Geology of Japan

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The islands of Japan were separated from mainland Asia by back-arc spreading. Japan separation.png
The islands of Japan were separated from mainland Asia by back-arc spreading.

The islands of Japan are primarily the result of several large ocean movements occurring over hundreds of millions of years from the mid-Silurian to the Pleistocene, as a result of the subduction of the Philippine Sea Plate beneath the continental Amurian Plate and Okinawa Plate to the south, and subduction of the Pacific Plate under the Okhotsk Plate to the north.

Contents

Japan was originally attached to the eastern coast of the Eurasian continent. The subducting plates, being deeper than the Eurasian plate, pulled Japan eastward in the process of back-arc extension, opening the Sea of Japan around 15 million years ago. [1] The Strait of Tartary and the Korea Strait opened much later.

Japan is situated in a volcanic zone on the Pacific Ring of Fire. Frequent low intensity earth tremors and occasional volcanic activity are felt throughout the islands. Destructive earthquakes, often resulting in tsunamis, occur several times per century. The most recent major quakes include the 2024 Ishikawa earthquake and tsunami, the 2011 Tōhoku earthquake and tsunami, the 2004 Chūetsu earthquake, and the Great Hanshin earthquake of 1995.

The geological features and bedrock composition of the Japanese main islands Geological map Japan basement.png
The geological features and bedrock composition of the Japanese main islands

Geological history

Orogeny phase

Japanese archipelago relief (including submerged parts) Japan Relief Map of Land and Seabed.png
Japanese archipelago relief (including submerged parts)

The breakup of Rodinia about 750 million years ago formed the Panthalassa ocean, with rocks that eventually became Japan sitting on its eastern margin. [2] In the Early Silurian (450 million years ago), [3] the subduction of the oceanic plates started, and this process continues to the present day, forming a roughly 400 km wide orogeny at the convergent boundary. Several (9 or 10) oceanic plates were completely subducted and their remains have formed paired metamorphic belts. The most recent complete subduction of a plate was that of the Izanagi Plate 95 million years ago. Currently the Philippine Sea Plate is subducting beneath the continental Amurian Plate and the Okinawa Plate to the south at a speed of 4 cm/year, forming the Nankai Trough and the Ryukyu Trench. The Pacific Plate is subducting under the Okhotsk Plate to the north at a speed of 10 cm/year. The early stages of subduction-accretion have recycled the continental crust margin several times, leaving the majority of the modern Japanese archipelago composed of rocks formed in the Permian period or later.

Island arc phase

Around 23 million years ago, western Japan was a coastal region of the Eurasia continent. The subducting plates, being deeper than the Eurasian plate, pulled parts of Japan which become modern Chūgoku region and Kyushu eastward, opening the Sea of Japan (simultaneously with the Sea of Okhotsk) around 15-20 million years ago, with likely freshwater lake state before the sea has rushed in. [4] Around 16 million years ago, in the Miocene period, a peninsula attached to the eastern coast of the Eurasian continent was well formed. About 11 million years before present, the parts of Japan which become modern Tōhoku and Hokkaido were gradually uplifted from the seafloor, and terranes of Chūbu region were gradually accreted from the colliding island chains. The Strait of Tartary and the Korea Strait opened much later, about 2 million years ago. At the same time, a severe subduction of Fossa Magna graben have formed the Kantō Plain. [5]

Current state

General information

Overall, the geological composition of Japan is poorly understood. The Japanese islands are formed of several geological units parallel to the subduction front. The parts of islands facing oceanic plates are typically younger and display a larger proportion of volcanic products, while the parts facing the Sea of Japan are mostly heavily faulted and folded sedimentary deposits. In north-west Japan, the thick quaternary deposits make determination of the geological history especially difficult. [6]

Geological structure

The Japanese islands are divided into three major geological domains:

Research

The Geology of Japan is handled mostly by Geological Society of Japan  [ ja ], with the following major periodicals:

Geological hazards

Japan is in a volcanic zone on the Pacific Ring of Fire. Frequent low intensity earth tremors and occasional volcanic activity are felt throughout the islands. Destructive earthquakes, often resulting in tsunamis, occur several times a century. The most recent major quakes include the 2011 Tōhoku earthquake and tsunami, the 2004 Chūetsu earthquake and the Great Hanshin earthquake of 1995.

See also

Related Research Articles

<span class="mw-page-title-main">Geography of Japan</span>

Japan is an archipelagic country comprising a stratovolcanic archipelago over 3,000 km (1,900 mi) along the Pacific coast of East Asia. It consists of 14,125 islands. The five main islands are Hokkaido, Honshu, Kyushu, Shikoku, and Okinawa. The other 14,120 islands are classified as "remote islands" by the Japanese government. The Ryukyu Islands and Nanpō Islands are south and east of the main islands.

<span class="mw-page-title-main">Subduction</span> A geological process at convergent tectonic plate boundaries where one plate moves under the other

Subduction is a geological process in which the oceanic lithosphere and some continental 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, the heavier plate dives beneath the second plate and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year.

<span class="mw-page-title-main">Ring of Fire</span> Region around the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur

The Ring of Fire is a tectonic belt of volcanoes and earthquakes.

<span class="mw-page-title-main">Convergent boundary</span> Region of active deformation between colliding tectonic plates

A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.

<span class="mw-page-title-main">Australian Plate</span> Major tectonic plate separated from Indo-Australian Plate about 3 million years ago

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<span class="mw-page-title-main">Burma Plate</span> Minor tectonic plate in Southeast Asia

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<span class="mw-page-title-main">Caribbean Plate</span> A mostly oceanic tectonic plate including part of Central America and the Caribbean Sea

The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the northern coast of South America.

<span class="mw-page-title-main">Okhotsk microplate</span> Minor tectonic plate in Asia

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<span class="mw-page-title-main">Orogenic belt</span> Zone affected by mountain formation

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<span class="mw-page-title-main">Volcanic belt</span> Large volcanically active region

A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature where magma is created by partial melting of solid material in the Earth's crust and upper mantle. These areas usually form along tectonic plate boundaries at depths of 10 to 50 kilometres. For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 kilometres (560 mi) from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada.

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<span class="mw-page-title-main">Accretionary wedge</span> The sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary

An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.

<span class="mw-page-title-main">Aegean Sea Plate</span> A small tectonic plate in the eastern Mediterranean Sea

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This is a list of articles related to plate tectonics and tectonic plates.

<span class="mw-page-title-main">Philippine Mobile Belt</span> Tectonic boundary

In the geology of the Philippines, the Philippine Mobile Belt is a complex portion of the tectonic boundary between the Eurasian Plate and the Philippine Sea Plate, comprising most of the country of the Philippines. It includes two subduction zones, the Manila Trench to the west and the Philippine Trench to the east, as well as the Philippine Fault System. Within the Belt, a number of crustal blocks or microplates which have been shorn off the adjoining major plates are undergoing massive deformation.

<span class="mw-page-title-main">Geology of Russia</span> Overview of the geology of Russia

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<span class="mw-page-title-main">Geology of the Pacific Ocean</span> Overview about the geology of the Pacific Ocean

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<span class="mw-page-title-main">Qinling orogenic belt</span>

The Qinling orogenic belt is a tectonic feature that evolved throughout the Proterozoic and Phanerozoic eons due to a variety of tectonic activities. It is a part of the Central China Orogenic Belt, aligned in an east–west orientation across Central China, and spans portions of Shaanxi, Henan and Gansu provinces along the Qinling Mountains which are one of the greatest mountain ranges in China. The first materials involved in the Qinling orogenic belt formed around 2.5 billion years ago, whereas the main morphology of the belt now largely reflects the Triassic collision between the North China Plate and the South China Plate and Cenozoic extension across China. During these 2.5 billion years, various types of rocks have been formed here due to different tectonic processes and chemical reactions between rocks. Therefore, geologists are able to reconstruct the evolution of mountain belt based on evidence preserved in these rocks.

<span class="mw-page-title-main">Ryukyu Arc</span> Island arc between Kyushu and Taiwan

The Ryukyu Arc is an island arc which extends from the south of Kyushu along the Ryukyu Islands to the northeast of Taiwan, spanning about 1,200 kilometres (750 mi). It is located along a section of the convergent plate boundary where the Philippine Sea Plate is subducting northwestward beneath the Eurasian Plate along the Ryukyu Trench. The arc has an overall northeast to southwest trend and is located northwest of the Pacific Ocean and southeast of the East China Sea. It runs parallel to the Okinawa Trough, an active volcanic arc, and the Ryukyu Trench. The Ryukyu Arc, based on its geomorphology, can be segmented from north to south into Northern Ryukyu, Central Ryukyu, and Southern Ryukyu; the Tokara Strait separates Northern Ryukyu and Central Ryukyu at about 130˚E while the Kerama Gap separates Central Ryukyu and Southern Ryukyu at about 127 ˚E. The geological units of the arc include igneous, sedimentary, and metamorphic rocks, ranging from the Paleozoic to Cenozoic in age.

References

  1. Barnes, Gina L. (2003). "Origins of the Japanese Islands: The New "Big Picture"" (PDF). University of Durham. Archived from the original (PDF) on April 28, 2011. Retrieved August 11, 2009.
  2. Wakita, Koji (2013-08-10). "Geology and tectonics of Japanese islands: A review – The key to understanding the geology of Asia". Journal of Asian Earth Sciences. Geological Evolution of Asia. 72: 75–87. doi:10.1016/j.jseaes.2012.04.014. ISSN   1367-9120.
  3. Bor-ming Jahn (2010). "ACCRETIONARY OROGEN AND EVOLUTION OF THE JAPANESE ISLANDS—IMPLICATIONS FROM A Sr-Nd ISOTOPIC STUDY OF THE PHANEROZOIC GRANITOIDS FROM SW JAPAN" (PDF). American Journal of Science. American Journal of Science, Vol. 310, December, 2010, P. 1210–1249, DOI 10.2475/10.2010.02. 310 (10): 1210–1249. Bibcode:2010AmJS..310.1210J. doi:10.2475/10.2010.02. S2CID   129989718. Archived from the original (PDF) on August 9, 2017. Retrieved October 10, 2017.
  4. Barnes, Gina L. (2003). "Origins of the Japanese Islands: The New "Big Picture"" (PDF). University of Durham. Archived from the original (PDF) on April 28, 2011. Retrieved August 11, 2009.
  5. "Formation history of the Japanese Islands (4) -- GLGArcs". glgarcs.rgr.jp. Archived from the original on December 1, 2017. Retrieved July 16, 2017.
  6. "Geology of Japan|Geological Survey of Japan, AIST|産総研地質調査総合センター / Geological Survey of Japan, AIST". gsj.jp. Retrieved July 16, 2017.
  7. "Yurie SAWAHATA, Makoto Okada, Jun Hosoi, Kazuo Amano, "Paleomagnetic study of Neogene sediments in strike-slip basins along the Tanakura Fault". confit.atlas.jp. Retrieved July 16, 2017.
  8. connelly@geo.arizona.edu. "Southwest Japan". geo.arizona.edu. Archived from the original on October 10, 2017. Retrieved July 16, 2017.
  9. A. Taira, H. Okada, J. H. McD. Whitaker & A. J. Smith, The Shimanto Belt of Japan: Cretaceous-lower Miocene active-margin sedimentation
  10. "Sanbagawa belt (Sambagawa metamorphic belt), Shikoku Island, Japan". mindat.org. Retrieved July 16, 2017.
  11. "Chichibu belt from geo.arizona.edu". geo.arizona.edu. Archived from the original on December 5, 2017. Retrieved July 16, 2017.

Further reading

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Searchtool.svg Statistical map of location, size and depth of earthquakes near Japan