How the island arc in Japan was formed, and whether the island arc grew or died

Japan is an island arc formed by the subduction of the Pacific plate beneath the Eurasian plate, and is the only place on Earth where continents can now be seen.

The Japanese archipelago is located on the western side of the North Pacific Ocean and is part of a series of arc-shaped islands on the western edge of the Pacific Ocean. Including Hokkaido.

The four large islands of Honshu, Shikoku, and Kyushu and more than 3000 small islands nearby (including uninhabited islands.

Compose. Four of the large islands account for 98 of Japan's total area, with Honshu Island.

for the maximum. These islands are called the Japanese archipelago because they are part of Japan.

The formation of the Japanese archipelago dates back to ancient times, when it was separated from the Asian continent.

It was originally integrated and located on the eastern edge of Chinese mainland. Later due to the Pacific Rim.

The earth's crust has been continuously and violently changed, separating Japan from the Asian continent. It was only 12,000 years ago that today's Japanese archipelago was completely formed.

After extensive research, scientists believe that the parallel coexistence of island arcs and ocean trenches is the result of the oceanic crust falling under the continental crust when the oceanic crust and the continental crust collide with each other. For example, the Pacific crust, which is small in thickness and dense, and is located in a relatively low position, collides with the East Asian continental crust under the action of seafloor expansion, and the Pacific crust subducts under the East Asian continental crust, resulting in a huge deep trench on the ocean side. At the same time, the continued movement of the continental crust caused the surface sedimentary material of its leading edge to overlap each other, forming an island arc.

Plate theory (the dominant geological theory today) holds that the Pacific plate collided with the Eurasian plate, and that the Pacific plate subducted under the Eurasian plate, where the subduction formed the Japan Trench, and the Eurasian plate was uplifted to form the Japanese island arc.

Formed over time.

The island arc is extinction.

Extinction Boundary Classification.

1. Mountains are formed on land.

Between the continental crust and the continental crust, that is, the boundary of extinction on the land. The squeezing extinction border of tall mountain ranges such as the African plate and the Eurasian plate will be formed in the Alps.

The area is a famous orogenic belt. There is also the Himalayas between the Indian Ocean plate and the Eurasian plate.

System. Touching the gesture of remorse.

2. Trenches are formed in the ocean.

If it is the boundary between the extrusion of the oceanic plate and the continental plate, the oceanic plate subducts to the continental plate because of its higher density and lower position.

below, then on the side of the ocean will be formed a trench. The continental plate is squeezed upward, forming an island arc if it is in the sea, and mountains are forming on the land. Such as East Asia.

and the Cordillera Mountains that run through North and South America.

Topography. Most island arcs consist of two parallel, curved arch-shaped islands. The inner column of such a bi-island arc consists of a string of erupting volcanoes, while its outer row consists of islands that are not anterior cluster volcanoes.

In the case of only a single arc, many of the islands that make up it are volcanic.

An island arc that, in typical cases, has a land mass on the concave side, or a partially enclosed, particularly shallow sea. Along its convex side, there is a long, narrow deep trench almost constantly. The greatest depths of the ocean are found in such submarine depressions, as in the Mariana Trench.

As in the case of the Tonga Trench.

Destructive** often occurs at the site of the island arc. These are different from shallow sources recorded in other parts of the world, which originate from deep sources up to 600 km below the base of the island arc. These ** sources tend to be deeper and deeper towards the concave side of the island arc.

Volcanic island arcs are rising and subjected to strong denudation, and clastic material is transported to the surrounding basins and deep trenches, forming turbidites and other coarse clastic rocks. Metamorphic rocks are also common in the island arc area.

The outer side of the island arc is a high-pressure and low-temperature regional metamorphic zone, and the inner side is a high-temperature and low-pressure regional metamorphic zone, the former is represented by blue-amphibole, jadeite and angiolite, and the latter is represented by andalusite, and the two metamorphic zones are parallel to each other, called double metamorphic zones.

The word "islandarc" is interpreted as an arc of islands on the edge of the continent.

The term island arc is a long series of islands that are in the shape of an arc on the continental edge. Pinyin is: dǎohú. The phonetic pronunciation is: The structure is: island (semi-enclosed structure) arc (left and right structure).

What is the explanation of the limb loss of the island arc, we will introduce it to you through the following aspects:

Idioms about island arcs.

Mulberry arc artemisia arrows all over the world, Kyushu Island, mulberry arc ambition, mulberry arc Peng Ya, Qiong Island, Chunyun disdainful suburbs, cold island, thin island, thin suburbs, cold hanging arc, shooting arrows, arc set the day.

Words about island arcs.

Set the arc of the Chen, Qiongdao, Chunyun Island, thin suburbs, cold hanging arc, Qingsang arc, determined to shoot the arc, peach arc, spiny arrow, hanging arc, Chen, Sang arc, Artemisia arrow, despised.

Sentence formation about island arc.

1. In other places, the two plates may move in opposite directions and gradually converge along the deep trench and the island arc to form a sentence.

2. The Salto sea ophiolite is indicated by rare earths and trace elements** as an island arc ophiolite, which is consistent with the geological background.

3. The acid-** introductory rocks of the late Caledonian or early Hualixi invasion are the products of the island arc environment.

4. The magmatic activity in the Early Middle Carboniferous was controlled by type subduction and formed on the inner side of the continental island arc.

5. The Xiyingzi granite body in Guyang area of Inner Mongolia belongs to the calc-alkaline series, which has the characteristics of island arc granite.

Categories: Education Academic Exams >>**Report.

Problem description: It is best to give an example, such as the formation mechanism of the island arc.

Analysis: There is a group of arc-shaped islands between the Sea of China and the Pacific Ocean, because these islands are magnificent and magnificent like garlands, so they are called the colorful islands. It is also like a spring-only outer barrier on the Asian continent.

Interestingly, on the eastern side of the island arc are a series of the largest ocean trenches on Earth, some of which are deeper than Mount Everest. Among them, the Mariana Trench is more than 10,000 meters deep, more than 2,500 kilometers long, and 70 kilometers wide.

So how did this island arc trench area form?

Geologists believe that island arcs and trenches are caused by the collision of oceanic plates and continental plates, and the subduction of oceanic plates under the continental plates. Because the thickness of the ocean floor plate is small, the density is large, and the position is relatively low, when the ocean floor plate collides with the continental plate under the action of seafloor expansion stool infiltration, the ocean floor plate subducts, pulling the ocean floor upward, thus forming a deep trench.

During the subduction of the oceanic floor plate, it rubs against the continental plate, and the temperature rises to form magma, which is ejected and cooled by seawater, forming these island arcs parallel to the ocean trench.

Why are island arcs and ocean trenches arc-shaped?

This has to do with the fact that the surface of the earth is an earth's jujube ridge. Just as when we press a ball with our fingertips, the edge of the concave part must be arc-shaped, and ocean trenches and island arcs are traces of the downward bend of the oceanic plate into the Earth's interior.

The twin "siblings" of the trench are called island arcs. Trenches and island arcs are often born together. The island arc is the many islands in the ocean that are distributed in an arc, which is divided into an inner island arc and an outer island arc.

The inner island arc is on the land side, which is the contact zone between the oceanic plate and the continental plate, where volcanoes and ** are concentrated, such as the western Pacific island arc. According to statistics, there are more than 500 active volcanoes in the world, more than half of which are concentrated in the island arc. 95% of the world's most energy is also released here. Frequent magma eruptions caused by volcanic activity have made the island arc the most mineral-rich region in the world.

Outer island arc, near the ocean side, no volcanic ** zone. Most of them are distributed on the edge of the active oceanic plates, because they are at the junction of the oceanic plates and the continental plates, and are squeezed by the earth's plates, so in these places, volcanic activity occurs frequently.