Metamorphic isograds of Uwet area, southeastern Nigeria
Cristallin ; Géographie de l'Afrique ; Isograde de métamorphisme ; Métamorphisme ; Nigéria ; Uwet, région
-high temperature Barrovian-type regionalmetamorphism whereas the absence of staurolite in these alumina-rich rocks is indicative of the high fugacity of oxygen during the metamorphism of the area.
The distribution of isograds indicates a northwest to southeast increase in the intensity of metamorphism in the Uwet area from medium greenschist facies to uppermost amphibolite facies. The presence of kyanite and sillimanite indicate high pressure
Geochemistry ; Metamorphic rock ; Metamorphism ; Microstructure ; Mineralogy ; Regional geology ; Rock ; Zimbabwe
This paper focuses on dehydration of hornblende during the retrograde metamorphism to examine the rock-fluid interaction which produced the charnockite-enderbite suites in the Northern Marginal Zone, Zimbabwe, on the basis of available thermodynamic
foliations and effects of progress of contact metamorphic reactions in the contact aureole are shown on the structural map for each of the country rock-types of the Sesia-Lanzo Zone. The structural and metamorphic evolution was reconstructed across the north
-eastern margin of the pluton by separating the pre- and the post-intrusive tectonic history and defining the contact aureole outline. Contact metamorphic assemblages and thermobarometric estimates indicate that this intrusive body emplaced at shallow
structural levels (contact metamorphism peak conditions : T < 750°C; P < 0.2 GPa). - (NF)
Geología regional ; Geomorfología estructural ; Italia ; Los Apeninos ; Metamorfismo ; Petrográfia
This paper deals with a structural and petrographic study carried out on key outcrops belonging to the Tuscan Nappe exposed in the Colline Metallifere region (Montieri-Poggio Prugnoli). Here, the Tuscan Nappe was affected by polyphase deformation
characterised by superposed folding events (F1, F2 and F3) and related tectonic foliations (S1 and S2) in agreement with the structural setting described for the Tuscan Nappe exposed both in other places of southern Tuscany, and in the Alpi Apuane region. - (NF)
The structure of the Palaezoic schists in the Southern Menderes Massif, western Turkey : a new approach to the origin of the Main Menderes Metamorphism and its relation to the Lycian Nappes
In this paper, the AA. discuss the general characteristics of the structures formed during the Main Menderes Metamorphism, discuss the evidence for the sense of shearing, and test the previously proposed model for the origin of the Lycian Nappes
and their relation to the Main Menderes Metamorphism. The study area is located on the southern side of Besparmak Mountain, north of Selimiye in the southern sector of the Menderes Massif.
Analysis of regional data from metamorphic tectonites: derivation of deformation sequences from over printing relations in Recent advances in geomathematics. An international symposium.
and garnet-amphibole schists, locally with megablasts of garnet and amphibole. As the Schneeberg Complex is considered to be a monometamorphic unit with Alpine metamorphism only, its southern boundary with the polymetemorphic Texel Complex is a key-element
in deciphering the tectono-metamorphic evolution of the Austroalpine basement in the western sector of the Eastern Alps. - (NF)
This work investigates the interplay between fluids and metamorphic recrystallisation in the Austroalpine Dent Blanche Nappe (Western Alps, Italy). This nappe consists of the Arolla and Valpelline Units, respectively dominated by metagranitoids
Asia ; Comparative study ; Earth surface processes ; Geochronology ; High mountain ; Karokoram ; Mountain ; Pakistan ; Regional geology ; Tibet
Alta montaña ; Asia ; Estudio comparativo ; Geocronología ; Geología regional ; Geomorfodinámica ; Karakoram ; Montaña ; Pakistán ; Tibet
The Karakoram terrane in Northern Pakistan is geologically equivalent to the Qiangtang terrane of central Tibet but unlike Tibet shows extreme topographic relief, high uplift-exhumation and erosion rates and exposes deep crustal metamorphic
mountain range with semi-continuous crustal thickening, deformation, metamorphism and partial melting for at least the last 63 million years and continues to this day. - (NF)
Titres des différents volumes: 1. Classifications and historical studies| 2. Geochemical studies| 3. Supergene and surficial ore deposits| textures and fabrics| 4. Tectonics and metamorphism| 5. Regional studies| 6. Cu, Zn, Pb and Ag deposits| 7. Au
This paper reconstructs the State of the Art on the Peloritani Crust (Southern Italy). It illustrates the geometry, the real extension, petrographic and geochemical compositions and the techtono-metamorphic evolution of its terrains, with special
Subduction- and non-subduction-related igneous rocks in the Central European Variscides : geochemical and Nd isotope evidence from the Kłodzko Metamorphic Complex, Polish Sudetes
Within the frame of a meso- and microstructural investigation on the metamorphic rocks of the Alpi Apuane, this contribution deals with an area located northeast of Carrara, the upper Colonnata valley. Studies of the geometry of folds and related
plutonic and high rank metamorphic sources. This provenance is supported by the occurence of well rounded plutonic and high rank metamorphic pebbles within some conglomerate lithofacies of the Beni Ider Flysch, never found so far. Petrography
Dating ; Metamorphic rock ; Regional geology ; Rock ; Russia ; Soviet Far East
Description de plagio-migmatites du complexe Partizanskij. Détermination de leur âge par la méthode Rb-Sr. Schéma des régions tectoniques. La formation des granitoïdes et des migmatites remonte, peut-être, au Protérozoïque inférieur.
Antarctique ; Dérive des continents ; Gondwana ; Géographie des régions polaires ; Orogène ; Orogène de Ross ; Paléogéographie ; Paléozoïque ; Précambrien ; Ross Orogen ; Tectonique globale ; Transantarctic Mountains
Geography of polar regions
An orogenic sequence of sedimentary, volcanic metamorphic and plutonic rocks, truncated by a major middle to upper Paleozoic erosion surface occurs throughout the Transantarctic Mountains. Along its length the belt shows considerable variations