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Carbonatite-melilitite association in the Italian collision zone and the Ugandan rifted craton: significant common factors

Published online by Cambridge University Press:  05 July 2018

D. K. Bailey  and
J. D. Collier
D. K. Bailey*
Affiliation:
Department of Earth Sciences, University of Bristol, Queens Road, Bristol BS8 1RJ, UK
J. D. Collier
Affiliation:
Department of Earth Sciences, University of Bristol, Queens Road, Bristol BS8 1RJ, UK
*
*E-mail: ken.bailey@bris.ac.uk
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Abstract

Italian carbonatites form part of a suite with melilitites, normally an association characteristic of continental interiors; the perfect analogue of the Italian suite being the kamafugites (from the type area in SW Uganda, where the western branch of the East African Rift Zone cuts across the craton). The latter are commonly attributed to plume generation, whereas the Italian carbonatites, strung along the Appennine front, are usually linked to subduction. Evidently these two mechanisms are not essential, since neither can apply in both provinces. This conclusion is re-inforced by the related magmatism registered in both provinces in the Cretaceous. Phlogopite is ubiquitous in the mantle debris, and compositions from the two provinces overlap. Xenolithic phlogopites are distinct from cognate micas in the lavas, and from the carrier melt compositions, with similar distribution patterns in both suites. Kamafugitic magmas must be products of exceptional conditions, and added to the many near-identical magmatic features, the Italian and Ugandan volcanoes have sampled similar mantle conditions. Although the large scale geodynamic regimes are in total contrast, as are the deep mantle tomographic structures, the crucial common factor at the igneous province level is extensional tectonics. Extension, promoting release of volatiles (esp. CO2), is the vital trigger for this small volume, primary magmatism.

Keywords

carbonatitemelilititemantle phlogopitelithosphere extensiontomographykimberlite
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 4 , August 2000 , pp. 675 - 682
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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References

Bailey, D.K. (1980) Volatile flux, geotherms, and the generation of the kimberlite-carbonatite-alkaline magma spectrum. Mineral. Mag., 43, 695–9.CrossRefGoogle Scholar
Bailey, D.K. (1985) Fluids, melts, flowage and styles of eruption in alkaline ultramafic magmatism. Trans. Geol. Soc. South Africa, 88, 449–57.Google Scholar
Bailey, D.K. (1993 a) Carbonate magmas. J. Geol. Soc., 150, 637–51.CrossRefGoogle Scholar
Bailey, D.K. (1993 b) Petrogenetic implications of the timing of alkaline, carbonatite, and kimberlite activity in Africa. S. Afr. J. Geol., 96, 67–74.Google Scholar
Barbieri, M., Castorina, F., Cundari, A. and Stoppa, F. (1996) Late-Pleistocene melilitite-carbonatite volcanism in the Umbria-Latium district (Italy). 30th Int. Geol. Congr., Beijing. Abstract Vol.2, 388.Google Scholar
Barker, D.S. and Nixon, P.H., (1989) High-Ca, low-alkali carbonatite volcanism at Fort Portal, Uganda. Contrib. Mineral. Petrol., 103, 166–77.CrossRefGoogle Scholar
Burke, K. (1996) The African plate. S. Afr. J. Geol., 99, 339–410.Google Scholar
Castorina, F., Stoppa, F., Cundari, A., and Barbieri, M. (2000) An enriched mantle source for Italy's melilitite-carbonatite association as inferred by its Nd-Sr isotope signature. Mineral. Mag., 64, 625–39.CrossRefGoogle Scholar
Conticelli, S. and Peccarillo, A. (1990) Petrological significance of high-pressure ultramafic xenoliths from ultrapotassic rocks of central Italy. Lithos, 24, 305–22.CrossRefGoogle Scholar
Cundari, A. (1979) Petrogenesis of leucite-bearing lavas in the Roman volcanic region, Italy. Contrib. Mineral. Petrol., 70, 9–21.CrossRefGoogle Scholar
De Mets, C., Gordon, R.G., Argus, D.F. and Stein, S. (1990) Current plate motions. Geophys. J. Int., 101, 425–78.CrossRefGoogle Scholar
Engdahl, E. R., van derHilst, R., and Buland, R. (1998) Global teleseismic earthquake relocation with improved travel times and procedures for depth determinations. Bull. Seismol. Soc. Amer., 88, 722–43.Google Scholar
Exley, R.A., Sills, J.D. and Smith, J.V. (1982) Geochemistry of micas from the Finero spinellherzolite, Italian Alps. Contrib. Mineral. Petrol., 81, 59–63.CrossRefGoogle Scholar
George, R., Rogers, N. and Kelly, S. (1998) Earliest magmatism in Ethiopia: Evidence for two mantle plumes in one flood basalt province. Geology, 26, 923–36.2.3.CO;2>CrossRefGoogle Scholar
Hawkesworth, C.J., Fraser, K.J. and Rogers, N.W. (1985) Kimberlites and lamproites: extreme products of mantle enrichment processes. Trans. Geol. Soc. South Africa, 88, 439–47.Google Scholar
Kennett, B.L.N., Engdahl, E.R. and Buland, R. (1995) Constraints on seismic velocities in the Earth from traveltimes. Geophys. J. Int., 122, 108–24.CrossRefGoogle Scholar
Lavecchia, G. and Stoppa, F. (1990) The Tyrrhenian zone: a case of lithosphere extensional tectonic control of intra-continental magmatism. Earth Planet. Sci. Lett., 99, 336–50.CrossRefGoogle Scholar
Lavecchia, G. and Stoppa, F. (1996) The tectonic significance of Italian magmatism: an alternative view to the popular interpretation. Terra Nova, 8, 435–46.CrossRefGoogle Scholar
Lloyd, F.E. and Bailey, D.K. (1975) Light element metasomatism of the continental mantle: the evidence and the consequences. Pp. 389–416 in: Physics and Chemistry of the Earth, Vol. 9 (Ahrens, L.H., Dawson, J.B., Duncan, A.R. and Erlank, A.J., editors). Pergamon Press, Oxford and New York.CrossRefGoogle Scholar
Lloyd, F.E., Huntingdon, A.T., Davies, G.R. and Nixon, P.H. (1991) Phanerozoic volcanism of SW Uganda: a case for regional K and LILE enrichment beneath a domed rifted continental plate. Pp 23–72 in: Magmatism in Extensional Structural Settings (Kampunzu, A.B. and Lubala, R.T., editors ). Springer-Verlag, Berlin.CrossRefGoogle Scholar
Lloyd, F.E., Woolley, A.R., Stoppa, F. and Eby, N. (1999) Rift Valley magmatism – is there evidence for laterally variable alkali clinopyroxenite mantle? Geolines, 9, 76–83.Google Scholar
Mittempergher, M. (1965) Volcanism and petrogenesis in the S. Venanzo area (Italy). Bull. Volcanol., 28, 1–12.CrossRefGoogle Scholar
Nixon, P.H. and Davies, G.R. (1987) Mantle xenolith perspectives. Pp. 741–56 in: Mantle Xenoliths (Nixon, P.H., editor). John Wiley & Sons, New York.Google Scholar
Sahama, Th.G. (1974) Potassium-rich alkaline rocks. Pp. 96–109 in: The Alkaline Rocks (Sørensen, H., editor), Wiley, London.Google Scholar
Stoppa, F. (1988) L'Euremite di Colli Fabbri (Spoleto): un litotipo ad affinita carbonatitica in Italia. Boll. Soc. Geol. Ital., 107, 239–48.Google Scholar
Stoppa, F. and Cundari, A. (1995) A new Italian carbonatite occurrence at Cupaello (Rieti) and its genetic significance. Contrib. Mineral. Petrol., 122, 275–88.CrossRefGoogle Scholar
Stoppa, F. and Lupini, L. (1993) Mineralogy and petrology of the Polino monticellite-calciocarbonatite (Central Italy). Mineral. Petrol., 49, 213–31.CrossRefGoogle Scholar
van der Hilst, R.D., Widiyantoro, S. and Engdahl, E.R. (1997) Evidence for deep mantle circulation from global tomography. Nature, 386, 578–84.CrossRefGoogle Scholar
Vollmer, R. (1989) On the origin of the Italian potassic magmas. Chem. Geol., 74, 229–39.CrossRefGoogle Scholar