PRELIMINARY GRAVITY AND MAGNETIC STUDY OF THE TRI-STATE MINING DISTRICT, KANSAS, MISSOURI AND OKLAHOMA

The Tri-State district of NE Oklahoma, SE Kansas and SW Missouri was one of the major world class lead-zinc mining districts. It is one of several Mississippi Valley type (MVT) deposits occurring in the Ozarks region of the U.S. mid-continent with the ore formation being related to ore fluids being expelled from the Arkoma basin and Reelfoot rift into structurally controlled hydrological regimes. Even though the exact location of deposition of the strata-bound ore minerals are mainly related to carbonate lithologies including dolomitic breccias and bioherms, the fluids were brought into the mining district by regional faults and there is a close association with major ore deposits and intersection of faults. To study the nature and extent of these structures, the existing gravity data which are relatively sparse especially in Missouri and Oklahoma were obtained. Aeromagnetic data were also obtained from the USGS. Bouguer gravity and magnetic anomaly maps showed that the regional anomalies trend toward the northwest with a large variation in the anomaly amplitude. This anomaly trend has been noted elsewhere with the Ozark's region and is inferred to be caused by basement topography however the variation of anomaly amplitude can also be explained by changes in lithologies (e.g., more mafic material causing the large amplitude gravity and magnetic maxima) within the basement. In order to further investigate these anomalies, a series of residual (wavelength filtered and polynomial trend surfaces) and horizontal derivatives maps will be constructed. These anomaly maps will be interpreted in conjunction with the available geologic and drill hole information.