Geology of Saipan, Mariana Islands; Part 2, Petrology and soils
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- Document: Report (pdf)
- Plates:
- Companion File: Chart 1 (pdf)
- NGMDB Index Page: National Geologic Map Database Index Page (html)
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Abstract
The rocks that comprise the volcanic formations of Saipan are of two principal types: dacites, which are characteristically glassy, and andesites, which are comparatively crystalline. The dacites consist primarily of silicic glass, oligoclase, and silica minerals (quartz, tridymite, cristobalite, chalcedony, and opal). Minor constituents in these rocks are green hornblende, biotite, magnetite, and hematite. The andesites are composed principally of labradorite, hypersthene, augite, and subcalcrc augite. Minor but also characteristic constituents of the andesites are quartz, tridymite, cristobalite, anorthoclase, and accessory magnetite, ilmenite, rutile, and apatite. Nine varieties of dacite and andesite are recognized on the basis of chemical composition, mineralogy, and texture. These are dacite, dacite vitrophyre, dacite perlite, hornblende-bearing dacite porphyry, augite-hypersthene andesite, quartz-bearing augite-hypersthene andesite, quartz-bearing augite-hypersthene andesite porphyry, augite andesite, and hypersthene andesite.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Geology of Saipan, Mariana Islands; Part 2, Petrology and soils |
| Series title | Professional Paper |
| Series number | 280 |
| Chapter | B-D |
| DOI | 10.3133/pp280BD |
| Year Published | 1957 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Washington, D.C. |
| Description | Report: 122 p.; 3 Plates: 27.31 x 35.94 inches or smaller; Chart |
| First page | 127 |
| Last page | 207 |
| Country | Saipan |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |