Geothermal Resources of Rifts- a Comparison of the Rio Grande Rift and the Salton Trough

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Journal Article: Geothermal Resources of Rifts- a Comparison of the Rio Grande Rift and the Salton Trough

Abstract
The Rio Grande Rift and the Salton Trough are the best developed rift systems in the United States and both share many features common to rifts in general, including geothermal resources. These two rifts have different tectonic and magmatic histories, however, and these differences are reflected in the nature of their geothermal resources. The Salton Trough is a well developed and successful rift. It is the landward extension of the Gulf of California spreading center, which has separated Baja, California, from the remainder of Mexico. Quaternary silicic magmatization has occurred and several of the geothermal resources are associated with recent rhyolitic intrusions. Such resources tend to be high temperature (> 200°C). Greenschist facies metamorphism has been observed in several of the geothermal wells. Localized upper crustal melting is a distinct possibility and there is increasing speculation that very high temperature (> 300°C) geothermal fluids may underlie a large portion of the central trough at depths in excess of 4 km. Low temperature geothermal resources associated with shallow hydrothermal convection are less common and tend to be located on the flanks of the trough or in the Coachella Valley to the north of the zone of active rifting.In contrast, the Rio Grande Rift is less well developed. Recent volcanism consists primarily of mantle-derived basalts, which have not had sufficient residence time within the crust to generate significant crustal melting. The geothermal resources within the Rio Grande Rift do not correlate well with these young basalts. Rather, the quantity of geothermal resources are low temperature (< 100°C) and result from forced hydrothermal convection which discharges at constrictions within or at the end of the major sedimentary basins. High temperature resources are less common and the only discovered example is the Valles Caldera of northern New Mexico (T = 250-300°C). The deep interiors of the sedimentary basins of the Rio Grande Rift do not appear to be major geothermal exploration targets.

Author 
Chandler A. Swanberg








Published Journal 
Tectonophysics, 1983





DOI 
10.1016/0040-1951(83)90039-2

Online 
Internet link for Geothermal Resources of Rifts- a Comparison of the Rio Grande Rift and the Salton Trough

Citation

Chandler A. Swanberg. 1983. Geothermal Resources of Rifts- a Comparison of the Rio Grande Rift and the Salton Trough. Tectonophysics. 94(1-4):659-678.