MARIBNO project: Structure of the NorthWest Iberian margin: influence of inherited tectonics in the Alpine extension and inversion

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - GasteizLa zona noroeste de Iberia reúne rasgos geológicos excepcionales relacionados con el desarrollo de un margen continental hiperextendido cerca de un punto triple y la posterior inversión tectónica parcial. Es una zona de gran interés para el estudio del papel de la herencia tectónica y la posterior inversión en márgenes continentales extensionales, pero hay un gran déficit de información. Todo esto sienta las bases del proyecto anfibio MARIBNO (PGC2018-095999-B-I00) donde a lo largo de 2021 y 2022 se adquirirán sísmica marina de reflexión multicanal 2D (~4000 km), sísmica de gran ángulo en 3 transectos tierra-mar (~600 km), batimetría multihaz, grav-mag y sísmica de alta resolución. Se complementará en tierra con adquisición de datos grav-mag y varias campañas de cartografía geológica. Los objetivos se centran en el estudio de la estructura cortical, el control tectónico ejercido por estructuras previas a las etapas alpinas y la cartografía y caracterización de los dominios corticales aunando criterios geológicos y geofísicos.Todo esto sienta las bases del proyecto anfibio MARIBNO (PGC2018-095999-B-I00) donde a lo largo de 2021 y 2022 se adquirirán sísmica marina de reflexión multicanal 2D (~4000 km), sísmica de gran ángulo en 3 transectos tierra-mar (~600 km), batimetría multihaz, grav-mag y sísmica de alta resolución

Physico-chemical, biological and geological study of an underwater volcano in a degassing stage: Island of El Hierro

El objetivo principal del proyecto “Physico-chemical, biological and geological study of an underwater volcano in a degassing stage: Island of El Hierro”, (VULCANO-II) es estudiar, desde un punto de vista totalmente interdisciplinar, la fase de desgasificación activa del único volcán submarino monitoreado desde su nacimiento en aguas españolas. De esta forma, se pretende además, dar continuidad a los estudios multidisciplinares realizados sobre el volcán submarino de la isla de El Hierro en el contexto del proyecto del Plan Nacional VULCANO-I, (CTM2012-36317) y VULCANA (Vulcanología Canaria Submarina, IEO). Para ello, se realizará la monitorización de las propiedades físico-químicas, biológicas y geológicas del proceso eruptivo submarino de la isla de El Hierro y otros puntos sensibles, como el volcán de Enmedio entre Gran Canaria y Tenerif

Curie Depth, Heat Flux, and Thermal Subsidence Reveal the Pacific Mantle Outflow Through the Scotia Sea

The sinking of the ocean sea bottom is produced by thermal cooling of the lithosphere. This evolution is determined by the underlying asthenospheric mantle. Estimation of the Curie Depth variations in the Scotia Sea by using a spectral approach and applied on magnetic anomaly data led us to determine a thermal model and derive a heat flux map. Using multichannel seismic and bathymetry data, we show that the West Scotia Sea reaches thermal equilibrium more quickly than other oceans do and thermally behaves like old oceanic crust in large oceans, following a different empirical age (t, in Ma)-depth (d, in m) relationship, d(t) = 4,480 ¿ 19,380 exp(¿t/4). For oceanic crusts of the same age, underlain by different shallow mantle controlling the heat supply, low heat flux values imply older ages than those predicted for large oceans based on the empirical relationships of the standard plate model. These circumstances, together with the new heat flux map, shed light on the anomalous evolution of the Scotia Sea, a consequence of the present Pacific mantle outflow through the Drake Passage. Two branches of elevated heat flux surround the Shackleton Fracture Zone and extend to the northern and southern boundaries of the Scotia Plate. Most of the heat sources are located in the flanks, whereas the colder parts are centrally located. This signature supports the Drake Passage's role as a main mantle gateway for Pacific outflow toward the Atlantic reservoir favoring the oceanic spreading activity of this ocean. ©2019. American Geophysical Union. All Rights Reserved.We thank the CTM2008‐06386‐C01/ ANT, CTM2011‐30241‐CO2‐01, CGL2016‐80687‐R AEI/FEDER, and RTI2018‐099615‐B‐I00 projects funded by the Spanish Government. Foundations We thank the CTM2008‐06386‐C01/ ANT, CTM2011‐30241‐CO2‐01, CGL2016‐80687‐R AEI/FEDER, and RTI2018‐099615‐B‐I00 projects funded by the Spanish Government. Foundations of this study were initially carried out as a part of the PhD of Y.M. M. who wishes to thank Dr. Andres Maldonado as a PhD advisor. We wish to thank the two anonymous reviewers who helped us to improve our manuscript. The data to evaluate this manuscript are available at Martos, Catalán, et al., 2014 and at the http:// wdmam.org/. The resulting Curie Depth and geothermal heat flux models canbefoundatPANGAEA(https://doi. org/10.1594/PANGAEA.905428). of this study were initially carried out as a part of the PhD of Y.M. M. who wishes to thank Dr. Andres Maldonado as a PhD advisor. We wish to thank the two anonymous reviewers who helped us to improve our manuscript. The data to evaluate this manuscript are available at Martos, Catalán, et al., 2014 and at the http:// wdmam.org/. The resulting Curie Depth and geothermal heat flux models canbefoundatPANGAEA(https://doi. org/10.1594/PANGAEA.905428)

Lithospheric structure of the Alboran Sea and the relationship with the seismic activity

Joint Assembly IAPSO-AIAMA-IAGA , Good Hope for Earth Sciences, 27 August - 1 September 2017, Cape Town, South AfricaThe Alboran Sea basin is part of the Alboran Domain, and locates in the south-westernmost part of the Mediterranean, where the Eurasian and African plates interact. The geological evolution of this basin is consequence of the westward motion of the Alboran Domain since the Oligocene. It provides a good example of an extensional basin formed in a convergence regime, where the Eurasian and African plates experienced about 200 km of roughly N-S convergence between the mid-Oligocene and the late Miocene, followed by further 50 km of NW-SE oblique convergence in the late Miocene to recent times. Although seismic activity is widely distributed along the basin, its south central area (Al Hoceima area) constitutes the most active zone. In this study we use the most advance compilation of potential field marine data to get the most updated and complete picture of the Alboran Sea. Additionally we applied different image processing tools to identify the fault systems in the area, and analyzed their relationships with the most recent seismic activity. The results suggest a crustal thinning related to the southward end of the today active Al Idrissi and a new fault zone discovered in the Al-Hoceima area. Magnetic data also gives new insights in the geometry of the intermediate and basic rock bodies emplaced during the recent geodynamic evolution of the Alboran basinPeer Reviewe

Geodynamic evolution of Powell Basin in the context of the Weddell Sea and the Scotia (Antarctica)

AGU's Fall Meeting, 9 – 13 December 2019 in San Francisco (EE.UU)Powell basin is an elliptical shaped basin located in the northwestern Weddell Sea. It is bounded by the South Orkney Microcontinent to the east, by the South Scotia Ridge to the north, and north-western tip of the Antarctic Peninsula to the west. It is limited in the south by a bathymetric ridge bordering the Weddell Sea. Powell basin is characterized by a smooth relief that varies from 3000 m to 2400 m b.s.l.. Although there is a certain agreement regarding its evolution and timing, its tectonic history is not fully understood, making this place an excellent example of creation of a small oceanic basin as a consequence of continental blocks rotation. We use potential field data and sediment thickness information from public databases to understand the Total Tectonic subsidence and inferred the position of the continental-ocean boundary as well as delimit different zones regarding its oceanic, continental or transitional nature. Next 2020-21 austral summer there is going to take place a new marine magnetic surveying under the so-called ¿ElGeoPower¿ Project. This is an international initiative where german, british and american institutions are involved under the leadership of Royal Observatory of the Spanish Navy. During this survey, and among other goals, we plan to perform deep-tow profiles which are expected to shed some light regarding its age. In this communication we will present new insights about the plausible tectonic evolution of Powell Basin according with our results, and details about the next ElGeoPower initiative

Continental margin radiography from a potential field and sediment thickness standpoint: the Iberian Atlantic Margin

[ES] El presente estudio realiza una revisión del estado del conocimiento en el Margen Atlántico Ibérico atendiendo a las tres provincias en las que clásicamente se sub-divide éste: margen gallego, planicie abisal suribérica, y planicie abisal del Tagus, utilizando como fuente de información datos de campos potenciales e información derivada de espesor de sedimentos. Se estudian las características de su basamento, estableciendo límites para la extensión de la corteza continental, y la amplitud del dominio denominado transición océano-continente cuyo fin marca el inicio de la corteza oceánica. La corteza continental en el margen gallego ocupa aproximadamente 210 km, la mayor de las tres provincias, mientras que su zona de transición océano- continente varía ligeramente entre los 65 km en su zona sur y los 56 km más al norte, difiriendo de lo propuesto por otros autores que consideran ronda los 30 km. La situación en la planicie abisal sur-ibérica es aproximadamente la contraria. El dominio continental se extiende menos que en el gallego, aproximadamente unos 60 km, mientras que la zona de transición océano-continente lo hace unos 185 km. El estudio de la planicie abisal del Tagus muestra una evolución morfológica más rápida que las otras dos, registrando a partir del análisis de la variación del factor de adelgazamiento ß una zona de transición océano-continente de aproximadamente 100 km. Los resultados obtenidos apoyarían una naturaleza intermedia a la corteza en prácticamente todo el dominio del Tagus, en contra de lo establecido por otros autores.[EN] This study reviews the state of knowledge in the Iberian Atlantic margin. In order to do this, the margin has been divided into three provinces: the Galicia margin, the southern Iberian abyssal plain, and the Tagus abyssal plain. We have used potential field and sediment thickness data. This has allowed us to study the crust, setting limits for the continental crust domain, and the amplitude of the so-called ocean-continent transition, whose end marks the beginning of the oceanic crust. The study shows the continental crust in the Galician margin to be the widest, about 210 km in length, whilst the ocean-continent transition varies slightly in this province: between 65 km wide in the south and 56 km wide in the north. This result shows up some differences with the hypothesis of other authors. The situation in the southern Iberian abyssal plain is nearly the opposite. Its continental crust extends approximately 60 km, whilst the ocean-continent transition zone is 185 km long. The Tagus abyssal plain study shows a faster morphological evolution than the others, according with the amount of crustal thinning ß, the ocean-continent transition domain spanning 100 km. These results support a transitional intermediate character for almost the whole Tagus plain, in contrary to what other authors have stated.Este trabajo ha sido financiado parcialmente con el Proyecto de investigación “Sistema de alerta sísmica temprana: aplicación al sur de España - ALERTES” (CGL2010-19803-C03-02) del Ministerio de Economía y Competitividad.Peer reviewe

New clues on the Alboran Sea geodynamic evolution from magnetic anomalies

X Simposio sobre el Margen Ibérico Atlántico - X Simpósio sobre a Margen Ibérica Atlántica, 7-9 de julio de 2022, BilbaoThe magnetic anomalies of the Alboran Sea have been modeled along several profiles revealingthe presence of crustal scale, basicigneous intrusionslocated at depths from8 to 14 km. Some ofthem are located under volcanic highs, such as the Djibouti bank,but the most intenseanomalies of central Alboran Seaare related to aNE-SW alignmentof igneous intrusionslocated below the Alboran Channel that runs from the Ibn-Batouta bank to the East Alboran Basin.It is remarkable that these intrusions are northwards displaced with respect to the Alboran Ridge, which is supposed to be the main volcanic high of the Alboran Sea. TheNE-SW elongated anomalyturnseastwardsto NW-SE, parallelingto the Yusuf fault and reachingthe Algerian coast, where it becomes more irregular.According with the geodynamic history of the Alboran Sea, the emplacement of thesebasic igneous intrusions may be related to the rifting of the AlKaPeCa Domain during Oligocene-Early Miocene. This rifting process, which is due to a NW-SE extension associated with slab retreat,led to the spreading of the Algerian basin and the individualization of the Alboran Domain. Thus, the intrusions wouldrepresent the western tip of that rift,since they have the same trend that the rift axis and are also not related with the Miocene volcanic highs. Afterwards, these intrusions were affected by the STEPfault (Subduction Tear Edge Propagator fault)that accommodated the westward displacement of the Alboran Domainalong its southern limit. Since Late Miocene, the tectonic inversion of the Alboran basin curved the STEP fault and originated theYusuf fault, along which some new intrusions could take place. During Pliocene-Quaternary, tectonic indentation was develop as a result of the Eurasia-Africa convergence and the reduction of the Alboran Domain westwards displacement. In this setting, the intrusions act as a backstop that have favored the folding and uplift of the Alboran Ridgein the front of the indenter. Altogether shows that the deep igneous intrusions originated during the extensional, initial stages of a basin can condition and control the style of the later tectonic inversion of the basinPeer reviewe

Early stages of oceanic spreading in the NE extremity of Antarctic Peninsula: relationships between Ona and Powell basins

ISAES 2019: XIII International Symposium on Antarctic Earth Sciences, Republic of Korea, 22-26 july (2019

Very recent seabottom deformation in the area affected by the 2016-2017 seismic crisis in the Alboran sea (Western Mediterranean)

2nd General Assembly for the African Seismological Commission, 23-27 April 2018, Al-Hoceima, Morocco.-- 1 pageThe Alboran Sea (Westernmost Mediterranean) is a Neogene basin located between the Betic and Rif cordilleras that undergoes shortening and orthogonal extension due to the Eurasian-African NW-SE oblique plate convergence. A NNE-SSW broad band of deformation and seismicity affects its central part extending from the northern Rif (Trougout Fault), the Alboran Sea (Al Idrisi Fault), to southern Betics (Balanegra Fault). After the 1993-1994 and 2004 seismic series, a new crisis shocked mainly the southern Alboran Sea in 2016-2017 (main event Mw=6.3, Jan 25). The nearsurface recent seafloor deformation of this area is investigated using seismic profiles, multibeam and gravimeter data, recovered during the INCRISIS cruise. Epicenters grouped into two main branches. The northern WSW-ENE branch parallels the northern face of the Alboran Ridge- Francesc Pagès seamount antiforms and intersects the Al Idrisi Fault. Mass-transport deposits occurred at least since recent times. The southern branch, that crosses the Francesc Pagès seamount and Nekor Basin, consists of a NNE-SSW vertical sinistral deformation zone, with early epicenters of higher magnitude earthquakes located along a narrow band paralleling the 10 km far east Al Idrisi Fault. Nearsurface deformation includes active NW-SE vertical and normal faults, unmapped until now. Later, the epicenter band spreads eastward, reaching the main Al Idrisi Fault characterized by discontinuous active NE-SW vertical fractures. Seismicity and tectonic structures suggest a westwards propagation of deformation and the growth of very recent incipient faults, comprising NNE-SSW sinistral fault zone in depth that is connected upwards with NW-SE vertical and normal faults. This new fault zone is segmented, including 1994 seismicity in coastal area, that propagates 2004 onshore and 2016 offshore. The new insights for the seismic hazard assessment, point to the growth of new faults can produce potential high magnitude earthquakes than already formed faultsPeer Reviewe