Quaternary lavas from the southern Cascades, western U.S.A.
Smith, A L; Carmichael, I S E (1968) Quaternary lavas from the southern Cascades, western U.S.A. Contributions to Mineralogy and Petrology. 19; 3, Pages 212-238. 1968.
| Authors | Smith, A L; Carmichael, I S E |
|---|---|
| Year | 1968 |
| Title | Quaternary lavas from the southern Cascades, western U.S.A. |
| Source | Contributions to Mineralogy and Petrology. 19; 3, Pages 212-238. 1968. |
| Publisher | Springer International. Heidelberg-New York, International. 1968. |
| Document type | Serial |
| ISSN | 0010-7999 |
| GeoRef | 1968-057233 |
| Keywords | andesites-; basalts-; California-; California-Oregon-lavas; Cascade-Range; composition-; genesis-; igneous-rocks; Oregon-; petrology-; Quaternary-lavas; United-States; volcanic-rocks |
| DOI | 10.1007/BF00508912 |
Abstract
Basaltic and andesitic lava from the Cascades have been studied. They are weakly porphyritic, containing phenocrysts of plagioclase, augite, and olivine or orthopyroxene; these phases are also found in the groundmass. Titanomagnetite is a groundmass phase in most of thelavas, and a subcalcic augite is found in the groundmass in some of thebasic lavas. Orthopyroxenes are present only in salic lavas and the Ca increases with increasing iron. The composition range of phenocryst and groundmass plagioclase is very similar except that phenocrysts extend to more calcic. Residual glasses in many lavas are rhyolitic. Lavas from the different craters can be distinguished from one another by chemistry and mineralogy. The most likely origin for the orogenic lavas of the Cascades is by partial melting of the upper mantle.