The Marshall Islands are the site of a number of seamounts. These volcanoes form several groups, including the Ralik Chain, the Ratak Chain and some seamounts around Anewetak. These seamounts are in turn part of a larger province that extends from the South Pacific to the Mariana Trench and is characterized by unusually shallow ocean ground.

These seamounts and volcanoes do not have simple hotspot-like age progressions, with some volcanoes being younger than one would expect from age progression and having more than one active episode. In some places, a middle Cretaceous and a late Cretaceous episode of volcanic activity have been determined by radiometric dating. Despite this, some hotspot-based genesis models have been formulated, often implying that French Polynesian hotspots are responsible for the formation of seamounts, with the Society hotspot, Rurutu hotspot, Rarotonga hotspot and the Macdonald hotspot being candidate hotspots responsible for the development of the Marshall Islands seamounts. Such linkages are in part supported by geochemical data. Some discrepancies between the age and position of such seamounts and the predictions of the hotspot model may reflect the activity of short-lived hotspots linked to large mantle plumes that produce more than one hotspot.

Name Other names Etymology Coordinates Depth below sea level Age Volume Details Aean̄-Kaņ Marovoiy A taboo fishing spot at Eniwetok Mid-Cretaceous . Since the Eocene manganese nodules developed on the seamount, which may have been created by the Macdonald hotspot. Neen-Koiaak According to legend, the fastest runner in the Marshall Islands 102 million years Samples dredged from Neen-Koiaak include hawaiite containing clinopyroxene, olivine and plagioclase. Wōd-Eņ Rok South-Wod-En A coral head 76 million yearsWhile its position makes it a candidate member of the Ralik hotspot trail, it appears to be too old. There is some geochemical similarity to the Rurutu hotspot. Wōd-Eņ Iōn̄ North-Wod-En, Nazimova A coral head 86 million yearsWhile its position makes it a candidate member of the Ralik hotspot trail, it appears to be too old. There is some geochemical similarity to the Rurutu hotspot. Ļewa A person who received canoe building knowledge, one of the first two100 million yearsPart of the Ralik Chain, Albian-age fossils have been dredged from this seamount. Ļōbbadede Lobhadode A chief from Bikini94 million years Depending on the plate reconstruction model chosen, Lobbadede appears to coincide with the location of the Macdonald hotspot. Limestone and fossils of Campanian-Cenomanian age have been found on Lobbadede, which appears to have had a second volcanic episode in the Cretaceous. Wōden-Kōpakut Ratak A coral head85 million years or 82.2 ± 1.6 million yearsPart of the Ratak Chain with Limalok, it was also active during the late Cretaceous and has a well developed summit platform. One reconstruction of plate motion places Woden-Kopakut close to the Rurutu hotspot. Hawaiite has been dredged from the seamount and contains iron oxides, plagioclase and zeolites. Radik A chief on Ujlan Ļainjin A legendary navigator Ļōjemeja A chief in Ujlan Steep upper flanks, and a volcanic pinnacle is found between the summit and a sediment-covered terrace. Ļami According to legend an Eniwetok giant 86 million yearsSlumps and terraces, terraces that appear to be congruent with these on Lomilik, surround this seamount. Its summit plateau is covered by sediments, sediment-filled basins and volcanic knolls. Peto-Eņ A taboo channel at Eniwetok Lomilik A place at Eniwetok with good fishing opportunities The summit has volcanic knobs and sediment-filled basins in between. The north flank has a terrace and the rest of the slopes is covered with slumps, talus and sediments. Litōrmālu A legendary navigator Ļo-Wūliej A cape at Eniwetok North Ļāānṃōjānjān Reference to shipbuilding techniques Has a rugged appearance with little sediment. It also features several terraces and two large slumps. South Ļāānṃōjānjān Reference to shipbuilding techniques Has a rugged appearance with little sediment. Bwewa Kaņ Named after canoe keels 88 million yearsPart of the Ralik Chain, may have been formed by a hotspot together with a stage of Wodejebato. Lōjabōn-Bar A strong traditional personage at Bikini WōdejebatoSylvaniaBikini's most feared sea god 82 million years Look 140 million years Look is the oldest known seamount.Flat-topped seamount that can be considered a guyot and is located between the Ratak Chain and the Ralik Chain, and fairly old. Its geochemistry is intermediate between these two chains as well, which may indicate that volcanism was strongly influenced by the crust. Look Seamount is dotted by volcanic cones and has a rilled appearance as well as slumps; the summit is covered by sediment that mostly buries small volcanic pinnacles and sediment-filled depressions.Ruwitūn̄tūn̄ 66 million yearsFlat-topped seamount that can be considered a guyot; basins and volcanic knolls dot its summit platform and some pinnacles contain craters. Fossils indicate that Ruwituntun developed either during or before the Albian. Ļāwūn-Pikaar Bikar Legendary chief in Pikaar Ankaramite-like rock containing clinopyroxene and degradation products of olivine and mellilite has been dredged Ļōkōto-N̄ōrn̄ōr Jebo Pali Name given by the government of Micronesia. Probably CretaceousThe seamount is surrounded by a sediment cover and might feature slumps. Hyaloclastite and phosphorite have been dredged from it. Likelep A site on Ujlan 82 million yearsBiotite, hornblende and plagioclase have been dredged from Likelep, and the seamount is of Campanian age. Likelep may be part of a seamount trail and is part of the Ujlān volcanic complex. A sediment cap and volcanic structures are found on its top, with a volcanic cone protruding through the sediment. Slumps occur on its flanks and a seamount farther north is connected to Likelep. Lalibjet A sea god74 million yearsMay have been produced by the Rarotonga hotspot together with Eniwetok and is part of the Ujlān volcanic complex. Part of the sediment cap on its summit appears to have been removed by a slump. Ujlān Ujelang 80 million yearsSeamount with three separate summits. Ujlan may be part of a seamount trail and is part of the Ujlān volcanic complex. The southwestern flank has a terrace. Ļōtab A descendant of Litōrmālu 80 million yearsLotab may be part of a seamount trail and is part of the Ujlān volcanic complex; it also features traces of mass failures and on the northeastern flank it is connected to another seamount. Ļajutōkwa A navigator 81 million yearsLajutokwa may be part of a seamount trail and is part of the Ujlān volcanic complex. Lo-En Hess Named after the hibiscus tree 113 million years Mij-Lep A gap between islands on Ujlan 106 million yearsA number of pinnacles, including a flat topped one on the summit, cover Mij-Lep. Ļemkein Ļewōnjoui Ļōkkwōrkwōr Erikub 87 million yearsAlkali basalts and hawaiite have been dredged, which contain clinopyroxene, olivine derivatives and plagioclase and show evidence of having been eroded above the water surface Litakpooki Ṃaanjidep A chief from Jalwoj The depth probably does not refer to the actual summit. Ļoṃjenaelik A chief from Arno Ļōmōļkā A chief from Mile Limalok Harrie A chiefess from Mile 68 million years

See also

MIT Guyot Ioah Guyot

References

Sources