Coal, Uranium, and Oil and Gas in Mesozoic Rocks of the San Juan Basin: Anatomy of a Giant Energy-Rich Basin: Sandia Mountains to Mesita, New Mexico June 30-July 7, 1989

Published by the American Geophysical Union as part of the Field Trip Guidebooks Series.

The San Juan Basin of northwest New Mexico and south-west Colorado contains huge resources of subbituminous to bituminous coal, nearly half of the U.S. uranium resources, the second largest natural-gas field in the conterminous United States, and several large oil fields. The uranium is concentrated in continental rocks of the Upper Jurassic Morrison Formation in primary tabular and redistributed roll-type ore deposits. The coal and most of the oil and gas resources occur in transgressive-regressive rocks deposited in Late Cretaceous time on the southwestern edge of the Western Interior Seaway, principally in the Dakota Sandstone, Mancos Shale, Mesaverde Group, Pictured Cliffs Sandstone, and Fruitland Formation. The trip will examine in detail the various facies of the energy-producing Mesozoic rocks, which are well exposed in this arid and beautiful part of the Colorado Plateau. Tours of mines will include the Navajo coal strip mine west of Farmington, New Mexico, one of the largest coal mines in the U.S.; the Lee Ranch coal strip mine, north of San Mateo, producing subbituminous coal from the Menefee Formation; and the Mt. Taylor underground uranium mine north of Grants, New Mexico, producing ore from the largest primary ore deposit in the region.