Why is Lost City special?

The spectacular underwater world of the ‘Lost City’ hydrothermal field is perched near the summit of a huge underwater mountain called the Atlantis Massif. Geologists were studying the Atlantis Massif long before Lost City was discovered because it is made up of rocks that originated from the Earth’s mantle, which have been carried to the seafloor along major faults and have a distinct chemistry compared to most rocks exposed on the seafloor. Mantle rocks contain large amounts of the mineral olivine (a Mg-Fe silicate), which reacts with seawater and forms hydrous Mg-silicate minerals called serpentine and magnetite, an iron oxide that is highly magnetic. This process – referred to as serpentinization – produces methane, hydrogen and heat, among other things. These rock reactions excite scientists because they represent possible fuels for life in the absence of sunlight, and they could be analogous to conditions early in Earth’s history or found on other planets.

The extreme conditions in the impressive white towers of the Lost City are determined by these chemical reactions occurring in the rocks of the Atlantis Massif. The towers, which can be 60 meters (200 feet) tall, are formed when warm alkaline waters from deep within the Atlantis Massif exit the seafloor and mix with seawater. Unlike almost all other hot springs on the seafloor, the chemistry and circulation of water venting from the Lost City chimneys are not driven by hot lava or by cooling of magma at depth. In other words, the Lost City is not volcanic. Instead, it is a geochemical reactor. The hydrothermal activity is driven by the chemical reactions between seawater and the mantle rocks of the Atlantis Massif, which are cooling down as they are exposed to seawater. These same reactions could be providing fuel and food for microbial life, making them intriguing subjects for studying the origins of life. Our studies of the water venting from the Lost City chimneys could provide clues about how the first biochemical pathways might have emerged from geochemical reactions in seafloor rocks on the ancient Earth.

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Testing and Waiting

We are halfway to Lost City now, but slowing our approach because Hurricane Helene is on track to meet us there. While politely waiting for Helene to leave the area, we needed to find something to do, so we conducted tests and optimized our lab protocols. Because scientists are always happy to run tests and optimize protocols. Yesterday we stopped to do a test dive with ROV Jason, to make sure all of our equipment is working properly in the water. There were a few glitches, as usual, which should be easily solved. Today we collected samples of “background” seawater using Niskin bottles on a CTD rosette. We will use these samples to practice our lab protocols and to compare to the Lost City samples as control samples.

Hopefully, the weather will allow us to apply these optimized equipment and protocols at Lost City soon. Stay tuned!


Why are we out here?

Now that we are in the open sea, out of sight of land, and beyond range of easy communication with our friends and family, it seems like a good time to discuss why we are out here. Why are we spending a whole month away from our loved ones and normal lives? Why are we spending so much of our time (and public funds) in the middle of the ocean taking samples of the seafloor? My two-year old daughter is going to do a hundred little things for the first time while I’m out here on this ship getting very seasick – why would I do that?

The short answer is the thrill of discovery. This expedition is so exciting to us because of the very good chance that we might be able to see things that nobody in the history of the world has ever seen before. Like what? We don’t know! And that’s the exciting part. The Lost City was discovered in exactly this way: a group of scientists (many of whom are involved in our current expedition) in 2000 were pursuing their scientific interests by exploring the geology of the Atlantis Massif (the underwater mountain on which Lost City is perched) and accidentally discovered this amazing natural wonder that was directly related to those scientific interests and yet completely unexpected.

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We departed Woods Hole today, and are now on our way to Lost City. The transit will be approximately 5 days because Lost City is on the Mid-Atlantic Ridge, the underwater mountain chain that bisects the Atlantic Ocean into its western and eastern halves. Check out the map on the home page.



Final Preparations

The team is gathering in Woods Hole, MA for final preparations before we depart on the R/V Atlantis Saturday morning. Yesterday was spent moving boxes and crates onto the ship, unpacking, and organizing. Today we are preparing the lab spaces for our experiments and analyses. We are also being trained how to use the new HOG sampler designed and built by the Lang lab. The HOG sampler will be our primary tool for collecting water samples at the Lost City. Being on the ship is a reminder that these scientific research expeditions require the coordinated efforts of many different people including the ship’s crew, engineers, and administrative staff in addition to the ROV Jason team and the scientists.

Testing the HOG sampler!

Collecting pristine samples from deep sea hydrothermal vents is not easy. After a year and a half of design, UofSC machine shop time, special orders from awesome suppliers like McLane and Keika and Titanium Joe, funding from NSF and the Deep Carbon Observatory, the Hydrothermal Organic Geochemistry (HOG) sampler is ready for its pool test. The expedition launches on September 8!

New Paper on the Lost City Hydrothermal Field

Co-chief scientists Susan Lang at the University of South Carolina and William Brazelton at the University of Utah, along with several collaborators on the upcoming expedition, have published a new paper on the use of deep carbon by microbes at the Lost City Hydrothermal Field. This study addressed the question: how much of the carbon formed deep in the Earth’s interior is fueling microbial activity in the Lost City chimneys, and which microbes are using that carbon? The surprising answer is that methanogenic archaea are unable to use the deeply-sourced carbon and depend on other organisms, such as sulfate-reducing bacteria, to metabolize the deep carbon and convert it into other carbon compounds. We will continue to pursue this story with our upcoming expedition to the Lost City in September 2018.

Read a summary of the paper by the Deep Carbon Observatory.

Dive Deeper


Postdoctoral researcher Katrina Twing participated in a Chief-Scientist Training Cruise focusing on the use of Deep Submergence Vehicles in July 2017 onboard the R/V Atlantis. In addition to learning about leading oceanographic research expeditions and the latest uses of ship-to-shore communications (also known as telepresence), Katrina got the opportunity to dive in the HOV Alvin. During her dive, she tested out a large-volume in situ sampling device our group is helping develop for use on our upcoming expedition to sample the Lost City Hydrothermal Field. More details about the sampling device and her experience with Alvin can be found at https://vimeo.com/191864900.

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