Stratigraphy and geochronology of quaternary marine terraces of Tasmania, Southeastern Australia: implications on neotectonism

Abstract

This study documents emergent marine terraces of Tasmania in Southeast Australia that are commonly observed along the coasts with both the distribution and elevation of terraces varying around the island. The primary objective is to document existence, characteristics and geochronology of little known terrace sequences on each coastline and to establish correlations between them. In order to address variability in uplift in Tasmania this study attempts to correlate uplift records from a number of widely separated locations. Quartz OSL dating technique was applied to constrain the age of the late Quaternary terrace sequences. The results imply that the time-integrated uplift rates around the Tasmanian coasts ranged from 40 m/Ma to 112 m/Ma since the last interglacial period, suggesting a non-uniform uplift during the late Quaternary. In addition, likely Miocene paleo-shorelines ranging 160 to 270 m around Tasmania show a similar pattern with the non-uniform uplift during the Late Neogene. The vertical motion of Tasmania within a horizontal length scale of order 100 kms and amplitude of order 100 m accords well with the dynamic topography records documented elsewhere in Southern Australia over the Neogene.