Sulfide minerals in mantle xenoliths from the Kurose reef, Fukuoka Prefecture, Japan

Abstract

Mineral assemblages of sulfides in the mantle peridotite xenoliths embedded in the alkali basalts of the Kurose reef, northern Kyushu, Japan and the chemical compositions of the mineral assemblages are described. Sulfides occur as 1) inclusions and 2) interstitial sulfides in olivine or pyroxene. The mineral assemblages of sulfides that occur as inclusions are pentlandite, pentlandite + chalcopyrite, pentlandite + bornite, monosulfide solid solution (mss) + chalcopyrite ± pentlandite, pentlandite + pyrrhotite, and millerite; and the mineral assemblage of sulfides as interstitial sulfides is pyrrhotite + pentlandite + chalcopyrite. The contents of Ni, Fe, and S in pentlandite are 22.91 -33.45, 18.77 -28.82, and 46.57 -48.31 at%, respectively. The chemical composition of mss is variable. On the basis of the crystallization temperature of olivine and/or pyroxene and the phase relationship between the Fe -Ni -S and the Fe -Cu -S systems, it can be inferred that the mineral assemblage of mss + chalcopyrite ± pentlandite found in olivine is considered to have been initially trapped as a solid -phase Cu -bearing mss and that the other mineral assemblages were trapped as a sulfide liquid. The diversity of mineral assemblages of sulfides in the mantle peridotite xenoliths and the various chemical compositions of the mineral assemblages are due to timing of differential crystallization of mss and its capture in silicate minerals. It can also be inferred that the chemical composition of the initial sulfide liquid in the Kurose lherzolite is the S -poor portion of the Cu -bearing mss. This suggests that initial sulfide liquids in the upper mantle might have similar compositions.

Evolution of carbon dioxide-bearing saline fluids in the mantle wedge beneath the Northeast Japan arc

“…2e), and their chemical composition is presented in Table 3. The maximum crystallization temperature of the sulfide (mss) is estimated to be 900 °C using the chemical composition of the mss, based on phase relations in the Fe-Ni-S system (Kullerud et al 1969;Shindo et al 2009). …”

Trace-Element Geochemistry of Sulfides in Upper Mantle Lherzolite Xenoliths from East Antarctica

“…Although the majority of information on mantle sulfides from elsewhere is derived from the PGE, we also considered the concentrations and distributions of trace [48]. The green dashed line borders a field where mss coexists with sulfide liquid at 1000 • C. The thin dashed line borders sulfide liquid field from that of mss + liq at 1000 • C (after Shindo et al [13]). Empty symbols are for sulfides from Cpxpoor Spl lherzolites; grey symbols are for sulfides from Cpx-rich Spl lherzolites; solid symbols are for sulfides from Spl-Grt lherzolittes.…”

“…Sulfide minerals are a common accessory phase (<0.1%) in mantle rocks and are typically represented by pentlandite, pyrrhotite, and chalcopyrite [13][14][15][16]. Despite their Sulfide minerals in peridotite xenoliths from East Antarctica were heretofore almo completely unstudied.…”