What is the crust type of the Qinghai-Tibet Plateau? Which two plates formed the Qinghai-Tibet Plateau?

The Qinghai-Tibet Plateau has strong radiation, abundant sunshine, low temperature, and little accumulated heat. The temperature decreases with increasing altitude and latitude, and the daily temperature difference is large; there is a clear distinction between dry and wet, with frequent night rains; the winter is dry and cold for a long time, with frequent strong winds; the summer is warm and rainy, with frequent hail. The Qinghai-Tibet Plateau is densely covered with high mountains and rivers, with steep and changeable terrain and complex topography. Its average altitude is far higher than that of surrounding areas at the same latitude. Today, let's take a look at the crust types of the Qinghai-Tibet Plateau and which two plates formed the Qinghai-Tibet Plateau. Encyclopedia knowledge will give you a detailed introduction.

Contents of this article

1. Crustal type of the Qinghai-Tibet Plateau

2. Which two plates formed the Qinghai-Tibet Plateau?

3. Characteristics of the Qinghai-Tibet Plateau

Crustal type of the Qinghai-Tibet Plateau

The crust is divided into 12 main types. They are: shield, platform, Paleozoic orogenic belt, Mesozoic-Cenozoic orogenic belt, continental rift system, volcanic island, island arc, trench, ocean basin, ocean ridge, marginal basin, inland basin. The crust type refers to the crust segments with similar geological and geophysical characteristics.

1. Shield: It is composed of Precambrian rocks, with little or no sedimentary cover and little or no seismic activity. It is a stable part of the earth's crust. It is structurally stable for a long time and has a gentle terrain. The degree of metamorphism of the exposed rocks mostly reflects their original burial depth. They are generally formed under temperature and pressure conditions at a depth of 5-35 km. The largest shields in the world include the African Shield, the Canadian Shield and the Antarctic Shield.

2. Platform: It is also a stable part of the earth's crust. Its base is composed of Precambrian rocks, and it is covered with 1-3 km of undeformed or slightly deformed sedimentary rocks. The age of sedimentary rocks on the platform can range from the Precambrian to the Cenozoic, such as the North China Platform in China.

3. Paleozoic orogenic belt: It is a curved zone of Paleozoic folds, faults and igneous activities. Its width and extension can range from hundreds of kilometers to thousands of kilometers. It is composed of various geosyncline rocks. It is often characterized by low-lying eroded mountains or mountainous areas, representing moderately stable tectonic activity conditions. The most intense Mesozoic orogenic belt is the Cordillera Mountains in western America and similar mountainous areas in eastern Asia.

4. Mesozoic-Cenozoic orogenic belts: Their scale, rock types, characteristics, etc. are similar to those of the Paleozoic orogenic belts, but they differ from the latter in that they have unstable tectonic activity conditions. The most intense Cenozoic orogenic belts are the Alpine-Tethys belt that runs across southern Eurasia and the above-mentioned Cordillera Mountains, such as the Tibetan Plateau and the Colorado Plateau.

5. Continental rift system: a valley bounded by faults. It is 50-75 km wide and can be hundreds to thousands of kilometers long. It is characterized by tension structures. The longest rift system on Earth is the East African Rift, which stretches 5,600 km from western Asia Minor to southeastern Africa. Rift systems can be formed in rocks of any age. Young rift systems are characterized by unstable tectonic conditions.

6. Volcanic islands: Oceanic islands have various types and origins. Here we refer to islands of volcanic origin and unrelated to subduction zones. They are located on or near ocean ridges or in ocean basins, and their tectonic activity varies greatly.

7. Island arc: Island arcs are arc-shaped island chains formed on active or modern subduction zones. Island arc systems are mainly composed of young calc-alkaline volcanic rocks and intrusive rocks. Modern island arcs are characterized by strong earthquakes and volcanic activity.

8. Trench: The ocean trench is the mark of the beginning of the subduction zone, often accompanied by strong seismic activity. The trench is parallel to the island arc or volcanic chain on the subduction zone along the continental margin, representing the deepest part of the ocean, with a depth of generally 5-8 km. It usually contains a small amount of sediments from nearby island arcs or continental areas.

9. Ocean basin: It is a stable part of the crust with a thin deep-sea sediment cover and linear magnetic anomalies. The sediment layer thickens along the continental slope due to the supply of clastic sediments from the continent. Generally speaking, the ocean basin is relatively flat, but it has deep-sea hills, submarine mesas and oceanic islands.

10. Ocean ridge: It is a wide linear belt near the center of the ocean. It is high in terrain and unstable in structure. There is a rift system near the top of the ridge, from which basalt magma intrudes or erupts. The world-wide ocean ridge system is interconnected from one ocean to another, with a total length of 80,000 km. The top of the ridge is often cut by many transform faults. The sections of the ridge can be displaced by thousands of kilometers. Iceland is the only modern example of an ocean ridge exposed above the ground.

11. Marginal basin: It is a component of the oceanic crust, located between island arcs or between island arcs and continents, and the sediments come from the continents or island arcs. Marginal basins are widely developed in the western Pacific Ocean and can be divided into active and inactive categories. Tectonic active marginal basins have thin sedimentary cover, graben-horst topography and high heat flow values.

12. Inland sea basins: basins completely surrounded by land, and marginal seas not related to island arc systems. The latter are also almost surrounded by land, such as the Black Sea and the Gulf of Mexico, and are moderately stable to stable areas in terms of structure.

Which two plates formed the Qinghai-Tibet Plateau?

The Qinghai-Tibet Plateau was formed by the collision of the Indian Plate and the Eurasian Plate. The Qinghai-Tibet Plateau is the largest plateau in China and the highest plateau in the world in terms of average altitude. About 50 million years ago, the collision of the Indian Plate and the Eurasian Plate led to the formation of the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau is the largest plateau in China and the highest plateau in the world. It is known as the "Roof of the World" and the "Third Pole". It starts from the southern edge of the Himalayas in the south and ends at the Kunlun Mountains, the Altun Mountains and the northern edge of the Qilian Mountains in the north. The west is bordered by the Pamir Plateau and the Karakoram Mountains. The east and northeast are connected to the western section of the Qinling Mountains and the Loess Plateau. It lies between 26°00′~39°47′ north latitude and 73°19′~104°47′ east longitude.

Characteristics of the Qinghai-Tibet Plateau

The radiation is strong, the sunshine is abundant, the temperature is low, the accumulated heat is small, the temperature decreases with the increase of altitude and latitude, and the daily temperature difference is large; the dry and wet seasons are distinct, and there are many night rains; the winter is dry and cold for a long time, with many strong winds; the summer is warm and rainy, with many hailstorms. The Qinghai-Tibet Plateau is densely covered with high mountains and rivers, with steep and changeable terrain and complex topography. Its average altitude is far higher than that of surrounding areas at the same latitude.

1. Geological environment

From north to south, the Qinghai-Tibet Plateau includes six tectonic belts, namely the Qilian-Qaidam, Kunlun, Bayan Har, Gangdise, Himalaya, and Qiangtang-Chamdo. The tectonic belts are separated by suture zones represented by ophiolite mélanges, roughly bounded by the Longmu Co-Jinsha River suture zone.

2. Geomorphic features

The Qinghai-Tibet Plateau is densely covered with high mountains and rivers, with rugged and varied terrain and complex topography. Its average altitude is far higher than that of surrounding areas at the same latitude. The mountains on the Qinghai-Tibet Plateau are uneven and vary greatly. Areas above 4,000 meters above sea level account for 60.93% of the area of ​​Qinghai Province and 86.1% of the area of ​​Tibet.

3. Crustal structure

The crust and upper mantle of the Qinghai-Tibet Plateau show obvious inhomogeneity in both vertical and horizontal directions. The lithosphere has a clear block-layer structure: vertical stratification and horizontal block division. The thickness of the lithosphere is about 140 to 170 kilometers, and the average thickness of the crust is about 70 kilometers.