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Figure 7 | Geothermal Energy

Figure 7

From: Physical property relationships of the Rotokawa Andesite, a significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand

Figure 7

Backscattered scanning electron microscope photomicrographs of Rotokawa Andesite. Samples A to C are from RK28 at 2,310.6 m depth and D to F are from RK27 at 2,121.1 m depth. (A) Andesite with abundant ferromagnesian minerals (mag.), altered amygdale (amg.), and highly scattered magnetites (mag. bright hues). (B) Detail of a fractured plagioclase phenocryst showing the microfractured texture (frac.) and occasional magnetite (mag.). (C) Detail of a fracture infill showing chloritization (cl.) and abundant ferromagnesian minerals (mag.). (D) Groundmass of RK27 sample; pervasive fracturing is not apparent at this magnification but the porous network is quite apparent with pyroxene (pyx.), chlorite (cl.), and plagioclase (plag.). (E) Replacement mineralogy of likely pyroxene phenocryst (pyx.) showing abundant chloritization (cl.) and dissolution textures. (F) Detail of relict pyroxene and abundant chlorite (cl.) with abundant microfractures (cl.) apparent in the sample mass.

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