Browsing by Author "Yanez Carrizo, Gonzalo"

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    Characterizing the Water Storage Capacity and Hydrological Role of Mountain Peatlands in the Arid Andes of North-Central Chile
    (2020) Valois, Remi; Schaffer, Nicole; Figueroa, Ronny; Maldonado, Antonio; Yanez, Eduardo; Hevia, Andres; Yanez Carrizo, Gonzalo; MacDonell, Shelley
    High-altitude peatlands in the Andes, i.e., bofedales, play an essential role in alpine ecosystems, regulating the local water balance and supporting biodiversity. This is particularly true in semiarid Chile, where bofedales develop near the altitudinal and hydrological limits of plant life. The subterranean geometry and stratigraphy of one peatland was characterized in north-central Chile using Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR) and core extraction. Two sounding locations, two transversal and one longitudinal profile allowed a 3D interpretation of the bofedal's internal structure. A conceptual model of the current bofedal system is proposed. Geophysical results combined with porosity measurements were used to estimate the bofedal water storage capacity. Using hydrological data at the watershed scale, implications regarding the hydrological role of bofedales in the semiarid Andes were then briefly assessed. At the catchment scale, bofedal water storage capacity, evapotranspiration losses and annual streamflow are on the same order of magnitude. High-altitude peatlands are therefore storing a significant amount of water and their impact on basin hydrology should be investigated further.
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    Crustal dense blocks in the fore-arc and arc region of Chilean ranges and their role in the magma ascent and composition: Breaking paradigms in the Andean metallogeny
    (2019) Yanez Carrizo, Gonzalo; Rivera Herrera, Orlando
    We use Intermediate-to-short wavelength (20-150 km) gravity anomalies to investigate the role played by crustal scale dense blocks in the genesis of Cu ore deposits along the Andes. These dense blocks are widespread along the margin and located at the fore-arc, arc, and back-arc domains, including depths in the range of 12-18 km, and thickness of 5-8 km. The interplay of these dense blocks with long-lived Trans-Lithospheric-Faults (TLF) controls the emplacement, and most likely, provides the required fertile fluids for the Cu ore genesis. Dense blocks represent impervious crustal domains, surrounded by damage zones at the intersection with TLF systems. Concentration of seismicity, large Vp/Vs ratios, low gravity domains, active volcanism, and structural fabric, demonstrate that these damage zones are in fact the most likely places for magma as well as mineralized flow ascent and emplacement. Basic flow models in porous media show a flow path that migrates horizontally at the base of dense/impervious blocks until the high permeability edge flanks, where pressure gradients provide the ideal conditions for the upward and focusing hydrothermal fluid ascent. Although not fully addressed in this paper, evidence suggests that the interaction of subducting-related fluids and the mafic-dense block might produce a fertile fluid with a concentration of Cu.
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    Improving the underground structural characterization and hydrological functioning of an Andean peatland using geoelectrics and water stable isotopes in semi-arid Chile
    (2021) Valois, Remi; Araya Vargas, Jaime; MacDonell, Shelley; Guzman Pinones, Camilo; Fernandoy, Francisco; Yanez Carrizo, Gonzalo; Cuevas, Jaime G.; Sproles, Eric A.; Maldonado, Antonio
    High altitude, Andean wetlands, or bofedales as they are locally known, are important regulators of the local water balance and also play a key role in sustaining biodiversity. Nevertheless, there is almost no information regarding their hydrogeological structure and functioning. This paper aims to characterize the thickness of the alluvial filling of one peat-accumulating wetland in North-Central Chile using Electrical Resistivity Tomography (ERT) to assess its role as a water reservoir. To develop a quasi-3D understanding of the peatland's structure, four ERT profiles were conducted. Results highlight a conductive basin shape of the peatland, with a thicker interface downstream than upstream between alluvial materials and the underlying bedrock or rock screes. Those results allow the estimate of the water column (1000-3400 mm) within the peatland alluvial filling. The second objective is to better understand the water exchanges between the peatland and the streamflow using discharge measurements and water stable isotopes. Water and isotopes budgets highlight a streamflow loss towards the peatland groundwater reservoir at the end of spring season. In addition, ten delta O-18 and delta H-2 surveys were used to characterize the distinct wetland water sources and their temporal variations. A peatland conceptual model is proposed to connect groundwater, rock glaciers, snowmelt, and hillslope flows. Andean peatlands provide a pivotal control on water delivery downstream, and therefore, understanding their structure and function is important, because they are unique structures providing ecological services at high elevations.