Compositions, growth mechanisms, and temporal relations of hydrothermal sulfide‐sulfate‐silica chimneys at the northern Cleft segment, Juan de Fuca Ridge

摘要: Three active hydrothermal vents forming sulfide mounds and chimneys (Monolith, Fountain, Pipe Organ) more widely distributed inactive are spatially related to a system of discontinuous fissures young sheet flow lavas at the northern Cleft segment, Juan de Fuca Ridge. The formation zoned tubular Curich (type I) on Monolith mound is focused high-temperature (to 328°C) fluid. Bulbous II or “beehives”) Fountain products diffuse 315°C) discharge. A broader zone vigorous mixing between fluid seawater results in quench crystallization anhydrite-rich shells. Columnar Zn-sulfide-rich with narrow channelways III) constructed where relatively low-temperature (261°C) directly from basalt substrate. bulk chemistry (low Cu; high Pb, Ag, SiO2 contents), mineralogy (pyrite-marcasite-wurtzite-amorphous silica-anglesite), colloform filamentous textures, oxygen isotope characteristics IV) indicate (<250°C) origin involving sluggish patterns conductive cooling. Seafloor observations 210Pb data that (1) type IV an earlier period activity ended no than 60 years ago but prior eruption, (2) manifestations same heating event (shallow emplacement magma) led eruption recent megaplumes, (3) Organ Vent very youthful stage development chimney deposition postdates eruption.