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Hydrothermal eruptions are explosive events driven by the sudden and violent vaporization of the water present in many hot water geothermal fields worldwide. Over recent years, thermodynamical conditions of fluids and petrophisical-geomechanical features of host-rocks were mentioned as responsible of the wide range of eruptive styles and deposits of hydrothermal eruptions. Nevertheless, geological and historical records show that PDC and fallout processes are underestimated as common processes linked to hydrothermal eruptions. This paper analyzes from a multi-disciplinary approach —virtual outcrops modeling, sedimentology, petrographic and XDR studies, facies modeling, eye-witness source analysis, and stratigraphy— the pristine Holocene–historic hydrothermal eruptive record of El Humazo manifestation (Domuyo Geothermal Field, Patagonia, Argentina). Different eruptive scenarios are characterized by ballistic ejection, PDC and/or fallout mechanisms with discernible tefra-composition and granulometry, associated with both excavational and/or aggradational landforms. We show how diverse eruptive dynamics are controlled by pre-eruptive internal and external factors, such as reservoir energy, depth of the explosion/fragmentation levels, physical properties and structural anisotropy of the host-rocks and eruptive center migrations. We consider that this case study may be useful not only for the application in the assessment of the volcanic hazard associated with the Domuyo geothermal field, but also contributes to the knowledge of the eruptive dynamics in other geothermal systems with similar characteristics. • Hydrothermal eruptions show simple or compound mechanisms of transport–deposition. • Energy, fragmentation level, host-rock property control the hydrothermal eruptions. • Host-rock type influences the tephra granolumetry and eruptive dynamics. [ABSTRACT FROM AUTHOR]

The Pingüino deposit, located in the low sulfidation epithermal metallogenic province of the Deseado Massif, Patagonia, Argentina, represents a distinct deposit type for this region. It evolved through two different mineralization events: an early In-bearing polymetallic event that introduced In, Zn, Pb, Ag, Cd, Au, As, Cu, Sn, W and Bi, represented by a complex sulfide assemblage, and late Ag–Au quartz-rich veining that crosscut and overprinted the early polymetallic mineralization. Three In-bearing mineralization stages were identified within the polymetallic event. Iron-rich sphalerite of the second stage is the major In carrier in the deposit. The spatial distribution of In within the veins shows its maximum mean values in the Marta Centro and Ivonne Norte veins, in a pattern similar to the Zn distribution, showing a close spatial relation with the unexposed Kasia intrusive complex. At the vein scale, and in the hypogene zone, the In distribution is associated with variations in the temperature of mineralizing fluids. The vertical distribution of In within the veins exhibits consistent values both below and above the oxidation level, resembling the behavior of Pb and Sn, and therefore suggesting that In behaves as an immobile element during vein weathering. [ABSTRACT FROM AUTHOR]