Schoneveld, L and Barnes, SJ and Godel, B and Le Vaillant, M and Yudovskaya, MA and Kamenetsky, V and Sluzhenikin, SF, Oxide-sulfide-melt-bubble interactions in spinel-rich taxitic rocks of the Norilsk-Talnakh intrusions, polar Siberia, Economic Geology, 115, (6) pp. 1305-1320. ISSN 0361-0128 (2020) [Refereed Article]
© 2020 Society of Economic Geologists, Inc
Oxide-rimmed, spherical structures interpreted as former gas bubbles have been discovered within a chromitiferous taxitic lithology of the Norilsk-Talnakh intrusions. These rocks are represented by variable grain size, presence of reworked country-rock xenoliths and millimeter- to centimeter-scale irregular spinel-rich aggregates, patches, or disrupted seams and stringers. They contain spherical and subspherical agglomerations that we interpret as amygdules, partially or completely filled with low-temperature hydrothermal minerals and locally with magmatic phases including sulfide globules. In places these amygdules form clusters that are interpreted as former bubble foams.
The wetting relationships visible between vapor bubbles, silicate melt, sulfide liquid, and oxide were investigated in detail using 3-D μX-ray tomography and detailed 2-D X-ray fluorescence maps. They also reveal short-range spatial variability in silicate and oxide minerals, reflecting small-scale advanced fractionation of silicate melt.
Three possible mechanisms are considered for the formation of these bubble-spinel foams: (1) the abundant spinel allows for the in situ nucleation of vapor bubbles, (2) the vapor bubbles ascend through the magma and collect spinel, or (3) the vapor bubbles cause rapid nucleation of chromite within these layers. Although none of these mechanisms can be exclusively ruled out, the texture and chemistry of the Norilsk-Talnakh chromitiferous taxitic lithology is most indicative of in situ nucleation of vapor bubbles on spinel surfaces (i.e., mechanism 1).
|Item Type:||Refereed Article|
|Keywords:||Norilsk, Cr-spinel, noble metals|
|Research Division:||Earth Sciences|
|Research Field:||Igneous and metamorphic petrology|
|Objective Division:||Mineral Resources (Excl. Energy Resources)|
|Objective Group:||Mineral exploration|
|Objective Field:||Precious (noble) metal ore exploration|
|UTAS Author:||Kamenetsky, V (Professor Vadim Kamenetsky)|
|Web of Science® Times Cited:||8|
|Deposited By:||CODES ARC|
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