COLLECTING, ANALYZING, AND INTERPRETING DETRITAL ZIRCONS OF THE CATAHOULA ASH FORMATION IN THE LOWER RIO GRANDE VALLEY FLOODPLAIN

The Lower Rio Grande Valley Floodplain region in South Texas is host to one of the largest ashfall deposits within North America which dates back to ~27 Ma. Zircons have been identified in these deposits by past students of the UTRGV, SEEMS department. This study aims to analyze collected and sorted Detrital Zircon crystals from the Catahoula Ash Formation, within Rio Grande City, Texas, by conducting radiometric dating using a method called Uranium-Lead Dating (U-Pb Dating). This process will be hosted by the University of Houston using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). This study uses methods developed by the research team in a previous methodology study to identify, collect and sort zircon crystals from the same study area. LA-ICP-MS will allow the group to identify concentrations of Uranium (U) to Lead (Pb) within the zircons collected, which in turn will give an accurate date of deposition. With a very minute amount of research done on the Catahoula Formation, the place of origin for the deposition is still not known. The information gathered from this study will be helpful for future research to find the place of origin for the single event deposition that is known to be found along the Oligocene Gulf Coastal Plain within Mexico, Texas, and Louisiana. The research question that aims to be answered in this project is if the age of the Catahoula Ash Formation, that has been found using zircons in previous studies, can be replicated using a different methodology. There are few studies that have been done on this formation, especially on the deposit that exists in Rio Grande City, Texas, so this project aims to find zircons to redate, and potentially reconfirm, the age that has been identified in these studies.