Arc sections correlation along the Gondwana margin: Dynamic shifts tracked by detrital zircon

Abstract

Sections of the Gondwana margin recording the evolution of Ediacaran and Cambrian arc systems are preserved along the Variscan Orogen. The sedimentary sequences deposited in it and associated with its activity can provide significant keys to understanding the dynamics of the margin. In this sense, sections of the Gondwana margin that include arc magmatism between c. 602 and 500 Ma are well preserved in the SW and NW Iberian Massif. However, the activity in these areas was not synchronous, and the potential connection between both sectors along the Gondwana margin and its meaning is still poorly understood. U-Pb geochronology performed on detrital zircon grains of the Ediacaran Serie Negra Group (SW Iberia) show a maximum depositional age between 619 and 559 Ma for its Montemolín and Tentudía formations, respectively. The obtained Hf data from the same zircon grains supports significant crustal input. Meanwhile, U-Pb performed on detrital zircon grains of the Cambrian Betanzos Unit (NW Iberia) exhibit essentially mantle-derived Hf signature at 544–537 Ma (Maximum Depositional Age). Based on these data, a dynamic model for the Gondwana margin at c. 500 Ma has been proposed, comparable to the current processes operating on the Pacific edge of the North American plate. This model highlights a spatial and temporal connection between the Gondwana margin’s peripheral sections (SW and NW Iberia).