May 8, 2004, Day 12
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.