Tourmaline as a monitor of igneous and hydrothermal systems

The use of boron and lithium isotopes in studies of fluid-related geologic processes has boomed in the past decade and theoretical work on isotope fractionation has provided a good first-order understanding of the B and Li-isotope compositions of the major earth reservoirs, the physical-chemical processes that can cause isotopic fractionation in nature, and the partitioning of isotopes between coexisting fluid and mineral phases.
This project sets out to develop and apply B- and Li- isotope study of coexisting micas and tourmaline from hydrothermal systems. This is likely to be a fruitful area of research because the two minerals have different coordination environments for boron (tetrahedral in mica, trigonal in tourmaline), which should lead to significant fractionation and the potential of application as a geothermometer. The work requires in-situ measurement of individual mineral grains and the method of choice is the secondary ion mass spectrometry or SIMS, which offers rapid, nearly non-destructive analyses of B-isotope variations with a spatial resolution of less than 10 microns.

 

• Contact:  Dr. Robert Trumbull,  Dr. Michael Wiedenbeck

The Potsdam SIMS lab has considerable experience in the analysis of B-isotope variations in igneous and ore systems to better understand fluid-rock interactions. Our focus is on tourmaline, which as a common and highly stable mineral ideally suited for retaining isotopic “memory”.