Parageneses of TiB2in corundum xenoliths from Mt. Carmel, Israel: siderophile behavior of boron under reducing conditions

William L. Griffin*, Sarah E.M. Gain, Martin Saunders, Luca Bindi, Olivier Alard, Vered Toledo, Suzanne Y. O'Reilly

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Titanium diboride (TiB2) is a minor but common phase in melt pockets trapped in the corundum aggregates that occur as xenoliths in Cretaceous basaltic volcanoes on Mt. Carmel, north Israel. These melt pockets show extensive textural evidence of immiscibility between metallic (Fe-Ti-C-Si) melts, Ca-Al-Mg-Si-O melts, and Ti-(oxy)nitride melts. The metallic melts commonly form spherules in the coexisting oxide glass. Most of the observed TiB2 crystallized from the Fe-Ti-C silicide melts and a smaller proportion from the oxide melts. The parageneses in the melt pockets of the xenoliths require fO2 ≤ ΔIW-6, probably generated through interaction between evolved silicate melts and mantle-derived CH4+H2 fluids near the crust-mantle boundary. Under these highly reducing conditions boron, like carbon and nitrogen, behaved mainly as a siderophile element during the separation of immiscible metallic and oxide melts. These parageneses have implications for the residence of boron in the peridotitic mantle and for the occurrence of TiB2 in other less well-constrained environments such as ophiolitic chromitites.

Original languageEnglish
Pages (from-to)1609-1621
Number of pages13
JournalAmerican Mineralogist
Volume105
Issue number11
DOIs
Publication statusPublished - Nov 2020

Keywords

  • Titanium boride
  • reducing conditions
  • siderophile element
  • Mt. Carmel
  • paragenetic studies
  • Lithium
  • Beryllium
  • Boron: Quintessentially Crustal

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