The Atlantis Massif is a prominent undersea massif, a dome-shaped region approximately 10 mi. (16 km) across and about 14,000 ft. (4250 m) high, in the North Atlantic Ocean at approximately 30°N latitude just east of the intersection of the Mid-Atlantic Ridge with the Atlantis Transform Fault. In geology, a massif is a section of the Earths crust that is demarcated by faults or flexures. ... The Atlantic Ocean is Earths second-largest ocean, covering approximately one-fifth of its surface. ... Courtesy USGS The Mid-Atlantic Ridge is a mostly underwater mountain range of the Atlantic Ocean that runs from 87°N (close to the North Pole to close to Antarctica, where it continues West to the Scotia Ridge and East to the Southwest Indian Ridge, and is the longest mountain...
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 also corrugated and striated in a way that is representative of an exposed ultramafic 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. Basalt Basalt is an extrusive igneous rock, sometimes porphyritic, and is often both fine-grained and dense. ... Peridotite Peridotite is a dense, coarse grained ultrabasic rock, consisting mainly of the minerals olivine and pyroxene. ... Earth cutaway from core to exosphere. ... Ultramafic rocks are igneous rocks with very low silica content (less than 45%) and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). ... The tectonic plates of the world were mapped in the second half of the 20th century. ...
The Lost City hydrothermal field is near the summit of the ridge. An actively venting calcium carbonate chimney in the Lost City hudrothermal field Lost City is a field of hydrothermal vents in in the mid-Atlantic ocean that differ significanly from the black smoker vents described in the late 1970s. ...
External links
View of the Massif (http://www.lostcity.washington.edu/graphics/images/AtlantisMassif_viewN.jpg)
University of Washington: The Atlantis Massif (http://www.lostcity.washington.edu/science/geology/atlantis_mountain.html)
The AtlantisMassif rises 14, 000 feet above the surrounding seafloor.
Faulting and mass wasting (land slides) associated with the Atlantis Transform Fault or Fracture Zone, have dissected the mountain, resulting in a rugged and embayed southern face.
Harzburgites: From looking at the mantle rocks we recovered from the AtlantisMassif, we see that they are made up of about 10-15% diopside, and 85-90% olivine, with a little bit of chromite.
Geologic studies of the massif have indicated that it is not composed of the fl basalt typical of the ocean floor, but rather of dense green peridotite usually found in the mantle.
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.
Harvard University: Geology of the AtlantisMassif (http://adsabs.harvard.edu/cgi-bin/nph-bib_query?2002MarGR..23..443B)
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