Tectonic Setting of the San Juan Basin in the Jurassic
Published:January 01, 1986
Elmer S. Santos, Christine E. Turner-Peterson, 1986. "Tectonic Setting of the San Juan Basin in the Jurassic", A Basin Analysis Case Study: The Morrison Formation, Grants Uranium Region, New Mexico, Christine E. Turner-Peterson, Elmer S. Santos, Neil S. Fishman
Download citation file:
In the Middle and Late Jurassic, the structural configuration of the area occupied by the San Juan basin was different from the present-day configuration, which developed in response to Laramide deformation in the latest Cretaceous to early Tertiary. An isopach map indicates a thickening of Middle to Upper Jurassic strata near the southern margin of the area. The thickening is attributed to downwarping, mainly in the Jurassic, which may have controlled depositional patterns and influenced the distribution of primary uranium ore deposits in the host rocks of the Jurassic Morrison Formation. Paleotectonic reconstruction indicates the existence of a magmatic arc immediately west of the Colorado Plateau in the Jurassic. Jurassic folding in the basin and magmatic activity in the arc have important implications bearing on the uranium geology of the area. The folding probably exerted some control on depositional trends in the host rocks which, in turn, influenced the distribution of uranium deposits in them. Volcanism in the magmatic arc supplied silicic ash that may be the source of some, if not all, of the uranium in the host rocks.
Figures & Tables
A Basin Analysis Case Study: The Morrison Formation, Grants Uranium Region, New Mexico
This volume summarizes results of a U.S. Geological Survey multidisciplinary basin analysis research effort that encompasses all aspects of the geology of the Morrison Formation in the Grants uranium region, located in the San Juan basin of northwestern New Mexico, U.S.A. Tectonic, stratigraphic, sedimentologic, structural, petrographic, mineralogic, geochemical, and resource studies are drawn together to provide a geologic synthesis of the Jurassic Morrison Formation, the main uranium host rock in the region, and to provide background data for the formulation of genetic models for ore genesis. The result is a compendium of 21 papers that incorporates many recent and significant advances in our understanding of factors that favored uranium mineralization in the Morrison, and several new genetic models that incorporate these recent advances. The basin analysis approach used here has proved fruitful in that ore genesis can now be viewed in the context of the evolution of a sedimentary basin rather than as an isolated event. This approach to ore genesis has application not only to uranium deposits but also to all sediment-hosted ore deposits.