Meiji Seamount, named after

Emperor Meiji , also called or , was the 122nd emperor of Japan according to the traditional order of succession. Reigning from 13 February 1867 to his death, he was the first monarch of the Empire of Japan and presided over the Meiji era. He was the figur ...

, the 122nd Emperor of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...

, is the oldest

seamount A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise a ...

in the Hawaiian-Emperor seamount chain, with an estimated age of 82 million years. It lies at the northernmost end of the chain, and is perched at the outer slope of the Kuril–Kamchatka Trench. Like the rest of the Emperor seamounts, it was formed by the

Hawaii hotspot The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the H ...

volcanism, grew to become an island, and has since subsided to below sea level, all while being carried first north and now northwest by the motion of the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...

. Meiji Seamount is thus an example of a particular type of seamount known as a

guyot In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed .subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...

into the Kuril–Kamchatka Trench where it is carried by the ongoing plate motion, although this will not fully occur for several million more years if the current rate of motion is maintained. Although Meiji is the oldest extant seamount in the Hawaii-Emperor chain, the question of whether there were older seamounts in the chain which have already been subducted into the trench remains open, and is the subject of ongoing scientific research. The Deep Sea Drilling Project (DSDP) Leg 19, Hole 192A, recovered of pillow lava from near the summit of Meiji. The lavas were initially classified as

alkali basalts Alkali basalt or alkali olivine basalt is a dark-colored, porphyritic volcanic rock usually found in oceanic and continental areas associated with volcanic activity, such as oceanic islands, continental rifts and volcanic fields. Alkali basalt ...

on the basis of their mineralogy, but subsequent microprobe analyses of glass and

pyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe I ...

suggested that they are tholeiitic in origin. At least five flows were found.

References

Notes * {{Hawaiian volcanism Hawaiian–Emperor seamount chain Seamounts of the Pacific Ocean Guyots Hotspot volcanoes Cretaceous volcanoes Cretaceous Oceania

See also

References