Shimada Seamount is a seamount in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

located southwest of Baja California Sur in

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. It is a shallow seamount, reaching a depth of below sea level and is a regular single-peaked mountain with a westerly spur and little relief otherwise. A platform lies at a depth of . Talus deposits surround the seamount at its base. The seafloor underneath Shimada is between 18 million and 21 million years old and lies at a depth of about ; other than abyssal hills at a distance of up to from Shimada, Shimada is isolated. Volcanic rocks taken from Shimada are considered to be icelandites. Most seamounts form at

mid-ocean ridge A mid-ocean ridge (MOR) is a undersea mountain range, seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading ...

s, but hotspots and

transform fault A transform fault or transform boundary, is a fault (geology), fault along a plate boundary where the motion (physics), motion is predominantly Horizontal plane, horizontal. It ends abruptly where it connects to another plate boundary, either an ...

s can also produce seamounts. These mechanisms cannot really explain the origin of Shimada Seamount, however; it may be part of a hotspot trace. Evidence from core samples around the seamount, the appearance of the summit area, and the presence of thin

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

crusts imply an age of about 10,000 years for some volcanic rocks at Shimada; the rocks are too young to be dated by potassium-argon dating, and all the evidence indicates that volcanic activity at Shimada is of late

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

age. Possibly alive '' Lithothamnium''

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

s have been dredged at Shimada from a depth of . Shimada Seamount is named for the American fisheries scientist Bell M. Shimada (1922–1958). It has been known under a variety of names throughout its history, including Shimada Bank, Shamada Seamount, Hurricane Bank and Allaire Bank.

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External links

earthref.org Seamount Catalog: Shimada Seamount
{{Authority control Seamounts of the Pacific Ocean Quaternary volcanoes Undersea banks of the Pacific Ocean

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