PETROGRAPHY AND STATISTICAL DISTRIBUTION PROJECT FOR CRUSTAL XENOLITHS COLLECTED AT KILBOURNE HOLE MAAR, SOUTH-CENTRAL NEW MEXICO

The Hardin-Simmons University Geology Field Methods class of 1997 visited the Quaternary Kilbourne Hole maar for a project. Kilbourne Hole is located about 60 km west of El Paso, Texas, in south-central New Mexico. The crustal xenoliths exposed at Kilbourne Hole are mixed with a spectacular array of ultramafic mantle xenoliths. Kilbourne Hole is known as a world class xenolith collection site. The xenoliths were entrained by a batch of mafic magma that originated in the mantle and erupted onto the surface.

The project was to sample the crustal xenolith population for distribution bias and for rock type counts. No statistical or distribution bias was determined by the population count. An artifact of the project was the addition of an excellent teaching collection of crustal xenoliths for our department.

A review of 60 thin-sections made from selected crustal xenoliths reveals an interesting assemblage of rocks. Arrays of textures for volcanic, intrusive, sedimentary, and regionally metamorphosed crustal rocks were obtained. The presentation will show many photomicrographs of the crustal xenolith suite and offer a few brief descriptions.