Geological note: The Sydney basin: Composition of basement

Summary Qureshi (1984) suggested that a dense mafic pile existed beneath the Sydney Basin. Since his regional separation leading to residual anomalies does not allow for the negative effects of regional granitoids, his residual values and interpretation were too positive. An alternative solution requires no huge unexplained or localized positive sources. Instead, the known materials of the Sydney Basin and Lachlan Fold Belt are sufficient to explain all presently defined features of the gravity field. The basement to the Sydney Basin is almost certainly an extension of the Lachlan Fold Belt as exposed at Bathurst or Goulburn.