Wasylenki, Laura E. and Baker, Michael B. and Kent, Adam J. R. and Stolper, Edward M. (2003) Near-solidus Melting of the Shallow Upper Mantle: Partial Melting Experiments on Depleted Peridotite. Journal of Petrology, 44 (7). pp. 1163-1191. ISSN 0022-3530. http://resolver.caltech.edu/CaltechAUTHORS:20111026-152702674
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We present the results of melting experiments on a moderately depleted peridotite composition (DMM1) at 10 kbar and 1250–1390°C. Specially designed experiments demonstrate that liquids extracted into aggregates of vitreous carbon spheres maintained chemical contact with the bulk charge down to melt fractions of ~0·02–0·04 and approached equilibrium closely. With increasing melt fraction, SiO_2, FeO*, and MgO contents of the partial melts increase, Al_(2)O_3 and Na_(2)O contents decrease, and CaO contents first increase up to clinopyroxene-out at a melt fraction of 0·09–0·10, then decrease with further melting. A linear fit to melt fraction vs temperature data for lherzolite-bearing experiments yields a solidus of 1272 ± 11°C. The melting reaction is 0·56 orthopyroxene + 0·72 clinopyroxene + 0·04 spinel = 0·34 olivine + 1 liquid. Above clinopyroxene-out, the reaction is 1·24 orthopyroxene = 0·24 olivine + 1 liquid. Near the solidus, DMM1 glass compositions have lower SiO_2, TiO_2, Na_(2)O, and K_(2)O contents, higher FeO*, MgO, and CaO contents, and higher CaO/Al_(2)O_3 ratios compared with glasses from low-degree melting of fertile peridotite compositions. Recent computational models predict partial melting trends generally parallel to our experimental results. We present a parameterization of 10 kbar peridotite solidus temperatures suggesting that K_(2)O and P_(2)O_5 have greater effects on solidus depression than Na_(2)O, consistent with theoretical expectations. Our parameterization also suggests that abyssal peridotites have 10 kbar solidi of ~1278–1295°C.
|Additional Information:||© 2003 Oxford University Press. Received September 18, 2001; Accepted February 5, 2003. The authors are grateful for helpful discussions with and/or laboratory support from Marc Hirschmann, Glenn Gaetani, John Beckett, and Paul Asimow. We thank Ian Hutcheon and Doug Phinney for assistance with the ion microprobe measurements. We also thank Charles Lesher, Keith Putirka, and Brandon Schwab for helpful reviews. This work was supported by National Science Foundation grant OCE93-14505. This research was also funded in part by stipend support for L.E.W. from the National Physical Science Consortium and NASA-Johnson Space Center.|
|Subject Keywords:||depleted; experimental petrology; mantle melting; near-solidus; peridotite|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||27 Oct 2011 22:30|
|Last Modified:||09 Dec 2016 05:50|
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