Paleogeografía geoquímica de las series metasedimentarias del Macizo Ibérico

Résumé

Geochemical and isotopic features of the turbiditic series from the Iberian Massif reflect different tectonic scenarios in the periphery of Gondwana. These changes can be observed in the sedimentary record of the Ediacaran-Cambrian transition, which took place in the realm of an active continental margin. Young TDM and less negative Nd values are characteristic of more external sedimentary basins, with an important input of juvenile material from the most active sector of the volcanic arc (topmost metagreywackes of the Upper Units - Órdenes Complex). Sedimentary basins closer to the continent are distinguished by major contributions from domains away from the active arc, leading to older TDM and very negative Nd values (metagreywackes of the Basal Units - Malpica-Tui Complex). An evolution from active settings to others more related to passive margins is clearly identified in the Ediacaran-Cambrian transition, and it can be connected with a decrease of the volcanic arc activity and the transition towards a passive margin. The fSm/Nd vs Nd diagram confirms the change in the tectonic scenarios linked to the Gondwana margin, perfectly recorded in metasediments from different sectors and units of the Iberian Massif.