Ediacaran to Cambrian tectonomagmatic events in the Southern Dom Feliciano Belt, Uruguay: From a plate margin to an intraplate setting and the assembly of SW Gondwana

We present new zircon U-Pb geochronological and Hf-O isotope data as well as whole rock geochemical and Sr-Nd-Pb isotope geochemical data of Ediacaran magmatic rocks from the Cuchilla Dionisio (CDT), Nico Perez (NPT) and Tandilia (TT) terranes in Uruguay. Three different rock suites are recognized in the NPT. The Group 1 rocks are high Ba-Sr granodiorite, monzonite and syenite that formed from a subduction-related mafic source between 610 +/- 3 and 593 +/- 5 Ma, most likely in an extensional setting. The Group 2 plutons, syenite, formed from a mafic source between 573 +/- 8 and 563 +/- 7 Ma and were emplaced in an intraplate setting at the extended eastern Rio de la Plata cratonic margin. The Group 3 rocks as well as the La Paz Granite in the TT are intraplate granites that formed by crustal melting and/or by the incorporation of crustal melts at c. 557 +/- 4 Ma. The Early Ediacaran Valdivia Pluton in the CDT is a subduction-related granite that formed from a mafic melt at an active continental margin. The 571 +/- 3 and 566 +/- 6 Ma subduction-related CDT Jose Ignacio and Florencia granites were emplaced at or close to an active margin. They, like the Valdivia Granite provide only little evidence of incorporating crustal rocks and/or melts. The coeval Maldonado and Rocha granites in the CDT are subduction-related but were emplaced in a distal position to the arc. The Early Cambrian Santa Teresa Granite is a collision-related pluton that formed during the final assembly of SW Gondwana at 532 +/- 6 Ma. It is evident that the Ediacaran to Early Cambrian igneous rocks in the southern Dom Feliciano Belt in Uruguay originated from dissimilar source regions and were emplaced in different tectonic settings at different times. The data indicate a transition from Early Ediacaran subduction-related, arc-type magmatism to intraplate and, finally to Late Ediacaran/Early Cambrian collision-related igneous activity in the Uruguayan sector of the southern Dom Feliciano Belt.(c) 2022 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Automated summary

This study presents new geochronological and isotope data of Ediacaran magmatic rocks from several terranes in Uruguay. The results suggest that these rocks originated from different source regions and were emplaced in different tectonic settings at different times. It provides important insights into the geodynamic evolution of the southern Dom Feliciano Belt in Uruguay.