Evolved and Hybrid Lavas from the Snake River Plain, Idaho
Leeman WP. 1982. Evolved and Hybrid Lavas from the Snake River Plain, Idaho. Pages 193-212. In Bonnichsen B and Breckenridge RM (ed). Cenozoic Geology of Idaho. Idaho Bureau of Mines. Moscow, ID
Numerous suites of evolved or hybrid lavas from the Snake River Plain-Yellowstone Plateau province are briefly described in this paper. Despite that such rocks are widely dispersed in time and space through-out the province, they display remarkable coherence in their major element compositional variations from one place to another. In addition, these rocks typically have anomalous strontium, lead, and oxygen isotopic compositions compared with the associated more voluminous olivine tholeiites. Where sufficient data exist, the isotopic compositions in the lavas trend toward typical crustal values with increasing differentiation. This observation suggests that the magmas evolved at crustal levels where they were progressively contaminated by interactions with crustal wall rocks. However, crystal-liquid fractionation is considered to be the dominant factor in their evolution. Available petrochemical and experimental data support this view and reveal that the evolved lavas initially developed by high-pressure (about 8-10 kilobars) crystallization of olivine tholeiitic magmas.
- Type
- Book Chapter
- Authors
- Leeman, William
- Units
- CRMO , YELL
- Keywords
- Geology, Geomorphology, Lava, Snake River Plain, Volcanism
- Subjects
- Ecological Framework: Geology and Soils | Subsurface Geologic Processes | Volcanic Features and Processes