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| Registros recuperados: 12 | |
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| Zwart, H.J.. |
| Comme la carte de la page 8 le montre le Massif du Saint-Barthélemy se trouve dans le Dépt. de l'Ariège à l'Est et au Nord de la rivière dont le département porte le nom et entre Foix et Ax-les-Thermes. Le terrain examiné est formé entièrement de roches paléozoïques ou plus anciennes, bordées au Nord, au Sud et à l'Est par des formations mésozoïques. Ce terrain est limité également de Paléozoïque au côté Ouest, le long d'une faille qui sépare le Massif du Saint-Barthélemy du Massif de l'Arize. De cette manière le Massif du Saint-Barthélemy est un des Massifs primaires Nord-pyrénéens: c'est-à-dire l'une des îles de roches paléozoïques dans le Mésozoïque, situées au Nord de la zone axiale, qui est entièrement constituée de roches paléozoïques. Les principaux... |
| Tipo: Article / Letter to the editor |
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| Ano: 1953 |
URL: http://www.repository.naturalis.nl/record/505915 |
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| Sitter, L.U. de; Zwart, H.J.. |
| The geology of the map sheets 1:50.000, 1 Garonne and 2 Salat of the Geological map of the Central Pyrenees is described. The stratigraphic sequence consists of Paleozoic rocks from the Cambro-Ordovician to the Carboniferous, and of Mesozoic rocks from the Trias up to the Tertiary. Hercynian and Alpine orogenies have acted on this intercontinental mountain chain. The Hercynian orogeny is accompanied by epi-to cata-zonal metamorphism in which several successive stages can be recognized. The Alpine orogenesis consists also of successive stages of which the Pre-Cenomanian one has been accompanied by basic rock intrusion and a particular kind of metamorphism. In the structure presented on these sheets a stretch of the axial zone is represented and a part of... |
| Tipo: Article / Letter to the editor |
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| Ano: 1962 |
URL: http://www.repository.naturalis.nl/record/505981 |
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| Sitter, L.U. de; Zwart, H.J.. |
| In 1958 werden de karteringen in de Centrale Pyreneeën en in het noorden van de provincie Leon (zuidrand Ast.-Cantabrisch Gebergte) voortgezet, het werk in Galicië niet. In de Centrale Pyreneeën werd een eerste verkenning in het Ribagorzana dal aangevangen, waarover hier nog niet gerapporteerd wordt. Het werk in het Segre dal werd voortgezet, terwijl de kartering van een klein ingewikkeld gebied in een oostelijk zijdal van de Pallaresa werd begonnen en beëindigd. De karteringen in het noorden van Andorra en over de grens in Frankrijk werden eveneens voortgezet. |
| Tipo: Article / Letter to the editor |
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| Ano: 1959 |
URL: http://www.repository.naturalis.nl/record/505780 |
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| Zwart, H.J.. |
| The geology of the map sheet 6, Aston, is described. The stratigraphic sequence consists of Paleozoic rocks from Cambro-Ordovician to Carboniferous age and some Cretaceous rocks along the northern border of the axial zone. The lower part of the Cambro-Ordovician is strongly metamorphosed and consists of micaschists, migmatites and granites. A leucocratic augengneiss, probably an orthogneiss, forms the core of the Aston-Hospitalet massif. Two intrusive granites occur in the Paleozoic rocks. Two types of major structures are distinguished, the metamorphic infrastructure and the non-metamorphic suprastructure. Several phases of deformation, all belonging to the Hercynian orogeny have been recognized. The relationships of the metamorphism to these deformation... |
| Tipo: Article / Letter to the editor |
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| Ano: 1965 |
URL: http://www.repository.naturalis.nl/record/505739 |
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| Sitter, L.U. de; Zwart, H.J.. |
| In 1957 werden de karteringen in twee gescheiden gebieden in de Pyreneeën voortgezet, verder in een gebied in N.-Leon aansluitend aan het N.-Palenciagebied begonnen en in Galicia eveneens voortgezet. In de Spaanse Pyreneeën werd dit jaar begonnen met gebieden, die uit het Segredal te bereiken zijn en op de duur zullen aansluiten met het Pallaresagebied. In de Franse Pyreneeën werd het onderzoek aan het massief van Aston voortgezet. |
| Tipo: Article / Letter to the editor |
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| Ano: 1957 |
URL: http://www.repository.naturalis.nl/record/505968 |
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| Zwart, H.J.. |
| The present memoir is the final report of a geological mapping project which has been executed by staff and students of the Department of Structural Geology of the Geological Institute of Leiden University. The project was initiated by professor Dr. L.U. de Sitter, to whom this memoir is dedicated. In the first instance this project was intended as a field training program for undergraduate and M. Sc. students, but at the same time many important contributions to the geological knowledge of this mountain chain were obtained by these students, by Ph. D. students and by staff members. |
| Tipo: Article / Letter to the editor |
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| Ano: 1979 |
URL: http://www.repository.naturalis.nl/record/505614 |
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| Zwart, H.J.. |
| Depuis longtemps on trouve dans la littérature sur la géologie des Pyrénées des discussions sur les lherzolites et les ophites, concernant leur origine, leur âge et leur mode de formation. En général ces discussions ont rendu difficile l'éclaircissement de ce problème et un résumé de toute la littérature manque jusqu'ici. Dans un rapport inédit de l'Institut géologique de l'Université de Leyde M. H. Heetveld a rassemblé toutes les données sur les lherzolites et ophites, et en vérité il est difficile d'en tirer une conclusion. C'est pourquoi nous ferons dans cet article une proposition quant à leur définition et leur âge et mode de formation. Les deux termes lherzolite et ophite sont bien définis: la lherzolite est une roche consistant essentiellement en... |
| Tipo: Article / Letter to the editor |
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| Ano: 1953 |
URL: http://www.repository.naturalis.nl/record/505815 |
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| Sitter, L.U. de; Zwart, H.J.. |
| Mapping of the Paleozoic of the Central Pyrenees by students in geology of Leiden University under the directorship of Prof. Dr L.U. de Sitter started in 1948 with the Arize massif. Since then the survey has shifted first eastwards, 1949 St. Barthélemy massif; then westwards, 1950 Salat valley; 1951 Riberot valley (sheet 2); 1952, Garonne valley (sheet 1), and then southwards, 1953 and 1954 Valle de Arán, then south again to the Pallaresa and the Sègre (1955—1957). The survey has been restricted almost exclusively to the Paleozoic because the Mesozoic had been mapped by Casteras (1933) in the north and by Misch (1934), in the south, therefore only the Paleozoic rocks in their nonmetamorphic and metamorphic state have been differentiated on the map, whereas... |
| Tipo: Article / Letter to the editor |
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| Ano: 1957 |
URL: http://www.repository.naturalis.nl/record/505682 |
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| Zwart, H.J.. |
| The structural geology and metamorphic petrology of the Bosost area in the Valle de Arán (Central Pyrenees) is discussed. The rocks exposed in this area consist of Cambro-Ordovician mica-schists with numerous granite and pegmatite bodies, phyllites and limestones; Silurian slates and schists and Devonian schists and limestones. The major structure dating from the Hercynian orogeny is the Garonne dome with essentially horizontal schistosity. Large steep folds in the Devonian accompanied by axial plane slaty cleavage are folded disharmonically with regard to the Cambro-Ordovician. Both kinds of structures date from the main phase. A second and later phase with N-S foldaxes was accompanied by laminar flow in E-W direction as shown by numerous rotated... |
| Tipo: Article / Letter to the editor |
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| Ano: 1963 |
URL: http://www.repository.naturalis.nl/record/505959 |
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| Sitter, L.U. de; Zwart, H.J.. |
| In 1956 werden de karteringen in de Pyreneeën, N.-Palencia (Asturië) en Galicië voortgezet. Geen nieuwe gebieden werden in het onderzoek betrokken, die niet direct aansloten bij die van vorige jaren. In de Pyreneeën werd als nieuw werk voornamelijk uitgegaan van de kartering in het zuidelijk gedeelte van de Noguera Pallaresa tussen Llavorsi en Pobla de Segur. De Flamisell en de Mañanet werden in het onderzoek betrokken. Bovendien werd door Dr. Zwart en de Heer Allaart samen met de Heer Verspijck de metamorfe zone rond de Ariège opnieuw in studie genomen. |
| Tipo: Article / Letter to the editor |
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| Ano: 1957 |
URL: http://www.repository.naturalis.nl/record/505779 |
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| Zwart, H.J.. |
| The relation between orogenic movements and metamorphism is discussed. Schistosity and especially lineations are characteristic for metamorphites of the synkinematic phase. Lineations show a regular pattern. Late-kinematic metamorphism accompanied by different kinds of movement result in irregular rock flowage and rheomorphism. The structures of synkinematic mica-schists, gneisses, amphibolites and marbles are discussed. In the three satellite massifs a series of gneisses and granitic rocks exists which are the products of silica and sodium metasomatism of originally pelitic rocks. The time and duration of the metamorphism determines the final state of the rocks. Synkinematic metamorphism alone gave rise to the garnet-augen-gneisses which, being rather... |
| Tipo: Article / Letter to the editor |
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| Ano: 1957 |
URL: http://www.repository.naturalis.nl/record/505887 |
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| Registros recuperados: 12 | |
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