Carles Soriano

Magnetotelluric study of the Las Cañadas caldera (Tenerife, Canary Islands) : structural and hydrogeological implications

The Las Can ‹ adas caldera in Tenerife (Canary Islands) is a well-exposed caldera depression in which the active Teide^Pico Viejo complex stands. In addition to its volcanological interest, the Las Can ‹ adas caldera also holds the main groundwater reservoir of Tenerife. An audiomagnetotelluric and magnetotelluric survey was carried out in order to image the interior of the caldera depression. The field campaign consisted of 33 audiomagnetotelluric sites in the period range from 0.001 to 0.3 s and 11 magnetotelluric sites from 0.004 to 200 s. A detailed mapping of the electrical conductivity of the subsurface was obtained. For the long periods a three-dimensional modelling of the island ^ including the bathymetry ^ was carried out to study the effect of the ocean. This effect starts to be important at periods longer than 10 s. Accordingly, the sites were arranged into six profiles and a two-dimensional joint inversion of all data until 10 s was performed for each profile. The geometry of the high conductive zones found indicates that the caldera includes two closed depressions in the western (Ucanca) and central (Guajara) sectors, whereas in the

Hyaloclastite fragmentation below the glass transition: An example from El Barronal submarine volcanic complex (Spain)

This research has been funded by projects CGL2005-03511/BTE, HI2006-0073,PRIN2009 (PRIN 2009H37M59) and PRIN_2010-11 (2010TT22SC and 2010TT22SC_003).

Geologic map, volcanic stratigraphy and structure of the Cabo de Gata volcanic zone, Betic-Rif orogen, SE Spain

The geologic map of the Neogene Cabo de Gata volcanic zone is presented together with a comprehensive volcanic stratigraphy and structure based on logging, correlation and mapping. Volcanic rocks are interbedded with sedimentary rocks throughout the Cabo de Gata volcanic zone. The volcano-sedimentary succession of Cabo de Gata has been divided into formations according to lithology, age, composition and stratigraphic position. The contacts between sedimentary units and volcanic units and between formations are unconformities. Sedimentary units were deposited during periods of volcanic repose. The depositional environment of volcanism in Cabo de Gata is characterized as shallow-water submarine to emergent based on lithofacies of volcanic rocks and on fossil content and sedimentary structures of sedimentary rocks. The eruptive style in Cabo de Gata is dominantly effusive, although small-volume explosive eruptions due to magma-water interaction processes and to explosions of lava flow and domes complexes occurred.

Geochronology, Geochemistry and Geodynamics of the Cabo de Gata volcanic zone, Southeastern Spain

New 40Ar/39Ar ages and major and trace element geochemistry ofthe middle-late Miocene Cabo de Gata volcanic complex, southeastSpain, indicate that the volcanic activity of the Cabo de Gata volcaniczone developed over a short period through several pulses of geochemicallyand isotopically different parental magmas. The oldestvolcanic rocks exposed in the Cabo de Gata volcanic zone are theshoshonite and high-K calc-alkaline rocks of Bujo group, which cry -stallised from a parental magma transitional from calc-alkaline toalkaline potassic generated through large degrees of partial melting,and then affected by a minor contribution from metasomatised veinsand a larger one from the surrounding mantle wedge, in comparisonto ultrapotassic melts. Subsequent partial melting of the mantlesource produced typical calc-alkaline parental magmas belonging tothe Rodalquilar and Agua Amarga groups. Sr-Nd-Pb isotope andincompatible trace element distributions of Cabo de Gata rocks arein agreement with a mantle-wedge source affected by a two-foldmetasomatism. The data suggested that mild potassic to sub-alkalinesubduction-related parental magmas (i.e., high-K calc-alkaline andcalc-alkaline) were generated in the Cabo de Gata sector within amantle wedge metasomatised by a fluid-dominated agent. In contrast,the enrichment in K2O of shoshonitic to ultrapotassic magmaswas achieved through recycling of subducted sediments throughmelts that enriched the mantle wedge in K and related elements.Such a scenario can be easily reconciled with a geodynamic settingat the edge of a destructive plate margin with the subducted slabresponsible for the recycling of sediments within the mantle wedge.

Magma flow within dykes in submarine hyaloclastite environments: An AMS study of the Miocene Cabo de Gata volcanic units

Abstract The Miocene Cabo de Gata volcanic arc in SE Spain comprises a wide variety of volcanic facies and eruptive styles in subaqueous to subaerial environments. In the SW sector of the area, 5–100 m-thick, NNW–SSE-orientated dykes feed and intrude submarine hyaloclastite deposits. We analysed the anisotropy of magnetic susceptibility (AMS) of six dykes and five hyaloclastite sites from three volcanic units: the Cerro Cañadillas, Los Frailes, and El Barronal formations. The main magnetic minerals are primary low-Ti titanomagnetite and magnetite. The AMS ellipsoids in the dykes are generally oblate-triaxial in shape, with magnetic foliations subparallel to the dyke walls. Kinematic field evidence supports the inferred flow directions deduced from magnetic lineation and imbrication of magnetic foliation. The geometric relationships between dyke margins and AMS axes indicate that dykes at El Barronal were emplaced via prevalent subvertical upward magma flow. The inferred flow directions are reproduced well by analogue models of AMS simulating magma migration in dykes with a diapiric geometry. The other dykes were emplaced by lateral magma propagation. Conversely, hyaloclastite shows a large scatter of the AMS axes reflecting different degrees of fragmentation. We observe a gradual increase in scatter in the AMS from confined dykes to fragmented hyaloclastite.

The Anthropocene and the production and reproduction of capital

Regardless of the final fitting of the Anthropocene in the Geologic Time Scale, conceptualizing the Anthropocene as a human-induced ecological crisis of planetary scale linked to the capitalist mode of production allows addressing the research on the deep roots of such crisis into the fundamentals of this production mode. In this regard, a Marxian dialectical approach is pertinent to face some of the major challenges launched by the Anthropocene narrative. In particular, understanding capital as the automatic fetish that commands social production and reproduction in modern society allows not falling into mystified techno-scientific solutions for the crisis. Capital as the automatic fetish that mediates in the universal metabolism between humans and nature yields an alienated form of social metabolism that is at the base of the metabolic rift inherent to the production and reproduction of capital and that is enhanced by the tendency of the rate of profit to fall.

On theoretical approaches to the Anthropocene challenge

Frank Oldfield (Oldfield F (2018) A personal review of the book reviews. The Anthropocene Review 5: 97–101) reflects about the need for conceptual frameworks to confront the Anthropocene challenge and about the capability of Marxism in this regard. Against his view, I argue that conceptual or epistemological frameworks are necessary to face this challenge and that Marxism is in the best position to do so when it is compared with other theoretical approaches.

Submarine Volcanism of the Cabo de Gata Magmatic Arc in the Betic-Rif Orogen, SE Spain: Processes and Products

This research has been partly funded by project 2014SGR1595 and by grant PRX14/00303 to Carles Soriano.