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IODP 342: Scientific objectives and general information

May 14, 2012

In just 17 days I’ll be heading to Bermuda to board the JOIDES Resolution drill ship for IODP Expedition 342 to acquire cores of deep ocean sediment offshore the Grand Banks, northeastern Canada. I’ll be at sea for a full two months and see land again when we dock in St. John’s, Newfoundland in early August.

The scientific objectives are explained in detail on this site, but, in short, the goal is to acquire a series of cores of deep-sea sediment that have been accumulating since as far back as the Late Cretaceous (~70 million years ago). The primary goal is to obtain a record of climatic and oceanographic conditions during the Paleogene (65-23 million years ago), including important climatic events such as the Paleocene-Eocene Thermal Maximum. Deep-sea sediments can be treasure troves of information, containing microfossils from which ocean chemistry can be reconstructed over time.

Why target this particular area for this record of Earth history? The deep-sea sediments in this location aren’t the typical sediments that accumulate very slowly, known as pelagic oozes. While oozes can be great recorders of environmental conditions, they accumulate so slowly that shorter-duration episodes in Earth history aren’t captured as well. There are other areas of the deep sea, adjacent to continental margins, that accumulate sediment much faster. But, many of these submarine fan systems, fascinating and important themselves, are essentially too active and too dynamic.

Map and accompanying topographic/bathymetric profile showing general location of Exp 342 coring sites. Basemap created in GeoMapApp.org. Click on image to see larger version.

The deep-sea drift deposits that have accumulated on the submarine ridges offshore Newfoundland might be the perfect type of deposits to obtain a high-resolution record of these climatic events. Other deposits like them accumulated faster than typical deep-sea oozes and, thus, have a thicker interval of sediment for the same duration of time. (Drift deposits are also commonly referred to as contourites because the sediment is moved by currents that follow the contours of the continental slope.)

My job as a participant on this expedition, along with several other sedimentologists on board, is to describe the cores as they come on deck. The measurements and sampling for fossils and chemistry need to be placed within a description of the sediment itself — grain size, sedimentary structures, bed thickness, composition, and so on. The sediments that accumulate on the Earth’s surface aren’t perfect tape recorders of conditions and events. Although these deposits might be the best choice to go after this record, there will still very likely be some surprises related to dynamics of the deposition that could influence how the archive is used to interpret past climate. Most of the detailed investigation into the processes and dynamics of these deposits will be done after the cruise by a graduate student of mine as part of his master’s thesis.

I really have no idea how much I’ll be able to post during the cruise, I don’t have a good feel for how much down time there will be. The priority for me as a participating scientist is to do my job characterizing the cores and summarizing results into technical reports. I will try my best to write some posts, not only about the science as it happens, but about life on an extended marine expedition.

I’m so busy getting other things done before being away, I’m not sure if I’ll get another post up or not before boarding the JR. Stay tuned.

Here are some web resources if you want to follow the expedition:

I feel like I’m missing some sites in this list, I’ll make sure to update as we go.

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2 Comments leave one →
  1. lockwooddewitt permalink
    May 14, 2012 11:53 am

    Just seeing the phrase “Grand Banks” is evocative to me… don’t know if you’re familiar with Stan Rogers, but he was a Canadian treasure whose life was tragically ended much too soon. http://www.wtv-zone.com/phyrst/audio/nfld/03/wharf.htm

  2. May 14, 2012 1:14 pm

    @lockwooddewitt yes, I am familiar with Stan Rogers … good stuff, thanks for posting that, perhaps it should be our song while out there

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