THE DEVELOPMENT OF COMPONENTRY ISOTOPIC MICROSAMPLING: THE DAVIDSON YEARS (Invited Presentation)
These new techniques involved micromilling growth zones of crystals in situ and low-blank chemical processing. Isotopic microsampling, when used in concert with Nomarski Interferometry (NDIC) to enhance compositionally dependent textural features of crystals, and electron microprobe analyses to determine compositional variations in target crystals, provided a combined textural, chemical and isotopic relationship that was used to diagnose open system processes such as magma mixing, contamination and recharge.
A variety of volcanic and plutonic systems were addressed and new hypotheses tested under Davidson’s guidance during these developmental years. From these studies, it became clear that mineral phases are not always in isotopic equilibrium with other co-existing phases and/or their own host groundmass. Significantly, it was found that intracrystalline isotopic heterogeneities are common, reflecting crystal growth in isotopically changing magmatic systems. This shift in capabilities and collection of more detailed observations has led to significant advances in our understanding of magmatic evolutionary processes.