Distribution, origin, and mineral resource potential of Late Cretaceous heavy mineral, beach-placer sandstone deposits
Virginia T. McLemore
Beach-placer sandstone deposits are concentrations of heavy minerals that formed by mechanical concentrations (i.e. settling) of heavy minerals on beaches or in longshore bars in a marginal-marine environment. Numerous deposits are found in the San Juan Basin, New Mexico that contain high concentrations of Ti, Zr, rare earth elements (REE), Sc, Y, U, Th, Nb, Ta, Fe, and other elements. Potential sources of these deposits include Proterozoic granitic and metamorphic rocks, such as those found in the Zuni Mountains, the Jurassic arc volcanism and magmatism forming the Mogollon Highlands to the south and west, and recycling of older sediments. Many of these elements, especially Ti and REE (including Y and Sc), are increasingly becoming more important in our technological society and are used in many of our electronic devices, such as cell phones, computer monitors, televisions, wind turbines, etc. It is unlikely that any of the heavy mineral, beach-placer sandstone deposits in the San Juan Basin will be mined in the near future because of small tonnage, low grades, high degree of cementation through lithification, high iron content, and distance to processing plants and markets. However, as the demand for some of these elements increases because of increased demand and short supplies, the dollar value per ton of ore rises, enhancing deposit economics. Detailed mapping and exploration drilling of some of these deposits, particularly the Sanostee deposit and the deposits on the Ute Indian Reservation (northern San Juan Basin), are essential to fully evaluate the economic potential. Although, Zech et al. (1994) provided chemical analyses of the deposits on the Ute Indian Reservation, detailed chemical analyses of the remaining deposits in the San Juan Basin are essential to fully evaluate their resource potential in today’s ever changing economic market.
- McLemore, Virginia T., 2010, Distribution, origin, and mineral resource potential of Late Cretaceous heavy mineral, beach-placer sandstone deposits, in: Geology of the Four Corners Country, Fassett, James E.; Zeigler, Kate E.; Lueth, Virgil W., New Mexico Geological Society, Guidebook 61st Field Conference, pp. 197-212.