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Sample Y-57233
NavDat sample number 2918 · TRACHYANDESITE
Sample
| Sample ID | Y-57233 |
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| Rock name | TRACHYANDESITE |
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| Rock type | VOLCANIC |
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| Composition | INTERMEDIATE |
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| Material | IGNEOUS |
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| Collected by | Charles J. Vitaliano |
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| Comment | A black, fine-grained, meagerly porphyritic rock. Dark green olivine and pyroxene crystals as well as sparse colorless plagioclase phenocrysts up to 1.5 mm in diameter constitute less than 10% of the rock, and are embedded in an aphanitic slightly vesicular groundmass. Under the microscope the rock is distinctly microporphyritic with marked flow structure. Phenocrysts consist of diopside, olivine slightly iddingsitized and plagioclase An60, and are set in a trachytic to intergranular groundmass. Plagioclase microlites constitute 70% of the groundmass, the remainder is granular olivine slightly more iddingsitized than the phenocrysts 10%, iron ore 10%, clear diopside laths 5%, interstitial glass about 5%, and grains of apatite and zircon less than 1%. The cores of plagioclase phenocrysts also show evidence of very mild attack by the groundmass. Except for one vesicle partly lined with carbonate the sample was unaltered. See Y-B3-13. |
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Location
| Latitude | 38.1625 |
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| Longitude | -117.21 |
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| Location | Nye County, NV |
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| State / province | Nevada |
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| Volcanic field | Goldfield-Tonopah region, West-Central Nevada |
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| Location comment | Labradorite trachyandesite flow approx. 8 mi NW of Tonopah |
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Age
| Age (Ma) | Error | Min | Max | Geologic age | Dated by |
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| 18.4 |
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15.4 |
21.4 |
|
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Analyses
No chemical analyses are stored for this sample.
