Seamounts Cruise
May 8, 2004, Day 12
Locations of our dives from this expedition.
We completed our 10th and final dive Friday, May 7 at about 8 pm and
are now steaming to Moss Landing for arrival Saturday afternoon. Each
dive was a great success with new observations on submarine eruptive
deposits, benthic animal distribution, and even some great midwater
observations. We collected 332 rock samples, 19 push-cores, 7 sediment
scoops, and 175 animal samples (not counting the many animals recovered
from the rocks or from other collected animals).
The rocks will tell Alice, Dave, and Jenny about the formation of these
volcanoes (the what, where, when, how, and why questions!). We collected
volcaniclastic rocks from each seamount that formed during pyroclastic
(mildly explosive eruptions caused by escape of magmatic gases), even in
deep water. We have a broad collection of samples that should contain
glass rims or glass fragments that will allow us to analyze the volatile
components (water, carbon dioxide, and sulfur) that drive such
eruptions. The same collection of rocks will be chemically analyzed and
the data will help determine what melted to make the magmas and what
processes happened as the magmas were transported to the surface. We
also, once again, ended up with a small collection of erratics that we
will use to evaluate what the most abundant lithologies are. This
knowledge may help resolve some questions about the apparently complex
geology of the California Borderland, where much of the geology is
inferred from dredge samples that almost certainly include similar
erratics. Jim and Brandie will lead the study on the formation of Mn-Fe
crusts which will be analyzed to help us determine growth rates and
compositions of the crusts and how they buffer the compositions of many
metals in seawater. Finally, the large and small bamboo corals we
collected for Tessa will provide windows into past climate and ocean
circulation questions during her post-doctoral fellowship at University
of California at Davis. The single exploratory dive on the Patton
Escarpment recovered a range of rocks and sediments that Kathie will be
comparing with clastic sands recovered in several nearby Deep Sea
Drilling Sites.
The biologists also fared well. Joe, who is studying the genetic
relations of the seamount clams was rewarded with samples from
Rodriguez, San Juan, Patton Escarpment, and Northeast Bank. He also has
a new larger species recovered from shallower water to work on. We
collected three species of Paragorgia corals for an initial genetic
study that Amy Baco-Taylor at Woods Hole Oceanographic Institution is
undertaking. Amy was unable to come on the cruise, but we have samples
to send her that should provide enough information to plan a more
detailed study. Chuck Messing from Nova Southeastern University in
Florida, who was on our seamount cruise last fall, will be getting some
new samples of crinoids (his favorite animal) to study. Other collected
samples will be used to identify the many species we observed and will
become the basis of a study (perhaps by Lonny) on the distribution of
animals on seamounts and the relationships between animal populations
and environmental parameters. We also collected live predatory tunicates
and video of several animals for George Matsumoto at MBARI.
In addition to all this, we had several serendipitous encounters with a
foraging(?) Humboldt squid, a Vampyroteuthis squid, a Stauroteuthis
squid, a Tiburonia granrojo (Big Red jelly), and a large sleeper shark.
In each case we collected excellent video of these remarkable animals.--Dave Clague
The scientific party.