Examinando por Autor "Baeza, O."

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Acceso Abierto
Mars MOURA magnetometer demonstration for high-resolution mapping on terrestrial analogues
(European Geoscience Union (EGU), 2016-05-19) Díaz Michelena, M.; Kilian, R.; Sanz, Ruy; Ríos, F.; Baeza, O.; Ministerio de Economía y Competitividad (MINECO)
Satellite-based magnetic measurements of Mars indicate complex and very strong magnetic anomalies, which led to an intensive and long-lasting discussion about their possible origin. To make some progress in the investigation of the origin of these anomalies the MOURA vector magnetometer was developed for in situ measurements on Mars. In this work we propose the utilisation of such an instrument for future planetary on-ground surveys. The proof of its suitability is seen through testing it on various terrestrial analogues characterised by the distinct magnetic anomalies of their basement rocks: (1) a magnetite body of EL Laco (up to +110 000 nT) and its transition to surrounding andesites ( <  +2000 nT) in the northern Andes of Chile showing the highest local magnetic anomalies. The magnetite-bearing ore body has highly variable local anomalies due to its complex formation history where a significant dispersion in palaeo-orientations has been previously reported, while our vector data show relatively uniform and probably induced declinations. (2) A basaltic spatter cone of the Pali Aike volcanic field, in southern Chile, was characterised by very strong magnetic anomalies along the crater rim (up to +12 000 nT), controlled by the amount of single domain magnetites in the ground mass of the basalts. Due to their strong remanent signature, palaeo-declinations of the lavas and reorientations of collapsed blocks could be constrained by the vector data. (3) The Monturaqui meteorite crater (350 m diameter), in northern Chile, shows significant variations of its anomalies (from −2000 to >  +6000 nT) in restricted areas of several square metres along its crater rim related to unexposed iron-bearing fragments of the impactor while its granitic and ignimbritic target rocks exhibit only very weak anomalies. (4) An area with several amphibolitic dykes, which cross-cut a Cretaceous granitoid in the southernmost Andes, where a decimetre-scale mapping was performed. In this case, pyrrhotite is the only magnetic carrier. It was formed during hydrothermal processes within the dykes. Very low (+40 to +120 nT) positive magnetic anomalies clearly depict the amount of 1–4 vol % pyrrhotite in these dykes, which is important as a mineralogical indicator as well as to detect associated gold and copper enrichment.
Acceso Abierto
MOURA magnetometer for Mars MetNet Precursor Mission. Its potential for an in situ magnetic environment and surface characterization
(Universidad Complutense de Madrid, 2016-10-14) Díaz Michelena, Marina; Sanz, Ruy; Belén Fernández, A.; De Manuel, V.; Cerdán, M. F.; Apéstigue, Víctor; Domínguez, J. A.; González, Miguel; Guerrero, H.; Dolores Sabau, M.; Kilian, R.; Baeza, O.; Ríos, F.; Herraiz, M.; Vázquez, L.; Tordesillas, J. M.; Covisa, P.; Aguado, J.; Ministerio de Economía y Competitividad (MINECO)
El magnetómetro y gradiómetro MOURA forma parte de la instrumentación científica de la misión precursora de MetNet a Marte. En este trabajo se describen los objetivos de esta investigación, se recopilan las tareas de diseño y desarrollo del mismo así como su posterior calibración y se muestran las principales acciones de demostración emprendidas con el instrumento que muestran su capacidad para medidas magnéticas a bordo de aterrizadores y rovers. MOURA magnetometer and gradiometer is part of the scientific instrumentation for Mars MetNet Precursor mission. This work describes the objective of the investigation, summarizes the work done in the design and development of the sensor as well as its calibration, and shows the demonstration campaigns to show the potential of such instrument for planetary landers and rovers
Acceso Abierto
The formation of a giant collapse caprock sinkhole on the Barda Negra plateau basalts (Argentina): Magnetic, mineralogical and morphostructural evidences
(Elsevier BV, 2020-10-15) Díaz Michelena, Marina; Kilian, R.; Baeza, O.; Ríos, F.; Ángel Rivero, M.; Mesa, José Luis; González, Veracruz; Arlensiú Ordoñez, A.; Langlais, B.; Rocca, M. C. L.; Acevedo, R. D.; Agencia Estatal de Investigación (AEI); European Research Council (ERC)
The 1.5-km-wide, 40-m-deep, crater-like structure in the 10 Ma old Barda Negra basaltic plateau in Central Argentina was discovered in the early 2000s. Based on remote sensing surveys and on its morphological characteristics, similar to those of the Barringer crater in Arizona, the structure is described to be originated by an impact. In this study we ran several field work campaigns and collected and analysed samples, in order to find more evidences to endorse or reject this hypothesis. We observe a circular depression not generally surrounded by raised rims, in contrast to craters produced either by a meteorite impact or phreatomagmatic eruption (maars). Mineralogical investigations of rocks and sediments do not show high pressure and temperature minerals, such as coesite or stishovite, or any remnants of an impactite or impact melt/glass. Likewise, no textural evidences for impact-related fracturing or stress are observed. A detailed geomorphological mapping indicates a successive crater development which invokes local stepwise subsidence. Magnetic mapping performed with the EU-funded NEWTON multisensor novel instrument shows a ~2000 nT field anomaly associated to the edges of the crater, and susceptibility measurements cast an important contrast between the basaltic rims and plateau, and the crater interior. Therefore, we propose a sinkhole origin for the crater, with a former collapse of the plateau basalts and a latter infill with sedimentary material. This hypothesis is supported by the fact that the 40 to 85 m thick and 14 to 15 Ma old carbonate-bearing Collón Curá Formation, underneath the 100 to 150 m thick basaltic plateau lava sheet, represents ideal rocks for dissolution and karst formation; remote sensing data show other nearby sinkholes (20 km westward), with extensions of 3 × 6 km and 100 m depth, which are emplaced within a cogenetic neighboring basaltic plateau with a similar underlying lithology; and the consistence of the magnetic model computed with this scheme and on measured rock remanence and susceptibilities of the structure and surroundings. These giant collapse sinkholes, up to 6 km in diameter, within caprocks of very thick plateau basalts, represent unique examples for planetary surface shaping processes which also occur on Mars and comets in areas with basalts or rigid caprocks.
Restringido
The Seno Otway pockmark field and its relationship to thermogenic gas occurrence at the western margin of the Magallanes Basin (Chile)
(Springer Link, 2017-12-15) Kilian, R.; Breuer, S.; Behrmann, J. H.; Baeza, O.; Díaz Michelena, M.; Mutschke, E.; Arz, H.; Lamy, F.; Deutsche Forschungsgemeinschaft (DFG)
Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to >100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to >30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since ~15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.