http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3200 Paleomagnetic studies of Late Cretaceous basaltic dykes (K-Ar age of ca. 80Ma) and associated sediments reveal the presence of both normal and reverse polarity magnetizations. Correlation with the geomagnetic polarity time scale shows that the normal polarity magnetization could have been acquired in the geomagnetic polarity chron (C33n) and the reversed polarity magnetization may have been acquired in the C33r or C32r polarity chron, respectively. This indicates that pulses of magmatism occurred in the region over a substantial period. The normal and reverse magnetic directions show a clockwise deflection from the north-south direction of 40-50°, which may be related to block rotation associated with deformation events that have occurred subsequent to dyke emplacement or to the opening of the Tasman Sea. 2010-04-27T05:24:45.938Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3167 The occurrence of synkinematic and authigenic clay minerals is a common feature in fault gouges. Few attempts have been made to date fault gouges. We present the first age data in Australia for synkinematic illite–smectite growth in two fault zones of the northern Sydney Basin, NSW. The faults occur at Burwood Beach, NSW in the northern part of the Sydney Basin and are hosted by Early Permian siltstones, tuffs and coals of the Lambton Formation, Newcastle Coal Measures. The faults are 1.5 m apart, show normal displacement and trend N–S with steep easterly dips. Foliated gouge zones, comminution and dilational breccias are developed along both fault surfaces. K–Ar ages extracted from samples in the gouge and tuffs in the damage zones are 172 (6–10 μm) to 119 Ma (<0.4 μm), respectively. Older ages of 272–281 Ma for the coarse fractions (>2 μm), 237–245 Ma for the <2 μm fraction, 218 Ma for the <0.4 μm fraction and 196 Ma for the <0.1 μm fraction have been obtained from siltstones within and outside the damage zone. We believe the younger ages of 196–237 Ma indicate the time at which diagenetic illite–smectite formed and the 122–150 Ma dates from the <2 μm fraction represent the maximum age of gouge formation. The younger ages are thought to reflect the last slip event occurring on the faults, which is related to the rifting and dispersal of the eastern margin of the Australian continent. 2010-04-27T05:05:20.004Z ]]>