Sample: 10AZnye03i
| Sample ID: | 10AZnye03i [1] |
| Station ID: | 10AZ-i3 |
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| Volcano: | |
| Possible source: | |
| Eruption: | |
| Collector: | Nye, C. J. |
| Date sampled: | 2010-01-01 |
| Sample type 1: | Lava |
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| Final unit: | |
| Text Description: | This outcrop is a large lava mass consisting of host lava with abundant rounded magmatic inclusions several cm to 10s of cm across. Host is porphyritic pl-hb andesite w/ 15% pl (5-10mm) and 5% hb (1-3mm) in a fine-grained light greenish-grey gms. Inclusions are very fine-grained and equigranular with pl, px, hb in randomly oriented xl <<1mm (save a few percent mm-sized hb crystals). Northernmost of three domes shown by Coats (1956, USGS Bull 1028-C), who calls these, and two others near downtown Adak, Ta, Andesite porphyry domes. Coats notes these domes are glaciated (thus pre-late Pleistocene), but don't share the structural style of surrounding Finger Bay volcanics (thus not buried, much younger). Coats assigns an early Tertiary age (but he assigns late T to Moffett and Adagdak volcanoes; mid T to Andrew Bay volcano; and Paleozoic to Finger Bay volcs -- clearly too old. My guess would be early to mid Pleistocene for these domes.). |
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