Person: Negredo Moreno, Ana María
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First Name
Ana María
Last Name
Negredo Moreno
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Física de la Tierra
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item The topography of the Iberian Peninsula from integrated geophysical-petrological multi-data inversion(Physics of the Earth and Planetary Interiors, 2021) Fullea Urchulutegui, Javier; Negredo Moreno, Ana María; Charco, María; Palomeras, Imma; Afonso, Juan Carlos; Villaseñor, AntonioThe topography of the Iberian Peninsula is characterized by the presence of Variscan and Alpine orogenic belts and foreland basins, but what sets it apart from the rest of Western Europe are the large elevated flat surfaces (700 m above sea-level on average) in its central parts. The origin and support of such high average topography, whether isostatic or dynamic in nature, is a matter of intense debate. To understand Iberian topography, it is key to have a reliable image of the present-day lithospheric thermochemical structure. So far, this structure remains poorly constrained, particularly at mantle level. The goal of this paper is to derive robust estimates of the thermal, compositional and density structure of the lithosphere beneath the Iberian Peninsula from an integrated geophysical-petrological proba-bilistic inversion of surface wave, elevation, geoid anomaly and heat flow data. Our inversion reveals an average lithospheric thickness of 80-100 km in the Iberian Peninsula with only moderate lateral variations. The most prominent lithospheric thickness change is a steep decrease from the central to the easternmost Pyrenees. The thinnest lithosphere in our models is found below the south-eastern Mediterranean margin (<80 km), overlapping with the Neogene Tallante-Cabo de Gata volcanic fields. The present-day thermochemical structure reveals a clear imprint of the geodynamic evolution of Iberia. Lithospheric thickness and, therefore, lithospheric geotherms are to a large extent related to Alpine Cenozoic compression and extension. The western Pyrenees and Iberian chains seem to have been affected by Mesozoic rifting processes that imprinted a fertile signature into the originally more refractory Variscan Iberian lithosphere. In the Betic domain to the south, the lithospheric thermochemical structure is likely conditioned by the ongoing Alboran subduction. Except for the Mediterranean margin, where we find evidence for moderate negative dynamic topography, most of the surface elevation in Iberia can be explained by lateral density contrasts associated with variations in crustal and lithospheric thickness and lithology.Item The Gibraltar slab dynamics and its influence on past and present-day Alboran domain deformation: Insights from thermo-mechanical numerical modelling(Frontiers in Earth Science, 2023) Gea, Pedro J.; Negredo Moreno, Ana María; Mancilla, Flor de LisThe origin and tectonic evolution of the Gibraltar Arc system is the result of a complex geodynamic evolution involving the convergence of the Eurasian and African plates and the dynamic impact of the Gibraltar slab. Although geologic and geophysical data collected in the last few years have increased our knowledge of the Gibraltar Arc region, it is still unclear which are the mechanical links between the Gibraltar slab and the past deformation of the overriding Alboran lithosphere, as well as to which degree this subduction system is presently active. In this study, we use 2D numerical modelling to investigate the impact of the Gibraltar slab dynamics on the deformation of the overriding Alboran lithosphere. Our model simulates a WE generic vertical section at an approximate latitude of 36 degrees N and considers an initial setup at about Burdigalian times (similar to 20 Ma), when the subduction front position is relatively well constrained by recent tectonic reconstructions. Our modelling shows a switch in the overriding plate (OP) stress state from extensional stresses during the slab rollback to compressional stresses near the trench when the rollback velocity decreases, caused by the change in slab-induced mantle flow. We also find that much of the crustal and lithospheric deformation occur during fast slab rollback and OP extension in the first 10 Myr of evolution, while after that only moderate deformation associated with subduction is predicted. Finally, we find that despite the subduction rollback ceases, the ongoing motion of the deeper portion of the slab induces a mantle flow that causes some amount of west-directed basal drag of the Alboran lithosphere. This basal drag generates interplate compresional stresses compatible with the distribution of intermediate-depth earthquakes in western Alboran.Item Geophysical-petrological model for bidirectional mantle delamination of the Adria microplate beneath the northern Apennines and Dinarides orogenic systems(Journal of Geophysical Research: Solid Earth, 2022) Zhang, Wentao; Jiménez Munt, Ivone; Torne, Montserrat; Vergés, Jaume; Bravo Gutiérrez, Estefanía; Negredo Moreno, Ana María; Carminati, Eugenio; García Castellanos, Daniel; Fernàndez, ManelThis study presents a geophysical-geochemical integrated model of the thermochemical structure of the lithosphere and uppermost mantle along a transect from the Northern Tyrrhenian Sea to the Pannonian Basin, crossing the northern Apennines, the Adriatic Sea, and the Dinarides fold-thrust belt. The objectives are to image crustal thickness variations and characterize the different mantle domains. In addition, we evaluate the topographic response of opposed subductions along this transect and discuss their implications in the evolution of the region. Results show a more complex structure and slightly higher average crustal density of Adria compared to Tisza microplate. Below the Tyrrhenian Sea and Western Apennines, Moho lays at <25 km depth while along the Eastern Apennines it is as deep as 55 km. The modeled lithosphere-asthenosphere boundary (LAB) below the Tyrrhenian Sea and Pannonian Basin is flat lying at ∼75 and 90 km, respectively. Below the External Apennines and Dinarides the LAB deepens to 150 km, slightly shallowing toward the Adriatic foreland basin at 125 km depth. Our results are consistent with the presence of two mantle wedges, resulting from the rollback of the Ligurian-Tethys and Vardar-NeoTethys oceanic slabs followed by continental mantle delamination of the eastern and western distal margins of Adria. These two opposed slabs beneath the Apennines and Dinarides are modeled as two thermal sublithospheric anomalies of −200°C. Most of the elevation along the profile is under thermal isostasy and departures can be explained by regional isostasy with an elastic thickness between 10 and 20 km.Item On the origin of the Canary Islands: Insights from mantle convection modelling(Earth and Planetary Science Letters, 2022) Negredo Moreno, Ana María; van Hunen, Jeroen; Rodríguez González, Juan Tinguaro; Fullea Urchulutegui, JavierThe Canary Islands hotspot consists of seven volcanic islands, mainly of Neogene age, rooted on oceanic Jurassic lithosphere. Its complex structure and geodynamic setting have led to different hypotheses about its origin and evolution, which is still a matter of a vivid debate. In addition to the classic mantle plume hypothesis, a mechanism of small-scale mantle convection at the edge of cratons (Edge Driven Convection, EDC) has been proposed due to the close proximity of the archipelago to the NW edge of the NW African Craton. A combination of mantle plume upwelling and EDC has also been hypothesized. In this study we evaluate these hypotheses quantitatively by means of numerical two-dimensional thermo-mechanical models. We find that models assuming only EDC require sharp edges of the craton and predict too narrow areas of partial melting. Models where the ascent of an upper-mantle plume is forced result in an asymmetric mantle flow pattern due to the interplay between the plume and the strongly heterogeneous lithosphere. The resulting thermal anomaly in the asthenosphere migrates laterally, in agreement with the overall westward decrease of the age of the islands. We suggest that laterally moving plumes related to strong lithospheric heterogeneities could explain the observed discrepancies between geochronologically estimated hotspot rates and plate velocities for many hotspots.Item Advances in the modeling of the Iberian thermal lithosphere and perspectives on deep geothermal studies(Geothermal energy, 2023) Torne, M.; Jiménez Munt, I.; Negredo Moreno, Ana María; Fullea Urchulutegui, Javier; Vergés, J.; Marzán, I.; Alcalde, J.; Gómez Rivas, E.; García de la Noceda, C.Renewable energy sources are key to achieve the transition toward clean energy system. Among them, the geothermal energy has a production whose efectiveness requires sufcient understanding of the temperature distribution and fuid circulation at depth, as well as of the lithological and petrophysical properties of the crust. The focus of this paper is twofold: frst, we summarize the main advances in the develop ment of new methodologies and numerical codes to characterize the properties of the thermal lithosphere in terms of its, temperature, density and composition; second, based on the compilation of available thermal modelling results, we present the depth of the thermal Lithosphere–Asthenosphere Boundary (LAB) of the Iberian Peninsula and the temperature distribution at crustal depths of 5, 10, and 20 km, in addition to at Moho level. At 5 km depth, the temperature is above 110 °C with local anomalies (>130 °C) located in the Iberian Massif and Cenozoic volcanic provinces. A similar pattern is observed at 10 and 20 km depth, where temperatures are above 190 °C and 350 °C, respectively. At 20 km depth, anomalies above>500 °C, delineate the SE and NE Cenozoic volcanic provinces. At Moho depths, temperature ranges from 450 to 800 °C with hot regions mainly located along the Iberian Massif and the SE and NE volcanic provinces. The compiled results do not show any lithospheric anomaly that could give rise to high temperatures at shallow depths, but they do show an acceptable exploi tation potential at intermediate depths. With regard to the direct use of district and greenhouse heating and for industrial processes, the potential is great throughout the Peninsula, the main challenges being the availability of groundwater and drilling costs.Item Influence of cratonic lithosphere on the formation and evolution of flat slabs: Insights from 3-D time-dependent modeling.(Geochemistry, geophysics, geosystems, 2015) Taramón, Jorge M.; Rodríguez González, Juan; Negredo Moreno, Ana María; Billen, Magali I.Several mechanisms have been suggested for the formation of flat slabs including buoyant features on the subducting plate, trenchward motion and thermal or cratonic structure of the overriding plate. Analysis of episodes of flat subduction indicate that not all flat slabs can be attributed to only one of these mechanisms and it is likely that multiple mechanisms work together to create the necessary conditions for flat slab subduction. In this study we examine the role of localized regions of cratonic lithosphere in the overriding plate in the formation and evolution of flat slabs. We explicitly build on previous models, by using time-dependent simulations with three-dimensional variation in overriding plate structure. We find that there are two modes of flat subduction: permanent underplating occurs when the slab is more buoyant (shorter or younger), while transient flattening occurs when there is more negative buoyancy (longer or older slabs). Our models show how regions of the slab adjacent to the subcratonic flat portion continue to pull the slab into the mantle leading to highly contorted slab shapes with apparent slab gaps beneath the craton. These results show how the interpretation of seismic images of subduction zones can be complicated by the occurrence of either permanent or transient flattening of the slab, and how the signature of a recent flat slab episode may persist as the slab resumes normal subduction. Our models suggest that permanent underplating of slabs may preferentially occur below thick and cold lithosphere providing a built-in mechanism for regeneration of cratons.Item The Canary Islands hot spot: New insights from 3D coupled geophysical–petrological modelling of the lithosphere and uppermost mantle(Earth and Planetary Science Letters, 2015) Fullea Urchulutegui, Javier; Camacho, Antonio G.; Negredo Moreno, Ana María; Fernández, JoséThe Canary archipelago (NW Atlantic African margin) is one of the best studied volcanic chains in the world yet its structure and geodynamic evolution are still under considerable debate. Oceanic island volcanoes typically form over hot spots due to upwelling of plume material followed by decompression melting and melt migration up to the surface. Here, the 3D lithospheric-uppermost mantle thermochemical structure beneath the Canary Islands is studied using an integrated and self-consistent geophysical-petrological approach exploiting the wealth of available data after decades of geophysical and petrological studies plus recent satellite data. A precise knowledge of the present-day thermal and compositional mantle structure beneath the Canary Islands is a key element to understand the geodynamic evolution of the area and, on a global scale, the thermal state of the Earth's mantle beneath hot spots. Our results suggest a likely chemically depleted and mechanically strong lithosphere showing no significant thinning with respect to the surrounding oceanic and continental domains (110 +/- 20 km thick). Models without a positive temperature anomaly in the sub-lithosphere (characterized by mantle T-pot = 1335 degrees C) fail to reproduce the observed sub-lithospheric seismic anomaly over the Canary Islands. A thermal sub-lithospheric anomaly of +100 degrees C (mantle potential temperature of 1435 degrees C) with respect to ambient mantle beneath the Canaries is able to explain both observed seismic tomography anomalies and measured geophysical and geodetic data. Such a sub-lithospheric thermal anomaly requires a dynamic contribution of 150-400 m to the static topography to match the present-day observed elevation in the Canary Islands and associated swell.