Geochemical and isotopic (Sr, Nd) constraints on the origin of the calc-alkaline syn-orogenic association from the Anatectic Complex of Toledo (Hercynian Iberian Belt)

Résumé

New chemical and isotopic (Sr, Nd ) data obtained far the syn-orogenic (pre-metamorphic clímax) shoshonitic affinity gabbros (Toledo type) and Argés calc-alkaline affinity granitoids indicate the presence of a marked isotopic heterogeneity. This contrasts with the other gabbroic series of the area (La Bastida gabbros) which in spite of the fact that they are spatially and temporal/y re/ated to the Toledo gabbros and the Argés granites, are isotopically homogeneous and have a more mantle-like signature. The shoshonitic affinity of the Toledo gabbros cou/d be produced by local-sea/e interaction with hydrothermal (magmatic?) fluids related to the Argés granites; this may a/so explain the presence of the isotopic heterogeneities in the Toledo gabbros and a/so in the intermediate members of the Argés series.