The Lava-Sedimentary Mesozoic Association of Lacustrine Environment of Byers Peninsula, South Shetland Islands

CABALERI, N; PARICA, C A,; REMESAL, M B,; SALANI, F M,; VALENCIO, S

The Antarctic Region: Geological Evolution and Processes

Terra Antartica Publication

Lugar: Siena; Año: 1997; p. 361 - 366

The facial study of a carbonate volcanic sequence at Byers Peninsula, Livingston Island, suggests a lacustrine environment. The sequence represents a shallow lake environment, with warm temperatures, where quiet deposition of carbonate sediments took place. Afterwards, a phreatomagmatic event built up peperite deposits and produced mixed facies with pyroclastic material and carbonates. A depositional model has been generated based on facial analysis and isotopic determinations. Two sections were studied: 1) West of the Sealer Hill, carbonate and mixed facies, typical of a shallow lake, were developed. Peperite deposits resulting from interaction of basaltic flows and wet unconsolidated sediments are also present in this section. 2) At the Rat611 Hill carbonate sedimentation occurred in a marshy environment, being represented by laminae of mudstone and wackestone, with evidence of re-mobilization. The lacustrine facies allow to determine climatic seasonal changes that occurred in the area. They reveal an arid climate, also indicated by stable isotopes, with seasonal rainfalls. The Carbon-13 values indicate a continental freshwater environment, with presence of considerable organic matter.