A succession of metamorphic zones can be recognized along the Molong Geanticline, an ancient rise within the Tasman Geosyncline of Eastern Australia. In order of increasing grade, the zones in the volcanogenic rocks are: (1) an albite-quartz zone, containing neither prehnite, pumpellyite, actinolite, nor biotite; (2) a prehnite zone; (3) a prehnite-pumpellyite zone; (4) an actinolite zone; and (5) a biotite zone. Zeolite associations are not developed. Zones 4 and 5 lie within the greenschist facies. The rocks along this geanticline are generally only slightly deformed, lacking cleavage.The grade of this metamorphism within the Molong Geanticline increases partly in accordance with increasing stratigraphic depth and partly increases eastwards towards the adjacent Hill End Trough. Within the Trough, rocks show metamorphic assemblages akin to those of Zones 4 and 5 as defined within the Molong Geanticline, but deformation is more extreme and a regional cleavage is characteristic. In the region about the Hill End Trough and the adjacent geanticlines there is an apparent variation from essentially static burial metamorphism of the geanticlines through transitional types to tectonic dynamothermal metamorphism of the trough. Both metamorphisms are envisaged as having arisen during the same general period of metamorphism, but deformation of the geanticlines was much less than deformation in the intervening Hill End Trough. © 1969 Oxford University Press.
