Analogue Geothermal Systems in Mexico: Insights from the Deep Part of Los Humeros Geothermal Field in the Las Minas Mining Area (Eastern Mexico)

Abstract

AUTHORS: Eivind BASTESEN, Caterina BIANCO, Andrea BROGI, Alfredo CAGGIANELLI, Victor H.G.MONROY, Edoardo G.PARTIDA, Adrian J.HARO, Wieslaw KOZDROJ, Marinella LAURENZI, Domenico LIOTTA, Guia MORELLI, Jerzy NAWROCKI, Emmanuel O.GARCIA, Magdalena P.NAWROCKA, Christopher A.ROCHELLE, Giovanni RUGGIERI, Anita TORABI, Walter H.WHEELER, Martina ZUCCHI. This study is part of the H2020-GEMEx Project, collaboration between E.U. and Mexico for investigating the super-hot geothermal systems. The novelty of this work is in the integrated methodological approach which bridges the past to the present and contributes to the reconstruction of the conceptual model of the deep geothermal systems, thus aiding appropriate strategies for deep exploration. The Las Minas mining area (Veracruz State) where Cu-Fe-Au ore-deposits are historically exploited, is considered as an exhumed Neogene geothermal system analogue to the deeper part of the Los Humeros geothermal field (Puebla State). We used an integrated approach, which involves structural, kinematic, 3D outcrop models, petrological, geochemical, geochronological and fluids inclusion analyses of the pre-volcanic Paleozoic-Cretaceous succession, intruded by intruded by Miocene-Pliocene magmatic bodies of dioritic to granitic composition and by mafic to felsic dykes. Our emphasis is on the (paleo) fluid-rocks interaction and the related structural control. The results indicate that fluids magmatic derived fluids were channeled along and in the intersection between the regional NW- and NE-trending faults and their damage zones, contemporaneously active. The faults are characterized by strike-slip to oblique-slip/normal movements. Fluids were also stored in carbonate rock-volumes at the contact with the magmatic intrusions. The distribution of the ore-deposits and hydrothermal alteration related to the interaction of geothermal fluids and hosting rocks indicates the importance of conduits (such as fractures and faults) in the reservoirs. Hence, the relationships between ore-deposits, hydrothermal alteration and structures can increase our knowledge of the present geothermal fluids deep circulation in Los Humeros geothermal field.