caa a22 4500 463217179 CHVBK 20180405153200.0 cr unu---uuuuu 170326e20071101xx s 000 0 eng 10.1007/s00269-007-0178-2 doi (NATIONALLICENCE)springer-10.1007/s00269-007-0178-2 Decompression and unmixing of crystals included in diamonds from the mantle transition zone [Elektronische Daten] [Ben Harte, Nicola Cayzer] A suite of exceptional mineral inclusions in diamonds from the São Luiz river, Juina province, Brazil, shows a wide range of garnet/majorite mineral compositions co-existing with clinopyroxene; the overall bulk compositions are eclogitic. The inclusions have a wide variety of textural arrangements, but crystallographic data obtained by EBSD shows that each inclusion consists of a single garnet with constant crystallographic orientation whilst clinopyroxene grains have preferred orientation with relation to garnet {110} and <111>. This suggests that the inclusions were originally single phase majoritic garnets, and that they preserve various states of progressive unmixing (exsolution) into lower pressure garnet and clinopyroxene compositions during transport of the host diamonds towards the Earth's surface. On the basis of high pressure-temperature experimental data some of the original majoritic garnets must have come from depths of 450km or more, and therefore resided in the transition zone and asthenospheric upper mantle. Particularly extensive re-equilibration of many inclusions took place at depths of ca 180-200km (probably close to the base of the continental lithosphere). The partially unmixed state of the inclusions provides a unique opportunity for using mineral diffusion data to roughly estimate the rate of transport through the asthenospheric upper mantle, and within error this rate is found to be broadly compatible with expected transport rates by upper mantle convection or plume flow. Springer-Verlag, 2007 Majorite nationallicence Exsolution nationallicence Eclogite nationallicence Garnetite nationallicence EBSD nationallicence Harte Ben Grant Institute of Earth Science, School of GeoSciences, University of Edinburgh, King's Buildings, EH9 3JW, Edinburgh, UK aut Cayzer Nicola Grant Institute of Earth Science, School of GeoSciences, University of Edinburgh, King's Buildings, EH9 3JW, Edinburgh, UK aut Physics and Chemistry of Minerals Springer-Verlag 34/9(2007-11-01), 647-656 0342-1791 34:9<647 2007 34 269 https://doi.org/10.1007/s00269-007-0178-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00269-007-0178-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Harte Ben Grant Institute of Earth Science, School of GeoSciences, University of Edinburgh, King's Buildings, EH9 3JW, Edinburgh, UK aut NATIONALLICENCE 700 1- Cayzer Nicola Grant Institute of Earth Science, School of GeoSciences, University of Edinburgh, King's Buildings, EH9 3JW, Edinburgh, UK aut NATIONALLICENCE 773 0- Physics and Chemistry of Minerals Springer-Verlag 34/9(2007-11-01), 647-656 0342-1791 34:9<647 2007 34 269 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer