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Subducted upper and lower continental crust contributes to magmatism in the collision sector of the Sunda-Banda Arc, Indonesia

M. A. Elburg, M. J. van Bergen and J. D. Foden
Subducted upper and lower continental crust contributes to magmatism in the collision sector of the Sunda-Banda Arc, Indonesia
Geology (Boulder) (January 2004) 32 (1): 41-44

Abstract

Pb isotopes in igneous rocks from the Banda-Sunda arc show extreme along-arc variations, which correspond to major lithologic changes in crustal components entering the subduction system. An increase in (super 206) Pb/ (super 204) Pb ratios toward the zone of collision with the Australian continent reflects input of subducted upper-crustal material; maximum values coincide with anomalously radiogenic (super 3) He/ (super 4) He ratios that have been earlier attributed to the involvement of the continental margin. The collision zone is further characterized by (super 208) Pb/ (super 204) Pb ratios that are higher for a given (super 207) Pb/ (super 204) Pb value than observed in the noncollisional sectors, and in the central part of the collision zone, the (super 206) Pb/ (super 204) Pb ratios are lower than the most radiogenic values in the adjacent areas. We propose that these Pb isotope signatures reflect input of subducted lower crust, mobilized as a result of slab-window formation during arc-continent collision. Variations in Pb isotopes in the collision zone are solely determined by variations in the nature and proportions of different subducted components. The Pb isotope arrays in the noncollision area may be dominated by slab components as well and could reflect mixing between subducted oceanic crust and entrained sediments, rather than between subarc mantle and subducted sediments. Our new interpretation of the Indonesian Pb isotope data does not call for involvement of ocean-island basalt (OIB)-type mantle or Australian subcontinental lithospheric mantle, as has been suggested previously.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 32
Serial Issue: 1
Title: Subducted upper and lower continental crust contributes to magmatism in the collision sector of the Sunda-Banda Arc, Indonesia
Affiliation: Max Planck Institute for Chemistry, Geochemistry Division, Mainz, Federal Republic of Germany
Pages: 41-44
Published: 200401
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 34
Accession Number: 2004-014671
Categories: Solid-earth geophysicsIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 200405
Illustration Description: illus. incl. 1 table, sketch map
S11°00'00" - N06°00'00", E95°00'00" - E128°00'00"
Secondary Affiliation: Utrecht University, NLD, NetherlandsUniversity of Adelaide, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200405
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