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 Fabric and Fluid Inclusions Characterization of a Stalagmite from Eastern Spain: A Precondition for Noble Gas Analysis by Step-Crushing Methodology(Minerals, 2024) López Elorza, Maialen; Weißbach, Therese; Muñoz García, María Belén; Kluge, Tobias; Aeschbach, Werner; Martín Chivelet, JavierFluid inclusions in stalagmites are becoming increasingly important for paleoclimate research. Within this framework, noble gas thermometry, based on noble gases dissolved in water from fluid inclusions, provides quantitative estimations of cave air paleotemperature. Two major issues of Noble Gas Temperature (NGT) determination on speleothems are (1) the potential lack of enough water for the analysis and (2) the presence of trapped gas not dissolved in water that can be released during the analysis from biphasic or all-gas fluid inclusions, as its contribution to the bulk noble gas signal can hinder NGT results. Although the step-crushing method helps to reduce the second issue, it also decreases the amount of water available for the calculations. In order to obtain reliable NGT results with low uncertainties, a major challenge is still to reach a balance between sufficient water for analysis and a small amount of “atmospheric” gas. The difficulty is that the extraction process cannot be standardized since it strongly depends on the type of sample. The objective of this work is to investigate how the characteristics of the speleothem can determine the adequacy of the extraction process. For this purpose, we consider a stalagmite from a Mediterranean cave that consists of columnar elongated calcite and contains a significant quantity of fluid inclusions, which suggests good potential for NGT analysis. Results, however, were poorly satisfactory. Trying to understand the source of the problems, an integrated study of petrography and petrophysical features was performed. The samples were found to be different depending on the stage of coalescence of crystals and thus separated into “open” and “closed” fabrics. Classic petrographic analysis and non-destructive (nuclear magnetic resonance) techniques were used to characterize the type and amount of fluid inclusions present in both types of fabrics. The study indicates that the closed fabric (total coalescence of calcite crystals) has most water trapped in water-filled, small intracrystalline fluid inclusions that usually contain very little gas. This fabric is very suitable for NGT determination, but since the amount of water is quite small, the sample should be crushed in only one step with a large number of beats to break all the inclusions. In contrast, samples with open fabric (partial coalescence of calcite crystals) contain a higher amount of water and, also, gas-filled large intercrystalline fluid inclusions. For this fabric, step-crushing of the sample is necessary. However, the low amount of water left for the second and third crushings could lead to flawed NGT results. Thus, we suggest modifying the method to get rid of part of the gas in the first crushing while leaving enough water for the following steps. This work shows the importance of characterizing speleothems and fluid inclusions, including their petrography and petrophysical characteristics, before starting NGT analysis, allowing the selection of the most favorable samples and the customization of the step-crushing procedure.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, Mª 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.Item El contaje de puntos como método de estimación de la cantidad de agua de las inclusiones fluidas en espeleotemas(Geotemas, 2021) López Elorza, Maialen; Muñoz García, María Belén; Martín Chivelet, JavierLas inclusiones fluidas albergan el agua que originó el crecimiento del mineral huésped, y su estudio proporciona información relevante sobre las condiciones de crecimiento del propio mineral. En el caso de los espeleotemas, las inclusiones fluidas primarias atrapan el agua de goteo que originó el crecimiento del espeleotema. Esta agua proviene del agua meteórica que se infiltró desde el epikarst hasta la cueva, lo que supone que las inclusiones fluidas albergan el agua fósil derivada de la que precipitó en los alrededores de la cueva durante el periodo de crecimiento del espeleotema. Estas inclusiones de agua presentan una estrecha relación genética con la fábrica calcítica, y su distribución o la cantidad de agua que contienen dependen de las condiciones de crecimiento del cristal colindante. Para poder analizar todo ello, en este trabajo presentamos un nuevo método de estimación de la cantidad de agua de las inclusiones fluidas de los espeleotemas basada en el contaje de puntos petrográfico. Esta técnica permite 1) caracterizar la fábrica de calcita; 2) determinar la relación espacial entre inclusión-calcita; y por último, 3) cuantificar la cantidad de agua y aire que contienen las inclusiones. La técnica pretende ser una herramienta de gran utilidad previa a los diferentes estudios geoquímicos que se llevan a cabo en las inclusiones fluidas de los espeleotemas.Item Microstratigraphy of fluid inclusions in Pleisthocene speleothems from Cueva del Tortero (Valencia) and its application in paleoclimatology(2019) López Elorza, Maialen; Martín Chivelet, Javier; Muñoz García, Mª BelénThe cave drip-water is trapped as fluid inclusions during the active growing of speleothems. This water comes from the epikarts and represents the meteoric water that seeps from the ground to the cave. Then, speleothems are the unique geologic formations in continental environments that host fossil meteoric water. The geochemical measurements of this water provide relevant information about the past regional climate conditions. The main objectives of this PhD thesis are focused, for the first time and especifically, on the study of speleothem fluid inclusions and their application as a climate proxy. For that purpose, in this study mainly fluid inclusions of three stalagmites (Tortero-2, Tortero-4 and Tortero-10) from Cueva del Tortero were analysed. The geographic setting of the cave in Tous (Valencia), eastern Spain, is suitable to analyse the influence of high and low pressure systems that reached the Iberian Peninsula in the past...