47035
Accession Number
37313
Title Of Article Chaper
Basaltic Glass with High-Temperature Equilibrated Immiscible Sulphide Bodies with Native Iron from Disko, Central West Greenland
Title Of Journal Book
Contributions to Mineralogy and Petrology
Volume
69
Issue
4
Pages
397-407
Collation
11 p. : ills.
Reference Bibliography
Includes bibliographic references
Language Of Text
English
Literature Type
Serial
Literature Level
Analytic
Abstract
Immiscible sulphide bodies show eutectic quench textures in a basaltic glass rock (mg=66) from a native iron-bearing dyke chilled at T=1,200° C and P=250 bars. The sulphide bodies are composed of troilite (90–91%), iron (9–10%) and very scarce vanadium-rich chromite and approach a ternary cotectic in the Ni-poor part of the system Fe-Ni-S. Transition element partition between olivine (mg=83), silicate glass (mg=59) and sulphide blebs indicate that the phases were equilibrated at 1,200° C. Dvanadium(olivine/glass) is close to unity and reflect the reducing nature of the rock, for which estimates of fO2?10?12 to ?13 and fS2?10?5 have been made. Dnickel, cobalt, copper (sulphide/glass)=4,300, 230 and 380 respectively, are much higher than reported experimentally determined D's onmonosulphide/basalt glass at the same temperature and show increasing positive deviation (?Ni>?Co>?Cu) with the increasingly siderophile character of the elements. KDnickel-iron (sulphide/olivine)=63 is much higher than an experimentally reported value (33) and comparison with published thermodynamic data on Ni-partition between olivine and iron metal suggests that the positive deviation is roughly proportional to the excess metal component in the sulphide melt. The occurrence of strongly Ni-depleted reduced basalts on Disko shows that fractionation of metal and sulphides was a common and geologically important process.
Keywords
basalt;glass;temperature;iron
pub_id
47035