Major and trace element composition of olivine from magnesian skarns and silicate marbles

Abstract

Olivine is a major rock-forming mineral in various magmatic and metamorphic rocks and the upper mantle. In this paper, we present the first high-precision analyses of olivine from 15 samples of magnesian skarns and silicate marbles (MSSM) from the collection of the Fersman Mineralogical Museum (Moscow, Russia). Mg# [Mg/(Mg+Fe2+)·100, mol%] of olivine from the samples studied varies from 86 to nearly 100. The main distinctive features of the olivine are anomalously low contents of Co (<51 mg/g), Cr (<5 mg/g), and Ni (<44 mg/g) and high content of B (23–856 mg/g), which correlate with host-rock compositions. Phosphorus (5–377 mg/g) incorporation in olivine is charge balanced by the incorporation of Li (0.15–61 mg/g) and Na (<14.3 mg/g). Y and REE contents exhibit positive correlations with Na, which suggests that REE incorporation into MSSM olivine could occur via charge-balanced coupled substitution with Na at low temperature and low aSiO2 conditions during MSSM formation. The documented compositional features of olivine from magnesian skarns and silicate marbles can help reconstruct the genesis of the host-rocks and identify xenocrysts of MSSM olivine in magmatic rocks.

Extremely Stable, Highly Conductive Boron‐Hydrogen Complexes in Forsterite and Olivine

“…Despite this olivines with very high boron concentrations (23–2,100 wt. ppm) have been found (Demouchy & Mackwell, 2003; Kent & Rossman, 2002; Nekrylov et al., 2021; Sykes et al., 1994; Wang et al., 2020) and forsterite enriched in boron (160–230 wt. ppm) have been produced in wet conditions (Gose et al., 2010; Ingrin et al., 2014).…”

“…Boron enrichment in olivine is generally considered to occur through contact with boron‐containing fluids in metasomatic processes (Nekrylov et al., 2021; Ottolini et al., 2004; Sykes et al., 1994; Tenthorey & Hermann, 2004). One such process is serpentine dehydration which can produce olivine with [B] up to 100 wt.…”

“…Another is through the formation of magnesian skarns through contact metasomatism which can have up to 856 wt. ppm B (Nekrylov et al., 2021). The jianite in Wang et al.…”

“…Another is through the formation of magnesian skarns through contact metasomatism which can have up to 856 wt. ppm B (Nekrylov et al, 2021). The jianite in Wang et al (2020) is of unknown petrogenesis but has a very high B content (1,697-1,804 wt.…”

Experiments on Distribution of Divalent Metal Cations between Olivine Solid Solutions and Aqueous Chloride Solutions at 700 °C and 100 MPa

“…Olivine is one of major silicate minerals of ultramafic and mafic igneous rocks. Olivine also produced by the involvement of hydrothermal fluids occurring in skarns formed by replacing dolomite or magnesite (e.g., [8]). Granitic rocks are often involved in the formation of the skarns.…”