Record Details
Volatile mobility of trace metals in volcanic systems
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Volatile mobility of trace metals in volcanic systems |
| Names |
Loewen, Matthew W.
(creator) Kent, Adam J.R. (advisor) |
| Date Issued | 2013-12-16 (iso8601) |
| Note | Graduation date: 2014 |
| Abstract | Semi-volatile trace metals like Li, Cu, Mo, Sn, In, and Pb have the potential to track mobility of a volatile phase in volcanic systems. In this dissertation four studies are presented that either directly investigate or are motivated by observations of trace metal behavior in volcanic systems. A common tool for trace element determination in solid materials is laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Although this technique has the potential to measure concentrations of many elements to << 1 ppm, it also has the potential to fractionate elements of different volatility resulting in increased analytical uncertainty. Potential sources of fractionation in two different laser ablation systems are characterized, including a previously unrecognized source of fractionation related to differential carrier gas flow at the site of ablation. Glass and melt inclusions from the 1959 eruption of Kilauea Iki record little evidence for volatile behavior of metals, but do record variations related to mixing of distinct batches of magma. Variations in concentrations of metals like Cu, Zn, and Mo can be explained with olivine fractionation. Only Sn variations appear to be compatible with volatile mobility. Lithophile element variations in both glass and melt inclusions require that the Kilauea Iki magma was a mixture of melts generated from different mantle sources by variable degrees of melting. Amphibole phenocrysts from Mt. Pinatubo, Mt. Hood, Mt. St. Helens, and Shiveluch Volcano record a variety of trace element signatures related to the sources and fractionation processes acting in each of these systems. Variations in Li and Cu in amphiboles are decoupled from any other trace element but positively correlate with each other. Their behavior appears to be consistent with mobility in volatile-rich fluids followed by rapid equilibration with amphibole phenocrysts. New ⁴⁰Ar-³⁹Ar incremental heating age determinations and whole rock major and trace element analyses from the Curaçao Lava Formation and the Dumisseau Formation have provided a revision of the timing and geochemical character of the Caribbean Large Igneous Province. These data provide evidence for almost 30 million years of volcanic history beginning around 94-60 Ma with mantle plume-like geochemical character. To reconcile the duration of volcanism and the observed geochemical signature with models of mantle plume impingement, a new model for development of the Caribbean Large Igneous Province is proposed that calls on nearby subduction zones to induce asthenospheric flow in the mantle that allows for continuous tapping of plume-influenced mantle for a 30 million year period. |
| Genre | Thesis/Dissertation |
| Access Condition | http://creativecommons.org/licenses/by-nc-nd/3.0/us/ |
| Topic | Trace Metals |
| Identifier | http://hdl.handle.net/1957/45129 |
