Person: López Elorza, Maialen
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First Name
Maialen
Last Name
López Elorza
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
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Item Fluid migration recorded by fluid inclusions in crack-sealed quartz veins and sandstone host rock; Cameros Basin, Spain(Journal of iberian geology, 2021) González Acebrón, Laura; López Elorza, Maialen; Mas Mayoral, José Ramón; Arribas Mocoroa, José; Omodeo-Salé, SilviaThe role of deep hydrothermal fluid circulation through fractures and their impact on the sandstone host rock is studied in an extensional sedimentary basin (Cameros Basin, Spain) affected by a post-extensional hydrothermal metamorphism. The quartzarenites of the Urbión Group constituted a hydrocarbon carrier affected by very low to low-grade hydrothermal metamorphism during Late Albian to Coniacian. This process generated abundant quartz veins and transformed the quartzarenites into quartzites. This study compares the microthermometry of the fluid inclusion asemblages (FIAs) in the veins and in the quartz grain overgrowths in the quartzites, in order to understand the behavior of the hydrothermal fluids through fractures and their effects in the host rock. Fluid inclusions in the quartz grain overgrowths contain liquid and vapor at room temperature and homogenize to the liquid (Th: 124–265 °C, H2O + NaCl system). Those of quartz veins present both liquid and vapor CO2 and an aqueous liquid phase (room temperature). Final homogenization is to the liquid (Th: 109–282 °C, H2O + NaCl + CO2, mean values of amount-of-substance fractions: 0.92, 0.01, 0.07). Large Th variation within each FIA is common, due to crack and sealing processes and to reequilibration by successive thermal pulses. In contrast, the narrow Th range in each FIA towards the top of the record indicates that these inclusions are probably not reequilibrated. Two growing stages are recognized under SEM-CL in the quartz grain overgrowths, one diagenetic and another hydrothermal, the later with FIAs showing Th similar than the veins. The results can help in the evaluation of the geo-energy resources in sedimentary basins.Item Petrografía de inclusiones fluidas en espeleotemas: comparación con calcitas no espeleotémicas(Geotemas, 2016) López Elorza, Maialen; Muñoz García, María Belén; González Acebrón, Laura; Martín Chivelet, JavierLos espeleotemas presentan inclusiones fluidas que pueden utilizarse como proxy paleoclimático ya que sus características dependen de las condiciones físicoquímicas y ambientales bajo las que se generaron. En esta línea, su caracterización petrográfica aparece como una tarea fundamental, previa a cualquier otro tipo de análisis. En este trabajo se presenta el estudio petrográfico de las inclusiones fluidas de dos coladas de Cueva del Cobre (Palencia), que ha permitido clasificarlas en siete tipos en función de su morfología (thorn shaped, boudin shaped, elongate, amorphous, oval shaped, pyriform y round shaped). Todas ellas son monofásicas líquidas. Dependiendo del tipo de morfología de las inclusiones, su posición en relación al cristal encajante es variable, siendo las elongated y thorn shaped exclusivamente intercristalinas, y todas las demás intracristalinas. Un análisis comparativo con inclusiones descritas en calcitas no espeleotémicas revela que las inclusiones fluidas elongated, amorphous y oval shaped son también comunes en esas calcitas, mientras que las pyriform y las boudin shaped no han sido descritas hasta ahora.Item Fluid-inclusion petrography in calcite stalagmites: Implications for entrapment processes(Journal of sedimentary research, 2021) López Elorza, Maialen; Muñoz García, María Belén; González Acebrón, Laura; Martín Chivelet, JavierFluids trapped in speleothems have an enormous potential in frontier fields of paleoclimate and paleohydrological research. This potential is, however, hampered by diverse scientific and technical limitations, among which the lack of a systematic methodology for genetically characterizing fluid inclusions is a major one, as these can have different origins, and thus, the trapped fluid (usually water), different meanings. In this work, we propose a systematic petrological classification of fluid inclusions, based on: 1) the temporal relation between fluid inclusions and the host calcite, 2) the spatial relation between fluid inclusions and the “crystallites” and crystals aggregates, and 3) the phases (water, air) trapped inside fluid inclusions. The first criterion allows dividing fluid inclusions in two main categories: primary and secondary, whose identification is critical in any research based on trapped fluids. The other two criteria allow the definition of eight types of primary and four types of secondary fluid inclusions. Primary fluid inclusions contain the drip water that fed stalagmites at the time of crystal growth, and can be intercrystalline, i.e., located between adjacent crystallites, or intracrystalline, i.e., with the fluid trapped within crystallites. We differentiate six main types among the intercrystalline fluid inclusions (elongate, thorn-shaped, down-arrow, interbranch, macro-elongate, and bucket) and other two among intracrystalline inclusions (pyriform and boudin). In primary inclusions, water is the main phase, while gas is much less abundant. The presence of gas could be related to slow drip rates or degassing in the cave, but also to later leakage due to changes in temperature and humidity often occurring during inadequate handling of speleothem samples. Secondary fluid inclusions were clearly related to younger water inlet through stratigraphic disruptions or unconformities. They are formed after water infiltration, but sealed before the renewed crystal growth. We differentiate four main types of secondary inclusions: interconnected, rounded, triangular, and vertical fluid inclusions. The identification of primary and secondary fluid inclusions in speleothems is a key for interpretation in paleoclimate studies. Integration of petrological results allow establishment of three different genetic scenarios for the formation of fluid inclusions, whose identification can be relevant because of their predictive character.