Late Cainozoic stratigraphy, palaeomagnetic chronology and vegetational history from Lake George, N.S.W.

Abstract

Abstract The sedimentary record from Lake George provides the longest relatively continuous Quaternary continental sequence yet available from Australia, and may record one of the longest Upper Cainozoic lacustrine records in the world. Palaeomagnetic analysis of a 36 m core from the lake floor identifies a sequence of deposition extending through the Brunhes and Matuyama, to the Gauss magnetic Chron. A longer core from the same site, but with incomplete recovery, extends to 72 m in lacustrine sediment; the age of the base of this core estimated by extrapolation is between 4.2 and 7 Ma. As there are still older and deeper sediments in the basin, extending to an estimated depth of 134 m, the age of the tectonic formation of the Lake George basin must be reckoned as Middle Miocene or older. The pattern of facies organisation through time demonstrates a phase of deep water deposition extending from the base of the cored sequence (72 m) up to 51.5 m, at which time a major change took place. A disconformity de...