17 May – 20 June 2026
#Doldrums
Our planet’s longest mountain range is located in the center of the Atlantic Ocean: the Mid-Atlantic Ridge. This submarine volcanic mountain chain stretches for more than 16,000 kilometers, shaping Earth’s geology where tectonic plates drift apart. As the plates separate, mantle material rises, partially melts, and generates magma that forms new oceanic crust. The movement of plates forms wrinkles and lines along the planet’s surface, known as fault zones, which tell the story of Earth’s tectonic history. These fault zones circulate water into the seafloor and through the crust, later releasing it with new chemical compositions— some of which feed deep-sea bacteria that fuel thriving ecosystems in the deepest, darkest parts of the Ocean. While chemosynthetic ecosystems are well documented along the ridge, little is known about what lives on the fault zones.
The Doldrums Megatransform System is one of these fault zones formed where offset ridge segments are linked by transform faults as the Atlantic seafloor spreads apart. Here, tectonic plates scrape and slide past one another, creating fascinating geologic formations like fault scarps and sedimented basins, both of which can host areas of chemically altered seawater and deep-sea ecosystems. Dr. Aaron Micallef of MBARI (Monterey Bay Aquarium Research Institute) and the international team will travel to the Doldrums Fracture Zone to map and identify interesting geological features, and then use ROV SuBastian to visualize them. Key to their work will be The Childlike Empress AUV, which will both create high-resolution maps of the seafloor and use its sensors to sniff out interesting chemicals that indicate venting. This expedition marks the first time Schmidt Ocean Institute’s new AUV will be used for scientific research.
The Doldrums Fracture Zone and Megatransform System
The Mid-Atlantic Ridge runs from the Arctic Ocean and ends near Bouvet Island in the South Atlantic just above Antarctica. Running perpendicular to the Mid-Atlantic Ride are numerous fracture zones. Fracture zones are long scars in Earth’s oceanic lithosphere, formed by tectonic plate movement along offset segments of mid-ocean ridges. The Mid-Atlantic Ridge comprises multiple tectonic plates moving apart from one another, each moving in a slightly different direction, which applies stress and pressure that result in the fracture zones.
At sections of the ridge where two plates move in slightly different directions, there are transform faults; tectonic boundaries where two different plates slide past and grind against each other. This grinding movement results in large rift valleys, steep scarps, and earthquakes. One side of the fault is usually older than the other.
Fracture zones and transform faults are our planet’s wrinkles and fine lines— they are the history of the Earth recorded on the planet’s surface. Geologists interpret this history to understand how tectonic plates moved in the past, and the directions they might take in the future.
The Doldrums Fracture Zone is a large megatransform system composed of numerous transform faults. The region is nearly 60,000 square kilometers, about the size of Lake Michigan. Little research has been conducted in this area, and not much is known about the fault systems created by the Mid-Atlantic Ridge, making it an ideal laboratory for studying geologic processes perpendicular to our planet’s longest mountain range.
In the deep sea, geology, chemistry, and biology are irrevocably intertwined. Because the Doldrums hosts numerous transform faults, it is an area where ocean water is sucked into and out of the seafloor. When the water re-emerges from its travels beneath the Earth, it has been chemically changed. There are also areas where the mantle is exposed to seawater, allowing volcanic gases to escape. Both water re-emerging from the crust and mantle exposure can result in chemosynthetic ecosystems like hydrothermal vents and methane seeps. The right chemical mix feeds bacteria in the deepest, darkest parts of the Ocean, which in turn support massive ecosystems that host animals like shrimp, octopus, and crabs. While these ecosystems have been well documented on the ridge, few have been observed at the fracture zones.
The team’s goal will be to identify geologically interesting areas, analyze any chemicals seeping from the seafloor, and document the ecosystems that may dwell there.
Exploring the deep
Finding interesting geologic seafloor features is no easy task. Key to this work will be the inclusion of the Schmidt Ocean Institute’s new autonomous underwater vehicle, or AUV, The Childlike Empress; this expedition represents the first time the AUV will be deployed for science.
The first step will be to use R/V Falkor (too)’s echosounders to map the Doldrums Fracture Zone to 50-meter resolution. These large-scale maps will be used to identify areas of interest that require more detailed mapping with the AUV, which uses multibeam sonar to create 1-meter-resolution maps and synthetic aperture sonar to create 3-centimeter-resolution maps. The AUV also has sensors that will sniff out chemicals associated with hydrothermal vents and methane seeps.
Once interesting geologic features are detected by the AUV, the team will use the ROV SuBastian to image the seafloor and obtain visual confirmation of features such as hydrothermal vents, and collect chemical and biological samples.
Team
