Intellectual merit. The relationship between silicic volcanic and plutonic systems is a matter of great interest in petrology. Shallow crustal magma reservoirs are important because they are sites of magma storage and differentiation, they are commonly associated with ore deposits, and, what is especially significant to this proposal, the relations between such systems may provide important insights into magmatic and eruptive processes. Plausible textural fingerprints of eruptions have recently been recognized in some rhyolites and it is likely that similar markers of eruptions will be preserved in plutonic granites. The current project concerns: (1) Can fingerprints of eruptions be found in crystals of plutonic rocks? (2) Can these fingerprints be correlated with those in associated volcanic rocks? (3) What can be inferred about the eruption history of a system based on this plutonic record?
These questions will be addressed by studying crystal populations in plausibly correlated granites and rhyolites in terms of (a) trace-element zoning, (b) crystal size distributions, (c) the compositions of melts from which they grew, as recorded in melt inclusions, and (d) the ages of crystallization recorded by zircon crystals. The Colorado River Extensional Corridor (Nevada) includes several plutons and volcanic sequences where links between volcanic and plutonic systems have been documented. The exceptional exposures in this area of tilted plutons and volcanic units will provide a unique opportunity to explore the combined record in volcanic and plutonic rocks towards a better understanding of eruptions and the relationships between plutonic and volcanic magma systems.
Broader impacts. This project (as proposed) would support a post-doctoral associate, a graduate student, and one or more undergraduate students. This study will also involve collaboration between the PI and a team of geologists working in the Colorado River Extensional Corridor for more than a decade. Although principally a basic science project, The results of this work would be relevant to understanding the dynamics of volcanic systems and related volcanic hazards.
