UPPER CAMBRIAN CARBONATES FROM THE PRECORDILLERA, WESTERN ARGENTINA: INSIGHTS FROM C AND Sr-ISOTOPE CHEMOSTRATIGRAPHY

SIAL, ALCIDES N.; PERALTA, SILVIO H.; FERREIRA, VALDEREZ P.; GAUCHER, CLAUDIO; TOSELLI, ALEJANDRO J.; PARADA, MIGUEL ANGEL; PIMENTEL, MARCIO M.

Stellenbosch South Africa, 10-14 September, 2007

Simposio; 7th Internacional Symposium on Applied Isotope Geochemistry, AIG7 Stellenbosch South Africa; 2007

AIG

A large and global positive excursion of d13C (~+5?) for the Steptoean stage, Upper Cambrian (SPICE) carbonates represents a major perturbation of the Cambrian carbon cycle at ~500Ma (Saltzman et al., 1998; 2000). In contrast, C-isotope variation curves for the Cambrian-Ordovician boundary in Australia and United States reveal a pronounced negative C-isotope excursion (-4?) in the uppermost Cambrian (Sunwaptan stage; Ripperdan et al., 1995; 1998). Both anomalies have been recognized in carbonates of the Precordillera of western Argentina: SPICE in the La Flecha Formation, Quebrada de La Angostura, and the negative anomaly (named as SNICE by Sial et al., in press) in the La Flecha Formation, Quebrada de La Flecha.