The Upper Permian sedimentary successions of the southern Sydney Basin have been the subject of several stratigraphic, sedimentological, and petrographic studies and more recently several studies dating the sedimentary succession using U-Pb zircon and 40Ar-39Ar geochronology. In this study the Broughton Formation of the Lower Permian, part of the upper Shoalhaven Group succeeding the Talaterang Group and underneath the Illawarra Coal Measures was studied. The Broughton Formation is part of a Permian retroarc depositional basin within the Southern Sydney Basin (SSB) which is unconformable on the Lachlan Fold belt to south and west, and in tectonic contact with the New England Fold Belt to the north and east. The chronology of the Upper Permian of the SSB is well constrained. However, the chronology of the Lower Permian of the SSB, including the Broughton Formation, is less well constrained. Thus, there is debate over the timing and absolute length of several glacial and interglacial cyc