| Autor: |
Bell, Brian R., Williamson, Ian T. |
| Zdroj: |
Mineralogical Magazine; September 1994, Vol. 58 Issue: 392 p347-356, 10p |
| Abstrakt: |
AbstractMineral chemistry and whole-rock compositional data are reported for two lavas of picritic basalt from the Palaeocene lava field of west-central Skye, Scotland. Whole-rock compositions for both flows plot on Thompson's (1982) 9 kbar cotectic for olivine + plagioclase + clinopyroxene + liquid. Both flows contain highly forsteritic olivine phenocrysts (c.Fo89), which enclose early-precipitated crystals of chrome-spinel (Al2O3: c.25 wt.%; Cr2O3: c.36 wt.%; FeO + Fe2O3: c.20 wt.%; MgO: c.15 wt.%). The olivine compositions indicate equilibrium with picritic basalt magma compositions, as represented by the whole-rock compositions of both lavas. A high-pressure origin for the chrome-spinels is suspected on the basis of their textural association and aluminous composition. Compositional comparisons between the whole-rock and mineral chemistry characteristics of both flows and a picritic basalt chill facies of the temporally- and spatially-associated Rum Igneous Complex suggests that similar parental magmas were involved. |
| Databáze: |
Supplemental Index |
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