Person: Muñoz García, María Belén
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First Name
María Belén
Last Name
Muñoz García
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Estratigrafía
Identifiers
22 results
Search Results
Now showing 1 - 10 of 22
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.- Project number: 2
Item Geodivulgar: Geología y Sociedad(2017) García Frank, Alejandra; Canales Fernández, María Luisa; Muñoz García, María Belén; Rodríguez García, Sergio; Martínez Gutierrez, Gemma; Sarmiento, Graciela N.; Cózar Maldonado, Pedro; Gómez Heras, Miguel; Díaz Megias, Isabel; Rico Arjona, Rocio; Alonso Recio, Carlos; Salazar Ramirez, Roselis Waikiria; Berrocal Casero, Melani; Rodríguez García de Castro, Isabel; Borrego Salgado, David; Sánchez Fontela, Noelia; Martín Perea, David Manuel; Montesinos del Valle, Mercedes; Fesharaki, Omid; Iglesias Álvarez, Nuria; Navalpotro Gordo, Tania; Portales Níñez, Killian; Armendáriz Sanz, Andrés; Rey Samper, Jesús Javier; Del Moral González, Begoña; Gonzalo Parra, Lorena; Coronado Vila, Ismael; Pérez Martín del Campo, Daniel; Hontecillas Tamayo, Daniel; Calonge García, María Amelia; Taboada Trujols, Irene; Rodrigo Sanz, Ana; Moreno De Alborán Calvo, Fernando; Poves Garrido, Consuelo; Hernández Fragua, Laura; Silva, Silvia Item Comparison of speleothem fabrics and microstratigraphic stacking patterns in calcite stalagmites as indicators of paleoenvironmental change(Quaternary International, 2016) Muñoz García, María Belén; Cruz, J.; Martín Chivelet, Javier; Ortega, Ana Isabel; Turrero, M.J.; López Elorza, M.In the necessary task of obtaining high-resolution paleoclimate series from speleothems, the characterization of their internal microstratigraphy is a useful tool for: a) improving geochronology, and b) reaching a more complete knowledge of the speleothem formation and evolution through time and thus obtaining additional paleoenvironmental information. However, the development of standardized methodologies for microstratigraphic characterization is a pending task. In this paper, two different approaches allow construction of microstratigraphic logs for three stalagmites retrieved from two different caves. The logs correspond to vertical variations in speleothem fabrics and in microstratigraphic stacking patterns. The “fabrics logs” essentially provide information about the drip rate (sometimes used as a precipitation proxy) and the regularity or irregularity of each drip in the short-term. The “microstratigraphic stacking patterns logs” can be interpreted to obtain information about the changes in drip rates in the mid- and long-term. The results show a broad correlation between both kinds of logs that supports their validity as paleoenvironmental proxies. Fabrics formed under relatively constant and regular drips (columnar compact, open and elongated) usually constitute aggradational or progradational microstratigraphic stacking patterns. On the other hand, retractional stacking patterns are usually related with fabrics precipitated under more irregular drips (dendritic and columnar microcrystalline).However, this relation is not rigid and the information obtained from the logs is not equivalent, but complementary. The combination of both logs allows reconstruction of the hydrological history for each drip site. As all the obtained information derives directly from the drip conditions, drip effects result to be very important and can, in some cases, overwhelm the paleoclimate information recorded in each stalagmite.Item Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems(Global and Planetary Change, 2011) Martín Chivelet, Javier; Muñoz García, María Belén; Edwards, R. Lawrence; Turrero, María J.; Ortega, Ana I.The surface temperature changes for the last 4000 years in northern inland Iberia (an area particularly sensitive to climate change) are determined by a high resolution study of carbon stable isotope records of stalagmites from three caves (Kaite, Cueva del Cobre, and Cueva Mayor) separated several tens of kilometers away in N Spain. Despite the local conditions of each cave, the isotopic series show a good overall coherence, and resulted to be strongly sensitive to surface temperature changes. The record reflects alternating warmer and colder intervals, always within a temperature range of 1.6 °C. The timing and duration of the intervals were provided by 43 230Th–234U (ICP-MS) ages. Main climatic recognized periods are: (1) 3950–3000 yr BP: warm period punctuated by cool events around ~3950, 3550 and 3250 yr BP; (2) 2850–2500 yr BP cold interval (Iron Age Cold Period); (3) 2500–1650 yr BP moderate warm period (Roman Warm Period), with maximum temperatures between 2150 and 1750 yr BP; (4) 1650– 1350 yr BP cold interval (Dark Ages Cold Period), with a thermal minimum at ~1500 yr BP; (5) 1350– 750 yr BP warm period (Medieval Warm Period) punctuated by two cooler events at ~1250 and ~850 yr BP; (6) 750–100 yr BP cold period (Little Ice Age) with extremes occurring at 600–500 yr BP, 350–300 yr BP, and 150–100 yr BP; and (7) the last 150 years, characterized by rapid but no linear warming (Modern Warming). Remarkably, the presented records allow direct comparison of recent warming with former warm intervals such as the Roman or the Medieval periods. That comparison reveals the 20th century as the time with highest surface temperatures of the last 4000 years for the studied area. Spectral analysis of the time series shows consistent climatic cycles of ~400, ~900 and ~1300 yr, comparable with those recognized in the North Atlantic marine record, the Greenland ice cores, and other terrestrial records for the middle–late Holocene, suggesting common climate forcing mechanisms related to changes in solar irradiance and North Atlantic circulation patterns.Item Efectos de la separación de flujo en las secuencias de barras de meandro. Ejemplos del Oligoceno Superior de la Cuenca de Loranca(Geotemas, 2008) Muñoz García, María Belén; Díaz Molina, MargaritaEl registro estratigráfico del Eoceno-Mioceno de la cuenca de Loranca está formado por sedimentos fluviales, aluviales y lacustres. Durante el Oligoceno Superior los depósitos de ríos meandriformes del abanico fluvial de Tórtola se extendieron por el centro de la cuenca y su margen oeste. Las barras de meandro del abanico de Tórtola presentan diferencias con el modelo de facies básico, en el que la secuencia de estructuras sedimentarias está producida por una disminución de la velocidad de la corriente. Las secuencias fining-upwards graduales no son las más frecuentes en las barras de meandro del Oligoceno de la cuenca de Loranca. La estructura sedimentaria más abundante es la estratificación cruzada de pequeña escala rellenando surcos erosivos, que puede presentarse en toda la sección de la barra de meandro. La estratificación cruzada de ripples compone a su vez otras formas del lecho que se caracterizan por una morfología de crestas longitudinales. Estas formas compuestas se interpretan como formas del lecho generadas por vórtices espirales en zonas de separación de flujo.Item Estudios paleoclimáticos y paleoambientales en cuevas kársticas(2011) Martín Chivelet, Javier; Muñoz García, María Belén; Garralón, A.; Gómez, P.; Turrero, M.J.; Ortega, A.I.; Edwards, R.L.; Cheng, H.; Santisteban, J.I.; Mediavilla, R.; Pérez-Monserrat, Elena M.; Charco Romero, MaríaItem Sedimentary evolution of tectonically-controlled Cenozoic shallow marine glaucony, fluviatile and lacustrine-palustrine deposits at Bahariya region, Egypt(Journal of African earth sciences, 2022) Afify, A.M.; Sanz Montero, M. Esther; González Acebrón, Laura; Muñoz García, María BelénThe Cenozoic basin of the tectonically-active Bahariya region (Western Desert, Egypt) contains a unique paleoenvironmental, paleotectonic and paleoclimatic record displaying a large variety of sedimentary facies, stratigraphic discontinuities, and geochemical changes. This study deals with the sedimentary evolution and tectono-stratigraphic modelling of shallow marine Upper Eocene glaucony facies (Upper Hamra Formation) that changes upward into a sequence of Oligocene continental fluviatile sandstone-calcrete (Radwan Formation) and then into Miocene lacustrine-palustrine deposits (Continental Carbonate Unit). The tectonic instability of the Bahariya basin can be deduced from occurrence of sedimentary discontinuities, development of pedogenic features, and unconformable relations among rock units. Both sedimentation pattern and facies distribution seem to have been controlled by fault activity through time. Two types of glaucony facies (pelloidal and massive smectitic glaucony) were deposited in a narrow sub-basin along main faults reaching the basin center. These faults also conditioned the deposition of the Oligocene fluviatile sandstone and Miocene lacustrine-palustrine carbonates. A transition from greenhouse (global warming event of the Middle Eocene Climatic Optimum) to icehouse climatic conditions (Eocene-Oligocene climatic cooling) is probably represented by the deposition of the shallow marine glaucony facies during the Priabonian. Semi-arid to sub-humid conditions were dominant during the formation of the Oligocene calcretes and the Miocene lacustrine-palustrine carbonates. The latter carbonate deposits consist of basal thin-bedded chert deposits displaying hydro-plastic sedimentary structures that are possibly coeval with the Miocene basaltic extrusions along faulted and low-lying areas. We conclude that both paleoclimate and intraplate tectonic activity related to the Red Sea rifting influenced the pattern of sea level, continental drainage, sedimentation rate and clastic supply since the Priabonian up to the middle Miocene in the Bahariya basin.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.- Project number: 102
Item GEODIVULGAR: Geología y Sociedad(2022) García Frank, Alejandra; Acedo Peñato, Abel; Alonso Zarza, Ana María; Alonso Recio, Carlos; Alonso García, Rocío; Armendáriz Sanz, Andrés; Berrocal Casero, Melani; Calonge García, María Amelia; Cambronero García-Miguel, Irene; Campos Millán, Eduardo; Canales Fernández, María Luisa; Carvajal de Lago, Alba María; Cervilla Muros, Miguel Ángel; Chicote Alvira, Gabriel; Chiri Pérez, Oliver; Corbalán García, Judit; Coronado Vila, Ismael; Cózar Maldonado, Pedro; del Moral González, Begoña; Díaz Megías, Isabel; Díez García, Irene Pilar; Esteve Serrano, Jorge Vicente; Fajardo Portera, Pilar; Fesharaki, Omid; Fraguas Herráez, Ángela; Galán Casado, José Miguel; Gamallo Paz, Isabel; Gamarra González, Jesus; García Peco, Víctor; Gómez Heras, Miguel; González Acebrón, Laura; Paiva Henriques, María Helena; Herrero Domínguez, Santiago; Hontecillas Tamayo, Daniel; Iglesias Álvarez, Núria; López Martín, Mª del Valle; López Martín, Pablo Santiago; Martín Aguilar, Lourdes; Martín Madrid, Yolanda; Martínez Gutiérrez, Gemma; Mateos Carralafuente, José Ricardo; Mediato Arribas, José Francisco; Molero Monsonis, Andrea; Montesinos del Valle, Mercedes; Muñoz García, María Belén; Nacenta Torres, Pablo; Navarro Terrón, Esther; Oliete Puertas, Elena; Oliva Martín, Anabel; Ozkaya de Juanas, Senay Amalia; Pérez Martín del Campo, Daniel; Portales Núñez, Killian; Rodrigo Sanz, Ana; Rodríguez García, Sergio; Rodríguez García de Castro, Isabel; Salas Herrera, Javier; Salazar Ramirez, Roselis Waikiria; Sánchez Fontela, Noelia; Sanz Pérez, Dánae; Torices Hernández, Angélica; Vega Carricondo, Alejandro; Vitón García, Íñigo
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