Magnetics and gravity image tectonic framework of the Mount Melbourne Volcano area (Antarctica)

Mt. Melbourne volcano (Northern Victoria Land-Antarctica) is part of the McMurdo Igneous complex, which spans a considerable time interval between 38 Ma to the Present. It is generally accepted that both the location and the magmatic products of the volcano are genetically linked to Ross Sea rifting and uplift of the Transantarctic Mountains (TAM) rift shoulder. Studies on pyroclastic falls suggest that an eruption likely occurred in the last few centuries. Presently the volcano has a low level of activity which has been highlighted and monitored by means of integrated geophysical networks. After a review of previous geophysical and geological findings at both regional and at a more local scale, in our study we display and interpret newly compiled magnetic and gravity images over the Mount Melbourne area to better constrain the tectonic framework of the region. We propose that the structural setting is dominated by major NW-SE right-lateral strike-slip faults generating uplifted crustal blocks, namely the Deep Freeze Range block and more subsided N-S graben-Iike structures such as the one in which Mount Melbourne volcano itself appears to be located. Local seismic events could well be associated with the N-S faults within this graben. Gravity data is consistent with crustal thickening beneath the TAM and offshore it highlights together with heat flow data and seismic constraints a NNE trending pull- apart basin with extended crust also linked to the strike-slip tectonics of the region. Local gravity anomalies are also discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.