Day 38 Good-bye Forearc - Hello Backarc

Good-by Mariana forearc. The last piston core of this expedition was on deck by 0100. Tom C. attempted to find the transponders one more time but without success. The general consensus on the ship is that their disappearance has something to do with Tandem Thrust.

It has been 6 weeks of wonderful exploration and discovery, but we are not done yet. We are now headed west, past Guam, to the Mariana Trough. The trough is an active extensional backarc basin where we expect to find hydrothermal vents. In February of this year a NOAA expedition on this very ship, explored the active arc volcanoes of the Mariana Islands.

They did extensive mapping and tested the ocean water looking for physical and chemical evidence of hydrothermal activity. The volcanoes on this side of the arc system have eruptions of magma rather than mud.

The NOAA expedition found evidence of about a dozen active sites along the Mariana island arc and backarc. One of the sites was the Malaguana-Gadao spreading center. I am particularly interested in this site because it was named by Guam students in 2001 and I am a Guam school teacher.

The opportunity to name geologic features on the seafloor came about because of Patty’s enthusiasm. She has been studying the geology of the Marianas for 25 years and wants to share her amazing discoveries with the students of the Mariana Islands. One of her methods is this very website—Patty not only came up with the idea but also found a source of funding. The naming was also her idea and she hopes it will give the students a sense of pride and even ownership of their own geology. An annual academic challenge, open to all high schools in Guam and the Northern Marianas, results in a school team winning the grand prize—the honor of naming a particular feature on the seafloor. The winner of this year’s competition, held in March, will be naming the entire spreading center of the Mariana Trough.

Students interested in a career in marine science will be interested in Terra’s experience. Terra is the youngest member of this expedition. She is a college freshman interested in pursuing an education in the sciences. She has a love for both biological and physical sciences. Terra learned about this expedition through her boyfriend, Sam. He is a graduate student at Moss Landing in California. Sam is here studying elements in the pore water. I wrote about their work in the freezer on Day 31.

Science Summary - Day 38, April 29th

Science Objectives, Day 38:

The thirty-eighth day of the cruise, Apr. 29, we will survey the Mariana forearc south of Guam at a locality that we hope to dive at the maximum depth capacity of Jason2/Medea on the last day of the cruise. The site is one at which we hope to recover mid-crustal level plutonic rocks of the arc crust. We will then continue west into the backarc region and will collect bathymetry data for the rest of the day. We expect to arrive at our spreading center dive target at about midnight.