Person:
Lunar Hernández, María Del Rosario

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First Name
María Del Rosario
Last Name
Lunar Hernández
URI
https://hdl.handle.net/20.500.14352/75241
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Cristalografía y Mineralogía
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2004 - 200922010 - 20161
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    The Patricia Zn–Pb–Ag epithermal ore deposit: An uncommon type of mineralization in northeastern Chile
    (Ore Geology Reviews, 2016) Chinchilla Benavides, Darío; Ortega Menor, Lorena; Piña García, Rubén; Merinero Palomares, Raúl; Moncada, Daniel; Bodnar, Robert J.; Quesada Ochoa, Cecilio; Valverde, Antonio; Lunar Hernández, María Del Rosario
    The Patricia ore deposit represents an unusual example of economic Zn–Pb–Ag mineralization at the northernmost end of the Late Eocene–Oligocene metallogenic belt in Chile. It is hosted by volcano-sedimentary units, which are typically tuffaceous and andesitic breccias. The ore body consists of a set of subvertical E-W vein systems developed under a sinistral strike-slip regime that included transtensive domains with generalized extensional structures where the ores were deposited. The deposit is divided into two blocks by a set of NNW-ESE-trending reverse faults, which uplifted the eastern block and exhumed thicker and deeper parts of the deposit. At least 200 m of volcano-sedimentary pile hosting the mineralization has been eroded in this block. By contrast, the western block exposes a shallower part of the system where cherts, amorphous silica and jasperoids occur. Three main stages of mineralization have been defined: (1) pre-ore stage is characterized by early quartz, pyrite and arsenopyrite, (2) base-metal and silver stage; characterized by sphalerite (6 to 15 mol% FeS), galena, chalcopyrite, pyrrhotite and Ag-bearing minerals (freibergite, polybasite, stephanite, pyrargyrite, freieslebenite and acanthite) and (3) post-ore stage; characterized by late quartz, kutnohorite and minor sulfides (arsenopyrite, sphalerite, pyrite, galena, Ag-bearing minerals and Pb-sulfosalts). Whole-ore geochemistry shows two groups of elements that are positively correlated; 1) Ag–Cd–Cu–Pb–Zn related to the base metal sulfides and 2) Au–As–Ge–Sb–W related to arsenopyrite and pyrite. Hydrothermal alteration is pervasive in the outcropping mineralized areas, including silicification and locally, vuggy silica textures. At depth, chloritic and sericitic alteration is developed along vein selvages and is superimposed to the regional propylitic alteration. Fluid inclusions indicate that the base-metal ores were deposited from 250 to 150 °C moderate salinity fluids (1–9 wt.% NaCl). The pre-ore stage is characterized by a saline fluid (6–22 wt.% NaCl) and between 210 and 250 °C whereas the post-ore stage has salinity of 4–8 wt.% and temperature from 175 to 215 °C. Cooling was the mechanism of ore mineral precipitation in the Patricia deposit, although mixing of fluids could have occurred in the pre-ore stage. Mineralogical, geochemical and fluid inclusion evidence is consistent with an intermediate sulfidation (IS) epithermal deposit type. This study highlights the high potential for hidden economic mineralization at depth in the western block and for extension of the ore body both to the south and to deeper levels in the eastern block of the Patricia ore deposit. To a larger extent, the implications of finding such polymetallic epithermal style of mineralization in the northern Chile Precordillera is relevant both to the regional metallogenic perspective and to the exploration potential of the region, where the late Eocene–early Oligocene metallogenic belt apparently disappears.
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    Crystallographic preferred orientations and microstructure of a Variscan marble mylonite in the Ossa-Morena Zone (SW Iberia)
    (Journal of Structural Geology, 2007) Romeo Briones, Ignacio; Capote Del Villar, Ramón; Lunar Hernández, María Del Rosario
    The mylonitic marbles of the Cherneca shear zone, a Variscan sinistral strike-slip structure developed in the Ossa-Morena Zone (SW Iberia) related to the emplacement of the Santa Olalla Igneous Complex, were studied in detail. Different mylonites (from protomylonites to ultramylonites) were analyzed by Electron Back-Scattering Diffraction (EBSD) in order to determine the crystallographic preferred orientation (CPO) of calcite. The CPOs show very good agreement with experimental torsion work giving suitable interpretations of the operative slip systems and strain quantifications, thus the obtained natural CPOs validate the experimental approaches. A wide range of observed textures and microstructures are mainly controlled by the amount of shear strain, the presence of secondary phases, and the development of antithetic subsidiary shears. The effect of secondary phases and the nucleation of antithetic shear bands on texture development are discussed.
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    Edades de cristalización U-Pb en circones del complejo ígneo de Santa Olalla de Cala: implicaciones en la edad del yacimiento d e Ni-Cu-EGP de Aguablanca (Badajoz)
    (Macla, 2004) Rombo, I.; Lunar Hernández, María Del Rosario; Capote Del Villar, Ramón; Quesada Ochoa, Cecilio; Dunning, G. R.; Piña García, Rubén; Ortega Menor, Lorena; Sociedad Española de Mineralogía