Genesis and evolution of volcanism in back-arc areas; a case history, the Island of Deception (western Antarctica)

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Authors:Peccerillo, A.; Tripodo, A.; Villari, L.; Gurrieri, S.; Zimbalatti, E.
Author Affiliations:Primary:
Universita di Messina, Istituto di Scienze della Terra, Messina, Italy
Volume Title:Periodico di Mineralogia
Source:Periodico di Mineralogia, 60(1-3), p.29-44. Publisher: Bardi Editore, Rome, Italy. ISSN: 0369-8963
Publication Date:1991
Note:In English with Italian summary. 30 refs.; illus., incl. geol. sketch map, 2 tables, anals.
Summary:The Deception Island is an active volcano sited in the Bransfield Strait, a rifting area behind the South Shetland archipelago, an island arc which has been active during Late Mesozoic-Tertiary times. The island consists entirely of volcanic rocks with variable composition. Major and trace element data reported on a suite of representative lava samples indicate that the Deception rocks make up a continuous Na-transitional series ranging from basalt to trachyte. Major and trace element abundances show smooth variations from mafic to acidic rocks and are consistent with an evolution of the magma by closed-system crystal/liquid fractionation in a shallow-level magma chamber. Sr isotopic ratios determined on three samples with different degrees of evolution show poorly variable values (0.70340-0.70356), thus supporting closed-system evolutionary processes. The Deception volcanics, including the most mafic ones, have some geochemical characteristics such as negative anomalies of HFSE and positive spikes of Sr which indicate an island-arc affinity for these rocks. Quantitative modelling suggest that it is unlikely that these characteristics were all acquired during the shallow level evolution of the magmas and indicate that they are partially inherited from the source. This strongly indicates that an island-arc component affected the source of the Deception magma, possibly by introduction within the mantle wedge of fluids or melts released from the oceanic slab which was subducting under the South Shetland during Tertiary times.
Subjects:Alkaline earth metals; Back-arc basins; Basalts; Basins; Fractional crystallization; Geochemical anomalies; Igneous rocks; Island arcs; Magma chambers; Major elements; Metals; Strontium; Subduction; Trace elements; Trachytes; Volcanic rocks; Volcanism; Volcanoes; Antarctica; Bransfield Strait; Deception Island; Scotia Sea Islands; South Shetland Islands; Southern Ocean
Coordinates:S630000 S625500 W0603000 W0604500
Abstract Numbers:94M/694
Record ID:2007028137
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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