Northern 2016 Expedition
July 26-August 16, 2016
MBARI’s research vessel Western Flyer and remotely operated vehicle Doc Ricketts are on a three-week expedition to the waters off the coasts of Oregon and Washington. The Submarine Volcanism Project has been studying the formation of Axial Seamount for about 10 years. This year we have three subjects we want to address. The first of these is to characterize and map the new flows erupted about a year ago. This work involves AUV mapping of the upper half of the north rift zone followed by ROV dives to collect all the flows that remain unsampled. The second study is to determine the age, volume, flow emplacement style, and composition of several extensive lava flows on the distal south rift. These flows are so voluminous that their eruption may have led to collapse or formation of the caldera at the summit of Axial Seamount. We will study them by first mapping them with our mapping AUVs and then sampling the flows and the sediments on top to determine their compositions and ages. The third research topic is to continue to collect and analyze a two-meter thick section of volcanic sediments on the caldera rims. These deposits of volcanic fragments formed during explosive eruptions that were also symptomatic of caldera formation.
The Submarine Volcanism group is sharing the first leg of the dive program with the Molecular Ecology group at MBARI and the National Oceanography Centre in Southampton, UK. They are interested in understanding genetic differences that produce the extremely different body shapes (long and skinny or short and fat) of the vent tubeworm, Ridgeia piscesae. We are also studying similar genetic differences in two closely related species of palm worms, Paralvinella sulfincola and P. palmiformis, that live in different temperatures on vent chimneys. They will be collected at hydrothermal vent sites at Escanaba Trough, N. Gorda Ridge, N. Cleft, and the summit of Axial Seamount. In addition, water samples will be collected around vent fields to understand how chemosynthetic microbes and the larvae of benthic invertebrates that inhabit hydrothermal vents are distributed. Hydrothermal vents are really exciting to visit, especially since, with the exception of Axial Seamount, these sites have not been observed or sampled since the early 2000s so geochemical fluids will be sampled to determine changes in the systems over time.