First documented deep submarine explosive eruptions at the Marsili Seamount (Tyrrhenian Sea,Italy): A case of historical volcanism in the Mediterranean Sea |
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| Institution: | 1. Dipartimento di Ingegneria & Geologia, Università G. d''Annunzio, Chieti, Italy;2. Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy;3. Schlumberger Information Solutions, Madrid, Spain;4. Istituto Ambiente Marino Costiero IAMC, CNR, Napoli, Italy;5. Institute for Mineralogy, Leibniz University, Hannover, Germany;6. Eurobuilding, Servigliano (AP), Italy;1. Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, 20164 Hamburg, FRG;2. Institut für Geowissenschaften, Universität Kiel, 24118 Kiel, FRG;3. Research School of Earth Sciences, The Australian National University, Canberra, Australia;4. SOEST, University of Hawaii, Dept. of Geology and Geophysics, 1680 East–West Road, POST612B, Honolulu, HI 96822, USA;5. Physikalisches Institut, Klima- und Umweltphysik, Universität Bern, CH-3012, Switzerland;1. Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy;2. Istituto Nazionale di Astrofisica (INAF), Bologna, Italy;3. Istituto di Scienze Marine-CNR (ISMAR), Bologna, Italy;1. IAMC, CNR, Calata Porta di Massa, Porto di Napoli, I-80100 Naples, Italy;2. DST, Università del Sannio, Via dei Mulini 59/A, I-82100 Benevento, Italy;3. Utrecht University, Budapestlaan, 6, 3584 CD Utrecht, The Netherlands;1. Institute of Geophysics, Center for Earth System Research and Sustainability, University of Hamburg, Bundesstrasse 55, D-20146 Hamburg, Germany;2. Department of Geology and Geoenvironment, University of Athens, Panepistimioupoli Zografou, 15784 Athens, Greece |
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| Abstract: | The Marsili Seamount (MS) is an about 3200 m high volcanic complex measuring 70 × 30 km with the top at ~ 500 m b.s.l. MS is interpreted as the ridge of the 2 Ma old Marsili back-arc basin belonging to the Calabrian Arc–Ionian Sea subduction system (Southern Tyrrhenian Sea, Italy). Previous studies indicate that the MS activity developed between 1 and 0.1 Ma through effusions of lava flows. Here, new stratigraphic, textural, geochemical, and 14C geochronological data from a 95 cm long gravity core (COR02) recovered at 839 m bsl in the MS central sector are presented. COR02 contains mud and two tephras consisting of 98 to 100 area% of volcanic ash. The thickness of the upper tephra (TEPH01) is 15 cm, and that of the lower tephra (TEPH02) is 60 cm. The tephras have poor to moderate sorting, loose to partly welded levels, and erosive contacts, which imply a short distance source of the pyroclastics. 14C dating on fossils above and below TEPH01 gives an age of 3 ka BP. Calculations of the sedimentation rates from the mud sediments above and between the tephras suggest that a formation of TEPH02 at 5 ka BP MS ashes has a high-K calcalkaline affinity with 53 wt.% < SiO2 < 68 wt.%, and their composition overlaps that of the MS lava flows. The trace element pattern is consistent with fractional crystallization from a common, OIB-like basalt. The source area of ashes is the central sector of MS and not a subaerial volcano of the Campanian and/or Aeolian Quaternary volcanic districts. Submarine, explosive eruptions occurred at MS in historical times: this is the first evidence of explosive volcanic activity at a significant (500–800 m bsl) water depth in the Mediterranean Sea. MS is still active, the monitoring and an evaluation of the different types of hazards are highly recommended. |
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