Publication: Paleogeografía geoquímica de las series metasedimentarias del Macizo Ibérico
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Publication Date
2016
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Sociedad Geológica de España.
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Abstract
Las características geoquímicas e isotópicas de las series turbidíticas del Macizo Ibérico reflejan distintos escenarios tectónicos en la periferia de Gondwana. Estos cambios se observan en el registro sedimentario de la transición Ediacarense-Cámbrico, que tuvo lugar en el contexto general de un margen continental activo. TDM jóvenes y ɛNd menos negativos resultan característicos de cuencas sedimentarias más exteriores, con una importante contribución de material juvenil derivado del sector más activo del arco volcánico (metagrauvacas culminantes de las Unidades Superiores del Complejo de Órdenes). Las cuencas sedimentarias más próximas al continente se caracterizan por mayores aportes desde dominios alejados del arco activo que dan lugar a valores de TDM más antiguos y ɛNd muy negativos (metagrauvacas de las Unidades Basales del Complejo de Malpica-Tui). Una evolución desde contextos activos hasta otros más propios de márgenes pasivos se detecta con claridad en la transición Ediacarense-Cámbrico, y debe relacionarse con una disminución de la actividad del arco volcánico y la transición hacia un margen pasivo. El diagrama de fSm/Nd vs ɛNd confirma esta variación de los escenarios tectónicos asociados al margen de Gondwana, perfectamente registrados en los metasedimentos de diferentes sectores y unidades del Macizo Ibérico.
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 ɛNd 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 ɛNd 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 ɛNd 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.
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 ɛNd 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 ɛNd 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 ɛNd 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.