Physical Sciences and Mathematics Commons^™

The Geochronology And Geochemistry Of The Bearhead Rhyolite, Jemez Volcanic Field, New Mexico, Leigh Justet

UNLV Theses, Dissertations, Professional Papers, and Capstones

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 (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 …

Compositional Variations In The Fire Clay Coal Bed Of Eastern Kentucky: Geochemistry, Petrography, Palynology, And Paleoecology, Cortland F. Eble, James C. Hower, William Morton Andrews Jr.

Report of Investigations--KGS

Bench samples of the Fire Clay coal bed, collected from 28 localities in a study area of eight 7.5-minute quadrangles in the Eastern Kentucky Coal Field, were analyzed geochemically, petrographically, and palynologically to determine any spatial or temporal trends among the studied parameters.

At most sample sites the Fire Clay is split by a flint-clay parting of probable volcanic origin. The upper bench of the Fire Clay coal generally is thick, laterally continuous, low in ash yield and sulfur content, has a moderate to high calorific value, and is high in total vitrinite content. In contrast, the lower bench generally …