Brothers Volcano Multidisciplinar Drilling Project
IODP PEP PROPOSAL: 818-Pre
Brothers Volcano is located in the Kermadec Arc, north of New Zealand. The Brothers volcano has been extensively surveyed from surface vessels and submersibles. However, it lacks deep drilling, which is needed to understand its subseafloor hydrology and potential to form large accumulations of Cu-Au mineralisation. Two distinct hydrothermal systems of very different end-member chemical compositions exist within the same area, and drilling provides the opportunity to address scientific questions relevant to microbiology (this could be a biological hotspot), volcanology, and to the formation of significant ore bodies.
Proponents: C. de Ronde, W. Bach, L. Anderson, R. Arculus, F. Barriga, F. Caratori-Tontini, A. Dias, K. Haase, F. Marques, R. Henley, S. Humphris, J. Ishibashi, J. Parr, S. Petersen, A. Pinto, J. Relvas, A. Reyes, A. Reysenbachs, S. Robert, O. Rouxel, M. Schrenk, C. Timm, M. Tivey, M. Tivey, R. Wysoczanski, C. Yeats, R. Zierenberg, O. Ishizuka,
Summary
Drilling Brothers Volcano would provide the missing link (i.e., the 3rd dimension) in our understanding of mineral deposit formation along arcs, the sub-seafloor architecture of these volcanoes and their related permeability, and the relationship between the discharge of magmatic fluids and the deep biosphere. Through the recovery of cores at Brothers Volcano, we plan to pursue this objective through the following aims: (i) Characterizing the sub-volcano, magma chamber-derived volatile phase to test model-based predictions that this is either a single-phase gas, or two-phase brine-vapor. This will be achieved through the study of mineralogical, chemical and isotopic analysis of trapped volatiles and precipitates in veins and wall-rock reaction products; (ii) Exploring the sub-seafloor distribution of base and precious metals and metalloids, and the reactions that have taken place along pathways to the seafloor; (iii) Quantifying the mechanisms and extent of fluid-rock interaction, and consequences for mass transfer of sulfur and carbon metals and metalloid species, into the ocean; (iv) Assessing the diversity and extent of microbial life in an extreme, metal-toxic and acidic volcanic environment. The proposed drilling at Brothers Volcano is directly related to challenges identified in the IODP New Science Plan 2013-2023, including two under the Earth Connections theme, one under the Earth in Motion theme, and two under the Biosphere Frontiers Theme. Drilling through a thin veneer of sediments and into the Brothers volcanic architecture is proposed to achieve the aims identified above. Conceptual models of the sub-seafloor hydrothermal plumbing system at Brothers show hydrothermal flow has been interpreted in terms of advective flow structures and the direct discharge of magmatic volatiles, as given by the distinct setting of some of the vent fields. By contrast, the data also suggest that the flow system beneath the NW flank of Brothers Volcano could be defined at depth by a gas plume structure with shallow seafloor interactions leading to the geochemistry of the observed vent discharges and their surrounds. Recognizing the major differences between the gas- and water-dominated cone and caldera wall sites respectively, we will explore through drilling the evolution from juvenile (magmatic) to more evolved (seawater-dominated) fluids. Only through direct sampling of active systems will competing hypotheses regarding genesis and evolution of the feeder zones of seafloor hydrothermal systems be resolved. These systems are geomicrobiological frontiers, as the influence of magma degassing on the nature and activity of the subseafloor biosphere is unknown.
Drilling Brothers Volcano would provide the 3rd dimension in our understanding of mineral deposit formation along arcs, the sub-seafloor architecture of these volcanoes and their related permeability, and the relationship between the discharge of magmatic fluids and the deep biosphere. The recovery of cores at Brothers Volcano will allow the following to be achieved: (i) Characterization of the sub-volcano, magma chamber-derived volatile phase to test model-based predictions that this is either a single-phase gas, or two-phase brine-vapor. This will be achieved through the study of mineralogical, chemical and isotopic analysisof trapped volatiles and precipitates in veins and wall-rock reaction products; (ii) Exploration of the sub-seafloor distribution of base and precious metals and metalloids, and the reactions that have taken place along pathways to the seafloor; (iii) Quantification of the mechanisms and extent of fluid-rock interaction, and consequences for mass transfer of sulfur and carbon metals and metalloid species, into the ocean; (iv) Assessment of the diversity and extent of microbial life in an extreme, metal-toxic and acidic volcanic environment.
Magellan+ Workshop Report “Drilling an active hydrothermal system associated with a submarine intraoceanic arc volcano”: The purpose of the workshop was to bring together an international group of geologists, petrologists, geochemists, geophysicsists, and microbiologists to discuss and plan an IODP proposal to drill into a hydrothermal system hosted by the submarine Brothers volcano of the Kermadec intraoceanic arc. The group included specialists in volcanic processes, fluid geochemistry, fluid-rock interaction, ore deposit formation, petrology and geochemistry, geophysical exploration, and microbiology of extremophiles.