238 AUSTRALIA/Tasman Orogenic Belt Figure Simplified geological map of Gondwana with modern day continental outlines, showing regions of Precambrian shield and the younger orogenic belts IGCP, Gondwana map base by peaks of deformation in the Early to Middle Cambrian, Late Ordovician–Silurian, and Permian–Triassic in the respective orogenic belts (Table 1) Crustal growth occurred largely by the addition of turbidites (ocean-floor submarine-fan deposits), cherts (ocean-basin deposits), mid-ocean ridge basalts (oceanic crust), andesites (island arc), and granites These younger, largely Palaeozoic, rocks occur to the east of the exposed Precambrian cratonic crystalline basement; the boundary between the two is known as the Tasman Line (Figure 2) They represent a significant addition (approximately 30% by surface area) to the Australian continent whilst it was part of Gondwana Younger basinal sedimentary sequences