Exploring the Abyss
Expanding Deep Sea Horizons: Setting Scientific Priorities in Abyssal Research
Alvin in the Abyss - Workshop
The final phase of the Alvin overhaul has just begun. When completed, it will enable human-occupied submersible diving to depths to 6,500 meters, and double the US research community's capacity to work at abyssal depths. Join the team that will identify and describe the critical scientific objectives for abyssal research and the technological requirements to achieve them. A series of three online, open workshops will provide a forum for community input. Participants will watch presentations by subject matter experts prior to the workshops, which will be kept short (90 min) and will be focused on small-group discussion. The results of the discussions will be used to develop a manuscript describing abyssal science objectives and a white-paper outlining key tasks for a 6500-meter Alvin Science Verification Cruise.
Workshops
(Attend one of the following: 10am EDT, 2pm PDT)
Abyssal Plains & Seamounts
Tuesday, June 16, 2020
Trenches & Transforms
Tuesday, June 30, 2020
Abyssal Technology & Societal Relevance
Tuesday, July 7, 2020
In-person meeting
Fall 2020
Workshop Website
Questions? ndsf@whoi.edu
Organizing Committee
Adam Soule, Woods Hole Oceanographic Institution (WHOI) Chief Scientist for Deep Submergence
Anna-Louise Reysenbach, Portland State University, Chair of DeSSC
Dorsey Wanless, Boise State University
Andreas Teske, University of North Carolina Chapel Hill
Tim Shank, WHOI
Jeff Marlow, Boston University
Rika Anderson, Carleton College
Jeff Seewald, WHOI
Bruce Strickrott, WHOI, Alvin Program Manager
Mid-Cayman Rise
The Mid-Cayman Rise the deepest spreading center at mid-latitudes. The spreading center sites within a transform margin between the N and S American Plates and is spreading at an ultraslow 1.5-1.7 cm/yr. There are thermally and chemically distinct hydrothermal vents and benthic biological communities at the spreading center driven by a diversity of geologic processes including magmatic accretion and oceanic core complex development that is exhuming lower crustal and upper mantle lithologies. The spreading center hydrothermal systems span depth ranges from ~2300 m at the rift margins to ~5000 m at the active magmatic section. The latter is the deepest known hydrothermal vent. Areas of the spreading center reach depths in excess of 7500 m.
Related Papers
Clarion-Clipperton Zone
The abyssal plain between the Clarion and Clipperton fracture zones and extending between Hawaii and Mexico is referred to as the Clarion-Clipperton Zone (CCZ). This region of the seafloor sits atop oceanic crust 30-80 Ma at depths of 4000-5500m. This area is notable for its rich polymetallic sulfide nodule deposits that has made it a primary target of companies and nation-states investigating the possibility of seafloor mineral extraction. The International Seabed Authority has granted 16 exploration contracts to assess mining.
Related Papers
Vema Fracture Zone
The Vema Fracture Zone is a transform boundary that separates the African and South American plate and has been active for 109 Ma. It offsets the Mid-Atlantic Ridge by 300 km juxtaposing 20 Ma and 0 Ma crust. The floor of the fracture zone lies below 5000 m for nearly all of its length. Signs of active hydrothermal fluid flow have been recognized within the fracture zone up to 120 km from the ridge axis. A diversity of benthic fauna are active within the fracture zone and are dominated by Crustacea. Most species are equally distributed across the entire fracture zone, but some species appear to be blocked by the MAR, leaving the question of the role of fracture zones as physical barriers to dispersal unanswered. Enhanced mixing of water masses in the Vema fracture zone have been shown to alter the relative abundance of viruses and bacteria.
Related Papers
Japan Trench
Owing to the Shinkai 6500 HOV and Kaiko ROV, the Japan trench is perhaps the best explored trench at abyssal depths. A steep subduction angle, due to 150 Ma ocean crust subducting under the Okhotsk plate, leads to a trench with an average depth >7500 m. On the forearm (landward side) of the trench, methane cold seeps have been located at depths from 5800 to 7500 m. Researchers have shown that deeper seeps show increased microbial abundances and have hypothesized that seep activity may increase approaching the trench. On the seaward side of the subduction zone, a new type of volcanism has been identified, ‘petit-spot volcanism’. These young (relative to plate age), small seafloor volcanoes are thought to form in response to the upward flexing of the subducting plate before it dives into the subduction zone. Decompression melting beneath this ‘bulge’ provides unique samples of depleted oceanic asthenosphere that is otherwise inaccessible.
Related Papers
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