Sample: 72-ARh-307
| Sample ID: | 72-ARh-307 [1] |
| Station ID: | 72-ARh-307 |
| AT Num: | |
| Volcano: | Jarvis |
| Possible source: | |
| Eruption: | |
| Collector: | Richter, D. H. |
| Date sampled: | 1972-00-00 |
| Sample type 1: | Lava |
| Color: | |
| Final unit: | |
| Text Description: | Dacitic andesite and dacite flows. Thick sequence of thin to medium flows with minor interbedded tuffs and breccias representing main cone-building state of Jarvis volcanoes which extend into the McCarthy D-7 and Nabesna A-6 quadrangles. Rocks are gray, dark gray, and pinkish gray. Chiefly two-pyroxene andesite containing hypersthene, augite, plagioclase, and rare olivine phenocrysts in a felty plagioclase-rich matrix. In southwest corner of quadrangle sequence is cut by numerous dark-colored dikes probably chiefly of andesite composition. K-Ar date (M.A. Lanphere, written commun., 1974) on plagioclase indicates age of 1.63 +/- 0.42 m.y. (Sample 72-ARh-307a). |
| Sample Location: |