Evidence for large-scale Laramide tectonic inversion and a mid-Tertiary caldera ring fracture zone at the Lightening Dock geothermal system, New Mexico
Stratigraphy in a recent intermediate depth (2100 ft) geothermal test hole is interpreted along side previous deep (7001 to 7404 ft depth) exploration holes to study large-scale structural controls for the Lightning Dock geothermal system and refine the stratigraphic and structural characterization of the shallow reservoir. Laramide compression and large-scale tectonic inversion of a northwest-trending Late Jurassic-Early Cretaceous extensional structure at the Lightning Dock geothermal site represents deformation that may exceed Neogene extensional processes in magnitude and duration and provide potential for a significant volume of shattered rock. Also, volcanic stratigraphy supports the hypothesis of Elston et al. (1983) for a midTertiary caldera ring fracture zone in the vicinity the geothermal area. Northeastand north-trending Neogene normal faults that cross cut older structures provide additional preparation of fractured ground. A north-trending Pleistocene normal fault may reopen older fractures that are favorably oriented and allow concentration and upward flow of deep-seated geothermal fluids. Because the Lightning Dock geothermal system is “blind” and has no surface manifestations, a better understanding of structures buried beneath Neogene alluvial basin fill may have application in geothermal exploration to find similar “blind” geothermal systems elsewhere in southern New Mexico and southeastern Arizona. FIGURE 1. Shaded relief topographic location map of the Lightning Dock geothermal area.
LIGHTNING DOCK KGRA NEW MEXICO'S LARGEST GEOTHERMAL GREENHOUSE, LARGEST AQUACULTURE FACILITY, AND FIRST BINARY ELECTRICAL POWER PLANT
LIGHTNING DOCK KGRA The Lightning Dock Known Geothermal Resource Area (KGRA) is located in the Animas Valley of the “boot heel country” of southwest New Mexico about 10 miles south of Interstate 10 off of the Animas-Cotton City exit or about 20 road miles southwest of Lordsburg, New Mexico. The name Lightning Dock comes from a peak in the Pyramid Mountains just east of the geothermal area in the Animas Valley. The Lightning Dock geothermal system is a blind system with no surface manifestations and the resource was fortuitously discovered during cable tool drilling of an irrigation well in 1948 (Summers, 1976). Since that time, geochemical sampling of fluids, electrical and gravity geophysical surveys, temperature gradient drilling, shallow production well drilling of the resource for direct-use heating for green-housing and aquaculture, and a deep geothermal exploration hole has been done at the site (Cunniff and Bowers, 1988; Dellechaie, 1977; Elston, et al., 1983; Jiracek,
Chemistry, origin, and potential of geothermal resources of southwestern New Mexico and southeastern Arizona
Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico.