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

Geothermal Energy

Research

D. Morata¹  S. Maza¹  J. Vidal¹  G. Rivera²  G. Volpi²  P. Patrier³  D. Beaufort³ 

[1] Department of Geology and Andean Geothermal Center of Excellence (CEGA), Faculty of Physical and Mathematical Sciences, University of Chile, Plaza Ercilla 803, Santiago, Chile;ENEL Green Power Chile and Andean Countries. Av., Santa Rosa 76, Santiago, Chile;University of Poitiers, CNRS UMR7285, IC2MP, HydrASA, Bat B8, Rue Albert Turpain, TSA51106, F-86073, Poitiers Cedex 9, France;

关键词: Geothermal reservoir;    High-enthalpy system;    Low-sulfidation epithermal system;    Clay minerals;    Hydrothermal alteration;    Cerro Pabellón;    Chile;    Andean Cordillera;   

DOI  :  10.1186/s40517-023-00260-8

 received in 2023-01-07, accepted in 2023-06-12,  发布年份 2023

来源: Springer

【 摘 要 】

This study focuses on hydrothermal alteration in the geothermal reservoir of Cerro Pabellón (Andean Cordillera, Northern Chile). It is based on CP2A and CP5A production wells drilled above a local normal fault and presenting unlike hydraulic properties. Cuttings from 300 to 1555 m depth were sampled and analyzed using X-ray diffraction (XRD) to observe distribution of hydrothermal minerals and crystal chemistry variations of clays (fraction < 5 μm). Then, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM–EDX) allowed to perform microanalysis of hydrothermal minerals. These results highlight a mineral assemblage that was not observed before, composed of adularia + Ba-rich feldspar + feathery quartz + chalcedony + calcium arsenates + illite. They are characteristics of high-temperature hydrothermal alteration in epithermal settings and are restricted to shallow permeable fracture zones of the active part of the reservoir. Another fracture-controlled event related to a typical illitization is observed in all permeable fracture and fault zones of the geothermal system. This multi-event alteration seems strongly controlled by the western graben fault and the associated interconnected fracture network.

【 授权许可】

CC BY   
© The Author(s) 2023

【 图 表 】

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