Reference 1970

Abstract

Quaternary basaltic rocks of the bimodal Blackfoot Volcanic FieldBVF in southeastern Idaho are normatively classified as olivine andquartz tholeiites. Eruptive vents and lava flows are located in theBasin and Range tectonic province, adjacent to the southern border ofthe eastern Snake River Plain ESRP volcanic province. This studycompares physical volcanology, petrography, and geochemistry of BVFbasalts with contemporaneous basalts in the Basin and Range and on theESRP in order to determine possible influences of ESRP magmatism onBasin and Range magmatism. Basalts in the study area represent bothstrombolian and hawaiian styles of volcanism, which are typicallyfound in the Basin and Range, and not on the ESRP. Geochemicalcomparisons between the above provinces and the study area indicatethat BVF basalts share many characteristics with ESRP basalts and notwith Basin and Range basalts. Geochemical and isotopic evidencesuggests a lithospheric source for BVF basalts, similar to the sourcebelieved to have produced the ESRP basalts. Typical Basin and Rangebasalts are not likely represented in the study area. The proposedsimilarity in ESRP and BVF source regions has significant implicationfor the extent of ESRP magmatic influence in southeastern Idaho; thisis consistent with recently proposed geophysical models that depictESRP-like source material beneath the BVF.

35 samples from this reference