Determinación de la ciclicidad temporal en los sedimentos varvados de la Laguna Mar Chiquita (Córdoba, República Argentina)

Abstract

Laguna Mar Chiquita is the biggest lake in Argentina, probably originated 30.000 years ago. Three are the rivers discharging to this lake, which can pass from brackish-saline to hypersaline conditions related to changes in its water level. Changes in water salinity induce consequent changes in the sedimentary conditions, originating a varvate sedimentation consisting in a cyclic lamination when organic, non-organic and evaporitic laminae alternate. The combination between granulometric, radiometric and historic data permit to assert that the milimetric laminae correspond to normal varves, nevertheless centimetric varves and evaporitic levels are not originated by seasonal variations in the lake, but by cyclic wet and dry climatic periods