Summary
Phlogopite and biotite coexist in the ultrapotassic rocks from Cabezo Negro de Zeneta (SE Spain). The compositional range of the early crystallizing phlogopite is comparable to other Spanish lamproitic occurrences, except that it is higher in Al2O3, probably reflecting the higher Al2O3 and/or different oxygen fugacity of the Zeneta magma. Magmatic Al-rich and metamorphic Al-poor biotites also occur in these rocks. The magmatic biotite probably crystallised from intermediate to silicic peraluminous magma(s), whereas the metamorphic type comes from crustal relics of metapelitic rocks entrained and dismembered into the lamproitic melt. It is concluded that the melt of Zeneta was generated through the mixing of a Mg-rich lamproitic component, quantitatively dominant, with a crustal-derived anatectic component, both already partially crystallised before mixing. The “mixed” melt attained chemical homogenization as suggested by the development of late overgrowths of similar composition on the two micas.
Zusammenfassung
Phlogopit und Biotit koexistieren in den ultrapotassischen Gesteinen von Cabézo Negro de Zeneta (Südost-Spanien). Die Zusammensetzung des frühkristallisierenden Phlogopits ist mit der anderer spanischer Lamproit-Lokalitäten vergleichbar, mit der einen Ausnahme, daß die Al2O3-Gehalte höher sind. Letzteres geht wahrscheinlich auf den höheren Al2O3-Gehalt, und/oder auf verschiedene Sauerstoff-Fugazität des Zeneta-Magmas zurück. Magmatische Al-reiche und metamorphe Al-arme Biotite kommen auch in diesen Gesteinen vor. Der magmatische Biotit kristallisierte wahrscheinlich aus intermediären bis sauren Al-reichen Magmen, während der metamorphe Typ auf krustale Relikte metapelitischer Gesteine in der lamproitischen Schmelze zurückgeht. So ergibt sich die SchluBfolgerung, daß die Schmelze von Zeneta durch Mischung eines Mg-reichen lamproitischen, und quantitativ dominierenden Magmas, mit einer anatektischen Komponente von Krusten-Herkunft entstanden ist. Beide dürften vor der Mischung bereits teilweise kristallisiert gewesen sein. Die „gemischte” Schmelze erreichte chemische Homogenisierung wie durch die Entwicklung späterer Überwachsungszonen von ähnlicher Zusammensetzung auf beiden Glimmertypen gezeigt wird.
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References
Brigatti MF, Gregnanin A (1987) Crystal chemistry of igneous rock biotites. Mineral Petrol 37: 323–341
Campbell IH, Turner JS (1986) The influence of viscosity on fountains in magma chambers. J Petrol 30: 1–30
Clarke DB (1981) The mineralogy of peraluminous granites: a review. Can Mineral 19: 3–17
Clarke DB, McKenzie CB, Muecke GK, Richardson SW (1976) Magmatic andalusite from the South Mountain Batholith, Nova Scotia. Contrib Mineral Petrol 56: 279–287
Clemens JD, Wall VJ (1981) Origin and crystallization of some peraluminous (S-type) granitic magmas. Can Mineral 19: 111–131
Contini S, Venturelli G, Toscani L, Capedri S, Barbieri M (1993) Cr-Zr-armalcolite-bearing lamproites of Cancarix, SE Spain. Min Mag 57: 203–216
De Larouzière FD, Bolze J, Bordet P, Hernandez J, Montenat C, Ott d'Estevou P (1988) The Betic segment of the lithospheric trans-Alboran shear zone during the Late Miocene. Tectonophysics 152: 41–52
Dostal J, Toscani L, Photiades A, Capedri S (1991) Geochemistry and petrogenesis of Tethyan ophiolites from Northern Argolis (Peloponnesus, Greece). Eur J Mineral 3: 105–121
Fairbairn HW, Hurley PH (1971) Evaluation of X-ray fluorescence and mass spectrometric analyses of Rb and Sr in some silicate standards. Geochim Cosmochim Acta 35: 149–156
Fernandez S, Hernandez-Pacheco A (1972) Las rocas lamproiticas de Cabezo Negro, Zeneta (Murcia). Estudios Geol (Madrid) 28: 267–276
Foley SF (1989) Experimental constraints on phlogopite chemistry in lamproites. 1. The effect of water activity and oxygen fugacity. Eur J Mineral 1: 411–426
Foley SF (1990) Experimental constaints on phlogopite chemistry in lamproites. 2. Effect of pressure-temperature variations. Eur J Mineral 2: 327–341
Foley SF, Venturelli G (1989) High-K2O rocks with high-MgO, high-SiO2 affinities. In:Crawford AJ (ed) Boninites and related rocks. Unwin Hyman, London, pp 72–88
Foley SF;Venturelli G, Green DH, Toscani L (1987) The ultrapotassic rocks: characteristic, classification and constraints for petrogenetic models. Earth Sci Rev 24: 81–134
Franzini M, Leoni L, Saitta M (1972) A simple method to evaluate the matrix effects in X-ray fluorescence analysis. X-ray Spectrometry 1: 151–154
Franzini M, Leoni L, Saitta M (1975) Revisione di una metodologia analitica per fluorescenza X basata sulla correzione completa degli effetti di matrice. Rend Soc Ital Mineral Petrol 31: 365–378
Fuster JM (1956) Las erupciones delleniticas del Terciario superior de la fosa de Vera (Provincia de Almeria). Bol R Soc Esp Hist Nat (Madrid) 54: 53–88
Huppert HE, Sparks RSJ, Turner JS (1984) Some effects on the dynamics of replenished magma chambers. J Geophys Res 89: 6857–6877
Kretz R (1983) Symbols for rock-forming minerals. Am Min 68: 277–279
Kouchi A, Sunagawa I (1985) A model for mixing basaltic and dacitic magmas as deduced from experimental data. Contrib Mineral Petrol 89: 17–23
Lopez-Ruiz J, Rodriguez-Badiola E (1980) La region volcanica Neogenica del sureste de Espana. Estudios Geol (Madrid) 36: 5–63
Mitchell RH (1985) A review of the mineralogy of lamproites. Trans Geol Soc S Africa 88: 411–437
Mitchell RH, Bergman SC (1991) Petrology of lamproites. Plenum Press, New York London, 441pp
Munksgaard NC (1984) High δ18O and possible pre-eruptional Rb-Sr isochrons in cordierite-bearing Neogene volcanica from SE Spain. Contrib Min Petrol 87: 351–358
Nelson DR, McCulloch MT, Sun SS (1986) The origin of ultrapotassic rocks as inferred from Sr, Nd and Pb isotopes. Geochim Cosmochim Acta 50: 231–254
Nixon PH, Thirlwall MF, Buckley F, Davies CJ (1984) Spanish and western Australian lamproites aspects of whole rock geochemistry. In:Kornprobst J (ed) Kimberlites and related rocks, vol 1. Elsevier, Amsterdam, pp 285–296
Peccerillo A, Poli G, Serri G (1988) Petrogenesis of orenditic and kamafugitic rocks from Central Italy. Can Mineral 26: 45–65
Sparks RSJ, Marshall LA (1986) Thermal and mechanical constraints on mixing between mafic and silicic magmas. J Volc Geoth Res 29: 99–124
Venturelli G, Contini S (1993) Bilanci chimici durante l'alterazione delle rocce. Esempio di alterazione idrotermale di rocce ultrapotassiche. Congresso AIPEA, Potenza
Venturelli G, Contini S (1995) Hydrothermal alteration of the ultrapotassic rocks of Zeneta, SE Spain. Acta Vulcanol (in press)
Venturelli G, Capedri S, Di Battistim G, Crawford JA, Kogarko LN, Celestini S (1984) The ultrapotassic rocks from southeastern Spain. Lithos 17: 37–54
Venturelli G, Salvioli Mariani E, Foley SF, Capedri S, Crawford AJ (1988) Petrogenesis and conditions of crystallization of Spanish lamprotitic rocks. Can Mineral 26: 67–79
Venturelli G, Capedri S, Barbieri M, Toscani L, Salvioli Mariani E, Zerbi M (1991a) The Jumilla lamproites revisited: a petrological oddity. Eur J Mineral 3: 123–145
Venturelli G, Toscani L, Salvioli Mariani E, Capedri S (1991b) Mixing between lamproitec and dacitic components in Miocene volcanic rocks of SE Spain. Min Mag 55: 282–285
White AJR, Chappell BW (1977) Ultrametamorphism and granitoid genesis. Tectonophysics 43: 7–22
Zeck HP (1970) An erupted migmatite from Cerro de Hoyazo, SE Spain. Contrib Mineral Petrol 26: 225–246
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Toscani, L., Contini, S. & Ferrarini, M. Lamproitic rocks from Cabezo Negro de Zeneta: Brown micas as a record of magma mixing. Mineralogy and Petrology 55, 281–292 (1995). https://doi.org/10.1007/BF01165122
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DOI: https://doi.org/10.1007/BF01165122