Abstract:

Based on detailed geological mapping and petrographical study the volcanic sequence and volcanic activities at Hannah Point, Livingston Island have been described and discussed. As a part of Antarctic Peninsula Volcanic Group, the measured cross-section consisting of interbedded volcaniclastic rocks and lavas could be divided into three volcanic cycles formed in three different stages of volcanism. The unconformity between cycle 1 and 2 recorded a relatively long intermission of eruptions between the first two stages of volcanism. The dacitic to rhyolitic lava and tuff-breccias of the first cycle were formed at the end phase of eruption. The second stage included three intermittent eruptive activities and the erupted products evaluated from mainly andesitic pyroclastic, through predominant basaltic-andesitic lava,to andesitic or rhyolitic melted ash lapillistone. The volcanism in the third stage might be more intense and differ greatly from that in other stages both in geology and petrography. Stable and gentle dipping of the volcanic strata suggests that there was no obvious tectonic effect and the eruptive centers might gradually migrates northeastwards. The facts that dykes and sills were concentrated in the lower part of the second stage volcanism, and that strong zeolitization was developed in the tuffaceous rocks at the two sides of unconformity suggest a weaker zone near the contact betweet two cycles, where structural activity and alteration were easily occurred.