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(2006) 'Adakites without slab melting : high pressure dierentiation of island arc magma, Mindanao, the Philippines.', Earth and planetary science letters., 243 (3-4). pp. 581-593. Further information on publisher's website:http://dx.doi.org/10.1016/j.epsl.2005.12.034Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Pliocene arc lavas generated in the same subduction zone. Excepting the heavy rare earth 27 elements, the adakites and arc lavas also possess similar ratios of incompatible elements 28 suggesting that the adakites were ultimately derived from melting of the mantle wedge. 29The wide range of SiO 2 in the adakites and its strong correlation with trace element 30 concentrations and ratios indicate two possible mechanisms for generating the adakitic 31 signature. (1) Adakitic melt was produced from basaltic arc magma by fractional 32 crystallisation of a garnet-bearing assemblage. (2) Solidified basaltic rock containing 33 garnet melted to yield adakitic magma. In either case the basaltic precursor was generated 34 from fluid-modified mantle then differentiated within the garnet stability field. In Surigao 35 this requires differentiation within mantle. The Surigao example suggests that any 36 subduction zone has the potential to produce adakitic magma if basalt crystallises at 37 sufficient depth. This has important implications for the geodynamics of modern and 38 ancient subduction zones that have generated similar rocks. 39

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