|
|
|
|
|
| Arps, C.E.S.; Calsteren, P.W.C. van; Hilgen, J.D.; Kuijper, R.P.; Tex, E. den. |
| In Galicia occur several polymetamorphic complexes that contain mafic and ultramafic rocks. Mafic volcanics and gabbros are situated in or near the complexes. An episode of metamorphism and granitization encompassed the generation of the volcanics and gabbros. Gravity surveys revealed the existence of deep roots below polymetamorphic complexes. Geochronological investigations yielded Palaeozoic ages from about 500 Ma for the generation of ultramafic rocks and calcalkaline granite series, till ages of around 300 Ma for postkinematic alkaline and calcalkaline granites. A model involving mantle-plume diapirism and rejuvenation of the lower crust is proposed for the Early Palaeozoic evolution of the continental lithosphere of Galicia. An excursion route is... |
| Tipo: Article / Letter to the editor |
|
| Ano: 1978 |
URL: http://www.repository.naturalis.nl/record/505595 |
| |
|
|
| Tex, E. den. |
| La région que j’ai étudiée et relevée est située dans les Alpes françaises, à environ 4° longitude est et 50°15’ latitude nord, et à environ 2000 mètres d’altitude. Elle fait partie de la chaîne dite „chaîne de Belledonne” qui s’étend des massifs de Beaufort et du Grand Mont dans le N N E jusqu’à ceux du Taillefer et de la Mure dans le S S W. Cette chaîne forme du point de vue géographique comme du point de vue géologique le prolongement méridional de la chaîne des Aiguilles Rouges et de la chaîne du Mont Blanc. Celles-ci font partie de la zone externe des massifs cristallins des Alpes, dont le prolongement en Suisse est connu sous le nom de „massifs centraux des Alpes”. On entend par là les chaînes anté-alpines, et principalement hercyniennes des Alpes,... |
| Tipo: Article / Letter to the editor |
|
| Ano: 1950 |
URL: http://www.repository.naturalis.nl/record/505737 |
| |
|
|
| Tex, E. den. |
| Historical notes on Galician geology, and on the work of the Leiden University petrology team in particular, are first provided. This is followed by an introduction to the geology of Galicia with emphasis on its crystalline basement and upper mantle inliers. Six lithotectonic units are distinguished: 1) the Variscan granitic rocks and migmatites. 2) the Palaeozoic supracrustal rocks and dismembered meta-ophiolites, 3) the blastomylonitic graben between Malpica and Tuy, 4) the Lalin and Forcarey Units, 5) the Ordenes basin and its mesocatazonal peripheral belt, 6) the predominantly mafic-ultramafic catazonal complex at Cabo Ortegal. The supracrustal history of western Galicia in late Precambrian and early Palaeozoic times, as inferred from neighbouring... |
| Tipo: Article / Letter to the editor |
|
| Ano: 1981 |
URL: http://www.repository.naturalis.nl/record/506014 |
| |
|
|
| Tex, E. den. |
| Discordant bedding is being reported with increasing frequency from rocks of almost any grade of metamorphism. It is, usually without much discrimination, cited as evidence of sedimentary origin or even as an indication of the sequence of deposition. In the present paper examples are given of discordant structures simulating both deltaic and torrential cross lamination but on closer inspection obviously due to differential stretching and variable orientation of cleavage in a thinly laminated quartzphyllite which has been isoclinally folded and subsequently flattened in the bedding plane. Microfabric analysis of micaceous cleavage planes can be a valuable aid in the distinction between discordant structures of sedimentary and deformational nature, and the... |
| Tipo: Article / Letter to the editor |
|
| Ano: 1955 |
URL: http://www.repository.naturalis.nl/record/505933 |
| |
|
|
| Tex, E. den. |
| The Spanish region of Galicia is situated in the extreme north-western part of the country due North of Portugal and West of Asturias. It is bordered by the Atlantic Ocean to the West and by the Bay of Biscay to the North (see fig. 1). The area under investigation concerns the western provinces of La Coruña and Pontevedra mainly. Apart from early reconnaissance work by Schulz (1858), Barrois (1892), Sampelayo (1922), Lotze (1945), Carlé (1945), Navarro and del Valle (1959) the area is at present being investigated and mapped on a scale of 1:50.000 by López de Azcona, Parga Pondal and their associates for the Instituto Geológico y Minero de España. So far nine sheets and explanatory memoirs have been published between 1948 and 1956. Parga Pondal has also... |
| Tipo: Article / Letter to the editor |
|
| Ano: 1961 |
URL: http://www.repository.naturalis.nl/record/505836 |
| |
|
|
| Tex, E. den. |
| Recent contributions by penologists of Leiden University to the present state of knowledge concerning crystalline Galicia are summarized. An enumeration of the most important rock-types is given and their grouping in geotectonic units is attempted. The structural and metamorphic history is outlined and shown to comprise a variety of pre-hercynian (pre-Cambro-ordovician) as well as hercynian and post-hercynian elements. It is argued that originally geosynclinal rocks of the pre-hercynian orogen (frequently attaining the eclogite, granulite or charnockite metamorphic facies) were intruded by Cambro-ordovician granitic rocks, and were subsequently incorporated in the hercynian orogen, where they were re-deformed, predominantly to N-S trending isoclinal folds,... |
| Tipo: Article / Letter to the editor |
|
| Ano: 1967 |
URL: http://www.repository.naturalis.nl/record/505876 |
| |
|
|
|
