The stratigraphic palynology of the Murray Basin in New South Wales. III. The Lachlan area

The geology and palynology of the Lachlan area of the eastern edge of the Murray Basin is generally similar to that of the Murrumbidgee area.The oldest Tertiary sediments are the Mid-Late Eocene Middle Nothofagidites asperus Zone.The Oligocene-Early Miocene Proteacidites tuberculatus Zone may form thick sections which require subdivision.The Mid-Late Miocene Triporopollenites bellus Zone is not found here.In the southwestern region of the Lachlan area, the basement is deeper and the sedimentary sequence thicker.Here the P. tuberculatus Zone may be subdivided using the quantitative events (i.e.high ratios), similar to that of the Murrumbidgee area.Elsewhere, the pre-Tertiary basement is shallower and the sedimentary sequence thinner.Here, the quantitative events show different patterns to those of the Murrumbidgee area.It is thought that better drainage over the shallower basement is the likely cause of the different patterns.The two records of basement assemblages are both the Early Cretaceous Dictyotosporites speciosus Zone.