September 13, 2012 Cores Galore!
We've now made it back to the stations we missed due to the weather and, starting yesterday around 3 PM, we did an afternoon station, another at 2:30 this morning, and one more right after breakfast. We'll have another right after dinner, and then three more to wrap things up. There may be a few other short stations in between. The original cruise plan called for these stations to be done right after we started, but the storm changed all of that.
Most of the time when we go on deck to work, the Russian team of geologists is there as well. Their team is actually made up of four smaller teams. I've already told you about the work of Alexander Savvichev in the journal from 9 September. The others are Alexander Bosin and Alexander Kolesnik from the Pacific Oceanological Institute (Vladivostok), Tatiana Matveeva and Elizaveta Logvina (Liza), geologists from "I.S. Gramberg VNIIOkeangeologia" (Saint-Petersburg), and Elena Vologina, Institute of Earth Crust, Siberian Branch of the Russian Academy of Sciences (Irkutsk).
The box corer is a heavy piece of gear when it's empty, but when it's full and the weather is rough, it takes a lot of effort to bring it back on board. See the picture in my journal from 31 August. Once the gear is on board, the team will take core samples through the center of the larger core. Their goal is to analyze rare elements in the sediments in order to do a paleographic study (going "back in time" using the information from the sediments). Once they've brought the samples home, they'll do an array of tests for water content, chemical properties, and other factors.
I´ve shown you a picture of the Haps corer that Jackie uses in my journal from 9 September, but the Russian gravity corer is very different. Once the corer comes to the surface, the team removes the plastic liner with the sediment core inside and slices it longitudinally. See pictures of both the gravity corer entering the water and the sediment core itself in my 4 September journal. The core halves are split among all team members. If it´s a "typical" core the team from Pacific Oceanographic Institute of the Russian Academy of Sciences cut it into 10 cm sections. If there are interesting layers, they´ll sample each layer. Tatiana and Liza take samples from most parts of the geological stations and freeze them for further analysis, others are squeezed to remove pore water. The latter are used for later chemical analysis and isotopic composition. In addition, they´ll analyze grain size, age of the sediments, TC (total carbon) and TOC (total organic carbon), and possibly complete a mineralogical investigation. Tatiana and Liza, who are interested in the origin and concentration of methane, will do all these studies. In 2009, we reached a northern area identified during a 2003 cruise of the USCGC Healy as one with pockmarks. Pockmarks are circle-shaped holes on the sediment surface, often associated with methane. There was no visual indication of the presence of methane found at that time, but later laboratory analysis of the collected samples showed indirect evidence of the presence of methane. During the '09 cruise the group's focus was the pockmark area in the north and an additional area north of Wrangell Island and into Herald Canyon. On this cruise, their goal was to return to areas in Herald Canyon where information gathered from the '09 cruise showed anomalies that might indicate the presence of methane.
Elena is interested in both the box core and the gravity core sediments. Her own research at home in Russia, has been primarily on Lake Baikal, but she's collecting here for her science colleagues. On board, she looks for undisturbed sediments from the gravity corer and will take samples from the box corer done at the same sites. The task is to analyze the samples using high-resolution geochemical analysis, and the goal is paleoclimate (past climate) reconstruction. When we reach Nome, most of the scientists will get off and head home, but Elena, Alexander Bosin and Alexander Kolesnik will stay with the ship until it returns to Vladivostok where they'll work with the box core samples for two additional days.
Note: Since I've already included 4 pictures from the Russian geology team, today's picture is of Jackie holding one of her cores.