TRANS-ATLANTIC CORRELATION OF ERUPTIVE SEQUENCES AND INDIVIDUAL SILICIC VOLCANIC UNITS WITHIN THE PARANA ETENDEKA IGNEOUS PROVINCE

The Mesozoic volcanic rocks of the Serra Geral Formation in Parana Bas in, South America, and of the Etendeka Group in northwestern Namibia w ere erupted shortly before the opening of the South Atlantic. The majo r widespread silicic volcanic units in the Etendeka Group are interpre ted as rheoignimbrites (Milner et al., 1992) and are interbedded with tholeiitic basalts and basaltic andesites. The southern portion of the Etendeka Group is subdivided into a basal Awahab Formation which is o verlain disconformably by the Tafelberg Formation. Both formations con tain silicic and mafic units. Bulk composition, initial Sr-87/Sr-86 ra tios, phenocryst assemblages and mineral compositions are used to corr elate silicic units of the Awahab Formation with the basal units of th e Palmas silicic volcanic rocks in the southern Parana Basin. Silicic units of the Tafelberg Formation can similarly be correlated with sili cic units in the upper portion of the Palmas succession, which are als o disconformable on the units below them. Not all silicic units in the se successions are present in both the Etendeka and Parana areas, but where correlation of individual units is possible, then this is found to be consistent with the overall stratigraphic sequence. Silicic unit s in the Awahab Formation were erupted from the Messum Igneous Complex in Namibia and their correlation into Brazil indicates that individua l eruptive units must have travelled over 340 km from their source. Se rial changes in the composition of silicic units in the Awahab Formati on and their correlatives indicates that they were erupted from a sing le magma system from which a total of similar to 8600 km(3) of materia l was erupted.