Geologic evolution of the westernmost part of the internal Betic zone (Betic Cordilleras,Southern Spain)

The Serranía de Ronda (western Betic Cordilleras, S-Spain) is formed by different tectonic units of the Betic internal domain. Stratigraphic correlations of the Permo-Triassic and Triassic sedimentary sequences imply that one part of the Mesozoic carbonates of the Rondaides (Dorsale bétique), namely the Cabrilla unit (Dorsale interne), is shearedoff from the frontal part of the Malaguides, and another part (Nieves unit, Dorsale externe) forms the Mesozoic cover of the alpujarride Casares unit. The first alpine compressional phases took place in the Paleogene; post-metamorphic movements followed in the time between the Upper Aquitanian and the Upper Tortonian. From geometrical considerations it can be concluded that the Malaguides originated paleogeographically from a more internal region than the Alpujarrides.

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Zusammenfassung Am Aufbau der Serranía de Ronda (westliche Betische Kordilleren, S-Spanien) nehmen verschiedene Einheiten der betischen Intemzonen teil. Stratigraphische Vergleiche der permotriadischen und triadischen Sedimentserien erlauben den Schluß, daß die mesozoischen Karbonate der Rondaiden (Dorsale bétique) zu einem Teil (Cabrilla-Einheit, Dorsale interne) von der frontalen Partie der Malagiden abglitten und zum anderen Teil (Nieves-Einheit, Dorsale externe) das abgescherte Mesozoikum der alpujarriden Casares-Einheit bilden. Die ersten alpinen Kompressionsphasen sind im Paleogen anzusetzen, da für mesozoische Deckenbewegungen beweiskräftige Argumente fehlen. Zwischen Oberaquitanian und Obertortonian fanden post-metamorphe Überschiebungen statt. Aus geometrischen Gründen wird angenommen, daß die Malagiden paläogeographisch internerer Herkunft sein müssen als die benachbarten Alpujarriden.

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Resumen La Serranía de Ronda (Cordilleras béticas occidentales, Prov. Málaga) está formado por diferentes unidades del conjunto bético interno. Correlaciones estratigráficas del Permo-Triásico y del Triásico de los diferentes unidades permiten la conclusión que los Rondáides (Dorsal bética) está por una parte (unidad de Cabrilla, Dorsal interna) el revestimiento mesozóico de la parte frontal de los mantos maláguides, y por otra parte (unidad de las Nievas, Dorsal externa) la parte mesozóica de la unidad alpujárride de Casares. Las primeras fases alpinas de compresión deben ser situadas en el Paleógeno. Las traslaciones post-metamórficas de mantos son de edad aquitaniense superior hasta pre-tortoniense superior. Con argumentación geométrica se puede concluir que los Maláguides son de un orígen paleográfico más interno que los Alpujárrides.

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Stratigraphisch-fazielle Identifizierung von Sedimenten auf chemisch-geologischem Wege

Zusammenfassung Die Bor-Gehalte des paralischen Oberkarbons sind vorwiegend von der ursprünglichen Salinität im Ablagerungsgebiet abhängig. Daneben scheint das Klima eine Auswirkung zu haben, die sich durch die Erhöhung der Bor-Gehalte vom Westfal B an und im Rotliegenden, Keuper und Tertiär bemerkbar macht.

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The boron contents of the paralic Upper Carboniferous depend principally on the original salinity in the area of sedimentation. Besides, the climate appears to have an effect that manifests itself by increase in the boron contents from the Westphalian B on and in the Rotliegendes, Keuper and tertiary.

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Résumé Les teneurs en bore du Carbonifère supérieur pralique dépendent avant tout de la salinité originale de la région de sédimentation. Par ailleurs, le climat paraît avoir eu une influence qui se traduit par un accroissement des teneurs en bore dans le Westphalien B, le Rotliegende, le Keuper et le Tertiaire.

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Das Sockelstockwerk in den Randzonen der Urkontinente

The rocks of the cratonic foreland extend underneath many orogens, where they are subjected to “regeneration” during the geosynclinal phase and to superimposed structures during the folding of the orogen. Such structural and metamorphic alterations are now exposed in the “Sockelstockwerk” of certain orogenic belts in Africa, America, Australia and Europe. In this deep level, originally situated between the bottom of the geosyncline and the migmatite stockwerk, the following zones have been observed along the total length of the orogenic belt: border zone along the margin of the cratonic foreland: broad belt with superimposed structures of two (ore more) different orogenic deformations; main vergency fan, marking the central axis of the orogen. This fan often is a lineament with deep roots and a structure of continental importance.     

Homogeneous cosmological solutions of the Einstein equation

Homogeneous solutions in the framework of general relativity form the basis to understand the properties of gravitation on global scale. Presently favoured models describe the evolution of the universe by an expansion of space, governed by a scale function, which depends on a global time parameter. Dropping the restriction that a global time parameter exists, and instead assuming that the time scale depends on spatial distance, leads to static solutions, which exhibit no singularities, need no unobserved dark energy and which can explain the cosmological red shift without expansion. In contrast to the expanding world model energy is globally conserved. Observations of high energy emission and absorption from the intergalactic medium, which can scarcely be understood in the ‘concordance model’, find a natural explanation.     

SHRIMP zircon dating and Nd isotopic systematics of Palaeoproterozoic migmatitic orthogneisses in the Epupa Metamorphic Complex of northwestern Namibia

The Epupa Metamorphic Complex constitutes the southwestern margin of the Congo Craton and is exposed in a hilly to mountainous terrain of northwestern Namibia, bordering the Kunene River and extending into southern Angola. It consists predominantly of granitoid gneisses which are migmatized over large areas. This migmatization locally led to anatexis and produced crustal-melt granites such as the Otjitanda Granite. We have undertaken reconnaissance geochemical studies and single zircon U–Pb SHRIMP and Pb–Pb evaporation dating of rocks of the Epupa Complex. The granitoid gneisses, migmatites and anatectic melts are similar in composition and constitute a suite of metaluminous to peraluminous, calc-alkaline granitoids, predominantly with volcanic arc geochemical signatures. The zircon protolith ages for the orthogneisses range from 1861 ± 3 to 1758 ± 3 Ma. Anatexis in the migmatitic Epupa gneisses was dated from a melt patch at 1762 ± 4 Ma, and the anatectic Otjitanda Granite has a zircon age of 1757 ± 4 Ma. Migmatization and anatexis therefore occurred almost immediately after granitoid emplacement and date a widespread high-temperature Palaeoproterozoic event at ∼1760 Ma which has not been recorded elswhere in northern Namibia. The Nd isotopic systematics of all dated samples are surprisingly similar and suggest formation of the protolith from a source region that probably separated from the depleted mantle about 2.4–2.0 Ga ago. A major Archaean component in the source area is unlikely.