Abstract
A hawaute dyke dated at 3 88 +/- 0 05 M-1 from the Mount Morning eruptive centre intrudes a diamictite deposit at Gandalf Ridge in the southern Ross Sea The dyke has been dextrally offset up to 6 m horizontally by faults interpreted is the onshore continuation of the West Antarctic rift system (WARS) fault array Felsic dykes emplaced during the Miocene are also present at Gandalf Ridge The offset of the Miocene dykes is equivalent to the offset on the hawaute dyke suggesting that at this locality movement on faults within WARS Ins been restricted to a period more recent than c 3 88 Ma over this period the minimum average rite of movement on these faults within WARS is 0 0015 mm yr(1)