Internal distribution of Li and B in serpentinites from the Feather River Ophiolite, California, based on laser ablation inductively coupled plasma mass spectrometry

Abstract

[1] Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of B and Li in serpentinized peridotites from the Feather River Ophiolite (California) indicates that B is enriched in serpentine minerals compared to the whole-rock and less altered olivine grains, while Li in serpentine is depleted or comparable to whole-rock Li. The high B contents of serpentine minerals correlate with the relatively enriched whole-rock B contents. The low Li contents of serpentine minerals are consistent with the relatively low Li whole-rock contents and suggest that only small amounts of Li were added during serpentinization or that some Li was even leached out. A simple model of partial melting shows that Li/Yb increases with increasing melt depletion (and clinopyroxene depletion) in the peridotitic residue because Li is most compatible in olivine while Yb is most compatible in clinopyroxene. Thus, high Li/Yb ratios in peridotites by themselves do not indicate secondary enrichments in Li. However, Li/Yb and Yb contents of many of the Feather River Ophiolites plot above the melt depletion curve in Li/Yb versus Yb space, indicating that these serpentinites experienced subtle and preferential enrichments in Li during serpentinization. If serpentinized oceanic lithospheric mantle, as represented by the Feather River Ophiolite, is important in subduction recycling, then recycled mantle domains having a serpentinite protolith might be characterized by strong B enrichments but only small Li enrichments.

Zn/Fe systematics in mafic and ultramafic systems: Implications for detecting major element heterogeneities in the Earth’s mantle

“…For each analysis, the detection limit was estimated at three times the standard deviation of the background divided by the sensitivity. Additional details of analytical procedures are given in Lee et al (2008).…”

Mineral replacement rate of olivine by chrysotile and brucite under high alkaline conditions

“…where (-OH) theoretical is the theoretical weight (in %) of hydroxyl groups incorporated in chrysotile (400 1C-700 1C) with a chemical formula simplified to Mg 3 Si 2 O 5 (OH) 4 for the (-OH) theoretical considered. Then, the serpetinization extent was correlated with reaction time (x t vs. t).…”

“…Serpentine mineralization is of great interest in several fields of research. Serpentinized rocks present a great enrichment in trace elements compared to primary mantle rocks [1][2][3][4][5][6]. Serpentine appears as a vector for trace elements between crustal and mantle reservoirs [2,5,7,8].…”

Field and model constraints on silicic melt segregation by compaction/hindered settling: The role of water and its effect on latent heat release

“…Whole-rock analyses were completed at the USGS by fusion of powders followed by solution ICP-AES. Mineral chemistries were determined by laser ablation ICP-MS at Rice University (Lee et al 2009). Data are available in the supplementary tables (Appendix Tables 1-6 1 ).…”