Geothermal Abundance in the Cascade Range (Washington / Oregon / N. California)

2nd International Geothermal Conference, GEOHEAT2018

Jones, Adam^1

LAIKA LLC, Portland

OR, United States^1

关键词: Cascade ranges;    Geothermal potential;    Hydrothermal convection;    Hydrothermal system;    Intermediate temperatures;    Internal deformation;    Structural feature;    Vertical permeabilities;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/249/1/012012/pdf
DOI  :  10.1088/1755-1315/249/1/012012

来源: IOP

【 摘 要 】

Arc volcanism is typically associated with high geothermal potential and the Cascade Range of North America is no different. As an active continental arc, the Cascades have an abundance of mid-to-upper crustal heat sources. Yet the region has a scarcity of active hydrothermal systems that is typical in geologically similar areas. What is different about the Cascades? Elevated geothermal heat flow and few hydrothermal occurrences convey that heat from magmatic influence is mostly dissipating conductively. The region has low internal deformation with few extensional structures that would facilitate hydrothermal convection. The area is seismically quiet despite evidence of active subduction and frequent volcanism. A staccato extrusive history and a regional layer-cake of basalts and altered volcanoclastic deposits lack vertical permeability. This restricts the structures needed for the circulation of fluids from the underlying hot rock upward to the surface, limiting the development of hydrothermal systems. Hydrothermal systems that do exist have relatively small volumes and low-to-intermediate temperature, and are associated with esoteric structural features or recent near-surface volcanics.