Ancient subcontinental mantle; a source for K-rich orogenic volcanics

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doi: 10.1130/0091-7613(1985)13<405:ASMASF>2.0.CO;2
Authors:Varne, R.
Author Affiliations:Primary:
Univ. Tasmania, Dep. Geol., Hobart, Tasmania, Australia
Volume Title:Geology (Boulder)
Source:Geology (Boulder), 13(6), p.405-408. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613
Publication Date:1985
Note:In English. 26 refs.; illus. incl. sketch map
Summary:The mafic arc volcanics erupting along the arc/continent collision between the Sunda Arc and NW Australia display a three-fold enrichment in K, Rb, Sr, Ba, La and Nb contents along the arc from Bali to Flores, increasing toward the collision zone. The enrichment is very well correlated with increasing 87Sr/86Sr and decreasing 143Nd/144Nd values. The geochemical and isotope data imply that the arc volcanics are being generated from two source materials: one yielding material poor in K-group elements, with relatively low 87Sr/86Sr (<0.704) and high 143Nd/144Nd values, the other yielding material opposite in nature. The K-rich material in the arc volcanics is being derived from ancient sub-continental mantle involved in the collision zone. Eastern Sunda K-rich volcanism first appeared after the collision began. Striking geochemical and isotopic resemblances between eastern Sunda leucitites and K-rich orogenic volcanics elsewhere in the world imply a similar origin involving K-rich sub-continental mantle material. Where a 'K-h' correlation occurs it might be only a signal that subduction of a lithospheric slab beneath a continental margin is inducing melting in old mantle, deep in the continental lithosphere. [L.di H.]
Subjects:Alkali metals; Alkaline earth metals; Basalts; Calc-alkalic composition; Eruptions; Geochemistry; Igneous rocks; Island arcs; Isotopes; Kimberlite; Leucitite; Mafic composition; Mantle; Metals; Nd-144/Nd-143; Neodymium; Orogeny; Potassium; Rare earths; Shoshonite; Sr-87/Sr-86; Stable isotopes; Strontium; Trace elements; Ultramafic composition; Volcanic rocks; Volcanoes; Volcanology; Asia; Australasia; Australia; Far East; Indonesia; Indonesian Seas; Pacific Ocean; Sunda Arc; West Pacific; Western Australia; Sunda Islands
Abstract Numbers:85M/4153
Record ID:1985060521
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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