Geochronology, Geochemistry and Geodynamics of the Cabo de Gata volcanic zone, Southeastern Spain

Massimo Mattei (1), Nancy R. Riggs (2), Guido Giordano (1), Luisa Guarnieri (3), Francesca Cifelli (1), Carles C. Soriano (4), Brian Jicha (5), Alia Jasim (6), Sara Marchionni (3), Luigi Franciosi (7), Simone Tommasini (3), Massimiliano Porreca (8) & Sandro Conticelli (3)
(1) Dipartimento di Scienze, Università degli Studi Roma Tre, Largo San Leonardo Murialdo, 1 - I-00146 Roma, Italy. Corresponding author e-mail: massimo.mattei@uniroma3.it(2) School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Flagstaff AZ 86011 (USA).(3) Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via Giorgio La Pira, 4 - I-50121 Firenze, Italy.(4) Institut de Ciències de la Terra Jaume Almera, CSIC (Spain).C/ Lluís Solé Sabarís s/n, Barcelona E-08028, Spain.(5) Department of Geosciences, University of Wisconsin-Madison, Madison, WI 53706, United States of America.(6) School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, United Kingdom.(7) Dipartimento di Scienze della Terra, dell'ambiente e delle Risorse, Università degli Studi di Napoli 'Federico II', Via Mezzocannone, 8 - I-80100 Napoli, Italy.(8) Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sez. Roma 2, Via dell'Arcivescovado, 8 - I-67100 L'Aquila, Italy.

New 40Ar/39Ar ages and major and trace element geochemistry of the middle-late Miocene Cabo de Gata volcanic complex, southeast Spain, indicate that the volcanic activity of the Cabo de Gata volcanic zone developed over a short period through several pulses of geochemically and isotopically different parental magmas. The oldest volcanic rocks exposed in the Cabo de Gata volcanic zone are the shoshonite and high-K calc-alkaline rocks of Bujo group, which cry - stallised from a parental magma transitional from calc-alkaline to alkaline potassic generated through large degrees of partial melting, and then affected by a minor contribution from metasomatised veins and a larger one from the surrounding mantle wedge, in comparison to ultrapotassic melts. Subsequent partial melting of the mantle source produced typical calc-alkaline parental magmas belonging to the Rodalquilar and Agua Amarga groups. Sr-Nd-Pb isotope and incompatible trace element distributions of Cabo de Gata rocks are in agreement with a mantle-wedge source affected by a two-fold metasomatism. The data suggested that mild potassic to sub-alkaline subduction-related parental magmas (i.e., high-K calc-alkaline and calc-alkaline) were generated in the Cabo de Gata sector within a mantle wedge metasomatised by a fluid-dominated agent. In contrast, the enrichment in K2O of shoshonitic to ultrapotassic magmas was achieved through recycling of subducted sediments through melts that enriched the mantle wedge in K and related elements. Such a scenario can be easily reconciled with a geodynamic setting at the edge of a destructive plate margin with the subducted slab responsible for the recycling of sediments within the mantle wedge.

Western Mediterranean, Neogene, Volcanism, Geochronology, Geochemistry.