New evidence on the form of the granitic intrusions in new England, N.S.W.

Four hundred and thirty‐two gravity stations have been established at intervals of about 1 km in the Uralla‐Kingstown district. The Bouguer gravity anomaly map shows close correlation with the surface geology. There are gravity lows over the granitic intrusions; this is to be expected, because the surrounding sedimentary rock is 0.06 g/cm3 denser than the granite. The gravity work shows that the granitic intrusion in the Uralla‐Kingstown district, which forms part of the ‘New England Batholith’, does not continue to any great depth, as had been postulated previously from geological field mapping, but is a lenticular body with a thickness of 4 km. From the regional gravity anomaly throughout the area (—60 mgal) it can be seen that the 1 km high New England Plateau is isostatically compensated in terms of an Airy crustal model.