Browsing by Author "Sumino H"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Cosmogenic helium signatures at Deception Island volcano (Antarctica): geochronological implications for its eruptive history
    (Springer Nature Limited, 2025-12-01) Álvarez-Valero AM; Sumino H; Burgess R; Arribas L; Polo-Sánchez A; Geyer A; Caracausi A; Albert H; Aulinas M; Ban M; Borrajo J; García-Arias M; Ichikawa G; Kereszturi G; Rodríguez JAL
    Cosmogenic nuclei production for dating the Earth surface exposure of rock/mineral samples, especially 3He, is a robust technique in geochronology. We describe its application to constrain the ages of key eruptive episodes of the volcanic history of Deception Island (Antarctica): (i) the volcanic products of the island formed before the caldera collapse (pre-caldera material); and (ii) the caldera-forming event (syn-caldera material). High 3He/4He ratios (up to 910 RA; RA = 1.39 × 10–6) in the crystal structure of olivine phenocrysts measured through total fusion He release are much higher than the magmatic values previously obtained in the inclusions of the same olivines obtained by hydraulic crushing. Such high values indicate a cosmogenic origin and reveal an age of c. 4 Ma for the pre-caldera material, and c. 4.6 ka and 170 ka for the syn-caldera deposits. The result of c. 4.6 ka for the caldera collapse episode is consistent with previous age estimations based on tephrochronology, whereas the c. 170 ka result reveals the presence of pre-caldera olivines embedded in the syn-caldera deposits that experienced less exposure to cosmic rays compared to the samples with ages of 4 Ma. This oldest age estimate represents the first quantitative geochronological approach attempting to date Deception Island formation.
  • Thumbnail Image
    Item
    Formation of Stanley Patch volcanic cone: New insights into the evolution of Deception Island caldera (Antarctica)
    (Elsevier B.V., 2021-05-06) Hopfenblatt J; Geyer A; Aulinas M; Álvarez-Valero AM; Gisbert G; Kereszturi G; Ercilla G; Gómez-Ballesteros M; Márquez A; García-Castellanos D; Pedrazzi D; Sumino H; Höskuldsson A; Giralt S; Angulo-Preckler C
    Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 20 explosive eruptive events registered over the past centuries. Recent eruptions (1967, 1969, and 1970) and volcanic unrest episodes (1992, 1999, and 2014–2015) demonstrate that volcanic activity is likely occurring in the future. This is of special concern for scientists, logistic personnel, and tourists, since the South Shetland Islands are an important tourist destination and host numerous year-round and seasonal scientific stations and base camps. Significant efforts have been made to understand the complex magmatic and volcanic evolution of Deception Island with special interest on its subaerial part. However, studies on submerged volcanic cones within Port Foster, the sea-flooded part of Deception Island's caldera depression, are comparatively scarce. Here, we provide a full characterization of Stanley Patch volcano, the largest of these volcanic edifices. Estimated morphometric parameters based on new multibeam bathymetric data, supported by petrographic and chemical observations from rock samples collected on the crater rim, reveal that Stanley Patch volcano grew in a subaerial environment. This result, combined with previous findings and new sedimentological evidence from our ultra-high resolution seismic profiles, allow to further detail the island's geologic evolution since the caldera collapse. We conclude that the complete flooding of Port Foster could have only occurred after the formation of Stanley Patch volcano, i.e. during the last ~2000 years, and in a time period of a few days or less.