The entire modern relief of both Russia and the whole world began to form a very long time ago, at the dawn of the geological history of the Earth. This also applies to the folding of the planet - mountain ranges, depressions. It was formed over many geological epochs, and also continues to change its appearance even now. In this article, we would like to draw your attention to the Cenozoic folding - the "youngest" one. And let's start with a general analysis of geological epochs.
What are folding?
The relief of our planet is historically heterogeneous - some objects formed earlier, some - millions of years later. Accordingly, all existing foldings are named after the era in which they acquired their appearance. Let's get to know them briefly.
Archaean folding. The oldest - its age is 1.6 billion years. Basically, it includes platforms - a kind of "core" of the continents, their most stable and even areas.
Baikal folding. Age - 1200-500 million years. It got its name from the name of the Russian lake, because the area where it is located was formed during this period. The Baikal also includes the Brazilian Plateau, the Arabian Peninsula, the Patom Highlands,Yenisei Ridge and others.
Caledonian folding. Formed 500-400 million years ago. Named after about. Caledonia, where it was first discovered by geologists. Great Britain, eastern Australia, Scandinavia, southern China were formed during this era.
Hercynian folding. Relief formed 400-230 million years ago. Here we will include the Urals, most of Europe, the Great Dividing Range, the Cape Mountains, the Appalachians.
Mesozoic folding. Age - 65-160 million years. Formed when dinosaurs ruled the earth. The Russian Far East, the Cordillera appeared just then.
Alpine or Cenozoic folding was the last to take shape. Let's talk more about her era.
Cenozoic - what is it?
Cenozoic - the Cenozoic era is the geological era in which we live today. And it began 66 million years ago. Its border was marked by the mass extinction of biological species, which began at the end of the Cretaceous.
This name was first used in 1861 by John Phillips, an English geologist. Its short designation, which you can find in the scientific literature, is KZ. The word is formed from the fusion of two ancient Greek words: καινός ("new") + ζωή ("life"). Accordingly, "new life".
The Cenozoic itself is divided within itself into several more periods:
-
Paleogene (65.5-23.03 Maback). Includes:
- Paleocene;
- Eocene;
- Oligocene.
-
Neogene (23, 03-2, 59 million years ago). Consists of two stages:
- Miocene;
- Pliocene.
- Quaternary period. It began 2.59 million years ago and continues to this day. So far, scientists have identified only two epochs within it - the Pleistocene and the Holocene.
What is remarkable about the Cenozoic era?
What happened significant for geological history in the Cenozoic era? The following events are highlighted:
- Separation of New Guinea and Australia from Gondwana.
- Approximation of the above arrays to Southeast Asia.
- Setting Antarctica at the South Pole.
- Expansion of the Atlantic Ocean.
- Continuation of the drift of the continents, the junction of North America to South.
Transformations in the biological world also turned out to be significant:
- All animals larger than a crocodile have disappeared from the face of the Earth.
- As a result of continental drift, unique biocommunities have formed on the continents.
- The advent of the era of mammals and angiosperms.
- The era of savannas, insects, flowering.
- The emergence of a new biospecies - Homo sapiens.
What is Cenozoic folding?
Alpine folding began to form 65 million years ago and is still at this stage. Its components are the youngest, and therefore the most restless areas of the earth's crust. In the districtsmountainous reliefs are still formed with Cenozoic folding - as a result of earthquakes, volcanic eruptions. Another feature is the location near the boundaries of lithospheric plates.
The main areas of Cenozoic folding are as follows:
- Andes.
- Caribbean.
- Aleutian Islands.
- Asia Minor.
- Mediterranean Sea.
- Southwest Asia.
- Caucasus.
- Philippines.
- Antarctic Peninsula.
- New Zealand.
- Himalayas.
- New Guinea.
- Kurils.
- Kamchatka.
- Greater Sunda Islands.
- Japan.
Types of folding in Russia
Mountain systems of Cenozoic folding, like other systems, are common in our country. All geologists have identified five of their varieties:
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Baikal and Early Caledonian (700-520 million years ago):
- Transbaikalia;
- Baikal region;
- Tuva;
- Eastern Sayan;
- Timan and Yenisei Ridge.
-
Caledonian (460-400 million years ago):
- Gorny Altai;
- Western Sayan.
-
Hercynian (300-230 million years ago):
- Rudny Altai;
- Ural Mountains.
-
Mesozoic (160-70 million years ago):
- Sikhote-Alin;
- north-eastern part of the country.
-
Young Cenozoic folding (30 million ago to the present day):
- Koryak Highlands;
- Caucasian relief;
- Kuril Islands;
- Sakhalin;
- Kamchatka.
Cenozoic folding of Russia
If we look at the map of the Russian Federation and the former Soviet Union, we will notice that the Alpine folding in the south and southwest of the country includes:
- Eastern Carpathians.
- Greater Caucasus.
- Mountain Crimea.
- Pamir.
- Kopet-Dag.
- Small Balkhan.
Together, these systems adjoin the Alpine-Himalayan belt.
Now let's turn to the eastern part of the state. The Kuriles, Sakhalin, Kamchatka can be attributed to the Cenozoic zone of the Pacific fold belt.
Let's take a closer look at the features of these systems.
Alpine-Himalayan belt: characteristics
This geological zone has a very complex structure. In the latter, the main role is played by large median massifs and basins of inland seas. In terms of their area, they are not inferior to the mountain systems of the Cenozoic folding of the belt. The latter here characteristically flow around the middle platforms, branching.
As for the massifs of the Alpine-Himalayan belt, they are much older than folded formations. They are mainly represented by intermountain (elevated) uplands, as well as sea depressions. According to geologists, they were formed in the Hercynian or even later.
It is important to note that in the basins of the inland seas (western Mediterranean, southern Caspian, Black Sea) of the Alpine-HimalayanThe earth's crust has gone through some rebirth, has experienced a kind of "oceanization". From here, today we can talk about the oceanic type of structure of the basins of the listed seas.
The relief of Cenozoic folding is not the only component of the Alpine-Himalayan belt. Its mountain range is quite heterogeneous. Here we can highlight the following:
- Hercynian and older structures. I must say that over the course of history they were somewhat "recycled" by the Alpine (Cenozoic era).
- Some number of Mesozoic structures.
- And, finally, the Neogene and Paleogene reliefs, the formation of which, according to geologists, fell on the Alpine era of the Earth's history.
Note here quite often developed deep faults. They dismember the Alpine-Himalayan belt into blocks, which makes it possible to speak of its blocky structure.
Formation of the Alpine-Himalayan Belt
The period of the most active development of this belt fell on the Mesozoic and Cenozoic. In general, we can talk about its uneven and heterogeneous structure.
The Alpine-Himalayan belt was formed on the site of a complex and large-scale Paleosian Asian-European belt. In some places it stands on sites and more ancient platforms. It can rightfully be called a superimposed, secondary geosynclinal belt.
As we said, at present, geologists agree that the Alpine-Himalayan belt is quite difficultbuilt. Its development continues in our era - it is at the orogenic stage. For people, this is dangerously increased seismic activity, volcanic eruption, which leads to the destruction of structures, settlements, and human casu alties.
Cenozoic regions in the Russian Far East
Now let's look at the specifics of the Cenozoic folding mountains in the Far East. As for the West Kamchatka system, it is an Upper Cretaceous terigen complex. It is overlain by Paleogene and Neogene rocks.
Central and Eastern Kamchatka systems formed in the Paleogene. But the large bas alt volcanoes of this area appeared in the Pliocene-Pleistocene era. What is interesting: the Eastern zone is actively formed today due to modern volcanism (28 active volcanoes).
The Kuril island arc (Big and Small Ridge) was formed in the Cretaceous and Quaternary period. It is crushed by transverse grabens (faults, lowered terrain). A deep-sea trench is located in front of the arc front.
And, finally, the Cenozoic folding of Sakhalin. It is divided into the western and eastern parts by the Central Kuril graben. Sakhalin is rich in coal deposits, gas and oil deposits.
So we presented the mountain systems of the Cenozoic folding areas, along which the regions of Russia - the Caucasus and the Far East - are located. This geological zone is the youngest. Moreover, it is still being formed: for example, these processes are very noticeable onKamchatka. However, they are accompanied by dangerous earthquakes and volcanism.
