if you are interested in a more archaeological or geoarchaeological contexts some recent papers about multielement analysis in archaeological sites from e.g. Wilson et al. http://dx.doi.org/10.1016/j.jas.2009.06.022, Lubos et al. http://dx.doi.org/10.1016/j.jas.2012.07.022 or phosphorus from e.g. Holliday and Gartner http://dx.doi.org/10.1016/j.jas.2006.05.004 might be helpful. If you have no access to the journals and are interested in the papers I could send you.
We are analyzing the content of some trace elements in the profile of Paleolithic site. We have found traces of ancient hearths (we think so) and we want to find a correlation between the content of some trace elements that would become indicators of human activity, primarily hearth