Extension-related origin of magmas from a garnet-bearing source in the Los Tuxtlas volcanic field, Mexico

摘要: The Los Tuxtlas volcanic field (LTVF) of late Miocene to Recent age is a key area understand the consequences current subduction Cocos plate beneath North American plate, as well competing effects ongoing extension along Gulf Mexico coast. Geochemical and radiogenic (Sr, Nd, Pb) isotope data are used constrain origin these 7 Ma magmas in this area. basanitic alkaline basaltic rocks show highly steep light rare-earth element-enriched patterns implying residual garnet their mantle source, whereas evolved sub-alkaline have less element consistent with contribution from continental crust. LTVF compared those rifts, extension-related areas, break-up regions, island arcs, including Central arc related same oceanic (Cocos plate), two nearby Mexican provinces [the Eastern Alkaline Province (EAP) eastern part Volcanic Belt (E-MVB)]. These for primitive similar areas provinces, but different northern Arc (CAVA). an unusual Th U enrichment respect Ba Rb, which also renders distinct negative Nb anomaly (with K) them. La) that numerous rift, all arcs around world, indicating magma genesis processes rifts. “Sr-shift”, shown be typical feature most, if not all, CAVA, present rocks. Numerous discrimination diagrams, new discriminant function suggest rift setting LTVF. An essentially is, therefore, inferred study. Furthermore, major trace modelling incompatible garnet-bearing source seems plausible. likely reside lithosphere rather than asthenosphere although asthenospheric cannot completely ruled out. might lower crustal component. Finally, it appears shows more affinity EAP (MVB), should probably considered EAP.