title: Continuous eclogite melting and variable refertilisation in upwelling heterogeneous mantle.
abstract: Large-scale tectonic processes introduce a range of crustal lithologies into the Earth's mantle. These lithologies have been implicated as sources of compositional heterogeneity in mantle-derived magmas. The model being explored here assumes the presence of widely dispersed fragments of residual eclogite (derived from recycled oceanic crust), stretched and stirred by convection in the mantle. Here we show with an experimental study that these residual eclogites continuously melt during upwelling of such heterogeneous mantle and we characterize the melting reactions and compositional changes in the residue minerals. The chemical exchange between these partial melts and more refractory peridotite leads to a variably metasomatised mantle. Re-melting of these metasomatised peridotite lithologies at given pressures and temperatures results in diverse melt compositions, which may contribute to the observed heterogeneity of oceanic basalt suites. We also show that heterogeneous upwelling mantle is subject to diverse local freezing, hybridization and carbonate-carbon-silicate redox reactions along a mantle adiabat.
authors.affiliation: 1] Research School of Earth Sciences, The Australian National University, Canberra, Mills Road, ACT 0200, Australia [2] Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Rosenthal
authors.affiliation: Research School of Earth Sciences, The Australian National University, Canberra, Mills Road, ACT 0200, Australia.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Yaxley
authors.affiliation: 1] Research School of Earth Sciences, The Australian National University, Canberra, Mills Road, ACT 0200, Australia [2] School of Earth Sciences and Centre for Ore Deposit Studies, University of Tasmania, Hobart 7001, Tasmania, Australia.
authors.forename: David H
authors.initials: DH
authors.lastname: Green
authors.affiliation: 1] Research School of Earth Sciences, The Australian National University, Canberra, Mills Road, ACT 0200, Australia [2].
authors.forename: Joerg
authors.initials: J
authors.lastname: Hermann
authors.affiliation: 1] Research School of Earth Sciences, The Australian National University, Canberra, Mills Road, ACT 0200, Australia [2] Geochemical and Laboratory Department, Geological and Geophysical Institute of Hungary, Budapest, Stefánia Street 14, H-1143, Hungary [3].
authors.forename: István
authors.initials: I
authors.lastname: Kovács
authors.affiliation: 1] School of Earth and Environmental Sciences, James Cook University, Townsville, Australia [2].
authors.forename: Carl
authors.initials: C
authors.lastname: Spandler