Objectif Carbonatites are rare igneous rocks consisting predominantly of mantle-derived carbonate. They have extreme trace element compositions, with characteristic enrichment in REE, Nb, Ta and Zr, and occasionally also noble metals and PGE. Some carbonatites are major economic sources of these elements. However, despite the importance of carbonatites to mantle processes, and their economic value, fundamental questions about the mechanisms by which they are produced, their relationships to associated silicate rocks, and the processes of mineralisation remain to be answered.This project proposes a comprehensive and carefully coordinated approach to understanding the diverse processes of mineralisation in carbonatites, particularly by study of mineral chemistry, whole rock geochemistry, isotope geochemistry and fluid inclusions. It combines NIS and INTAS teams with expertise in various aspects of the mineralogy of carbonatites and links these with INTAS teams experienced in isotope systematics and whole rock geochemistry. It aims for a new classification scheme for carbonatite mineralisation, of use to researchers and exploration geologists, and also aims to apply the results to the fundamental problems of carbonatite petrogenesis.The specific objectives are(a) To determine the mineral chemistry and paragenesis of primary Nb,Zr, Ta and REE mineralisation associated with carbonatites and related rocks;(b) to characterise fully the secondary mineralisation, which has yielded many new minerals, formed during sub-solidus alteration of carbonatites;(c) to acquire major and trace element chemical data of the host rocks, in order to constrain their genetic relationships;(d) to characterize the sulphides, PGE and noble metal phases;(e) to measure S and Pb isotopic compositions of the sulphides in order to establish the conditions of formation and source of the ore metals;(f) to use stable and radiogenic isotope signatures of carbonatite mineral fractions, chosen from the mineral chemical and geochemical studies, so as to determine their origin and crust-mantle relationships and place the carbonatites within a detailed time frame, and;(g) to undertake a fluid inclusion study of rock forming minerals in selected examples to constrain better the conditions of various stages of mineralisation.The project concentrates on carbonatites of the Baltic Shield, Russia because they provide examples of all of the main varieties of mineralisation, including PGE minerals which have recently been described for the first time in carbonatites. Good material is available from drill core and working mines, and all project partners will carry out fieldwork together. A second fieldtrip to the Ural Mountains, and collections at The Natural History Museum, London, and in Russia, will enable comparison with other carbonatites to ensure that the results are generally applicable. State of the art electron microprobe, ICPMS, CL, whole rock geochemistry, isotopic and fluid inclusion analysis techniques and procedures are available at the INTAS institutions and will be used by the NIS partners, including 7 young scientists, during their visits. Preliminary analytical work will be done in Russia.The project will result in a number of publications in international scientific journals, arising from each of the specific objectives, as well the overall aims, and is the most comprehensive study of carbonatite mineralisation thus far attempted. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Thème(s) 5 - Earth Sciences, Environment, Energy INTAS - INTAS Appel à propositions Data not available Régime de financement Data not available Coordinateur Natural History Museum Contribution de l’UE Aucune donnée Adresse Cromwell Road SW7 5BD London Royaume-Uni Voir sur la carte Coût total Aucune donnée Participants (5) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire Ecole Des Mines France Contribution de l’UE Aucune donnée Adresse Cours Fauriel 158 42100 Saint-Etienne Voir sur la carte Coût total Aucune donnée Institut fur Mineralogie und Lagerstattenlehre Allemagne Contribution de l’UE Aucune donnée Adresse Wuellnerstrasse 2 52056 Aachen Voir sur la carte Coût total Aucune donnée Mechanobr Research Institute Russie Contribution de l’UE Aucune donnée Adresse 21 Line, 8a 199026 St. Petersburg Voir sur la carte Coût total Aucune donnée Russian Academy of Sciences Russie Contribution de l’UE Aucune donnée Adresse Fersman str., 14 184200 Apatity, Murmansk region Voir sur la carte Coût total Aucune donnée St. Petersburg State University Russie Contribution de l’UE Aucune donnée Adresse University Embankment, 7/9 199034 St. Petersburg Voir sur la carte Coût total Aucune donnée