Paleogene climate reconstruction using paleosol mineral assemblages, San Juan Basin, New Mexico.

Certain preserved minerals are stable within specific climate conditions, thus their presence can indicate the type of climate that was present during their deposition. The climate after the Cretaceous/Paleogene extinction event is unique based upon preceding circumstances and thus requires analysis. Through the analysis of outcrops within the Nacimiento Formation of the San Juan Basin, New Mexico, the paleoclimate of this time period can be reconstructed. This is done through X-ray diffractometry, where climatically significant minerals can be identified and quantified to lead to a conclusion. It had been discovered that kaolinite, one such mineral climate indicator, was present throughout all of the observed sections, indicating the climate was never completely dry. However, some sections contained more kaolinite than others, indicating varied climate across regions, but note that the climate was never dry due to the lack of calcite present. Thus, the climate was wet during the Nacimiento deposition.