Today I did a "Cover it live" chat with Erik Stokstad from Science Magazinediscussing some of our recent findings related to the BP oil well Blowout.  For any of you who might be interested, you can replay the chat here. Our papers related to our blowout work are starting to come out as well.  The first one was just published in Nature Geoscience last week.

Seafloor “cold seeps” are areas where cool fluids from the deep subsurface are leaking out of the seafloor.  The temperature of these fluids is usually less than 20ºC.  Most methane-fueled or methane and oil fueled cold seeps share some common features, such as gas vents or bubble streams, gas hydrate mounds, microbial mats, and chemosynthetic animals and associated heterotrophic fauna. The biological and chemical diversity of these habitats is high.

Every day at sea usually provides at least one surprise.The Orca Basin has provided us with quite a few big surprises, the most striking of which was the discovery of red and pink (!) sediments in the middle of the basin. In the Northern and Southern mini-basins, we collected cores of black, extremely sulfidic mud. When we sent the multiple-corer over the side in the central Orca Basin, we expected to retrieve something similar but much to our surprise, the mud recovered from the more shallow (2000 vs. 2200m) central basin was red (see image gallery below for more photos). Red and pink deep sea sediment…where in the world does that come from?

The Orca Basin occupies a large (~150 km2) depression (roughly SE  to NW) along the continental slope in the Northern Gulf ofMexico.  At the basin bottom, a hypersaline brine (260‰, about 7 times the salinity of seawater) fills depressions below roughly 2200m.  There are two deep depressions, one to the north and another to the south end of the basin (the dark purple colors on the map above) are the focus of our work here.  We will also sample in the middle of the basin, where it is less deep but where previous studies documented active brine flows. The brine layer is about 250m thick and it derives from dissolution of Jurassic age salt that underlies and surrounds the basin.  This basin is very different from the other brine lakes/pools and mud volcanoes we are studying because brine seeps from the canyon walls into the basin rather than venting up through the seafloor.  The  Orca basin could be more similar to brine basins in the Mediterranean than to mud volcanos and upward-advection-derived brine lakes and pools in the Gulf of Mexico.   We aim to make this comparison.

When fluids seep out of the seafloor, they provide chemical substrates to fuel both microbial and macro-biological communities.  Even hyper-salty brine seeps are “oases” of life along the seafloor.  While the salt content of some seafloor brines can create challenges for macro-organisms, microbial life thrives in brines.