Quaternary extrusion rates of the Cascade Range, northwestern United States and southern British Columbia
Article first published online: 20 SEP 2012
This paper is not subject to U.S. copyright. Published in 1990 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 95, Issue B12, pages 19465–19474, 10 November 1990
How to Cite
1990), Quaternary extrusion rates of the Cascade Range, northwestern United States and southern British Columbia, J. Geophys. Res., 95(B12), 19465–19474, doi:10.1029/JB095iB12p19465., and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 28 SEP 1989
- Manuscript Received: 24 MAY 1989
Quaternary (2–0 Ma) extrusion rates change significantly along the Cascade Range volcanic arc. The extrusion rate north of Mount Rainier is about 0.21 km3 km−1 m.y.−1; the rate in southern Washington and northern Oregon south to Mount Hood is about 1.6 km3 km−1 m.y.−1; in central Oregon the rate is 3–6 km3 km−1 m.y.−1; and in northern California, the rate is 3.2 km3 km−1 m.y.−1. Eruption style also changes along the arc but at latitudes different from rate changes. At the ends of the arc, volcanism is focused at isolated intermediate to silicic composite volcanoes. The composite volcanoes represent ∼30% of the total volume of the arc. Mafic volcanic fields partly ring some composite volcanoes, especially in the south. In contrast, volcanism is diffused in the middle of the arc, where numerous overlapping mafic shields and a few composite volcanoes have built a broad ridge. Contrasting eruption style may signify diffuse versus focused heat sources or may reflect changes in permeability to ascending magma along the arc.