Results of the Arctic Mid-Ocean Ridge Expedition (AMORE 2001) - Seafloor Spreading at the Top of the World

摘要

The Arctic Mid-Ocean Ridge Expedition (AMORE 2001) returned in early October 2001 after an incredibly sucessful ten-week study of the Gakkel Ridge and its surrounding basins in the high Arctic. AMORE 2001 was an international effort involving two icebreakers: PFS Polarstern, from the Alfred Wegener Institute in Bremerhaven, Germany and the new U.S. icebreaker, USCGC Healy. It was Healy's maiden scientific voyage, and she proved to be an excellent icebraker and scientific platform. This historic and highly sucessful expedition far exceeded anyone's expectations and went well beyond the goals set forth by InterRidge (Vol. 10 (1), 2001) in charting and sampling the Gakkel Ridge. Some of the highlights of the expedition are:1. Basalts and peridotites were recovered from over 200 sites within and near the axis of Gakkel Ridge, about three times as many sites as were planned. 2. Hydrothermal plumes were discovered and sampled along this ultraslow spreading ridge. 3. A high-resolution, well-navigated map of the ridge was unexpectedly produced using two hull-mounted multibeam sonar systems, which worked far better in the ice than anticipated. 4. Sucessful seismic measurements showed that crustal thickness varies strongly along the axis of Gakkel Ridge, most likely according to distinct volcanic centers. 5. The crustal thickness in the Nansen Basin does not follow theoretical models, which predict thin crust at slow spreading rates. The crust thickens towards the Gakkel Ridge.