percent quartz, 25-34 percent orthoclase slightly altered to kaolin, and 40-49 percent plagioclase (only one-sixth of which is twinned) slightly altered to sericite. The plagioclase composition, by extinction angle, is An7, [mean of 12 crystals, standard deviation is 3 percent An, average amount of zoning per individual plagioclase crystal is 0 percent An per crystal]. There are 2-6 percent mafic minerals of which 2-6 percent is biotite (?) completely altered to magnetite (0.5-1.5 percent), penninite (2-3 percent), epidote ( <0.1 percent), and sphene (0.1-1 percent), and <0.3 percent is allanite associated with minor epidote. The discrepancy in the amounts of normative and modal quartz may be due to unrecognized fine-grained quartz in the groundmass, or perhaps some of the quartz was mistakenly identified with the abundant untwinned plagioclase.

References:
Geology of Unalaska Island and adjacent insular shelf, 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
54-Sn-27053.88707-166.93202Snyder, G. L.1954-01-01 MakushinGranodiorite and related rocks from 1 mi SW of 3600 Mtn.Leuco albite quartz monzonite from an irregular aplitic body at the margin of the 3600 Mountain roof pendant, 0.7 mile southwest from the summit of the 3,600-foot peak for which the pendant is named. The texture is allotriomorphic-granular, locally subgraphic, locally pseudoperthitic. The specimen contains 94-98 percent felsic minerals: 20-24 percent quartz, 25-34 percent orthoclase slightly altered to kaolin, and 40-49 percent plagioclase (only one-sixth of which is twinned) slightly altered to sericite. The plagioclase composition, by extinction angle, is An7, [mean of 12 crystals, standard deviation is 3 percent An, average amount of zoning per individual plagioclase crystal is 0 percent An per crystal]. There are 2-6 percent mafic minerals of which 2-6 percent is biotite (?) completely altered to magnetite (0.5-1.5 percent), penninite (2-3 percent), epidote ( <0.1 percent), and sphene (0.1-1 percent), and <0.3 percent is allanite associated with minor epidote. The discrepancy in the amounts of normative and modal quartz may be due to unrecognized fine-grained quartz in the groundmass, or perhaps some of the quartz was mistakenly identified with the abundant untwinned plagioclase.54-Sn-270CountryrockEnclave/InclusionWhole-rock 74.6 0.23 13.1 1.43 0.02 0.38 0.56 3.4 5.7 0.03Total not given in table. 100.47315RAPIDA0.90.64H2OM=0.04; H2OP=0.51; CO2=0.05; Cl=0.05; F=0.01RAPIDA

SAMPLE LOCATION

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