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Geothermal Energy

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Fig. 5 | Geothermal Energy

Fig. 5

From: Structural control of the graben fault on hydrothermal alteration in the Cerro Pabellón geothermal system (Andean Cordillera, Northern Chile)

Fig. 5

SEM micrographs of volcanic rocks affected by pervasive hydrothermal alteration in both CP2A and CP5A wells of the CP geothermal system. a Igneous orthopyroxene (Opx) partly replaced by smectite (Sm) and quartz (Qtz) in altered andesitic tuffs sampled at 1400 m depth in CP2A well. b Groundmass replaced by quartz coexisting with chloritic minerals (Chl mnls) and minor smectite in altered andesitic lava sampled at 470 m depth in CP5A well. c Igneous clinopyroxene (Cpx) partly replaced by corrensite (Crr) and hematite (Hem) in altered andesitic lava sampled at 470 m depth in the CP5A well. d Mafic mineral of andesitic tuff (likely pyroxene) totally replaced by smectite, chlorite (Chl), calcite, and titanite (Ti) in altered andesitic lava sampled at 700 m depth in CP5A well. e Groundmass replaced by chloritic minerals, calcite, quartz, and minor titanite in altered andesitic tuffs sampled at 1400 m depth in CP2A well. f Groundmass replaced by corrensite, smectite, and quartz and by calcite with numerous inclusions of calcium-arsenic-bearing minerals (Ca–As mnls) in altered andesitic lava sampled at 470 m depth in CP5A well

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