Mapping Trace Element Distribution in Plagioclase

Trace elements and their spatial distribution in rocks and minerals are of substantial interest to geoscientists; for example, in igneous rocks, trace elements are valuable tracers for magma sources and geological processes affecting the subsequent evolution of magma. 

The present map shows the distribution of strontium (Sr) in a plagioclase (sodium-calcium feldspar). Sr is a trace element in plagioclases and of special interest since it can be used for diffusion chronometry or for studies of crystal-melt evolution. The analytical challenge in this case is not only related to the low concentration of the element of interest (Sr < 1000 ppm), but also to the distinct EDS peak overlap of Si Kα and Sr Lα.

QUANTAX WDS is perfectly suited for mapping and in-situ analyses of trace elements in minerals. The WDS technique is indispensable especially under such analytical circumstances where the close proximity of X-ray lines coincides with pronounced differences in line intensities.

X-ray element distribution map for Sr - a trace element in plagioclase
X-ray spectrum section for plagioclase in the energy region of Si K and Sr L showing the high spectral resolution of WDS