Summary
A detailed mineralogical investigation of a Pian di Celle sill rock (San Venanzo, Italy), classified asmelilitolite and associated withvenanzite and carbonatitic pyroclasts, revealed new and rare mineral parageneses, considered as characteristic of thekamafugite-carbonatite association. These are formed by several accessory minerals, including minerals of the cuspidine family, götzenite, khibinskite, minerals of the rhodesite- delhayelite- macdonaldite family, pyrrhotite, bartonite and (Fe, Ni, Co) monoarsenide, mostly optically and chemically identified also in fluid inclusions. The chemical composition of these minerals and their probable crystallisation succession, deduced from textural relationships, demonstrates extensive atomic substitutions, notably for Ca, Ti, Mg and alkali, essentially reflecting high concentrations of REE, Sr, Ba, Nb and Zr, which significantly varied during crystallisation. Molecular alkali excess over Al and high Ca content in (H2O, F, CO2)-rich, Siundersaturated liquid(s) are considered the dominant factors in controlling the stability of disilicate-type minerals. Separation of the carbonatite liquid from the silicate magma, constrained by textural and fluid inclusion data, was fundamental in moving the residuum onto a strongly peralkaline trend which stabilised the sulphides under changed redox conditions.
Zusammenfassung
Eine eingehende mineralogische Untersuchung eines Lagerganges von Pian di Celle, der als Melilitolit klassifiziert and mit Venanzit and karbonatitischen Pyroklasten assoziiert ist, ergab neue and seltene Mineral-Paragenesen, die als charakteristisch für die Kamafugit-Karbonatit-Assoziation gelten. Diese bestehen aus verschiedenen akzessorischen Mineralien, darunter Perovskit, Cuspidin, Götzenit, Khibinskit, Delhayelit, Macdonaldit, Bardonit and (Fe, Ni, Co) Monoarsenit; diese werden in Flüssigkeitseinschlüssen mit optischen and chemischen Methoden identifiziert. Die chemische Zusammensetzung dieser Minerale and ihre wahrscheinliche Kristallisationsabfolge, aus texturellen Beziehungen abgeleitet, zeigt extensive Substitutionen, vor allem für Ca, Ti, Mg and Alkelien, die im wesentlichen hohe Gehalte an SEE, Sr, Ba, Mb and Zr andeuten, die während der Kristallisation beträchtlichen Schwankungen unterlagen. Molekularer Alkali überschuß über Al in (H2O, F, CO2)-reichen Si-untersättigten Fluiden werden als wichtigste Faktoren für die Stabilität von Mineralen des DisilikatTyps gesehen. Trennung des Karbonatites vom Silikat, die durch texturelle und Flüssigkeitseinschluß-Daten genau fixiert werden konnte, war wichtig für die Verschiebung des Residuums auf einen deutlich peralkalinen Trend, welcher die Sulfide unter veränderten Redox-Bedingungen stabilisieren konnte.
Similar content being viewed by others
References
Albrecht A (1981) Mineralogische Untersuchung des Phonoliths vom Fohberg, Kaiserstuhl. Thesis, University of Freiburg, 137 pp (unpublished)
Blass G (1991) Götzenite als Neufund in einem sanidinitischen Auswürfling des Laacher See Vulkans. Mineral Welt 2: 76–78
Cannillo E, Rossi G, Ungaretti L (1970) The crystal structure of delhayelite. Rend Soc Ital Mineral Petrol 26: 63–75
Chao GY (1972) The crystal structure of carletonite, KNa4Ca4 Si8O18 s (CO3)4(F OH) H2O, a double-sheet silicate. Am Mineral 57: 765–778
Chiragov MI, Mamedov HS (1974) The crystal structure of delhayelite. Mineral Sbor Lvov Univ 28 (l): 3–7
Cundari A, Ferguson AK (1991) Petrogenetic relationships between melilitite and lamproite in the Roman Comagmatic Region: the lavas of S. Venanzo and Cupaello. Contrib Mineral Petrol 107: 343–357
Cundari A, Ferguson AK (1994) Appraisal of the new occurrence of götzenitess, khibinskite and apophyllite in kalsilite-bearing lavas from San Venanzo and Cupaello (Umbria), Italy. Lithos 31: 155–161
Czamanske GK, Erd RC, Leonard BF, Clark JN (1981) Bartonite, a new potassium iron sulfide mineral. Am Mineral 66: 369–375
Czygan W (1973) Götzenite ein komplexes Ti-Zr-Silikat aus dem Kaiserstuhl. Ber Naturf Ges Freiburg 63: 5–12
Dawson JB, Smith JV, Steele IM (1992) 1966 ash eruption of the carbonatite volcano Oldoinyo Lengai: mineralogy of lapilli and mixing of silicate and carbonate magmas. Mineral Mag 56: 1–16
Dawson JB, Smith JV, Steele IM (1995) Petrology and mineral chemistry of plutonic igneous xenoliths from the carbonatite volcano, Oldoinyo Lengai, Tanzania. J Petrol 36: 797–826
Dorfman MD, Belova Ye N Neronova NN (1961) Delhayelite from Khibini. Trudy Mineral Muz Akad Nauk USSR 12: 191–195
Evans H T-Ju, Clark JN (1981) The crystal structure of bartonite, a potassium iron sulfide, and its relationship to pentlandite and djerfisherite. Am Mineral 66: 376–384
Gallo F, Giammetti F, Venturelli G, Vernia L (1984) The kamafugitic rocks of San Venanzo and Cupaello, Central Italy. N Jahrb Mineral Monatsh 5: 198–210
Hesse K.-F, Liebau F, Merlino S (1992) Crystal structure of rhodesite, HK1-xNax+2y-Ca2_y{ lB,3,22 DC[Si8O19] (6-z)H2O, from three localities and its relations to other silicates with dreier double layers}. Z Kristallogr 199: 25–48
Kapustin Yu L (1980a) Götzenite and wöhlerite from alkaline massifs of Sangilen (Tuva). Zap Vses Mineral Obshch 87: 590–597
Kapustin Yu L (1980b) Mineralogy of carbonatites. Amerind, New Delhi, 256 pp
Kapustin Yu L (1982) Minerals of the rincolite group from nepheline-syenite massifs of Tuva. Tr Mineral Muz Akad Nauk USSR 30: 112–117
Keller J, William CT, Koberski U (1995) Niocalite and wöhlerite from the alkaline and carbonatite rocks at Kaiserstuhl, Germany. Mineral Mag 59: 561–565
Khomyakov AP, Voronkov AA, Lebedeva SI, Bykov VP, Yurkina KV (1974) Khibinskite, K2ZrSi2O7, a new mineral. Zap Vses Mineral Obshch 103: 110–116
Konev AA, Samoilov VS (1974) Contact metamorphism and metasomatism around the Tazheran alkaline intrusion. Nauka, Novosibirsk, 246 pp
Merlino S, Orlandi P, Vezzalini G (1979) Un nuovo minerale strutturalmente correlato alla macdonaldite. Rend Soc Mineral Petrol 35: 847
Mitchell RH (1984) Mineralogy and origin of carbonate-rich segregation in a composite kimberlite sill. N Jahrbuch Miner Abh 150: 185–197
Mitchell RH (1995) Kimberlites, orangeites, and related rocks. Plenum, New York, pp 410
Mitchell RH, Bergman SC (1991) Petrology of lamproites. Plenum, New York, 447 pp
Oen IS, Burke EAJ, Kieft C Westerhof AB (1972) Westerveldite, (Fe,Ni,Co)As, a new mineral from La Gallega, Spain. Am Mineral 57: 354–363
Peacor DR, Dunn PJ, Simmons WB, Tilmanns E, Reinhard XF (1984) Willhendersonite, a new zeolite isostructural with chabazite. Am Mineral 69: 186–189
Peccerillo A (1994) Mafic ultrapotassic magmas in central Italy: geochemical and petrological evidence against primary composition. Mineral Petrogr Acta 37: 229–245
Sahama Th G (1960) Identity of calcium rinkite and götzenite. Am Mineral 45: 221–224
Sahama Th G, Hytönen K (1959) Delhayelite, a new silicate from Belgian Congo. Mineral Mag 32: 6–9
Sharygin VV, Stoppa F, Kolesov BA (1996a) Cuspidine from melilitolites of San Venanzo, Italy. Dokl Russian Akad Sci 348: 800–804
Sharygin VV, Stoppa F, Kolesov BA (1996b) Zr-Ti-disilicates from the Pian di Celle volcano, Umbria, Italy. E J M 8: 1199–1212
Stoppa F (1995) The San Venanzo maar and tuff-ring, Umbria, Italy: eruptive behaviour of a carbonatite-melilitite volcano. Bull Volcano 57: 563–567
Stoppa F, Cundari A (1995) A new Italian carbonatitic occurrence at Cupaello (Rieti) and its genetic significance. Contrib Mineral Petrol 122: 275–288.
Stoppa F, Woolley AR (1997) The Italian carbonatites: field occurrence, petrology and regional significance. Mineral Petrol 59: 43–67
Stoppa F, Cundari A (1997) Evidence for multiple crystallization in the kamafugitecarbonatite association at S.Venanzo (Umbria, Italy). Mineral Mag (submitted)
Val'ter AA, Yeremenko GK, Stremovsky AM (1963) Calcium rinkite from alkaline rock of the Ukraine. Dokl Akad Sci USSR 50: 639–641
Author information
Authors and Affiliations
Additional information
With 2 Figures
Rights and permissions
About this article
Cite this article
Stoppa, F., Sharygin, V.V. & Cundari, A. New mineral data from the kamafugitecarbonatite association: The melilitolite from Pian di Celle, Italy. Mineralogy and Petrology 61, 27–45 (1997). https://doi.org/10.1007/BF01172476
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01172476