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Oligocene basaltic volcanism of the northern Rio Grande Rift: San Luis Hills, Colorado

Journal of Geophysical Research

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Abstract

The inception of the Rio Grande Rift in northern New Mexico and southern Colorado was accompanied by voluminous mafic volcanism preserved in part as erosional remnants on an intrarift horst within the current axial rift graben of the San Luis Valley. Major and trace element constraints support a petrogenetic model of fractionation plus lower crustal assimilation for petrologic suites within the San Luis Hills rocks, although the model cannot relate lavas for the entire series to a common parent. Most mafic lavas of the San Luis Hills were evolved (Mg # <60) and contaminated by LREE-enriched silicic partial melts of granulitic lower crust depleted in Rb, Th, and U. However, relatively noncontaminated lavas can be identified and indicate at least two mantle source regions were involved. -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Oligocene basaltic volcanism of the northern Rio Grande Rift: San Luis Hills, Colorado
Series title:
Journal of Geophysical Research
Volume
96
Issue:
B8
Year Published:
1991
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article