Master of Science (MS)
First Committee Member
Terry L. Spell, Chair
Second Committee Member
Third Committee Member
Fourth Committee Member
Fifth Committee Member
Number of Pages
Around 82% of mapped Bearhead Rhyolite (Main Cluster) and Peralta Tuff appears to have been derived from a relatively long-lived (~680 ka), large, shallow (<10 km below Earth's surface) magma chamber that did not produce a caldera-forming eruption. Although volatile contents were great enough (~ wt.% H2O), no large-scale explosive eruptions occurred because magma may have been tectonically vented. The lack of systematic chemical variation within the Main Cluster with time during this ~680 ka interval may imply that erupted magmas were physically separated from each other by fault-formed cupolas in the roof of the magma chamber. These results are significant because Bearhead Rhyolite may represent a poorly documented style of silicic volcanism that may be more common than realized.
The remaining ~18% of mapped Bearhead Rhyolite is chemically and/or temporally distinct from the majority of Bearhead Rhyolite and is located in the southwest periphery of the field area.
Geochemistry; Geological time; Magmas; New Mexico -- Jemez Region; Rhyolite; Volcanic ash; tuff; etc.; Volcanism
Geochemistry | Geology | Volcanology
Justet, Leigh, "The geochronology and geochemistry of the Bearhead Rhyolite, Jemez volcanic field, New Mexico" (1999). UNLV Theses, Dissertations, Professional Papers, and Capstones. 1444.