Program Update: Integrated Ocean Drilling Program – July 2012
This month, the JOIDES Resolution concluded Expedition 342 (Paleogene Newfoundland Sediment Drifts) in the North Atlantic. Here, near the final resting place of the ill-fated RMS Titanic, large sediment drifts contain detailed records of the Paleogene – a time when Earth’s climate experienced dramatic fluctuations. In the final weeks of the expedition, the team retrieved numerous cores from a very large drift of Miocene sediment, deposited from 23 to 5 million years ago. Because of its size and its conspicuous olive hue – the latter of which indicates a lack of carbonate fossils – the team nicknamed this sediment drift “The Green Monster.” The ship later transited to a new site where they drilled sediments from the Cretaceous period, deposited some 93 million years ago. Here, the team found evidence of a number of global Ocean Anoxic Events (OAEs) when the world’s oceans became almost totally depleted of oxygen. These events are linked to changing ocean currents, increases in atmospheric greenhouse gases (such as carbon dioxide) and a warming climate. OAEs appear in the geologic record as a thick layer of black carbon-rich shale with no evidence of marine life. For the final updates from Expedition 342, see the JOIDES Resolution blog. For more information on the expedition’s science goals, see the Expedition 342 website.
Also this month, the drillship Chikyu revisited the Japan Trench for Expedition 343T (Japan Trench Fast Drilling Project 2). The expedition, in conjunction with Expedition 343, aimed to collect data and samples that will allow scientists to better understand how the 2011 Tohoku earthquake fault slipped more than 50 meters, causing the devastating tsunami. Expedition 343 took place in April and May of this year, and successfully drilled across the Tohoku Earthquake megathrust into the downgoing Pacific plate. During Expedition 343T, the onboard scientists and engineers installed a temperature observatory into one of the previously drilled boreholes. The sensors will record the frictional heat from the earthquake, allowing scientists to determine the fault’s strength 800 meters below the seafloor. The observatory installation completes the prime objective of these expeditions and represents a major accomplishment for IODP. The Kaiko 7000II ROV will collect the sensors later this year, allowing scientists to begin analyzing the data. For more information, please see the Expedition 343 webpage.