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Ciudad Universitaria, Spain

Rossi C.,Complutense University of Madrid | Mertz-Kraus R.,Johannes Gutenberg University Mainz | Osete M.-L.,Complutense University of Madrid | Osete M.-L.,Institute Geociencias Igeo Csic Ucm
Quaternary Science Reviews

To evaluate possible connections between climate and the Earth's magnetic field, we examine paleoclimate proxies in a stalagmite (PA-8) recording the Blake excursion (~112-~116.4ka) from Cobre cave (N Spain). Trace element, δ13C, δ18O, δ234U, fluorescent lamination, growth rate, and paleomagnetic records were synchronized using a floating lamina-counted chronology constrained by U-Th dates, providing a high-resolution multi-proxy paleoclimate record for MIS 5d. The alpine cave setting and the combination of proxies contributed to improve the confidence of the paleoclimatic interpretation. Periods of relatively warm and humid climate likely favored forest development and resulted in high speleothem growth rates, arguably annual fluorescent laminae, low δ13C and [Mg], and increased [Sr] and [Ba]. Colder periods limited soil activity and drip water availability, leading to reduced speleothem growth, poor development of fluorescent lamination, enhanced water-rock interaction leading to increased [Mg], δ13C, and δ234U, and episodic flooding. In the coldest and driest period recorded, evaporation caused simultaneous 18O and 13C enrichments and perturbed the trace element patterns. The Blake took place in a relatively warm interestadial at the inception of the Last Glacial period, but during a global cooling trend recorded in PA-8 by an overall decrease of δ18O and growth rate and increasing [Mg]. That trend culminated in the cessation of growth between ~112 and ~101ka likely due to the onset of local glaciation correlated with Greenland stadial 25. That trend is consistent with a link between low geomagnetic intensity and climate cooling, but it does not prove it. Shorter term changes in relative paleointensity (RPI) relate to climate changes recorded in PA-8, particularly a prominent RPI low from ~114.5 to ~113ka coincident with a significant cooling indicated by all proxy records, suggesting a link between geomagnetic intensity and climate at millennial time scales. Although the reliability of such inference is limited by the inferior resolution of the paleomagnetic data and a possible contamination of the RPI data by unaccounted changes in magnetite concentration, the agreement of those data with the marine record of cosmogenic Be suggests that the RPI record of PA-8 may reflect truly geomagnetic intensity variations. © 2014 Elsevier Ltd. Source

Insua-Arevalo J.M.,Complutense University of Madrid | Martinez-Diaz J.J.,Complutense University of Madrid | Martinez-Diaz J.J.,Institute Geociencias Igeo Csic Ucm | Garcia-Mayordomo J.,Instituto Geologico Y Minero Of Espana | Martin-Gonzalez F.,Rey Juan Carlos University
Journal of Iberian Geology

The Malaga Basin is located in the westernmost part of the Betic Cordillera. This alpine cordillera in the south of Spain is the most active region of the Iberian Peninsula. Some of the most destructive earthquakes occurred historically in Spain took place within the Malaga Basin. In this work we focus on geomorphic and morphotectonic observations in the aim of finding active tectonic structures that could be seismogenic sources. First, we study the spatial arrangement and age of the Quaternary alluvial fan system as well as the drainage pattern of the basin, followed by the analysis of the distribution of regional markers like marine erosive surfaces and the extend of Pliocene marine deposits in the Malaga Basin. The tectonic structures inferred as active by the morphotectonic analysis are grouped into four main families: N60°-85°E folds associated with blind thrust faults, N20°-30°E and N40°-50°E high angle dip-slip faults, and N165°-170°E tear faults. Finally, their seismic potential in terms of maximum moment magnitude (Mw) is assessed by means of empirical relationships, varying between 6.0 and 7.0 depending on the hypothesis considered. Source

Perez-Monserrat E.M.,Institute Geociencias Igeo Csic Ucm | Fort R.,Institute Geociencias Igeo Csic Ucm | Lopez-Arce P.,Institute Geociencias Igeo Csic Ucm | de Buergo M.A.,Institute Geociencias Igeo Csic Ucm | And 2 more authors.
Journal of the European Ceramic Society

This study is focuses on the characterisation of the pastes and enamels constituents of the decorative ceramics, cladding ceramics and mosaic tiles, covering the façades and the central garden fountain of the Former Workers Hospital of Maudes at Madrid, Spain. The structural bricks of the inner fabric walls and those used at the courtyards are also studied. Both the original and restoration materials are analysed petrographically and mineralogically and the elemental composition of the enamel is determined. The major textural and compositional variations identified in the materials are mainly due to differences in the clay raw materials and additives used, as well as to the manufacturing processes, specially firing temperatures. In addition to comparing the results of the analyses conducted to the information obtained from the references consulted, the study provides unknown data on the raw materials and technologies involved in manufacturing the ceramic materials found in a heritage building. © 2012 Elsevier Ltd. Source

Coronado I.,Complutense University of Madrid | Fernandez-Martinez E.,University of Leon | Rodriguez S.,Complutense University of Madrid | Rodriguez S.,Institute Geociencias Igeo Csic Ucm

The taxonomic assignation and ecological implications of the genus Syringoalcyon Termier & Termier, 1945 have been a palaeontological problem for a long time. Carboniferous material from Morocco and Spain has been studied using a biomineralogical approach by means of petrographic microscopy, SEM, AFM, EMPA and CIP microscopy analysis. Detailed morphological, structural, chemical composition and crystallographic data enable a deeper understanding of the nature of Syringoalcyon. The coral walls and the so-called epithecal scales exhibit conspicuous differences in microstructure (lamellae and holacanthine fibres in the coral vs. single crystal in scales), nanostructure (pill-shaped vs. granule-shaped nanocrystals), composition (LMC vs. HMC) and crystallographic orientation. The results of these analyses imply that Syringoalcyon is an association between the tabulate coral Syringopora and an epibiont. They also suggest that the epibiont was an alcyonarian (a rare occurrence in the fossil record) that was attached to the syringoporoid. This work highlights the utility of the biomineralizational approaches for solving palaeontological problems, such as systematic affinities, and for advancing knowledge of the evolution of biocrystallization processes. © 2015 John Wiley & Sons Ltd. Source

Chiodo G.,Complutense University of Madrid | Marsh D.R.,U.S. National Center for Atmospheric Research | Garcia-Herrera R.,Complutense University of Madrid | Garcia-Herrera R.,Institute Geociencias Igeo Csic Ucm | And 2 more authors.
Atmospheric Chemistry and Physics

We investigate the relative role of volcanic eruptions, El Niño-Southern Oscillation (ENSO), and the quasi-biennial oscillation (QBO) in the quasi-decadal signal in the tropical stratosphere with regard to temperature and ozone commonly attributed to the 11\unit{yr} solar cycle. For this purpose, we perform transient simulations with the Whole Atmosphere Community Climate Model forced from 1960 to 2004 with an 11 yr solar cycle in irradiance and different combinations of other forcings. An improved multiple linear regression technique is used to diagnose the 11 yr solar signal in the simulations. One set of simulations includes all observed forcings, and is thereby aimed at closely reproducing observations. Three idealized sets exclude ENSO variability, volcanic aerosol forcing, and QBO in tropical stratospheric winds, respectively. Differences in the derived solar response in the tropical stratosphere in the four sets quantify the impact of ENSO, volcanic events and the QBO in attributing quasi-decadal changes to the solar cycle in the model simulations. The novel regression approach shows that most of the apparent solar-induced lower-stratospheric temperature and ozone increase diagnosed in the simulations with all observed forcings is due to two major volcanic eruptions (i.e., El Chichón in 1982 and Mt. Pinatubo in 1991). This is caused by the alignment of these eruptions with periods of high solar activity. While it is feasible to detect a robust solar signal in the middle and upper tropical stratosphere, this is not the case in the tropical lower stratosphere, at least in a 45 yr simulation. The present results suggest that in the tropical lower stratosphere, the portion of decadal variability that can be unambiguously linked to the solar cycle may be smaller than previously thought. © Author(s) 2014. Source

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