Implications of oxygen-isotope data and trace-element modeling for a large-scale mixing model for the Columbia River Basalt
Implications of oxygen-isotope data and trace-element modeling for a large-scale mixing model for the Columbia River Basalt
Geology (Boulder) (April 1983) 11 (4): 248-251
- alkaline earth metals
- basalts
- Cenozoic
- Columbia Plateau
- Columbia River Basalt Group
- genesis
- geochemistry
- Grande Ronde Basalt
- heterogeneity
- igneous rocks
- isotopes
- lava
- lava flows
- magmas
- mantle
- metals
- Miocene
- mixing
- Neogene
- O-18/O-16
- oxygen
- Picture Gorge Basalt
- pollution
- Saddle Mountains Basalt
- Sr-87/Sr-86
- stable isotopes
- strontium
- Tertiary
- tholeiitic basalt
- trace elements
- United States
- volcanic rocks
- Elephant Mountain Member
- Pomona Memer
Compositionally diverse rocks such as the Saddle Mountains Formation have identical (super 87) Sr/ (super 86) Sr ratios. These radiogenic rocks have nearly identical delta (super 18) O values (6.24-6.36) to those of Picture Gorge, the least radiogenic of the Columbia River Basalts. Mantle beneath the Columbia Plateau heterogeneous with respect to Sr. Basalts with low delta (super 18) O values can be found in all formations of the Columbia River Basalt. Evidence for crustal contamination for some flow rocks. Grande Ronde and Saddle Mountains basalts produced as numerous independent magmas from a heterogeneous mantle. The magmas ascended following independent paths, some undergoing crustal contamination, others not.--Modified journal abstract.
