Using Spatial Coherency of Crystal Zoning to Reveal Residence Time and Mixing Regimes in Calc-Alkaline Plutons

University Of Washington, Seattle WA

Investigators

Abstract

Bergantz EAR-0106441 Open system behavior is ubiquitous in magmatic systems but the timing and extent of mixing associated with any single event is poorly understood. The objective of this work is to develop and employ novel technologies from information science to extract new structures of data and combine them with physical models of multiphase mixing to reveal (in part) the physical history of the body. The central concept is that crystal zoning provides for a non-monotonic, but progressive time-series. We significantly extend this by doing simultaneous spatial-statistical inversion of all crystal zoning patterns for hundreds, and perhaps thousands, of samples. This provides not only the minimum number of chemical events, defined by volumes of unique chemical potential, it also allows one to estimate particle trajectories and minimum residence times in portions of the system. Once putative volumes of prior chemical potential can be identified (chambers within chambers) isotopic microdrilling will be performed on a sub-set of the samples. This leads to a significant savings in time and effort in isotopic analysis as one can focus efforts on samples of most interest. The analysis tools are innovative in that they combine a number of recent advances in 1) crystal-chemical isotopic studies, 2) information technology and spatial statistics and, 3) multiphase modeling, in a combined way that has not been applied previously to problems in petrology and volcanology.