Geology of Kazakhstan

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The geology of Kazakhstan includes extensive basement rocks from the Precambrian and widespread Paleozoic rocks, as well as sediments formed in rift basins during the Mesozoic.[1]

Bektau Ata

Geologic history, stratigraphy and tectonics

Altai mountains
, although they are present where the range extends into Russia and China.

Much of Eastern Europe and Central Asia has

stromatalite
fossils and quartzites are found in the Kazakh Uplands. Low-grade metamorphism and granitization took place from 1.2 billion to one billion years ago. All the Precambrian massifs hold Upper Riphean quartzite and quartz sandstone, dated with detritral zircon to 850 million years ago.

Riphean and

clastic rocks, acid tuff and alkali basalt flows.[2]

Paleozoic

Rock outcrop by the Ebita river, Aktobe Region, western Kazakhstan

Early Ordovician gives way to 200 meters of shale and chert, followed by flysch up to 3.5 kilometers thick and another thick sequence of andesite, basalt and coarse clastics. Silurian
rocks are absent in the uplands.

In Chu-Kungey, Tengiz, Zharma-Saur and other districts, island arc volcanic rocks such as tuff, clastics and reef limestone are up to seven kilometers thick.

In the North Caspian Depression, only Late Paleozoic rocks outcrop at the surface. Deepwater chert and carbonates are common, with deposits up to 25 kilometers thick. Permian up to five kilometers thick has formed domes, which intrude upward into Mesozoic and Paleogene rocks. Carboniferous deepwater limestone forms a four kilometer flysch in the Cis-Urals Foredeep Basin in the South Urals region, which also includes olistrosomes and a Permian salt-bearing marine molasse.

Middle Cambrian rocks in the Kazakh Uplands have an angular unconformity with older rocks because they were thrust onto a magmatic arc in the

Foredeep Basin
. Within the foredeep basin, limestone deposition shifted to coal-bearing molasse.

Small synclines in the Karaganda Foredeep Basin show deepwater limestone and shale 450 meters thick from the Carboniferous and Permian, as well as 4.5 kilometer thick coal-bearing molasse. Within the Tengiz Basin, deposits are never more than two kilometers thick and grow thicker to the south. The Chu Basin is filled with undeformed Middle Devonian through Permian red molasse and carbonate deposits.

Tien Shan Mountains. Geologists have recognized these rocks through magnetic anomalies, drillholes and occasional outcrops. The volcanic rocks include tuff, cooled lava and trachyandesite and rhyolite ignimbrite up to five kilometers thick.[3]

Mesozoic-Cenozoic (251 million years ago-present)

Layers of Paleogene rock in eastern Kazakhstan

Intraplate rifting began in the

Kizilkum basins contain sand, clay and coal-bearing shallow water terrigenous sediments and salt deposits two kilometers thick from the Middle Jurassic, up to three kilometers thick from the Cretaceous and one kilometer thick from the Cenozoic
.

The Triassic was a period of erosion in the Kazakh Uplands and the

Balkhash and Tengiz basins are all small and filled with Late Triassic through Jurassic lacustrine deposits. Cretaceous and Paleogene deposits are largely missing, followed by a 100-meter thick sequence of Neogene and Quaternary gypsum-bearing alluvial fan sediments.[4]

Geological research

Geological research in Kazakhstan began in the 18th century due to growing Russian influence along the

Kirgiz Steppe north of the Tien Shan mountains and the construction of the Trans-Siberian Railway prompted further study. The Russian Geological Committee launched regional mapping efforts in 1925, after foreign sources on Central Asian geology disappeared in the aftermath of the Russian Revolution. As recently as the early 1990s, geologists in Kazakhstan were split between plate tectonics and a different set of mobilist theories more similar to the old geosynclinal model.[5]

Natural resource geology

The North Caspian Depression contains oil and natural gas, together with the Chu Basin, where they are associated with salt

rare earths
, lead, zinc, copper and molybdenum.

See also

  • Charyn National Park – national park in Kazakhstan

References

Wikimedia Commons has media related to Geology of Kazakhstan.
  1. ^ Moores, E.M.; Fairbridge, Rhodes W. (1997). Encyclopedia of European & Asian Regional Geology. Springer. pp. 450–460.
  2. ^ Moores & Fairbridge 1997, pp. 451–452.
  3. ^ Moores & Fairbridge 1997, pp. 452–458.
  4. ^ Moores & Fairbridge 1997, pp. 458–459.
  5. ^ Moores & Fairbridge 1997, pp. 450–451.
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