New Mexico Geological Society Annual Spring Meeting — Abstracts

Geologic mapping, structural analysis, and microprobe analysis have been paired to improve our understanding of the origin and evolution of the Mazatzal Province in southern New Mexico. This study focuses on tackling the origin of various amphibolite units throughout the Salinas Peak region in the San Andres Mountains. The goal is to extrapolate the tectonic setting that was responsible for the development of the Mazatzal Province and how it evolved with the onset of the Mazatzal Orogeny.The diverse lithologies that make up the Mazatzal Province makes it difficult to propose a model that accounts for the generation of cogenetic and coterminal units. Many models have been proposed for the development of the Mazatzal Province, but there have been limited studies on the Mazatzal Province in southern New Mexico. Further studies throughout New Mexico can help identify tectonostratigraphic terranes that represent different tectonic settings of the Mazatzal Province. Preliminary mapping at a 1:12,000 was done to identify the variable lithologies that were previously unknown. Structural analysis is used to decipher sets of foliation trends that may be associated with different deformation events. Foliations plotted on a stereonet shows a SE hinge for folded foliations in the Salinas Peak area. SW and NE compression is responsible for the folding of these foliations. It is speculated that the foliations and their subsequent deformation took place during the Mazatzal or Picuris Orogeny. Petrography of some amphibolite shows evidence of prograde and retrograde metamorphism with poikiloblastic amphibole filled with quartz. Titanite in equilibrium with amphibole provides backing for future U-Pb titanite geochronology to date the age of metamorphic events. Microprobe analysis of amphibole and plagioclase from amphibolite was done to understand the composition of the protolith.