First hydrothermal discoveries on the Australian‐Antarctic Ridge: Discharge sites, plume chemistry, and vent organisms

摘要: The Australian-Antarctic Ridge (AAR) is one of the largest unexplored regions global mid-ocean ridge system. Here, we report a multiyear effort to locate and characterize hydrothermal activity on two first-order segments AAR: KR1 KR2. To vent sites each segment, used profiles collected by Miniature Autonomous Plume Recorders rock corers during R/V Araon cruises in March December 2011. Optical oxidation-reduction-potential anomalies indicate multiple active both segments. Seven KR2 found 3 sites, separated ∼25 km. Forty identified 17 some within few kilometer other. spatial density along (plume incidence 0.34) consistent with trend for spreading rate ∼70 mm/yr. densest area activity, named “Mujin,” occurred 20 km-long inflated section near segment center KR1. Continuous plume surveys conducted January–February 2013 CH4/3He (1 − 15 × 106) CH4/Mn (0.01–0.5) ratios samples, basaltic-hosted system typical ridges intermediate rates. Additionally, samples exhibited slightly higher H2/3He Fe/Mn than others, suggesting that those plumes are supported younger may have experienced recent eruption. Mujin-field was populated Kiwa crabs seven-armed Paulasterias starfish previously recorded East Scotia Ridge, raising possibility circum-Antarctic biogeographic connections fauna.