The Camaquã Extensional Basin: Neoproterozoic to Early Cambrian Sequences in Southernmost Brazil

The C.rmaquã lasin is an extensional post-orogenic and pre-cratonic rift system of Neoproterozoic-Early Cambrian age locatecl in the Gaúcho Shield, Rio Grande do Sul, southernmost Brazil.The basin is divided into a series of small sub:basins which were filleã with the Camaquã Group, a thick (>9,000 m) unit composed of three formations: (i) the siliciclastic Maricá Formation, (ii) the volcano-sedimentary Crespos.Formation and (iii) the siliciclastic Santa BárbaraFormation.These units correspond to three majorstratigraphic sequences, and are divided into h,igher order sequences.Provenance and paleocurent analysis of the siliciclaitic deposits show a closelelationshþ of the source- area with the lithologies that occur today in the neighborhood of these deposits, suggesting that ño important lateral transport tõok place along the border faults.Paleocuffent measurements indicate a northern position for the marine body that cyclically invaded the basin.