Abstract
Stilpnomelane is known to be index-mineral of lowest metamorphic facies in the northern zone of the Swiss Alps. In Montblanc-region the first stilpnomelane due to alpine metamorphism will be found in the Montblanc-granite, whereas until now the adjacent metamorphic rocks in the north of granite have not yielded any stilpnomelane. This could be explained by chemical control in the metamorphic rocks or by instability of stilpnomelane because a new formed biotite has been found in the shearing-zones in the northern part of granite and stilpnomelane is disappearing.
Metamorphic reactions in the very coarse granite are bound to the limits between constituents or to the interior of larger crystals. Stilpnomelane very often has been found in microcline situated near to biotite or chlorite of primary origin. Towards the southern part of granite stilpnomelane will be found in larger quantities and occasionally a new formed chlorite will appear. This evolution is accompanied by the appearance of larger quantities of patch-perthite and chessboard-perthite in the microcline-megacrysts.
Probably a green biotite coexists with stilpnomelane, but majority of alpine biotite has been formed in a later phase and is accompanied by a strong change of quartz-fabric and disappearance of stilpnomelane.
One might suppose, that the change of lowest greenschist-facies (stilpnomelane) to a higher degree (biotite) even over very short distances depends more on the influence of changing chemical composition in the coexisting aqueous-gaseous phases than on a real increase of pressure and temperature.
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Literatur
Bearth, P.: Versuch einer Gliederung alpinmetamorpher Serien der Westalpen. Schweiz. mineral. petrog. Mitt. 42, 127–137 (1962).
Brown, E. H.: The Greenschist facies in part of Eastern Otago, New Zealand. Contr. Mineral. and Petrol. 14, 259–292 (1967).
Chatterjee, N. D.: On the widespread ocurrence of oxidized chlorites in the pennine zone of the western alps. Contr. Mineral. and Petrol. 12, 325–339 (1966).
Dal Piaz, G. V., and M. Govi: Lo stilpnomelano in Valle d'Aosta: nuovi ritrovamenti. Bull. soc. geol. ital. 87, 91–108 (1968).
Debenedetti, A.: Stilpnomelano in rocce della val d'Aosta. Rend. soc. mineral. ital. 17, 625–626 (1961).
Eggleton, R. A., and S. W. Bailey: The crystal structure of stilpnomelane Part I: The subcell. Clay and clay minerals. Proc. of the 13th nat. Conference 49–63 (1963).
Ellenberger, F.: Le stilpnomélane, minéral de métamorphisme régional dans la Vanoise. Compt. rend. soc. géol. France 63–65 (1957).
Gay, M.: Etude d'un stilpnomélane des Alpes franco-italiennes. Bull. soc. franç. minéral. et crist. 89, 344–347 (1966).
Govi, M.: Elementi elastici di „rocce elogitiche“ nella zona mesozoica Avise-Valgrisanche (Alta Valle d'Aosta). Boll. soc. geol. ital. 86, 171–178 (1967).
Hutton, C. O.: The stilpnomelane group of minerals. Mineral. Mag. 25, 172–206 (1938).
—: Further data on the stilpnomelane mineral group. Am. Mineralogist 41, 608–615 (1956).
Jäger, E., E. Niggli u. E. Wenk: Rb-Sr Altersbestimmungen an Glimmern der Zentralalpen. Beitr. geol. Karte Schweiz, N. F. 134, 1–67 (1967).
Niggli, E.: Stilpnomelan als gesteinsbildendes Mineral in den Schweizer Alpen. Schweiz. mineral. petrog. Mitt. 36, 511–514 (1956).
- Mineral-Zonen der alpinen Metamorphose in den Schweizer Alpen. Intern. Geol. Congr. XXI Session, part XIII, p. 131–138, Copenhagen (1960).
—, W. Brückner u. E. Jäger: Über Vorkommen von Stilpnomelan und Alkali-Amphibol als Neubildungen der alpidischen Metamorphose in nordhelvetischen Sedimenten am Ostende des Aarmassivs (östliche Zentralschweiz). Eclogae Geol. Helv. 49, 469–480 (1956).
—, u. C. Niggli: Karten der Verbreitung einiger Mineralien der alpidischen Metamorphose in den Schweizer Alpen. Eclogae Geol. Helv. 58, 335–368 (1965).
Raumer, J. F. v.: Kristallisation und Gefügebildung im Mont-Blanc-Granit. Schweiz. mineral. petrog. Mitt. 47, 499–579 (1967).
Schaer, J. P.: Géologie de la partie septentrionale de l'éventail de Bagnes. Arch. sci. (Geneve) 12, 473–620 (1959).
Steck, A.: Petrographische und tektonische Untersuchungen am Zentralen Aaregranit und seinen altkristallinen Hüllgesteinen im westlichen Aarmassiv. Beitr. geol. Karte Schweiz, N. F. 130, 1–100 (1966).
Streckeisen, A.: Classification and nomenclature of igneous rocks. Neues Jahrb. Mineral., Abhandl. 107, 144–240 (1967).
—, u. E. Niggli: Über einige neue Vorkommen von Stilpnomelan in den Schweizer Alpen. Schweiz. mineral. petrog. Mitt. 38, 76–82 (1958).
Tröger, W. E.: Optische Bestimmung der gesteinsbildenden Minerale. Teil I u. II. Stuttgart: Schweizerbarth 1967.
Trümpy, R.: La zone de Sion-Courmayeur dans le haut Val Ferret valaisan. Eclogae Geol. Helv. 47, 315–359 (1954).
Vuagnat, M.: Sur les roches à stilpnomélane du Versoyen, Savoie. Arch. sci. (Genève) 9, 321–325 (1956).
Wenk, E.: Plagioklas als Indexmineral in den Zentralalpen. Schweiz. mineral. petrog. Mitt. 42, 139–152 (1962).
Winkler, H. G. F.: Die Genese der metamorphen Gesteine, 2. Aufl. Berlin-Heidelberg-New York: Springer 1967.
Wones, D. R.: Physical properties of synthetic biotites on the join Phlogopite-Annite. Am. Mineralogist 48, 1300–1316 (1963).
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Ich danke Herrn Prof. Dr. E. Niggli, Bern, für die Möglichkeit des ständigen Erfahrungsaustausches und die Bereitstellung der Nonius-Kamera und Herrn Prof. Dr. H. G. F. Winkler, Göttingen, für wertvolle Hinweise und kritische Stellungnahme. Endlich sei Herrn Prof. Dr. P. Bearth, Basel, herzlich gedankt für die Diskussion und die Mitteilung weiterer Fundpunkte von Stilpnomelan.
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von Raumer, J.F. Stilpnomelan als alpinmetamorphes Produkt im Mont-Blanc-Granit. Contr. Mineral. and Petrol. 21, 257–271 (1969). https://doi.org/10.1007/BF00371754
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DOI: https://doi.org/10.1007/BF00371754