Three dyke swarms in Uruguay range in age from Palaeoproterozoic (1.86 Ga, Florida region) to Neoproterozoic ( 0.7 Ga, Nico Perez and Treinta y Tres regions). The Florida and Nico Perez swarms are basalts, basaltic andesites and andesites with tholeiitic affinity, characterized by LILE and LREE enrichment with respect to HFSE, Nb depletion with respect to K and La, < 260, < 19, > 13, ()
n > 4.5. Both swarms have positive
Sr and negative
Nd, but the Florida isotopic array is dominated by
Nd variations (EM1 type) and that of Nico Perez by
Sr variation (EM2 type).