(705a) Rare Earth Occurrences Proximal to the Cretaceous/Tertiary Boundary

TheRaton Coal Basin of Colorado and New Mexico is one of the premier non-marine locals where the Cretaceous/Tertiary boundary can be viewed and sampled. Near Trinidad, CO, extensive coal deposits exist that straddle this boundary. Reconnaissance geochemical investigations utilizing a hand-held X-Ray Fluorescence Spectrometer (XRF) indicate that appreciable amounts of Ti, Zr, Y, and light rare-earth elements (REE) are present within coals and coal partings near the boundary of the Cretaceous Vermejo Formation and the overlying Tertiary Raton Formation. In some instances, semi-quantitative determinations indicate elevated quantities of Y and light REE (hundreds of parts per million) are present in select raw coal samples in the area.

In light of the fact that pyroclastic ash is present from the K/T impact event as well as from localized volcanic episodes within the basin, and there is an apparent proximal relationship between elevated Y and REE coal samples to these features, further study of REE occurrences associated with tonstein deposits and kaolinized ash within the coal as well as in the coal material itself is warranted. If the REE occurrence is found to be widespread and stratigraphically predictable, then methods for mining the coal and segregating coal ash and other coal waste products might be developed to exploit and extract REE resources when processing the coal.