The Atlantis Massif is a prominent undersea massif, a dome-shaped region approximately 10 mi. (16 km) across and rising about 14,000 ft. (4250 m) from the sea floor, in the North Atlantic Ocean. It is located at approximately 30°8'N latitude 42°8'W longitude; just east of the intersection of the Mid-Atlantic Ridge with the Atlantis Transform Fault. The highest point of the massif is approximately 700 m beneath the surface.
The massif was formed approximately 1.5-2.0 million years ago. Geologic studies of the massif have indicated that it is not composed of the black basalt typical of the ocean floor, but rather of dense green peridotite usually found in the mantle. The central dome is corrugated and striated in a way that is representative of an exposed ultramafic oceanic core complex. It is believed that the massif was formed underneath the nearby Mid-Atlantic Ridge but was pulled underneath the ridge during the movement of the plates.
The Lost City hydrothermal field, discovered in 2000, is near the summit of the ridge.
An expedition to the area in 1996 made an important advance in the study of the ocean floor. It found that a steeply sloping detachment fault is associated with the oceanic core complex structure. The dome was caused by mantle material being extruded to the surface.
- View of the Massif
- University of Washington: The Atlantis Massif
- Harvard University: Geology of the Atlantis Massif