首页|The Calatrava paradox to decipher the origin of carbonatites: A petrological insight on Finca La Nava, Calatrava Province (central Spain)
The Calatrava paradox to decipher the origin of carbonatites: A petrological insight on Finca La Nava, Calatrava Province (central Spain)
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The paper presents a detailed petrographic and geochemical study of the pyroclastites outcropping at La Nava maar (Calatrava Volcanic Province-CVP). Here, extrusive carbonatites mix with melilite nephelinite lapilli and bombs, crustal and mantle debris. Nephelinite and carbonatite are not characterised by a HFSE distribution typical of immiscible pairs. IREE and La/Lu ratios reflect primitive mantle carbonates and kimberlites. Igneous carbonates have 613C and 6180 isotopic ratios in the range of extrusive carbonatites and differ from local sedimentary carbonates. Carbonatites have 87Sr/86Sr and 144Nd/143Nd isotopic ratios similar to Calatrava leucitites but different to melilite nephelinite. The difference indicates that melilite nephelinites and carbonatites are co-eruptive but not comagmatic. The mingled magmatic convoy, underwent decarbonation processes, releasing Ca and Mg that reacted with parental silicate melt. Consequently, the nephelinitic melt evolved towards a melilititic composition producing Ca-rich overgrowths on mafic phenocrysts and reacted to produce high Mg#, low Cr + Ni forsterite. Mass balance calculations indicats that the nephelinite magma assimilated up to 30% of the carbonatite magma. Mixing modelling based on the Sr and Nd isotopic composition of mantle xenoliths and carbonatites indicate that La Nava carbonatite may represent the mantle metasomatic agent.
Carbonatite-nepheliniteMinglingDecarbonatationSilicate carbonate reactionMantle metasomatismCalatrava Volcanic Province
G. Rosatelli、E. Humphreys-Williams、F. Wall
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Department of Psychology, Health and Territory Sciences, G. d'Annunzio University of Chieti-Pescara, Via dei Vestmi 31, 06100 Chieti, Italy
Natural History Museum, London SW7 5BD, UK
Camborne School of Mines, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
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