Person: Muñoz Martín, Alfonso
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First Name
Alfonso
Last Name
Muñoz Martín
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Geodinámica Interna
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Longest and still longer: The Messejana-Plasencia dyke and its links with later Alpine deformation belt in Iberia(Tectonophysics, 2021) De Vicente Muñoz, Gerardo; Olaiz Campos, Antonio José; Muñoz Martín, Alfonso; Cunha, Pedro P.The Messejana-Plasencia dyke (End-Triassic), NE-SW oriented, is the longest simple structure in Iberia (~500 km) and constitutes a first-order rheological discontinuity that crosses the entire crust. During the Alpine deformation, this discontinuity nucleated the Messejana-Plasencia left-lateral strike-slip fault and its related strike-slip deformation belt, consisting of a series of wide coalescent stepovers and small basins developed on the footwalls. Both structures can be followed from offshore of SW mainland Portugal to the central sector of the Spanish-Portuguese Central System. Using tectonic, geophysical, magnetic, and gravimetric analyses, our study demonstrated that it extends NE more than ~100 km below the continental sediments of the Duero Cenozoic Basin, until the Iberian Chain. We used a tectonostratigraphic analysis to determine the age of the wrench fault movement and that of the Spanish-Portuguese thrusts. In this range, the largest displacement during the Cenozoic occurred in the southern thrust of the Spanish sector of the Central System over the Madrid Cenozoic Basin, and NE-SW trending. This thrust displaces the Moho more than 10 km and probably joins the Messejana-lasencia strike-slip fault at depth. The deduced age movement for both is Oligocene-Lower-Middle Miocene, related to the intraplate stresses transmitted from the Pyrenean orogen towards its foreland. A strain partitioning process was then deduced for the simultaneous movement of both main Alpine faults in Central Iberia.Item Variscan inheritance induces Alpine upper crustal delamination in East Spanish–Portuguese Central System(Tectonics, 2022) De Vicente Muñoz, Gerardo; Díez Fernández, Rubén; Olaiz Campos, Antonio José; Muñoz Martín, AlfonsoThe Spanish–Portuguese Central System (SPCS) is an Alpine Mountain range with crystalline basement characterised by a two-layer rheological structure. This structure formed after primary (protolith) and secondary (tectonometamorphic) processes during the extensional collapse of the Variscan Orogen. The SPCS structure is usually controlled by foreland-directed thrusts and strike-slip faults. However, the eastern SPCS is dominated by NW-directed, imbricate backthrusts and lacks the main thrust directed to the foreland basin located southeast of the mountain range (Madrid Cenozoic Basin). The SPCS exhibits a crustal root (> 40 km depth) supporting SE-directed crustal-scale thrusting. Alpine backthrusts sole into an SE-dipping décollement within the Variscan basement. Variscan extension-related structures parallel the SE-dipping geometry of Alpine backthrusts, so they provided favourably oriented rheological weaknesses to accommodate Alpine shortening. Backthrusts geometry, their hanging wall position within the fault that raised the SPCS and gravity modelling support an Alpine crustal delamination process. Tectonic wedging and delamination of the more competent basement occurred in the footwall of Variscan extensional faults (Daurius domain), which enforced the shearing off of a rheologically weaker upper layer of the crust, located in the hanging wall of the Variscan extensional faults (Arriaca domain) by inverting Variscan extensional faults. This led to NW-directed incipient continental subduction of the weaker crust. Intraplate subduction and crustal delamination can be independent from lithosphere-scale inheritance and be conditioned by structural inheritance in the overlying crust. Alpine shortening for the Cretaceous cover is around 17.7 km (10.5% shortening), and 11 km (7%) for the upper-lower crust limit.Item Geometría y modelado numérico de los cabalgamientos Alpinos y de los pliegues de propagación de falla asociados en el macizo de Honrubia-Sepúlveda (Sistema Central)(Geotemas, 2024) Muñoz Cemillán, Alfonso; Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo De; Olaiz Campos, Antonio JoséEl sector de Honrubia-Sepúlveda (Norte del Sistema Central) se caracteriza por presentar una serie de cabalgamientos imbricados con basamento implicado y vergencia hacia el norte. Estos cabalgamientos desarrollan pliegues de propagación de falla en la cobertera mesozoica con flancos largos de bajo buzamiento hacia el sur (entre 2 y 5º). Dada la ausencia de datos en profundidad, y debido a su estilo “de piel fina con basamento implicado”, algunos autores interpretan la presencia de un nivel de despegue relativamente somero en profundidad. Para discutir esta estructura se han analizado y modelizado con el método de trishear uno de estos pliegues que presentan mejor desarrollo (Allmendinger, 1998). Los resultados de la modelización sugieren desechar la presencia de geometrías rampa-rellano, y la ausencia de un nivel de despegue común superficial para los cabalgamientos. Los resultados obtenidos también descartan otras geometrías de la rampa, como son las de un aumento del buzamiento de los cabalgamientos en profundidad, o rampas con geometrías lístricas. Los modelos que mejor explican la geometría del pliegue de propagación se generan mediante fallas inversas de buzamiento constante (entre 40 y 50º), valores de p/s entre 1.5 y 1.8 y ángulos de trishear estrechos (de unos 60º).Item Geothermal Potential of Madrid Basin from Integrated Geophysical and Well Data Analysis (Central Spain)(Conference Proceedings, 83rd EAGE Annual Conference & Exhibition, 2022) Berriolópez, M.A.; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Zamora Valcarce, GonzaloNew energy demand linked to world population growth and awareness about climate change have brought out the need to develop new forms of energy guided by the urgency of an ecological transition. In this context geothermal resources have the potential of contributing significantly to sustainable use in many parts of the world. In Spain, during the 80´s, oil and gas explorations carried out in the Madrid Basin confirmed the existence of two geothermal reservoirs. Here we present diverse geological features of the basin essential in geothermal exploration. We use airborne radiogenic and magnetic data to characterize the basement. Detailed ground concentration estimates of the heat producing elements are used to calculate the heat production and heat flow in the near surface. The distribution pattern of both parameters is heterogeneous with two main areas separated by southward prolongation of the Berzosa Fault. The eastern sector is characterized by both low heat production and heat flow rates while the western area is distinguished by high values as a response of the exposed granites. In addition, we build one 3D geological model and one 3D isothermal model with Leapfrog Geothermal from seismic, well data and mapping information.Item Near surface geophysical analysis of the Navamuño depression (Sierra de Béjar, Iberian Central System): Geometry, sedimentary infill and genetic implications of tectonic and glacial footprint(Geomorphology, 2018) Carrasco González, Rosa María; Turu, Valenti; De Pedraza Gilsanz, Javier; Muñoz Martín, Alfonso; Ros, Xavier; Sánchez Vizcaíno, Jesús; Ruiz Zapata, Blanca; Olaiz Campos, Antonio José; Herrero-Simon, RamónThe geometric and genetic characterization of the Navamuño depression peatland system (Iberian Central System) is presented here using results from a geophysical survey. This depression is a ~30 ha pseudo-endorheic flat basin over granitic bedrock. Three geophysical techniques were used to map the subsurface geology, and identify and describe the infill sequence: shallow seismic refraction (SR), magnetic resonance sounding (MRS) and electrical resistivity measurements (VES and ERT). The three main geoelectrical layers (G1, G2, G3) identified in previous research, have also been identified in the present work. Using the data obtained in this new research we have been able to analyse these three geological layers in detail and reinterpret them. They can be grouped genetically into two sedimentary units: an ancient sedimentary body (G3), of unknown age and type, beneath an Upper Pleistocene (G2) and Holocene (G1) sedimentary infill. The facies distribution and geometry of the Upper Pleistocene was examined using the Sequence Stratigraphy method, revealing that the Navamuño depression was an ice-dammed in the last glacial cycle resulting in glaciolacustrine sedimentation. A highly permeable sedimentary layer or regolith exists beneath the glaciolacustrine deposits. Below 40 m depth, water content falls dramatically down to a depth of 80 m where unweathered bedrock may be present. The information obtained from geophysical, geological and geomorphological studies carried out in this research, enabled us to consider various hypotheses as to the origin of this depression. According to these data, the Navamuño depression may be explained as the result of a transtensional process from the Puerto de Navamuño strike-slip fault during the reactivation of the Iberian Central System (Paleogene-Lower Miocene, Alpine orogeny), and can be correlated with the pull-apart type basins described in these areas. The neotectonic activity of this fault and the icedammed processes in these areas during the Last Glacial Cycle (MIS2) were the main causes of recent sedimentary infill in this depression.Item The Spanish-Portuguese Central System: An Example of Intense Intraplate Deformation and Strain Partitioning(Tectonics, 2018) De Vicente Muñoz, Gerardo; Cunha, P.P.; Muñoz Martín, Alfonso; Cloetingh, S.A.P.L.; Olaiz Campos, Antonio José; Vegas Martínez, RamónThe intraplate deformation of Iberia during the Cenozoic produced a series of ranges and deformation belts with a wide variety of structural trends. The Spanish-Portuguese Central System is the most prominent feature crossing over the whole of central Iberia. It is a large thick-skinned crustal pop-up with NE-SW to E-W thrusts. However, the 500-km-long left-lateral strike-slip Messejana-Plasencia fault, also NE-SW oriented, bends these thrusts to produce NE-SW local paleostresses close to the fault, which seems to be consistent with a common deformational arrangement. This is also supported by the similar sedimentary infilling characteristics found in the surrounding Cenozoic basins. The moment of the maximum intraplate deformation is registered at the same time in all these basins during the upper Priabonian-lower Chattian. As there are two possible sources for the intraplate compressive stresses, the Pyrenean (N-S shortening) orogen to the north and the Betic (NW-SE shortening) orogen to the south, neither can simply explain both simultaneous movements (NE-SW strike-slip and NE-SW thrusting). The deduced age of the main deformation indicates a Pyrenean origin. In contrast, the concept of strain partitioning between the two types of faults gives as a result an overall north trending compression. Existing data do not support crustal detachment from the Betics neither from the Pyrenees but are consistent with a crustal uplift related to lithospheric folding. The subsequent Betic-related stress field only slightly reworked previously Pyrenean-related structures, except for the Portuguese sector, where tectonic activity occurred mainly in the Upper Miocene.Item Análisis estructural de la Falla de Santa María del Espino (Rama Castellana, Cordillera Ibérica): Transpresión debida a convergencia en dirección NNO-SSE(Geo-Temas, 2024) Alonso Henar, Jorge; Fernández Rodríguez, Carlos; Vicente Muñoz, Gerardo De; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Sociedad Geológica de EspañaLa Falla de Santa María del Espino se localiza en la Rama Castellana de la Cordillera Ibérica (CI). Se orienta en dirección NO-SE, buzando hacia el SO. Superpone, en su parte central, el basamento Paleozoico (pizarras y cuarcitas del Ordovícico y pizarras del Silúrico) sobre los materiales sedimentarios del Triásico (areniscas, arcillas y conglomerados del Buntsandstein). Se ha determinado la orientación y cinemática de las estructuras generadas por la falla en ambos bloques, que incluyen pliegues a distintas escalas, kink bands y un conjunto de fallas menores. Se han aplicado distintas técnicas de análisis estructural con objeto de determinar tanto la cinemática de la falla principal como la orientación de los ejes principales del esfuerzo. El resultado muestra la actuación de una transpresión lateral derecha triclínica, con una vorticidad cercana a la transición entre el dominio de la cizalla pura y de la cizalla simple, y una convergencia NNO-SSE entre los bloques separados por la falla. La máxima compresión horizontal (S1) se sitúa en dirección NO-SE. Estos resultados confirman la naturaleza transpresiva de las estructuras de la Rama Castellana de la CI.