Mineralogical changes as marker horizons for stratigraphic correlation in the Narrabeen group of the Sydney basin, N.S.W

Detailed petrological analysis of arenites and lutites of the Lower Triassic Narrabeen Group in the southern part of the Sydney Basin has provided additional marker horizons for stratigraphic correlation.Up to three such horizons can be recognized in various parts of the basin, corresponding to short stratigraphic intervals over which the composition of the sediments undergoes a sudden and significant change.These changes are best illustrated by following the variation, throughout the vertical succession, of the ratio between quartz grains and rock fragments in the sandstones, so that borehole and outcrop sections can be represented diagrammatically by petrological profiles.Comparison of such profiles for sections across the basin suggests a number of modifications to previously published correlation schemes, particularly those put forward for the coastal regions.Ward, Colin R. 1972."Mineralogical changes as marker horizons for stratigraphic correlation in the Narrabeen group of the Sydney basin, N.S.W."