Abstract

Magnetite (Fe3O4) is an iron ore mineral that is globally mined especially for steel production. It is denser (5.15 g/cm3) than Earth’s crust (~2.7 g/cm3) and is expected to accumulate at the bottom of melt-rich magma reservoirs. However, recent studies revealed heterogeneous fluid bubble nucleation on oxide minerals such as magnetite during fluid degassing in volcanic systems. To test if the attachment on fluid bubbles is strong enough to efficiently float magnetite in silicate magma, decompression experiments were conducted at geologically relevant magmatic conditions with subsequent annealing to simulate re-equilibration after decompression. The results demonstrate that magnetite-bubble pairs do ascend in silicate melt, accumulating in an upper layer that grows during re-equilibration. This outcome contradicts the paradigm that magnetite must settle gravitationally in silicate melt.

Details

Title
Accumulation of magnetite by flotation on bubbles during decompression of silicate magma
Author
Knipping, Jaayke L 1 ; Webster, James D 2 ; Simon, Adam C 3 ; Holtz François 4 

 Leibniz Universität Hannover, Institut für Mineralogie, Hannover, Germany (GRID:grid.9122.8) (ISNI:0000 0001 2163 2777); American Museum of Natural History, Department of Earth and Planetary Science, New York, USA (GRID:grid.241963.b) (ISNI:0000 0001 2152 1081) 
 American Museum of Natural History, Department of Earth and Planetary Science, New York, USA (GRID:grid.241963.b) (ISNI:0000 0001 2152 1081) 
 University of Michigan, Department of Earth and Environmental Sciences, Ann Arbor, USA (GRID:grid.214458.e) (ISNI:0000000086837370) 
 Leibniz Universität Hannover, Institut für Mineralogie, Hannover, Germany (GRID:grid.9122.8) (ISNI:0000 0001 2163 2777) 
Publication year
2019
Publication date
Dec 2019
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2188972637
Copyright
This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.