..., and the Upper Cone hydrothermal vent field (Site U1528 and Hole U1528D), which discharges predominantly diffuse, acidic fluids (pH 1.9). These two active vent sites were drilled in 2018 by International Ocean Discovery Program (IODP) Expedition 376. Fluid inclusions hosted in anhydrite, quartz, barite...

... in NRM intensity (i.e., <1% of the initial NRM value). Fig. 1. Brothers volcano bathymetry (m) with locations of International Ocean Discovery Program (IODP) drill sites (black dots). Inset shows the tectonic setting and location of Brothers volcano in the Havre Trough, between the Colville...

... with hydrothermal fluid upflow zones (Caratori Tontini et al., 2012) and incorporate the known vent fields (with the exception of the Lower Cone), including Upper Caldera, NW Caldera, West Caldera, SE Caldera (extinct), and Upper Cone. International Ocean Discovery Program (IODP) drill sites referred to throughout...

... et al., 2012 ) that are suggested to represent zones of high-temperature fluid upflow. Yellow stars mark drilling locations (IODP Expedition 376) from which samples used in this study came. The red line refers to the cross section shown in Figure 4 . The rocks at the Upper Cone site (U1528...

... of Hole U1530A ( de Ronde et al., 2019d ). Fig. 1. A) Detailed bathymetry of Brothers volcano and its environs (after Embley et al., 2012 ), and the location of sites drilled during IODP Expedition 376. Labels designate North fault (NF), South fault (SF), North rift zone (NRZ), Upper Cone (UC...

... the cooling magma have a high ore-forming potential. International Ocean Discovery Program (IODP) Expedition 376, “Brothers Arc Flux” (May 5–July 5, 2018), drilled a total of five sites (U1527 to U1531) into the edifice of Brothers volcano ( de Ronde et al., 2019a ). The objective of the expedition...

... forming. In 2018, International Ocean Discovery Program (IODP) Expedition 376 recovered drill cores from an active hydrothermal field at Brothers volcano, in the Kermadec arc. These provide insight into the formation of mineral deposits along arcs, the structure and permeability of hydrothermal sites...

... Program (IODP) Expedition 376 ( de Ronde et al., 2019a ) drilled five sites on Brothers volcano between May and July 2018, recovering 222.4 m of core that consists largely of dacitic volcaniclastics (breccia) and lava flows. Alteration is pervasive, and mineral assemblages are complex and variable...

... the relationship between hydrothermal fluid composition and host rock alteration. Fig. 2. Bathymetric map of Brothers volcano showing the approximate location of drill sites investigated in this study: NW Caldera rim (Site U1527), NW Caldera wall (Site U1530), and Upper Cone (Site U1528). See Table 1...