Flow‐field and palaeogeographic reconstruction of volcanic activity in the Permian Gerringong Volcanic Complex, southern Sydney Basin, Australia

The Broughton Formation, the basal part of the lower Upper Permian (ca 264–263 Ma) Gerringong Volcanics of the Kiama area of the southern Sydney Basin, comprises intercalated shoshonitic lava flows and shallow‐marine, predominantly volcaniclastic, sediments emplaced under periglacial climatic conditions at high palaeolatitude. Four lower members of the Gerringong Volcanics (the Westley Park Sandstone, Blow Hole Latite, Kiama Sandstone and Bumbo Latite Members) were examined to elucidate the lava‐flow directions and coeval palaeophysiography. Field evidence indicates that the individual flows that comprise the compound‐flow‐units of the Blow Hole and Bumbo Latites advanced toward the north‐northwest and north, respectively, from an emergent island volcano or volcanic archipelago that developed offshore of the present‐day coastline, some tens of kilometres south‐southeast of Kiama. The field evidence incorporates descriptions and interpretations of features including vesicles and amygdales, lava tubes, pill...