The lamprophyres of Afyon stratovolcano,western Anatolia,Turkey: description and genesis     

Erkan Aydar  Hasan Bayhan  Alain Gourgaud 《Comptes Rendus Geoscience》2003,335(3):279-288

The Afyon stratovolcano exhibits lamprophyric rocks, emplaced as hydrovolcanic products, aphanitic lava flows and dyke intrusions, during the final stages of volcanic activity. Most of the Afyon volcanics belong to the silica-saturated alkaline suite, as potassic trachyandesites and trachytes, while the products of the latest activity are lamproitic lamprophyres (jumillite, orendite, verite, fitztroyite) and alkaline lamprophyres (campto-sannaite, sannaite, hyalo-monchiquite, analcime–monchiquite). Afyon lamprophyres exhibit LILE and Zr enrichments, related to mantle metasomatism.  相似文献   

Volcanisme de l'ı̂le aux Pingouins,archipel Crozet,témoin de l'hétérogénéité du manteau fertile au sud de l'océan IndienPenguins Island,Crozet archipelago,volcanic evidence for a heterogeneous mantle in the southern Indian Ocean     

André Giret  Sylvie Tourpin  Sabine Marc  Olivier Verdier  Jean-Yves Cottin 《Comptes Rendus Geoscience》2002,334(7):481-488

Despite its small area (5.6 km²), the Penguins Island brings magmatic information concerning mantle geochemical heterogeneities in southwestern Indian Ocean. The volcanism that built the island was firstly associated with marine deposits, and secondly with aerial, giving then abundant volcanic breccias and lava flows. The rocks are weakly differentiated and result of magmatic fractionation from picritic to tephritic types. KAr ages are near 1.1 Ma. The magmatic source may be related to a HIMU reservoir or to EMI ± EMII ones, depending on the geochemical evidences that are taken into account. However, comparisons with the Marion Island, on the same oceanic plateau and far to the west, as well as with Kerguelen Islands, far to the east, suggest a very heterogeneous mantle source. To cite this article: A. Giret et al., C. R. Geoscience 334 (2002) 481–488.  相似文献   

Thermal effects of massive CO2 emissions associated with subduction volcanism     

Roelof D. Schuiling 《Comptes Rendus Geoscience》2004,336(12):1053-1059

Large volumes of CO₂ are emitted during volcanic activity at convergent plate boundaries, not only from volcanic centres. Their C isotopic signature indicates that this CO₂ is mainly derived from the decarbonation of subducted limestones or carbonated metabasalts, not as often admitted from magma degassing. On the example of Milos (Aegean Sea) it is argued that these fluids originate from intermediate depth in the mantle and carry sufficient heat to account for the generation of subduction-related magmas, as well as for the geothermal manifestations at the surface. The heat that is required for the decarbonation reactions is drawn by conduction from a wide zone surrounding the subducting slab and then rapidly transported upward by convection of the mixed CO₂–H₂O fluids that originate from the sediments in the slab. The transport takes place in a focused way through ‘chimneys’ in the upper mantle, where magmas are generated by the introduced heat and water. In the crust, the hot fluids cause thermal-dome-type metamorphism. In volcanic areas, magmas are commonly held responsible for the major part of heat transfer from the mantle to the surface. Here it is argued that most of the heat transfer is by hot gases. To cite this article: R.D. Schuiling, C. R. Geoscience 336 (2004).  相似文献   

Stratigraphie et paléoenvironnement des dép?ts volcano-détritiques à dinosauriens du Jurassique inférieur de Toundoute (Province de Ouarzazate, Haut-Atlas – Maroc)     

Christian Montenat  Michel Monbaron  Ronan Allain  Najat Aquesbi  Jean Dejax  Jean Hernandez  Dale Russell et Philippe Taquet 《Eclogae Geologicae Helvetiae》2005,98(2):261-270

Resume. Le gisement de dinosauriens du Jurassique inférieur de Toundoute, à sauropode primitif (Tazoudasaurus naimi), est examiné sous ses aspects stratigraphiques, sédimentologiques et paléoenvironnementaux. Les couches continentales détritiques à dinosaures, succédant en continuité à des niveaux marins carbonatés trés peu épais du Lias inférieur (Hettangien-Sinémurien probables), sont rapportées au Lias moyen-supérieur. Les dép?ts continentaux contiennent une part importante de produits volcanoclastiques différents des basaltes triasiques. Les centres d’émission, non connus, étaient sans doute proches. La sédimentation continentale, de type chenaux fluviatiles – plaine d’inondation, refléte un climat chaud à périodes alternativement humides et séches, ces derniéres étant fortement marquées. Les deux niveaux à ossements correspondent à des coulées boueuses ayant charrié des ossements et portions de carcasses (os en connexion) sur de courtes distances. Ce mode de transport a préservé les ossements de l’érosion et favorisé un enfouissement rapide permettant leur conservation. Manuscrit re?u le 16 juillet 2004 Révision acceptée le 17 mars 2005  相似文献   

Le volcanisme Pliocène inférieur de Maguelone (région de Montpellier,Hérault)     

Paul Ambert 《Comptes Rendus Geoscience》2003,335(15):1051-1058

The volcanism of the Maguelone Island indicates a surtseyan volcanism. It contains petrographical and mineralogical characteristics of coastal phreatic volcanism. Its discharges are interbedded in the marine or lagoon Pliocene context. Rodents fauna and high-stand in the curve of Vail indicate a period between 4.2 and 3.8 Myr. The geographical pattern of its markers suggests a new reading and dating of the Pliocene sequences, particularly known from the scarcity of chronological indications. To cite this article: P. Ambert, C. R. Geoscience 335 (2003).  相似文献