--> ABSTRACT: Geothermal Resource Potential of Cascade Volcanic Arc, by George R. Priest; #91040 (2010)

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Geothermal Resource Potential of Cascade Volcanic Arc

George R. Priest

The central and southern Cascade volcanic arc has the following features that suggest a high potential for geothermal resources: (1) extensive Quaternary volcanism with some silicic to intermediate volcanoes, (2) hundreds of square kilometers with regional background heat flow in excess of 100 mW/m2, (3) shallow (4-9 km) calculated depth to Curie point in the same areas that have heat flow in excess of 100 mW/m2, (4) a thick pile of volcanic rock with moderate to low thermal conductivity, (5) hot springs with minimum reservoir temperatures of 174°-186°C (from the anhydrite geothermometer of Mariner, 1985), and (5) fault zones for fracture permeability. These features are the result of interactions between the North American plate (NAP), the Pacific plate (PP), and the subducted Gorda, Juan de Fuca, and Explorer plates (GJEP). Interactions between the NAP and the PP produce north-south compression and east-west extension, causing extensive development of north-south normal faults and partial melting episodes in upper mantle. Northeast-southwest convergence between the NAP and the GJEP produce subduction-related magmas and crustal deformation from northeast-southwest compression. NAP-GJEP interactions dominate in the northern part of the arc, whereas NAP-PP and NAP-GJEP interactions have combined in the central and southern part of the arc to produce rates of magmatism and heat flow higher than in the north.

AAPG Search and Discovery Article #91040©1987 AAPG Rocky Mountain Section Meeting, Boise, Idaho, September 13-16, 1987.