Hot, shallow mantle melting under the Cascades volcanic arc

Linda T. Elkins Tanton; Timothy L. Grove; Julie Donnelly-Nolan

doi:10.1130/0091-7613(2001)029<0631:hsmmut>2.0.co;2

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USGS · 70093940

Hot, shallow mantle melting under the Cascades volcanic arc

Linda T. Elkins Tanton·Timothy L. Grove·Julie Donnelly-Nolan

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Abstract

Melting occurs at progressively greater depths and higher temperatures from west to east across the Cascades volcanic arc in northern California, as demonstrated by compositional variations observed in high-alumina olivine tholeiites. The lavas studied erupted from seven vents defining a 75-km-long, east-west transect across the arc, from near Mount Shasta to east of Medicine Lake volcano. The increase in melting depth across the arc parallels modeled isotherms in the mantle wedge and does not parallel the inferred dip of the slab. The depth of mantle melting at which the high-alumina olivine tholeiites were created is ∼36 km at the western end of the transect and 66 km at the eastern end. The very high temperatures of dry melting so close to the crust indicate a transitory condition of the mantle.

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Source-reported bounding extent: 40° to 44° latitude; -124° to -118° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Linda T. Elkins Tanton, Timothy L. Grove, Julie Donnelly-Nolan. 2001. Hot, shallow mantle melting under the Cascades volcanic arc. https://doi.org/10.1130/0091-7613(2001)029%3C0631%3Ahsmmut%3E2.0.co%3B2

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