30 Applications of Igneous Petrology, Geochemistry, and Geochronology to Understanding Earth and Other Planetary Systems
This session invites contributions that explore igneous systems through traditional and nontraditional methods. Studies that link crustal evolution, planetary formation, resource potential, and comparative planetology across temporal and spatial scales are especially encouraged.
Tuesday, 10 March 2026
1:30 PM - 3:30 PM
RCC, 104
Fe-Ti oxide infiltration and fluid pumping in mid-ocean ridge gabbros
Paper number: 30-4
Program: Technical Sessions
Time: 2:30 PM – 2:45 PM
Authors
Abstract
Fe-Ti oxides typically crystallize last on the solidus and make up a small portion of mid-ocean ridge gabbros. However, in some samples Fe-Ti oxides can reach up to 30%, especially in systems with deformation like oceanic core complexes formed at slow-spreading ridges. Oceanic core complexes are bathymetric highs that exhume lower crustal and upper mantle rocks along a detachment shear zone/fault. The Atlantis Bank oceanic core complex on the SW Indian Ridge has been drilled by three IODP expeditions to depths of up to 1.5 km below seafloor, including samples with high proportions of Fe-Ti oxides that range from having primary igneous textures to ultramylonites. These samples likely required a focusing mechanism to enrich the samples with Fe-Ti oxides, many of which include olivine. Fe-Ti oxides exhibit complex, lobate to angular contacts with silicate phases and often fully incorporate silicate phases and aggregates. Chemically, Fe-Ti oxide gabbro ranges from having distinct bulk rock compositions to overlapping with olivine gabbro. In Atlantis Bank, given the complex textures, it appears the Fe-Ti oxides crystallized from a melt and infiltrated both more evolved and more primitive gabbros. Fe-Ti oxide formation could be associated with differentiation by deformation where mushy zones are sheared causing efficient crystal-liquid separation driving the melt to more Fe-Ti enriched compositions. Fe-Ti rich melt should be denser than most silicate melts, but also much less viscous, making it more reactive to pressure gradients. As zones deform and pore spaces open, Fe-Ti rich melt may be drawn in, leading to a volume increase and dilation, which could lead to more influx of melt, creating a fluid pump as part of a positive feedback. It is suggested that Fe-Ti oxide rich systems are more likely in deformed systems from the creation of more evolved, Fe-Ti rich melt and opening of pore space for melt infiltration. These zones are mechanically weaker because of the influx of melt and the presence of Fe-Ti oxides, making them more likely to accommodate strain, and could be of interest for the localization of Ti.
Geological Society of America Abstracts with Programs. Vol. 58, No. 1
doi: 10.1130/abs/2026SE-411842
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