Ultramafic and Mafic Inclusions, Kanaga Island, Alaska, and the Occurrence of Alkaline Rocks in Island Arcs
| Autor: | Stephen E. DeLong, F. N. Hodges, R. J. Arculus |
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| Rok vydání: | 1975 |
| Předmět: | |
| Zdroj: | The Journal of Geology. 83:721-736 |
| ISSN: | 1537-5269 0022-1376 |
| DOI: | 10.1086/628164 |
| Popis: | Dunite nodules, bearing minor amounts of chromite and clinopyroxene, occur as inclusions in an isolated outcrop of alkaline basalt (limburgite) near the northwest coast of Kanaga Island in the Aleutian arc. Gabbroic inclusions with very calcic plagioclase (up to An91) are found in a nearby outcrop on the Kanaga coast, but their geological relationship, if any, to the dunitic material is unknown. The dunite nodules are not typical lherzolites from an alkali-basalt xenolith suite. Instead, the dunite nodules have mineralogical affinities with dunitic members of Alaskan-type zoned ultra-mafic complexes. In particular, olivine compositions (Fo86) and clinopyroxene major-element (Ca47Mg48Fe5) and minor-element (0.10 wt% TiO2, 1.41 wt% Al2O3) compositions are very similar to those of Alaskan-type dunites. Clinopyroxenes in the host limburgite from Kanaga also fall on the trend of calcic augites and accord with previous arguments for a genetic association of Alaskan-type zoned complexes with alkaline magmas. The... |
| Databáze: | OpenAIRE |
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