GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.2 GNGTS 2023 Figure 2: Comparison between the results and: (a) magnetic anomalies (Catalan et al., 2014); (b) morphotectonic zonation (Paredes et al., 2006); (c) main tectonic features obtained by Lopes et al. (2015) and sketched by Rey et al. (2002); (d) spatial distribution of arsenic (As) and manganese (Mn) (Somoza et al., 2004), where the lines contour the zones of highest concentration, and fumaroles (Rey et al., 2002). Geophysical Image of Eruptive Paths Controlling Fluid Migrations The highest-absorption anomalies correspond to ancient eruptive cones and areas currently affected by volcanic emissions (Smellie et al., 2002). Hawkes (1961) provide maps and sketches of geological formations focusing on the areas that erupted before 1967, like the volcanism of the pre-caldera group, that is, the Port Foster Group, within which the volcanism of Telefon Bay is placed (Figure 3, large white circles). The Aa1-Aa3 anomalies and the crossing point between NE-SW and NNW-SSE high-absorption trends leading to the site of the 1967/1970 eruption (Telefon Bay - see the zoom in Figure 1a) are all less than 2 km distant from the proposed centre of these ancient eruptions. Hawkes (1961) also describes the second volcanic event of the island and its eruptive centres (falling within the Neptune Bellow Group and following the Port Foster Group); these centres coincide with the Mount Pond Group in the Stonethrow Ridge Formation (Smellie, 2001). Among the four highlighted centres (Figure 3, black circles), Vapor Col and Entrance Point coincide with the Aa2 and Aa3 anomalies. In addition, the Ba2 anomaly is located near Mount Kirkwood, where the authors place two additional volcanic cones hidden under the ice cap. The cone located in the South East Point zone could not be linked to absorption features, but this zone remains unresolved in our models. The high-absorption anomalies are often co-located with the centres of the 1967, 1969 and 1970 eruptions (Figure 3, stars). In particular, the area related to the 1967 and 1970 eruptions coincides with the northern termination of the anomaly oriented