In may 1989, during NSF-sponsored investigations of the xenolith- bearing basanites of central Mexico, Luhr, graduate student Greg Pool, and our Mexican colleague Jorge Aranda-Gomez visited two of the principal localities of lower-crustal xenoliths in central Mexico. Each vent was investigated in detail with regard to the spatial abundance of crustal and mantle xenoliths, and attempts were made to quantify the relative abundances of xenolith types in outcrop based on hand-sample observations. Aranda-Gomez will continue with this statistical work in a petrographic study at the Mexican National University using thin sections from small fragments of 50-60 representative crustal xenoliths. This project constitutes the A.M. thesis topic of Greg Pool. Funds from this grant will support him for the fall semester as he completes his thesis. Funds provided by this grant will provide additional trace element analyses by instrumental neutron activation. U-Pb geochronological investigations will concentrate on zircons in several orthogneiss xenoliths from each vent.
