Abstract
A petrographical and chemical research carried out mainly for the rocks belonging to the 2nd cycle of volcanic activity of Boseti Mts., shows the predominance of the salic over the mafic and the intermediate products. The magmatic evolution, which chiefly took place in a thermodynamic environment with initial low\(P_{H_2 O} \) and\(f_{O_2 } \), has brought about subaluminiferous mugearitic types, also with trachytic affinity. Among peralkali-rhyolites, an anorthoclase fractionation can explain both their chemical variation and the production of pantelleritic liquids.
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References
Bailey, D. K., 1974,Origin of alkaline magmas as a result of anatexis: Melting in the deep crust. In:The Alkaline Rocks,Sørensen,H. Ed., p. 436–442, J. Wiley & Sons, Interscience Publishers, London.
————— andMacdonald, R., 1969,Alkali-feldspar fractionation trends and the derivation of peralkaline liquids. Am. J. Sci.,267, p. 242–248.
————— and —————, 1970,Petrochemical features of mildly peralkaline (comenditic) rhyolite glasses from continents and ocean basins. Contrib. Min. Petr.,28, p. 340–351.
————— andSchairer, J. A., 1966,The system Na 2O-Al2O3-SiO2 at 1 atmosphere and the petrogenesis of alkaline rocks. J. Petrol.,7, p. 114–170.
————— andSchairer, J. F., 1964,Feldspar-liquid equilibria in peralkaline liquids: the orthoclase effect. Am. J. Sci.,262, p. 1198–1206.
Baker, I., 1968,Intermediate oceanic volcanic rocks and the «Daly gap». Earth. Planet. Sci. Letters,4, p. 103–106.
Barberi, F., Borsi, S., Ferrara, G., Marinelli, G. andVaret, J., 1970,Relationship between tectonics and magmatology of the northern Afar (or Danakil) Depression. Phil. Trans. R. Soc. London, A267, p. 293–311.
Biasint, A., Morbidelli, L., andPiccirillo, E. M., 1974,Lineamenti geomorfologici, strutturali e vulcanologici dei Monti Boseti (Rift Etiopico Principale). Geol. Rom. (in press).
Bowen, N. L., 1945,Phase equilibria bearing on the origin and differentiation of alkaline rocks. Am. J. Sci., Daly Volume,243, p. 75–89.
Cann, J. R., 1968,Bimodal distribution of rocks from volcanic islands. Earth. Planet. Sci. Letters,4, p. 479–480.
Carmichael, I. S. E., 1962,Pantelleritic liquids and their phenocrysts. Mineral. Mag.,33, p. 86–113.
—————. andMacKenzie, W. S., 1963,Feldspar-liquid equilibria in pantellerites: an experimental study. Am. J. Sci.,261, p. 382–396.
Chayes, F., 1963,Relative abundance of intermediate members of the oceanic basalttrachyte association. J. Geophys. Res.,68, p. 1519–1534.
Cox, K. G., Gass, I. G., andMallick, D. I. J., 1970,The structural evolution and volcanic history of the Aden and Little Aden volcanoes. Q. J. Geol. Soc. London,124, p. 283.
Dakin, F., andGibson, I. L., 1971,Boseti Bariccia: a Quaternary pantelleritic volcano in the Main Ethiopian Rift. Bull. Geophys. Obs. Addis Ababa,13, p. 106–109.
Dickinson, D. R., andGibson, I. L., 1972,Feldspar fractionation and anomalous87Sr/86Sr ratios in a suite of peralkaline silicic rocks. Bull. Geol. Soc. Am.,83, p. 231–240.
Di Paola, G. M., 1972,The Ethiopian Rift Valley (between 7°00′ and 8°40′ lat. North). Bull. Volc.,36-4, p. 517–560.
Ernst, W. G., 1962,Synthesis, stability relations and occurrence of riebeckite and riebeckite-arfvedsonite solid solutions. J. Geol.,70, p. 951–980.
Ewart, A., Taylor, S. R., andCapp A. C., 1968,Geochemistry of the pantellerites of Maior Island, New Zealand. Contr. Min. Petr.,17, p. 116–140.
Gass, I. G., andMallick, D. I. J., 1968,Jebel Khariz: an Upper Miocene strato volcano of comenditic affinity, on the South Arabian Coast. Bull. Volc.,32-1, p. 33–88.
—————, —————,, andCox, K. G., 1965,The Royal Society Volcanological Expedition to the South Arabian Federation and the Red Sea. Nature, Lond.,205, p. 952.
Gibson, I. L., 1967,Preliminary account of the volcanics geology of Fantale, Shoa, Ethiopia. Bull. Geophys. Obs. Addis Ababa,10, p. 59–67.
—————, 1969,The structure and volcanic geology of an axial portion of the Main Ethiopian Rift. Tectonophysics,8, p. 561–565.
—————, 1972,The chemistry and petrogenesis of a suite of pantellerites from the Ethiopian Rift. J. Petrology,13, p. 31–44.
Goulin, P., 1970,Seismic and gravity data from Afar in relation to surrounding area. Phil. Trans. Roy. Soc. London, A-267, p. 339–358.
Harris, P. G., 1963,Comments on a paper by F. Chayes, «Relative abundance of intermediate members of the oceanic basalt-trachite association». J. Geophis. Res.,68, p. 5103–5107.
Hieke-Merlin, O., 1950,I basalti dell’Africa Orientale. Mem. Ist. Geol. Univ. Padova,17, p. 1–40.
—————, 1963,Le vulcaniti acide dell’Africa Orientale. Mem. Ist. Geol. Miner. Univ. Padova,18, p. 1–45.
Justin-Visentin, E., Nicoletti, M., Tolomeo, L., andZanettin, B., 1974,Miocene and Pliocene volcanics of the Addis Ababa-Debra Berhan area: geo-petrographic and radiometric study. Bull. Volc., (in press).
King, B. C., 1970,Vulcanicity and Rift tectonics in East Africa. In:African Magmatism and Tectonics, p. 263–283, Oliver & Boyd, Edinburgh.
Kuno, H., 1968,Differentiation of basalt magma. In:Basalts, Part 2, p. 623–688, Interscience Publishers, N. Y.
Le Maitre, R. W., 1968,Chemical variations between and within volcanic rock series: a statistical approach. J. Petrology,9, p. 220–252.
Macdonald, R., andBailey, D. K., 1972,The chemistry of the peralkaline oversaturated obsidians. U. S. Geol. Surv. Prof. Paper 440-N., Part 1.
—————, andGibson, I. L., 1969,Pantelleritic obsidians from the volcano Chabbi (Ethiopia). Contr. Min. Petr.,24, p. 239–244.
Makris, J., Menzel, H., andZimmermann, G., 1972,A preliminary interpretation of the gravity field of Afar, northeast Ethiopia. Tectonophysics,15, p. 31–41.
—————, —————, —————, andWohlemberg, J., 1969,Crustal and Upper Mantle structure of the Ethiopian Rift derived from seismic and gravity data. Zeitsch. für Geophys.,36, p. 387–391.
Mohr, P. A., 1962,The Ethiopian Rift System. Bull. Geophys. Obs. Addis Ababa,5, p. 33–62.
Mohr, P. A., 1967,The Ethiopian Rift System. Bull. Geophys. Obs. Addis Ababa,11, p. 1–65.
—————, 1974,Some new radiometric ages bearing on the evolution of the Main Ethiopian Rift, East of Addis Ababa. Smiths. Astr. Obs. Spec. Pap. 358, A, p. 1–9.
Morbidelli, L., Nicoletti, M., Petrucciani, C., andPiccirillo, E. M., 1974,Ethiopian southeastern plateau and related escarpment: K/Ar ages of the main volcanic events (Main Ethiopian Rift from 8°10′ to 9°00′ Lat. N.). Symp. on the Afar region of Ethiopia and Related problems, Bad Bergzabern, April 1974; Afar Monograph,A. Pilger Ed., Klausthal, W. Germany (in press).
—————, andPiccirillo, E. M., 1973,Tectonics and volcanism in the Main Ethiopian Rift (Preliminary report). Boll. Soc. Geol. It.,92, p. 273–286.
Muir, I. D., andTilley, C. E., 1961,Mugearites and their place in alkali igneous rock series. J. Geol.,69, p. 186–203.
Nesbitt, R. W., andHamilton, D. L., 1970,Crystallization of an alkali olivine basalt under controlled Po2conditions. Earth. Planet. Sci. Letters,3, p. 309–315.
Nicholls, J., andCarmichael, I. S. E., 1969,Peralkaline acid liquids: a petrological study. Contr. Min. Petr.,20, p. 268–294.
Noble, D. C., 1968,Systematic variation of major elements in comendite and pantellerite glass. Earth. Planet. Sci. Letters,4, p. 167–172.
—————, andPeck, L. C., 1967,Loss of halogens from crystallized and glassy silicic volcanic rocks. Geo. and Cosmoch. Acta,31, p. 215–224.
Searle, R. C., andGouin, P., 1972,A gravity survey of the central part of the Ethiopian Rift Valley. Tectonophysics,5, p. 41–52.
Sørensen, H., 1974,Glossary of alkaline and related rocks. In:The Alkaline rocks. J. Wiley & Sons, Interscience Publishers, London.
Thompson, R. N., andMacKenzie, W. S., 1967,Feldspar-liquid equilibria in peralkaline acid liquids: an experimental study. Am. J. Sci.,265, p. 714–734.
Tuttle, O. F., andBowen, N. L., 1958,Origin of granite in the light of experimental studies in the system NaAlSi3O8-KAlSi3O8-SiO2-H2O. Geol. Soc. Am. Mem.,74, p. 1–153.
Wager, L. R., andDeer, W. A., 1939,Geologic investigation in East Greenland. Part III: The petrology of the Skaergaard intrusion. Kangerdlng. Medd. Grønland,105, p. 1–352.
Zanettin, B., andJustin-Visentin, E., 1973,Serie di vulcaniti etiopiche I: La serie dell’altipiano etiopico centro-orientale. Boll. Soc. Geol. It.,91, p. 313–327.
-----, and -----, 1974,Serie di vulcaniti etiopiche II: La serie della scarpata dell’altipiano etiopico centro-orientale. Boll. Soc. Geol. It. (in press).
Zies, E. G., 1960,Chemical analyses of two pantellerites. J. Petrol.,1, p. 304–308.
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Brotzu, P., Morbidelli, L., Piccirillo, E.M. et al. Petrological features of boseti mountains, a complex volcanic system in the axial portion of the main Ethiopian rift. Bull Volcanol 38, 206–234 (1974). https://doi.org/10.1007/BF02597811
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DOI: https://doi.org/10.1007/BF02597811