Late Cenozoic volcanism in the western Woodlark Basin area, SW Pacific; the sources of marine volcanic ash layers based on their elemental and Sr-Nd isotope compositions

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Authors:Lackschewitz, K. S.; Mertz, D. F.; Devey, C. W.; Garbe-Schönberg, C. D.
Volume Title:Bulletin of Volcanology
Source:for the [Bulletin of Volcanology, 65(2-3), p.182-200. Publisher: Springer International] International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI), Heidelberg, International. ISSN: 0258-8900
Publication Date:2003
Note:In English; 6 tables, sketch maps
Summary:Glass shards from 57 volcanogenic layers within the Pliocene--Pleistocene sedimentary sequence sampled by ODP Leg 180 are dominantly rhyolitic in composition with subordinate basaltic andesites, basaltic trachy-andesites, andesites, trachy-andesites, dacites and phonolites. Strong compartmentalization of the sedimentary realms of this actively rifting margin render correlation difficult but in many cases chemical and isotopic compositions enabled eruption sources to be determined. Likely sources for high-K calc-alkaline glasses include Moresby and Dawson Strait volcanoes and the latter appears to be the source of five peralkaline tephra layers. Basaltic andesite sources include the Woodlark spreading tip and Cheshire Seamount. Clear correlation with other sources proved impossible but possible sources relate to SW Pacific subduction volcanism, e.g. New Britain and Tonga-Kermadec island arcs. The Trobriand Arc (Woodlark Island, Amphlett Islands and/or Egum Atoll) is the probable source for several 1.5-3 m.y. old layers, but the Lusancay Islands can be excluded as a source of Leg 180 layers. There has been much calc-alkaline activity in E Papua since 3.8 m.y., but the appearance of peralkaline tephra at 135 k.y. may reflect a change from crustal subduction to spreading in the D'Entrecasteaux Islands region where initial 143Nd/144Nd ratios as low as 0.5121 and 0.5127 may indicate that volcanism at < 2.9 m.y. occasionally interacted with late Archaean basement suggesting mobilization of deep continental crust during active rift propagation. [J.G.M.]
Subsections:Oceanic petrology
Subjects:Absolute age; Alkali metals; Alkaline earth metals; Borehole sections; Cenozoic; Chemical composition; Isotope ratios; Isotopes; Major elements; Metals; Miocene; Nd-144/Nd-143; Neodymium; Neogene; Ocean Drilling Program; Petrography; Pleistocene; Pliocene; Provenance; Quaternary; Rare earths; Rubidium; Sr-87/Sr-86; Stable isotopes; Strontium; Tertiary; Trace elements; Volcanic ash; Coral Sea; Pacific Ocean; Solomon Sea; South Pacific; Southwest Pacific; West Pacific; Woodlark Basin; Rb-87/Rb-86
Abstract Numbers:03M/4800
Record ID:2004020640
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe
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