1,721,110 research outputs found
Clauer N. (1976) — 87Sr,/86Sr composition of evaporitic carbonates and sulphates from Miocene sediment cores in the Mediterranean Sea (D.S.D.P., Leg 13). Sedimentology, 23, p. 133-140
No full textAunis Danièle. Clauer N. (1976) — 87Sr,/86Sr composition of evaporitic carbonates and sulphates from Miocene sediment cores in the Mediterranean Sea (D.S.D.P., Leg 13). Sedimentology, 23, p. 133-140. In: Sciences Géologiques. Bulletin, tome 29, n°4, 1976. Sédimentologie et géochimie de la surface. p. 322
Clauer N. et Lucas J. (1970). — Minéralogie de la fraction fine des schistes de Steige. Vosges septentrionales. Bull. Gr. fr. Argiles, 22, 2, p. 223-235
No full textClauer N. et Lucas J. (1970). — Minéralogie de la fraction fine des schistes de Steige. Vosges septentrionales. Bull. Gr. fr. Argiles, 22, 2, p. 223-235. In: Bulletin du Service de la carte géologique d'Alsace et de Lorraine, tome 23, n°3-4, 1970. Sédimentologie et géochimie de la surface. p. 225
Clauer N. (1976) — 87Sr,/86Sr composition of evaporitic carbonates and sulphates from Miocene sediment cores in the Mediterranean Sea (D.S.D.P., Leg 13). Sedimentology, 23, p. 133-140
No full textAunis Danièle. Clauer N. (1976) — 87Sr,/86Sr composition of evaporitic carbonates and sulphates from Miocene sediment cores in the Mediterranean Sea (D.S.D.P., Leg 13). Sedimentology, 23, p. 133-140. In: Sciences Géologiques. Bulletin, tome 29, n°4, 1976. Sédimentologie et géochimie de la surface. p. 322
Clauer N. et Bonhomme M. (1970). — Homogénéisation isotopique du strontium entre les schistes de Steige et la série de Villé (Vosges) pendant la phase bretonne de l'orogenèse hercynienne. C. R. Acad. Sci. Paris , 271 D, p. 1844-1847
No full textClauer N. et Bonhomme M. (1970). — Homogénéisation isotopique du strontium entre les schistes de Steige et la série de Villé (Vosges) pendant la phase bretonne de l'orogenèse hercynienne. C. R. Acad. Sci. Paris , 271 D, p. 1844-1847. In: Bulletin du Service de la carte géologique d'Alsace et de Lorraine, tome 23, n°3-4, 1970. Sédimentologie et géochimie de la surface. p. 225
Clauer N. et Hoffert M. (1976) — 87Sr/86Sr composition of recent authigenic sediments cored in the Pacific Ocean. IVth European Colloquium of Geochronology, Amsterdam, April 5-10, p. 22
No full textAunis Danièle. Clauer N. et Hoffert M. (1976) — 87Sr/86Sr composition of recent authigenic sediments cored in the Pacific Ocean. IVth European Colloquium of Geochronology, Amsterdam, April 5-10, p. 22. In: Sciences Géologiques. Bulletin, tome 29, n°4, 1976. Sédimentologie et géochimie de la surface. p. 322
Clauer N. et Bonhomme M. (1970). — Homogénéisation isotopique du strontium entre les schistes de Steige et la série de Villé (Vosges) pendant la phase bretonne de l'orogenèse hercynienne. C. R. Acad. Sci. Paris , 271 D, p. 1844-1847
No full textClauer N. et Bonhomme M. (1970). — Homogénéisation isotopique du strontium entre les schistes de Steige et la série de Villé (Vosges) pendant la phase bretonne de l'orogenèse hercynienne. C. R. Acad. Sci. Paris , 271 D, p. 1844-1847. In: Bulletin du Service de la carte géologique d'Alsace et de Lorraine, tome 23, n°3-4, 1970. Sédimentologie et géochimie de la surface. p. 225
Clauer N. (1973) — Rb-Sr isotopic study of very slight metamorphosed sediments : the Precambrian II from the Bou-Azzer-El Graara window. Illrd European Colloquium of Geochronology, Abstracts, Oxford, 3-8 sep., p. 25
No full textClauer N. (1973) — Rb-Sr isotopic study of very slight metamorphosed sediments : the Precambrian II from the Bou-Azzer-El Graara window. Illrd European Colloquium of Geochronology, Abstracts, Oxford, 3-8 sep., p. 25. In: Sciences Géologiques. Bulletin, tome 26, n°4, 1973. Sédimentologie et géochimie de la surface. p. 369
Clauer N., Trompette R., Caby R., Leblanc M., Affaton P. et Dars R. (1977) — Implications stratigraphiques d'une étude radiochronologique de la couverture sédimentaire précambrienne du craton ouest-africain. IX Colloquium on African Geology, Göttingen 28-30 avril, p. 39 -40
No full textAunis Danièle. Clauer N., Trompette R., Caby R., Leblanc M., Affaton P. et Dars R. (1977) — Implications stratigraphiques d'une étude radiochronologique de la couverture sédimentaire précambrienne du craton ouest-africain. IX Colloquium on African Geology, Göttingen 28-30 avril, p. 39 -40. In: Sciences Géologiques. Bulletin, tome 30, n°4, 1977. Géochimie de la surface et formes du relief. p. 304
Clauer N. et Tardy Y. (1976) — Effects of natural weathering on the mineralogical, chemical and isotopical composition of biotites. IVth European Colloquium of Geochronology, Amsterdam, April 5-10, p. 23
No full textAunis Danièle. Clauer N. et Tardy Y. (1976) — Effects of natural weathering on the mineralogical, chemical and isotopical composition of biotites. IVth European Colloquium of Geochronology, Amsterdam, April 5-10, p. 23. In: Sciences Géologiques. Bulletin, tome 29, n°4, 1976. Sédimentologie et géochimie de la surface. p. 322
Migration of Folding and Metamorphism in the Rheinische Schiefergebirge Deduced from K-Ar and Rb-Sr Age Determinations
No full textn the very low- to low-grade metamorphic Rhenohercynian Zone of the Variscides a migration of folding has been postulated which was deduced from the shifting of flysch sedimentation.
In order to get an idea of the time span which the “wave” of folding and metamorphism has needed to pass through the Rheinische Schiefergebirge, isotopic investigations by K-Ar and Rb-Sr methods were carried out. For these measurements the fine mineral fractions <2μm from pure sericite slates probably derived from acid to intermediate glass-tuffs were analyzed. Furthermore extremely fine-grained sericite- and celadonite-bearing tuffs were taken which probably belong to the Middle Devonian volcanism.
Because of the very low degree of metamorphism in the Rheinische Schiefergebirge it can be assumed, that the blocking temperatures for the K-Ar and Rb-Sr systems of white micas were not exceeded — except for the K-Ar system in the “Taunus-Pre-Devonian”. Therefore most of the age determinations are indicative of the peak of metamorphism.
A determination of the age of folding was only possible on the proved assumption that:
The metamorphism is syntectonic with respect to folding. Therefore a determination of the metamorphic ages includes the determination of the age of folding.
The samples used for the isotopic investigations were not allowed to contain old sedimentary — not recrystallized — white micas. Only rock samples containing phyllosilicate fabrics of metamorphic origin were selected.
According to the K-Ar and Rb-Sr age determinations the age of metamorphism and folding in the Rheinische Schiefergebirge decreases from about 330 Ma in the Taunus towards the north to 300 Ma at the northern border.
Three exceptions modify this evolutionary history from the south to the north:
Lower ages in the “Taunus-Pre-Devonian” rocks have to be interpreted as cooling ages because the temperatures in this area exceeded the blocking temperature for the K-Ar system of the micas during metamorphism.
Higher ages in the Lahn Syncline of about 330 to 340 Ma which belong to rocks emplaced into their present position by nappe movement from the southern margin of the Schiefergebirge. They therefore preserved the higher metamorphic ages of the southern margin.
The high K-Ar age of about 340 Ma at the northern margin of the Schiefergebirge is interpreted as an influence of the North European Caledonian orogeny.
The synmetamorphic “wave” of folding passed through the Rheinische Schiefergebirge from the northern border of the Mid-German Crystalline Rise to the present northern border in approx. 30 Ma. This would correspond to a “velocity of crustal shortening” of about 0,5 cm/year, if one assumes a mean tectonic shortening of about 50% in the Rheinische Schiefergebirge resulting from compression during deformation. These values have to be regarded as minimum values
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