Evidence for H2O-bearing fluids in the lower mantle from diamond inclusion

M. Palot*, S. D. Jacobsen, J. P. Townsend, F. Nestola, K. Marquardt, N. Miyajima, J. W. Harris, T. Stachel, C. A. McCammon, D. G. Pearson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

In this study, we report the first direct evidence for water-bearing fluids in the uppermost lower mantle from natural ferropericlase crystal contained within a diamond from São Luíz, Brazil. The ferropericlase exhibits exsolution of magnesioferrite, which places the origin of this assemblage in the uppermost part of the lower mantle. The presence of brucite–Mg(OH)2 precipitates in the ferropericlase crystal reflects the later-stage quenching of H2O-bearing fluid likely in the transition zone, which has been trapped during the inclusion process in the lower mantle. Dehydration melting may be one of the key processes involved in transporting water across the boundary between the upper and lower mantle.

Original languageEnglish (US)
Pages (from-to)237-243
Number of pages7
JournalLithos
Volume265
DOIs
StatePublished - Nov 15 2016

Funding

We are very grateful to the editor, Geoff Bromiley, and an anonymous reviewer for their constructive and careful reviews that improved the strength and clarity of this manuscript. MP was supported by the Deep Carbon Observatory and a Canada Excellence Research Chair award to DGP. SDJ acknowledges support from the NSF ( EAR-1452344 ), the Carnegie/DOE Alliance Center (CDAC) , the David and Lucile Packard Foundation , and the Alexander von Humboldt Foundation . Portions of this work were performed at beamline U2A of the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory. U2A is supported by COMPRES under NSF Cooperative Agreement EAR 11-57758 and DOE-NNSA ( DE-FC-52-O8NA28554 , CDAC). Use of the NSLS was supported by the DOE-BES ( DE-AC02-98CH10886 ). FN is supported by the ERC Starting Grant (no. 307322 ). The diamond used for this study was kindly donated by De Beers to JWH. We thank Zhenxian Liu for his help with the synchrotron–FTIR measurements and Sylvain Petitgirard for help with FIB sample preparation. The FIB facility at Bayerisches Geoinstitut is supported by DFG grant INST 91/315-1 FUGG .

Keywords

  • Brucite
  • Deep water cycle
  • Dehydration melting
  • Diamond
  • Ferropericlase
  • Lower mantle
  • Magnesioferrite

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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