Rio Grande Rift Geothermal Region

The Rio Grande Rift represents the easternmost manifestation of widespread extension in the western U.S. during the past 35 million years. The rift consists of three major basins and many smaller basins, less than 100 km2. The three major basins (from northernmost to southernmost) are the San Luis, Espanola, and Albuquerque basins. Further south, a network of smaller basins run together. These are less topographically distinct and are typified by alternating basin and ranges. The distinction between these smaller basins and the Basin and Range Province becomes blurred in northern Mexico, and is not well defined. Basin size generally decreases to the north in the rift, where the Española covers approximately 120 km north-south and 40 km east-west, and the San Luis is roughly 120 km by 80 km. These basins may contain smaller units within them, such as the Alamosa basin within the San Luis, which is bounded by the San Juan and Tusas mountains on the west and the Sangre de Cristo mountain range in the east.[4] The Albuquerque basin is the largest of the three basins, spanning 160 km north-south and 86 km east-west at its widest points. It is the oldest of the three major basins, and contains 7,350 m of Paleogene clastic sediments deposited on Precambrian basement. The southernmost Albuquerque basin contains pre-rift volcanic deposits, while the central and northern portions contain volcanics erupted during rifting. Assessment of Moderate- and High-Temperature Geothermal Resources of the United States^[1]