Nepedia
Back to Discover
Advanced Reader
🌍

Junggar Basin

earth science Maturity 7-9 Next article →

The Junggar Basin is a massive geological feature located in Northwest China.

Location of junggar basin
Location of junggar basin

It is situated in a region known as Dzungaria, within northern Xinjiang. The basin is physically enclosed by several major mountain ranges that act like a rim. To the northwest lie the Tarbagatai Mountains of Kazakhstan. The Altai Mountains of Mongolia border the northeast. To the south, the Heavenly Mountains, or Tian Shan, provide a massive boundary. This area is one of the largest sedimentary basins in Northwest China. It is a vital site for scientists studying how the Earth's crust moves and changes over millions of years.

The geological structure of the basin is built upon very old basement rocks. These basement rocks were largely formed during the development of the Pangea supercontinent. This occurred through complex tectonic events ranging from the Precambrian to the late Paleozoic era. The basin itself developed as a series of foreland basins. A foreland basin is a low area that forms immediately in front of growing mountain ranges. Over time, layers of sedimentary rocks have piled up on top of the basement. These sediments include materials like conglomerate, sandstone, siltstone, and mudstone.

Cross-section of Junggar Basin
Cross-section of Junggar Basin

The basin can be divided into six distinct structural parts. The Wulungu Depression was created by faulting and forms a flat depression. It contains sedimentary layers between 2,000 and 4,000 meters thick. The Luliang uplift, also called the Sangequan uplift, is surrounded by narrow, steeply dipping edges to the north. Its southern side is wider and dips more gently. This area contains sedimentary layers from 1,100 to 4,000 meters thick. The Central Depression consists of three major lowland plains: Manas, Central, and Wucaiwan. This section holds massive sedimentary layers reaching 5,000 meters in thickness.

Junggar basin map(3)
Junggar basin map(3)

Other parts of the basin show how tectonic forces shape the land. The West Uplift includes the Chepaizi-Paotai uplift and the Urho-Karamay monocline. The Chepaizi-Paotai uplift was formed by an eastward plunging fold and faulting. The Urho-Karamay monocline formed due to a thrust fault along the basin's boundary. Interestingly, the collision of the Indo-Australian plate during the Neogene caused the northern part of the basin to uplift. This movement re-activated old faults from the Permian period. These actions helped concentrate abundant hydrocarbons, such as oil and gas, in the anticline parts of the area.

The history of the basin involves the movement of several massive tectonic plates. Long ago, the Xinjiang paleocraton was pulled apart by rifting. This created the West Junggar Ocean during the Late Cambrian. Later, the Mayilashan ocean basin and a back-arc basin formed in the east. Eventually, the Tarim, Kazakhstan, and Siberian plates converged. This convergence trapped oceans and created volcanic arcs.

Basement(3)
Basement(3)

During the Mid-Carboniferous, these plates joined together. This process helped consolidate the area into a stable part of the modern Eurasian plate. This complex history of opening and closing oceans explains the variety of rocks found today.

The environment of the Junggar Basin has shifted dramatically over time. During the Mesozoic era, the area was mostly filled with rivers and lakes. The climate was initially humid and wet. However, as the Pangea supercontinent began to break apart, the climate changed. The large monsoon systems that brought moisture began to fade. This caused a transition from humid to arid, or dry, conditions.

Mesozoic to Cenozoic of Junggar Basin(2)
Mesozoic to Cenozoic of Junggar Basin(2)

As the Tian Shan mountains continued to rise, they created a rain-shadow effect. This meant the mountains blocked moisture, making the basin even drier and warmer. The lakes in the basin also became saltier as the water evaporated.

The Junggar Basin is extremely significant due to its rich natural resources. The combination of volcanism and sedimentary deposition has created large deposits of petroleum, coal, and various ores.

Petroleum Distribution(2)
Petroleum Distribution(2)

These resources are vital for energy and industry. Additionally, the basin holds a unique geographic record. According to Guinness World Records, it is the land location most remote from an open sea. It sits at a great-circle distance of 2,648 kilometers, or 1,645 miles, from the nearest open ocean. This isolation and its complex geological layers make it a unique window into Earth's past.

693 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (6)
File:Location of junggar basin.svg
Location of junggar basin.svg
File:Junggar basin map(3).png
Junggar basin map(3).png
File:Cross-section of Junggar Basin.png
Cross-section of Junggar Basin.png
File:Basement(3).png
Basement(3).png
File:Mesozoic to Cenozoic of Junggar Basin(2).gif
Mesozoic to Cenozoic of Junggar Basin(2).gif
File:Petroleum Distribution(2).png
Petroleum Distribution(2).png
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.