Correlation between chemical and mineralogical characteristics and permeability of phyllite clays using multivariate statistical analysis

Phyllite clays are applied as a layer on a surface to be waterproofed and subsequently compacted. For this purpose, phyllite clays deposits can be grouped by their chemical and mineralogical characteristics, and these characteristics can be connected with their properties, mainly permeability, in order to select those deposits with the lowest permeability values. Several deposits of phyllite clays in the provinces of Almería and Granada (SE Spain) have been studied. The results of applying a multivariate statistical analysis (MVA) to the chemical data analysed from 52 samples determined by XRF, mineralogical analysis by XRD and permeability are reported. Permeability, a characteristic physical property of phyllite clays, was calculated using the results for experimental nitrogen gas adsorption and nitrogen adsorption-desorption permeability dependence. According to the results, permeability values differentiated two groups, i.e. group 1 and group 2, with two subgroups in the latter. The influence of chemical as well as mineralogical characteristics on the permeability values of this set of phyllite clays was demonstrated using a multiple linear regression model. Two regression equations were deduced to describe the relationship between adsorption and desorption permeability values, which support this correlation. This was an indication of the statistical significance of each chemical and mineralogical variable, as it was added to the model. The statistical tests of the residuals suggested that there was no serious autocorrelation in the residuals.Peer ReviewedPostprint (author's final draft

A strike-slip fault corridor within the Alpujarra Mountains (Betic Cordilleras, Spain)

15 páginas, 6 figuras.[EN] In a long »corridor« in the internal zone of the Betic Cordilleras, bounded to the north by the Sierra Nevada and to the south by the Sierras Lujar, Contraviesa and Gador, two discernible bands of strike-slip faults exist: These bands lie in an approximately E-W direction and are well exposed throughout and beyond the 85 km long belt. The characteristic features of strike-slip faults, such as cataclastic rocks composed of variously textured fault breccia, which also include fragments of rocks up to several metres in size, incipient foliation, and striation demonstrate the right-lateral nature of the displacement. There are also fractures which run in a NW-SE and NNE-SSW direction, and apparently originated after formation of the E-W faults. The magnitude of lateral displacements is difficult to calculate. Evidence of considerable vertical movement can be found locally. These strike-slip displacements have essentially occurred since the middle Miocene period and might still be taking place.[AL] In einem langen Korridor in der Internzone der Betischen Kordilleren, der im Norden durch die Sierra Nevada und im Süden von den Sierren Lujar, Contraviesa und Gador begrenzt wird, sind zwei Streifen mit Blattverschiebungen zu beobachten. Sie streichen etwa E-W und sind gut entlang des 85-km-langen Gürtels aufgeschlossen. Die charakteristischen Merkmale von Blattverschiebungen wie etwa kataklastische Gesteine mit verschiedenen texturierten Verwerfungsbrekzien, welche auch bis zu mehreren Metern große Gesteinsblöcke enthalten, beginnende Schieferung und Harnischbildung, zeigen die dextrale Natur der Bewegung. Daneben treten NW-SE und NNE-SSW streichende Störungen auf, die offensichtlich nach der Bildung der E-W verlaufenden Blattverschiebungen entstanden sind. Das Ausmaß des lateralen Versatzes ist schwer abzuschätzen. Diese Bewegungen finden seit dem mittleren Miozän statt und sind möglicherweise immer noch aktiv.[FR] Dans un long couloir situé dans la zone interne des Chaînes Bétiques et limité au Nord par la Sierra Névada et au Sud par les Sierras de Lujar, Contraviesa et Gador, s'observent deux trains de failles de décrochements. Ces trains ont une direction à peu près E-W et sont bien exposés tout au long des 85 Km de cette zone. Les traits caractéristiques des décrochements, tels que cataclasites, brèche de faille avec fragments de roches jusqu'à plusieurs mètres de longueur, schistosité naissante et striation, démontrent la nature dextre du déplacement. Il existe aussi des fractures de direction NW-SE et NNW-SSW qui se sont vraisemblablement formées postérieurement aux failles E-W. La valeur du déplacement latéral est difficile à estimer. On rèléve localement des indices de mouvements verticaux importants. Ces décrochements se sont produits essentiellement à partir du Miocène moyen et peuvent encore se poursuivre aujourd'hui.This study was carried out under the auspices of the Departamento de Investigaciones Geológicas del C.S.I.C., Centro Coordinado con la Universidad de Granada, during a research project entitled: "Borde mediterráneo español: Evolución del Orógeno Bético y Geodinámica de las Depresiones Neógenas".Peer reviewe

New data from Orihuela and Callosa Mountains (Betic Internal Zone, Alicante, SE Spain). Implications for the “Almágride Complex” controversy

In this paper, we present the results of the stratigraphic and structural study of the Orihuela and Callosa Mountains (Alicante province, SE Spain), belonging to the Internal Betic Zone. The terrains cropping out in this area had been assigned by previous authors to the Ballabona-Cucharón Complex, lately redefi ned as the Almágride Complex. New data afforded in this work lead us to propose a new stratigraphic succesions, structural division, and geodynamic evolution. We also assign both mountains ranges to the lower Alpujarride Complex, confi rming that the Almágride Complex is not a singular element of the Betic Cordillera.En este trabajo presentamos los resultados del estudio estratigráfi co y estructural de las sierras de Orihuela y Callosa (provincia de Alicante, SE de España), pertenecientes ambas a la Zona Interna Bética. Estas sierras fueron asignadas por autores precedentes al Complejo Ballabona-Cucharón, más tarde redefi nido como Almágride. Los datos presentados en este trabajo nos llevan a proponer una nueva serie estratigráfi ca, división tectónica y evolución geodinámica del sector estudiado. Así mismo, asignamos las unidades reconocidas a la parte inferior del Complejo Alpujárride, confi rmando que el Complejo Almágride no debe ser considerado como elemento singular de la Zona Interna Bética

A "core-complex-type structure" formed by superposed ductile and brittle extension followed by folding and high-angle normal faulting. The Santi Petri dome (western Betics, Spain)

The Santi Petri dome (western Betics, southern Spain) shows a core-complex-like structure, where migmatitic gneisses and schists outcrop below low-grade slates and phyllites, all of which form the basement of the Neogene Málaga basin. The migmatites and schists suffered a coaxial-flattening event during isothermal decompression and were later exhumed by ductile ESE non-coaxial stretching. Further exhumation was achieved by W- to SW-transport brittle low-angle normal faulting. Subsequently these extensional structures were gently folded in the core of a NE/SW-oriented antiform during the Tortonian. Finally the Santi Petri domal geometry was accentuated by the interference of orthogonal high-angle faults with ENE–WSW and NNW–SSE orientation. This core-complex-like structure, formed by superposition of extensional and compressive tectonic events, does not represent a classical, purely extensional core complex, which shows that metamorphic structure and geometry are not decisive criteria to define a core-complex

Late orogenic doming in the Eastern Betics : final exhumation of the Nevado-Filabride complex and its relation to basin genesis.

The geometry, timing, and kinematics of late orogenic extension in the Betic Cordilleras pose the problem of a decoupling of upper crustal and lower crustal deformation regimes. Perpendicular directions of extension in metamorphic domes and nearby sedimentary basins remain unexplained. This paper puts kinematic constraints on the final exhumation of the Nevado-Filabride complex, focusing on the formation of metamorphic domes and their relations with the adjacent basins. Structural fabrics and kinematic indicators below the main shear zones as well as their relations with both published changing metamorphic P-T conditions and geochronological data were studied. Our approach describes (1) a consistent top-to-the-west shear parallel to dome axes of during D2 (i.e., during decompression) with distributed ductile flow and the onset of strain localization along major shear zones, (2) further strain localization along the major shear zones under greenschist facies conditions, during D3 leading to S-C′ mylonites formation accompanied with a rock strong thickness reduction, (3) the divergence of shear direction on either limbs of domes during D3 showing the appearance of the dome geometry, and (4) a local evolution toward N-S brittle extension (D4) in the upper plate and formation of sedimentary basins. Continuous ductile to brittle top-to-the-west shear is compatible with the slab retreat hypothesis from the Miocene; the formation of domes which adds gravitational forces responsible for the final stages of exhumation is thus characterized by important kinematics changes necessary to explain coeval N-S opened basins. Later, from the upper Tortonian, a contractional event (D5) amplified the earlier domal structures forming the present north vergent folds

Nuevos datos de la litología y de la estructura de los sectores central y oriental de Ceuta (Cordillera Bético-Rifeña)

In the central and eastern parts of Ceuta two tectonic units are differentiated: a) the Hacho unit, formed by two groups of orthogneisses which foliation permits to establish the structure: an anticline with a periclinal end at its western edge, and b) the Istmo unit, with peridotites at the bottom, followed by migmatitic granulites, gneisses, and dark mica schists. The thrust of the peridotites over the orthogneisses of the Hacho unit occurred under fragile conditions. For the first time several types of rocks, not previously described, have been localized: dark mica schist and phyllites and quartzites, these two last perhaps corresponding to the Federico units. With the new data, these units can be better compared, with those Alpujárride/Sebtide in the sectors of Jubrique-GuadaizaBenahavísEn los sectores central y oriental de Ceuta se diferencian dos unidades: a) la unidad del Hacho, formada por dos grupos de ortogneises cuya foliación permite establecer su estructura: un anticlinal que tiene una terminación periclinal en su parte occidental, y b) la unidad del Istmo, con peridotitas en la base seguidas por granulitas migmatíticas, gneises y esquistos oscuros. El cabalgamiento de las peridotitas sobre los ortogneises ocurrió en condiciones frágiles. Por primera vez se han localizado afloramientos de rocas no descritos previamente: esquistos oscuros y filitas y cuarcitas, estas dos últimas quizás correspondientes a unidades de tipo Federico. Con los datos presentados, estas unidades pueden compararse mejor con las del Alpujárride/Sébtide en los sectores de Jubrique-Guadaiza y Benahaví

The Alpujarride Triassic Platform (Internal Zones of the Betic Cordillera, Spain)

A partir de estudios estratigráficos, centrados en la sucesión triásica alpujárride de la Sierra de Gádor (Almería, Cordillera Bética) y su correlación con otros sectores, proponemos una columna estratigráfica sintética para la Plataforma Triásica Alpujárride. Esta columna estaría dividida en dos formaciones: una metasiliciclástica basal (subdividida en tres miembros: inferior, intermedio y superior) y una metacarbonática suprayacente (subdivididida en seis miembros, numerados del 1 al 6 de muro a techo). Esta plataforma habría sufrido una evolución morfológica en tres fases: Fase 1 de rampa homoclinal (Anisiense-Ladiniense); Fase 2 de plataforma fallada (Ladiniense-Carniense); y Fase 3 de plataforma orlada (Noriense). Además, a partir del análisis sedimentario de las asociaciones de facies reconocidas en la sucesión triásica de la Sierra de Gádor proponemos su división en cuatro secuencias deposicionales para el intervalo comprendido entre el Anisiense y el Noriense. La primera secuencia comprendería los miembros inferior e intermedio de la formación metasiliciclástica; la segunda secuencia deposicional incluiría el miembro superior de la formación metasiliciclástica y los miembros 1 y 2 de la formación metacarbonática; la tercera secuencia constaría de los miembros 3 y 4, mientras que la cuarta secuencia estaría constituida por los miembros 5 y 6.Taking into account previous detailed stratigraphic and facies analyses carried out in the Alpujarride succession from the Sierra de Gádor (Almeria province) and correlations with other sectors, we propose a synthetic stratigraphic column for the Alpujarride Triassic Platform; this column consists of two formations: a basal meta-siliciclastic formation (divided in three members, from base to top: lower, middle and upper) Anisian in age, and an overlying meta-carbonate formation (divided in six members, 1 to 6 from base to top) Anisian-Norian in age. We postulate a morphological evolution of the Alpujarride Triassic Platform including three phases: an Anisian-Ladinian homoclinal ramp first phase, a Ladinian-Carnian fault-block-type platform second phase, and a Norian rimmed platform third phase. We also divide the Anisian-Norian stratigraphic record in four depositional sequences (DS). DS1 should comprise the lower and middle members of the meta-siliciclastic formation; DS2 should be formed by the upper member of the meta-siliciclastic formation and members 1 and 2 of the meta-carbonate formation; DS3 should consist of members 3 and 4; SD4 should be composed of members 5 and 6.El presente trabajo ha sido financiado con el Proyecto de Investigación CGL2011-30153-C02-02 del Ministerio de Ciencia e Innovación, así como por el Grupo de Investigación de la Universidad de Alicante VIGROB053

Silver and lead mineralogy in gossan type deposits of Sierra de Cartagena, southeast Spain

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Evidence for the activity and paleoseismicity of the Padul fault (Betic Cordillera, southern Spain)

There is evidence of recent tectonic activity in the proximity of Padul, in the central sector of the Betic Cordillera. The principal active fault in this region is the Padul normal fault, running NW-SE, which displays spectacular geomorphological and structural features owing to its recent activity. However, there is no evidence of earthquakes of moderate-high magnitude occurring in this area during the historical or the instrumental period. In the vicinity of Padul we identified various soft-sediment deformation structures produced by liquefaction which we attributed to seismic shocks of a moderate-high magnitude. These structures are situated in detritic sediments, intercalated with layers of peat, which have enabled dating of these paleoearthquakes to the late Pleistocene (approx. 30,000 to 35,000 yr BP). Moreover, field observations in sediments of alluvial fans in the vicinity of the Padul fault, together with a retrodeformation analysis of an outcrop, enabled various deformation events to be dated to the recent Quaternary period.En el área de Padul, localizada en el sector central de la Cordillera Bética, existen numerosas evidencias de actividad tectónica reciente. La principal falla activa de la región es la falla normal de Padul, de dirección NW-SE, que presenta evidencias geomorfológicas y estructurales espectaculares de su actividad reciente. Sin embargo, no se tiene constancia de la ocurrencia de terremotos de magnitud moderada-alta en el área de Padul ni durante el periodo histórico ni el instrumental. En este sector hemos identificado varias estructuras sedimentarias de deformación producidas por licuefacción que interpretamos como resultado de sacudidas sísmicas de magnitud moderada-alta. Estas estructuras se localizan en sedimentos detríticos intercalados con niveles de turba que han permitido datar estos paleoterremotos como Pleistoceno superior (aproximadamente entre 30.000 y 35.000 años B.P.). Por otra parte, las observaciones de campo realizadas en algunos sedimentos de los abanicos aluviales de la zona de falla de Padul y el análisis de retrodeformación en un afloramiento han permitido identificar varios eventos de deformación durante el Cuaternario reciente