Detroit Seamount, which was formed around 76 million years ago, is one of 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 abru ...

s of the Hawaiian-Emperor seamount chain (

Meiji Seamount Meiji Seamount, named after Emperor Meiji, the 122nd Emperor of Japan, is the oldest seamount 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 ...

is the oldest, at 82 million years). It lies near the northernmost end of the chain and is south of

Aleutian Islands The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi language, Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a cha ...

(near

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

), at Seamounts Catalog
by EarthRef, a

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...

Project accessed 3-1-09. Detroit Seamount is one of the few seamounts to break the naming scheme of the

Emperor seamounts An emperor (from la, imperator, via fro, empereor) is a monarch, and usually the sovereign ruler of an empire or another type of imperial realm. Empress, the female equivalent, may indicate an emperor's wife ( empress consort), mother (empr ...

, which are named mostly after emperors or empresses of the

Kofun period The is an era in the history of Japan from about 300 to 538 AD (the date of the introduction of Buddhism), following the Yayoi period. The Kofun and the subsequent Asuka periods are sometimes collectively called the Yamato period. This period is ...

Japanese history The first human inhabitants of the Japanese archipelago have been traced to prehistoric times around 30,000 BC. The Jōmon period, named after its cord-marked pottery, was followed by the Yayoi period in the first millennium BC when new invent ...

. It is instead named after the

light cruiser A light cruiser is a type of small or medium-sized warship. The term is a shortening of the phrase "light armored cruiser", describing a small ship that carried armor in the same way as an armored cruiser: a protective belt and deck. Prior to thi ...

'' USS Detroit''. The Detroit Seamount is as big as the

island of Hawaii Hawaii ( ; haw, Hawaii ) is the largest island in the United States, located in the state of Hawaii. It is the southeasternmost of the Hawaiian Islands, a chain of volcanic islands in the North Pacific Ocean. With an area of , it has 63% of th ...

Mapping

The seamount was initially mapped by the

GLORIA Gloria may refer to: Arts and entertainment Music Christian liturgy and music * Gloria in excelsis Deo, the Greater Doxology, a hymn of praise * Gloria Patri, the Lesser Doxology, a short hymn of praise ** Gloria (Handel) ** Gloria (Jenkins) ...

program of the

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...

, and in far more detail in 2001 by leg 197 of the

Ocean Drilling Program The Ocean Drilling Program (ODP) was a multinational effort to explore and study the composition and structure of the Earth's oceanic basins. ODP, which began in 1985, was the successor to the Deep Sea Drilling Project initiated in 1968 by th ...

(ODP). 2001 marked a two-month excursion aboard the research vessel

JOIDES Resolution 295px, Drillship ''JOIDES Resolution'' in 1988 The riserless research vessel ''JOIDES Resolution'' (Joint Oceanographic Institutions for Deep Earth Sampling), often referred to as the JR, is one of the scientific drilling ships used by the Interna ...

to collect samples of lava flows from four submerged volcanoes, among them Detroit Seamount, which was drilled twice. The expedition was funded by the Ocean Drilling Program, an international research effort designed to study the world's seafloors, and the drill sites were numbers 1203 through 1206. The project drilled Detroit, Nintoku, and Koko

s, all in the far northwest of the chain. Detroit Seamount was drilled twice (numbered 1203 and 1204), on the summit and on one of its secondary cones; care was taken to put the locations away from major fault lines or other geological features that would otherwise invalidate or bias the results. In 2005 it underwent a detailed geological analysis by scientists from

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Geology

After its initial formation 81 million years ago, the volcano was active for 25 million years. Parts of the volcano appear to be older than the oldest volcano in the chain,

. The 2005 analysis found that the volcano had been active throughout much of the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

(circa 52–34 million years ago), and that activity may have extended into the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

(under 34 million years ago). The large difference between the youngest and oldest lavas provides evidence that 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 ...

migrated far more slowly than it does today; for example, Kohala volcano (the oldest volcano of

Hawaii island Hawaii ( ; haw, Hawaii ) is the largest island in the United States, located in the state of Hawaii. It is the southeasternmost of the Hawaiian Islands, a chain of volcanic islands in the North Pacific Ocean. With an area of , it has 63% of t ...

) first emerged from the sea 500,000 years ago, and last erupted 120,000 years ago, a period of only 380,000 years in comparison to Detroit's 18 million or more years of volcanic activity. The large age difference (51 vs. 34 million years) between the submarine preshield stages and the post-shield rejuvenated stage seems to indicate that volcanoes in the chain can erupt again long after they are believed to be extinct. The volcano is known to have erupted intermediately in an underwater and shallow-water environment. Detroit Seamount has a wide (100,000 square kilometers) base and rises from the bottom of the

abyssal plain An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. T ...

to a depth of approximately ; in fact, it is as wide as

at the head of the chain. The width of the seamount, as well as the extremely gentle slope, which is very shallow even for a Hawaiian

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

, seem to show that the seamount suffered a catastrophic collapse sometime in its history; such a collapse is a relatively common event in the growth of Hawaiian volcanoes, caused when the volcanoes grow so fast that they destabilize. A sequence of sediments to thick compose the volcano, in several layers. Some papers refer to only the shallowest part of the volcano as Detroit Seamount, and the rest of the seamount as the "Detroit Rise". The tallest volcanic cones of the seamount peak to above the rest of the seamount.

Mantle of sediment

The seamount was thought to be covered in a cap of sediment, which was confirmed in 2005. All but the topmost cones of Detroit Seamount are capped in a thick layer of sediments, which were found to have drifted there from a direction due northwest. The drift that carried the sediments onto the volcano was named the "Meiji Drift", after the oldest volcano in the chain,

, which was also in that direction. The drift is of

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). It follows the Neogene Period and spans from 2.58 million years ...

-era mud, deposited by

ocean current An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, s ...

s. The tallest parts of the seamount protrude above this "mud cap", which at its deepest is estimated to be thick. They formed 34 million years ago. A 2005 analysis of the results of the 2001 ''JOIDES Resolution'' excursion found the age, composition, structure, and history of growth for the seamount. The evaluation also focused on the strange cones that poked through the sedimentary layers. They were deposited onto the seamount before the Meiji Drift developed. Analysis put the latest date of their formation at 60 million years ago, 6 million years into the seamount's life.

References

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