Olivine and chromian spinel in primitive calc-alkaline and tholeiitic lavas from the southernmost Cascade Range, California: a reflection of relative fertility of the source
Clynne MA and Borg LE. 1997. Olivine and chromian spinel in primitive calc-alkaline and tholeiitic lavas from the southernmost Cascade Range, California: a reflection of relative fertility of the source. The Canadian Mineralogist. 35:453-472
Compositions of coexisting chromian spinel and olivine were used to infer the relative depletion in the peridotite sources of the suite of primitive Lassen lavas. The lavas were considered to give an excellent test of the usefulness of chromian spinel as a petrogenetic indicator because both the degree of partial melting and relative fertility of the source peridotite can be estimated for major, trace element, and isotope geometry. Conclusions made from the study were that the phenocryst compositions were primitive and also in equilbirium with peridotite. The systematic compositional differences between phenocrysts in the lavas result from bulk chemical variability in their mantle sources. Particularly important for studies of arc petrogenesis, is that compositions of chromian spinel included in olivine reflect the relative fertility of mantle sources of basaltic magmas.
- Type
- Journal Article
- Authors
- Clynne, Michael; Borg, Lars
- Units
- LAVO
- Keywords
- Basalt, chromian spinel, Geology, Magma, Petrogenesis, Phenocrysts, Physical Sciences, Volcanic Activity