Shimada Seamount
Shimada Seamount is a seamount in the Pacific Ocean located southwest of Baja California Sur in Mexico. It is a shallow seamount, reaching a depth of 30 metres (98 ft) below sea level[1] and is a regular single-peaked mountain with a westerly spur and little relief otherwise. A platform lies at a depth of 180 metres (590 ft).[2] 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 4,100 metres (13,500 ft); other than abyssal hills at a distance of up to 1 kilometre (0.62 mi) from Shimada, Shimada is isolated.[2] Volcanic rocks taken from Shimada are considered to be icelandites.[3]
Most seamounts form at mid-ocean ridges, but hotspots and transform faults can also produce seamounts.[1] These mechanisms cannot really explain the origin of Shimada Seamount, however;[2] it may be part of a hotspot trace.[4] Evidence from core samples around the seamount, the appearance of the summit area,[5] and the presence of thin manganese 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-Holocene age.[6]
Possibly alive Lithothamnium corals have been dredged at Shimada from a depth of 110 to 130 metres (360 to 430 ft).[7]
Shimada Seamount is named for the American fisheries scientist Bell M. Shimada (1922–1958).[8] It has been known under a variety of names throughout its history, including Shimada Bank, Shamada Seamount, Hurricane Bank and Allaire Bank.[9]
See also
[edit]References
[edit]- ^ a b Gardner, Dean & Blakely 1984, p. 855.
- ^ a b c Gardner, Dean & Blakely 1984, p. 856.
- ^ Graham, David W.; Zindler, Alan; Kurz, Mark D.; Jenkins, William J.; Batiza, Rodey; Staudigel, Hubert (August 1988). "He, Pb, Sr and Nd isotope constraints on magma genesis and mantle heterogeneity beneath young Pacific seamounts". Contributions to Mineralogy and Petrology. 99 (4): 448. Bibcode:1988CoMP...99..446G. doi:10.1007/bf00371936. ISSN 0010-7999. S2CID 128683155.
- ^ Gardner, Dean & Blakely 1984, p. 862.
- ^ Gardner, Dean & Blakely 1984, p. 861.
- ^ Gardner, Dean & Blakely 1984, p. 859.
- ^ Gardner, Dean & Blakely 1984, p. 858.
- ^ "Bell Masayuki Shimada (1922-1958)". NOAA.
- ^ "Marine Gazetteer Placedetails". Retrieved 2020-02-23.
Sources
[edit]- Gardner, James V.; Dean, Walter E.; Blakely, Richard J. (1984). "Shimada Seamount: An example of recent mid-plate volcanism". Geological Society of America Bulletin. 95 (7): 855. Bibcode:1984GSAB...95..855G. doi:10.1130/0016-7606(1984)95<855:SSAEOR>2.0.CO;2. ISSN 0016-7606.
