TOWARDS A GEOCHRONOLOGICAL DATABASE AND BASEMENT MAP OF TEXAS, OKLAHOMA, AND PARTS OF EASTERN NEW MEXICO

Towards A Geochronological Database and Basement Map of Texas,

Oklahoma, and parts of Eastern New Mexico

Daniel Puffer, Roger E. Denison, Robert J. Stern

We report here on our efforts to produce a geochronologic database for basement rocks of Texas and Oklahoma.  The purpose of this study is to produce a database for the ages of basement rocks that can be used by geologists, including generation of a basement map. This database is intended to assist with a range of geological interpretations, for example the source of detrital zircons in Phanerozoic sediments. Our procedure is to compile radiometrically dated samples from published geochronological studies,  update older ages so that these are consistent with modern decay constants, and to enter these into a GIS. Sample locations recorded in township and range coordinates have been converted to decimal degrees (for georeferencing). Lithology, depth below subsurface, and the reference is also input into the database; references are also entered into an Endnote file. This information along with scanned maps and USGS shapefiles are combined to create basement map of Texas, Oklahoma, and parts of New Mexico using ArcGIS software. This GIS will be updated as data becomes available. As of Dec. 2008, partial or complete data for 181 sample ages have been compiled, ranging from 487 to 1,408 Ma. Of these, 66 samples utilized U-Pb zircon ages with a mean age of 1.27 Ga, 100 are based on Rb-Sr techniques with a mean age of 1.10 Ga, and 15 are K-Ar ages with a mean age of 780 Ma compiled from eighteen papers published between 1951 and 2007. The mean age for the entire data set is 1.05 Ga. At this stage of the compilation, we invite feedback and especially additional age information from potential users.