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Stracke et al. 2003
Stracke, A., Bizimis, M. and Salters, V.J.M. (2003). Recycling oceanic crust: Quantitative constraints. Geochemistry Geophysics Geosystems 4: doi: 10.1029/2001GC000223. issn: 1525-2027.

Recycled ancient oceanic crust with variable amounts of aging, or inclusion of sediments of differing types and origins has often been invoked as a source for present-day ocean island basalts (OIB), but the current evidence remains largely qualitative. Previous quantitative modeling has shown that much has to be learned in order to better understand the implications of crustal recycling on mantle heterogeneity. Here, we present new model calculations incorporating recent constraints on subduction-zone processes and the composition of subducted sediments. Modeled compositions of the recycled oceanic crust vary widely as a function of the recycling age and composition of the oceanic crust. HIMU-type sources can only be created by recycling igneous oceanic crust if it has undergone substantial modification during subduction. Although the required modifications are qualitatively consistent with dehydration processes in subduction zones, the many uncertainties prevent a precise estimate of the isotopic composition of ancient recycled igneous crust. Inclusion of sediments increases the isotopic variability and although the resulting Sr and Nd isotopic signatures can be similar to enriched mantle (EM) signatures, the Pb isotopic composition of EM-type OIB is difficult to reconcile with the presence of sediment in their sources. The large variability of modeled compositions of the subducted crust suggests that if mantle heterogeneity is largely formed by crustal recycling, each OIB is likely to have a unique isotopic composition resulting from specific combinations of composition, age and subduction modification of the subducted crust. Given the variability of the recycled components, a small number of relatively well-defined enriched compositions can only be explained if either the subduction processing of oceanic crust is a far better defined process than observation would seem to indicate, or, the intramantle disaggregation and mixing of compositionally diverse recycled materials is surprisingly efficient.

BACKGROUND DATA FILES

Abstract
Abstract

Os Isotope Tracers 1
Os Isotope Tracers 1
Os Isotope Tracers 2
Os Isotope Tracers 2
Modeling of Oceanic Crust Comp
Modeling of Oceanic Crust Comp
Age of Recycled Crust
Age of Recycled Crust
Initial Isotopic Comp of Recycled Ocean Crust 1
Initial Isotopic Comp of Recycled Ocean Crust 1
Initial Isotopic Comp of Recycled Ocean Crust 2
Initial Isotopic Comp of Recycled Ocean Crust 2
Initial Isotopic Comp of Recycled Ocean Crust 3
Initial Isotopic Comp of Recycled Ocean Crust 3
Initial Isotopic Comp of Recycled Ocean Crust 4
Initial Isotopic Comp of Recycled Ocean Crust 4
Initial Isotopic Comp of Subducted Sediment 1
Initial Isotopic Comp of Subducted Sediment 1
Initial Isotopic Comp of Subducted Sediment 2
Initial Isotopic Comp of Subducted Sediment 2
Trace Element Comp of Recycled Oceanic Crust
Trace Element Comp of Recycled Oceanic Crust
Trace Element Comp of Recycled Sediments
Trace Element Comp of Recycled Sediments

Table 1
Table 1
Table 2
Table 2
Table 3
Table 3
Table A.1
Table A.1
Table A.2
Table A.2

Keywords
Geochemistry, Composition of the mantle, Geochemistry, Isotopic composition/chemistry, Geochemistry, Trace elements, Mineralogy and Petrology, Igneous petrology
Journal
Geochemistry Geophysics Geosystems
Publisher
American Geophysical Union
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