My Project on the Cruise
Although I won't get to dive in Alvin on this cruise, I do get to do some exciting science! Once the sub hits the deck in the evening, I get complete control of the ship for the night!
You my be wondering, "what can you do on a ship in the middle of the ocean at night??" Turns out, a lot! I, with the help of my assistant Stacy, will be taking gravity cores of sediment from hills away from the hot part of the East Pacific Rise (EPR). The ship will steam to
a location, and then we get to work. Gravity coring is exactly what it sounds like: dropping a big tube over the side of the ship and allowing gravity to push it into the sediment 2400 meters below. Gravity cores are about 1.5 meters long and 4" wide. Once the core hits the bottom, we pull it up with the winch to retrieve it.
Once the core gets on-deck, things get really interesting. We quickly put caps on the ends of the tube and label the top and bottom. We load up the next tube into the corer and drop it over the side.
Why do you want cores?
I am trying to figure out of hydrothermal activity only occurs near the ridge axis (high temperature) or if some hydrothermal fluid leaks out away from the ridge axis (lower temperature) along abyssal hills. There are many thousands of abyssal hills in the ocean, so if hydrothermal flow occurs there, it might change how we think about hydrothermal systems. I've selected a bunch of abyssal hills that might have hydrothermal flow for coring. The hills are all on oceanic crust that is less than 500,000 years old!
"But you still didn't say why you need cores!" Once we have the cores on-deck, we'll split them in half using a special core-splitter. Then we can sample the sediments from inside the core and take photos of the structure. I will be analyzing the chemical content of water from the sampled sediments.