Byers Peninsula, An Example Of The Palaeoenvironment For Cretaceous And Early Tertiary In Antarctica

PARICA, C.A.,; REMESAL, M.B.; SALANI, F.M.

Buenos Aires

Conferencia; SCAR XXXI & Open Science Conference; 2010

Instituto Antártico Argentino

The geological history of Byers Peninsula starts in Jurassic times with deep marine deposits (Anchorage Formation). The non marine regime took place in the Cretaceous times, near 130 Ma, according to oldest volcanic rocks emplaced in the surface. In these times a non marine basin was developed, ferns rich and a strong volcanism marked the features since the Cretaceous to Tertiary. Sedimentary rocks and their structures let to understand a seasonal regime, with rainfalls, and high energy environment. Because the carbonate deposits in lagoons were the tool to apply stable isotopes studies (d18O for palaeotemperatures, and d13C for environment). Anyway, some peperitic breccias in the Ratón Hill suggest the simultaneity in shorts distances of sea water and fresh water in the non marine environment. Data from the analyzed samples have values for d13C since -10.6 to -15.9? and d18O de 0.5 a -2.8?. These sensitive data confirm the non marine regime for the deposited carbonates, and the equilibrium rank of temperatures was established in between 15 to 20°C. The environmental frame for the upper Mesozoic and Tertiary is sustained by the palaeoflora, sedimentary features and the stable isotopes analytic al data. Some of the family ferns determined still continue alive in the Patagonian Andean forests. According paleomagnetic reconstructions the locatio n of the area for those times was close to the actual one, 62° South Latitude.