Alchemy in the Abyss—USGS Public Lecture on Deep-Ocean Minerals

By Helen Gibbons July 2007

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Above: White chimneys at Champagne vent site in the active Mariana Arc, western Pacific Ocean. Chimneys are approximately 20 cm (8 in) across and 50 cm (20 in) high, venting fluids at 103°C (217°F). Notice the unusual bubbles of liquid CO2 in upper left. Photograph taken April 2004 during Pacific Ring of Fire 2004 Expedition conducted by the National Oceanic and Atmospheric Administration (NOAA) Office of Ocean Exploration; Bob Embley (NOAA Pacific Marine Environmental Laboratory), chief scientist. (See related Sound Waves article, "Exciting New Discoveries in Submarine Hydrothermal Systems, Commonwealth of the Northern Mariana Islands".) [larger version]

U.S. Geological Survey (USGS) marine geologist James Hein introduced listeners to the mysteries of deep-ocean minerals in a public lecture titled "Alchemy in the Abyss" on May 31 at the USGS center in Menlo Park, California. The demand for metals is increasing dramatically, especially in Asia, and nations are exploring to see whether mineral deposits in the deep ocean can help supply the new markets. Jim described the three main types of deep-ocean deposits:

• Polymetallic sulfide deposits forming rapidly at submarine hot springs, called hydrothermal vents, along volcanically active midocean ridges and island arcs,
• Slow-forming manganese nodules occurring over vast areas of the sediment-covered abyssal depths, and
• Cobalt-rich ferromanganese crusts forming extremely slowly on sediment-free tops and flanks of undersea mountains called seamounts. (See Sound Waves article, "Beam Time at the Stanford Linear Accelerator Awarded to USGS Scientist," to learn about Jim's study of these crusts.)

The audience was fascinated by Jim's tales of deep-sea exploration using manned submersibles and remotely operated vehicles (ROVs). The lecture incorporated videos taken during some of Jim's cruises, including footage shot from an ROV of the first deep-sea volcanic eruption to be caught on film. The scientists thought they were filming a sulfur-rich hydrothermal plume until they saw dark rock fragments being ejected. The ROV was quickly retrieved and, once back on deck, was seen to be spattered with blobs of elemental sulfur from the eruption ejecta. (Read more about this expedition in "Exciting New Discoveries in Submarine Hydrothermal Systems," Sound Waves, July 2004.)

Nautilus Minerals, Inc., based in Canada and Australia, plans to begin mining polymetallic sulfides (for gold and copper) from extinct hydrothermal mounds in the Exclusive Economic Zone (sea floor within 200 nautical miles) of Papua New Guinea in 2009, a fact that sparked questions about possible environmental impacts. Not much is known about deep-ocean ecosystems outside those at active vent sites, but other deep-ocean ecosystems are beginning to receive increasing attention through major international cooperative programs.

The talk ended with a lively question-and-answer session, and many audience members lingered to speak to Jim afterwards. To see an archived video of the lecture, visit URL http://online.wr.usgs.gov/calendar/2007.html (scroll down).

Beam Time at the Stanford Linear Accelerator Awarded to USGS Scientist May 2007

Exciting New Discoveries in Submarine Hydrothermal Systems July 2004

USGS Western Region - Evening Public Lecture Series USGS (U.S. Geological Survey)

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July 2007

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in this issue:

cover story:
Newly-Discovered Fossil Sponges

Public Lecture: Alchemy in the Abyss

USGS at Florida's Marine Quest

College Students Introduced to USGS Studies

Potential Impacts of Future Sea-Level Rise

Onshore-Offshore Geologic Map Workshop

High-Resolution Map Merges Tampa Bay Bathymetry and Topography

70 Years of Coastal Cliff Retreat in California

July Publications List