Uruguayan dyke swarms

The Florida dyke swarm (also known as Piedra Alta dyke swarm and Uruguayan dyke swarm) crops out in the Piedra Alta Terrane of Río de la Plata Craton west of Sarandí del Yí Shear Zone. The strike of the dykes has an arcuate pattern: it changes from west to east from NE-SW to E-W and then near the shear zone to NW-SE. Despite having some characteristics similar to those of igneous rocks formed near subduction zones, the Florida dyke swarm rocks are unlikely to have formed in such environment. Instead, the magma that formed the dykes is thought to be derived from the partial melting of garnet peridotite in a parcel of the Earth's mantle that was metasomatized without the direct influence of subduction. These dykes are of Late Paleoproterozoic age. By the time of intrusion of the Florida dyke swarm, Piedra Alta Terrane was experiencing extensional tectonics. ==Nico Perez dyke swarm==

Tholeiitic basalt and basaltic andesite are the main rock types of Nico Perez dyke swarm. Before solidifying as dykes the magmas fractionated minerals at relatively shallow (upper crust) magma chambers. The dykes of the swarm have geochemical heterogeinities that indicate they did not originate from the same magmas. Despite having geochemical characteristics typical of subduction zone magmatism the dykes are judged unlikely to have formed in such environment and are instead considered an example of intraplate magmatism. ==Treinta y Tres dyke swarm==

The Treinta y Tres dyke swarm intrude Brasiliano Cycle granitoids that crop out east of Sierra Ballena Shear Zone. The dykes are about 750 million years old (Neoproterozoic). Compared to the two other Uruguayan dyke swarms the Treinta y Tres dyke swarm originated from lower degrees of partial melting in the mantle, but of similar garnet peridotite sources. ==References==