Gulf of California 2012
Faults, Vents, and Seeps I
March 26-April 17, 2012
Most of the Gulf of California’s long, narrow seafloor basins are associated with transform faults, where segments of the Earth’s crust slide past one another. Throughout the gulf, transform faults alternate with volcanic spreading centers (see map here). Researchers will use the ROV Doc Ricketts to search along the transform faults for evidence of recent geologic activity on the seafloor, especially active faulting, underwater landslides, gas vents, or fluid seeps.
During these legs, researchers will first conduct a series of exploratory dives, looking at potentially active seafloor areas that have been identified using maps created by the MBARI seafloor-mapping AUV. They will be ground truthing the recently collected AUV maps and collecting physical evidence of recent geologic activity. They will return to specific sites to collect samples of seafloor fluids and seafloor animals for biological and geochemical studies to further investigate sites of seafloor fluid seepage.
Some of the specific objectives of these cruises will be:
- To identify individual transform faults and determine how active they are.
- To determine whether fluid and gas venting occurs uniformly along these transform faults, or if it is focused near volcanic spreading centers (ridge crests)
- To collect deep-sea tubeworms (a typical inhabitant of seafloor seeps) so that biologists can study the unique microbes that live inside these tubeworms. The microbes allow tubeworms to live off of chemicals in the seep fluids that would be toxic to most other animals. Biologists on the cruise hope to use DNA and RNA from the microbes to determine how they vary from one part of the gulf to another, and if they are related to the chemistry of fluids or sediments at individual seeps.
- To use an instrument called an In Situ Ultraviolet Spectrometer (ISUS) to automatically measure concentrations of sulfides in seawater and in seafloor sediments. Sulfides are one of the main food sources for microbes, tubeworms, and other animals that live around seafloor seeps. Researchers will compare the sulfide measurements at different seeps with the types of animals and microbes found at these locations. Also, by measuring sulfide concentrations at different locations and different depths in the sediment, the researchers hope to better understand the factors that influence how much and what types of fluids are seeping out of the seafloor at a particular spot.
Dive sites for the Faults. Vents, and Seeps research program.
Logbook
