The crust of our planet consists of the so-called platforms (relatively homogeneous, stable blocks) and folded zones, which differ from each other in age. If you look at the tectonic map of the world, you can see that the folding areas occupy no more than 20% of the Earth's surface. What is Hercynian folding? What is its time frame? And what mountain systems were formed in this era of tectogenesis? Our article will tell about this.
Hercynian folding: where and when?
Tectogenesis - a set of tectonic movements and processes that form the structures of the earth's crust, occurs constantly, with greater or lesser force. There are several stages of tectogenesis in the history of the Earth: Baikal (the most ancient), Caledonian, Hercynian, Mesozoic and Alpine (the youngest).
The Hercynian folding is one of the most intense periods of mountain building in the history of our planet. It took place in the late Paleozoic, starting at the turn of the Devonian and Carboniferous (about 350 million years ago) and ending at the end of the Permian period (about 250 million years ago). The name of the folding is associated with the so-called Hercynian forest - an array in Central Europe. The very same areas of Hercynian folding in geology are usually called Hercynides.
This era of tectogenesis is associated with the formation of large mountain structures in Western, Central and Southern Europe, Central and East Asia, Australia, as well as northeastern Africa (which ones - we will tell below).
The Hercynian folding includes several successive time phases:
- Acadian (Mid Devonian).
- Breton (late Devonian).
- Sudetian (beginning and middle of the Carboniferous).
- Asturian (second half of the Carboniferous).
- Zaalskaya (Upper Carboniferous - early Permian).
Hercynian folding: mountains, ranges and minerals
Numerous deposits of oil (in Canada, Iran, North America, etc.) and coal (Donetsk, Pechora, Karaganda and other basins) are associated with Late Paleozoic sedimentary rocks. By the way, the Carboniferous period in the geochronological scale of the Earth bears this name for a reason. Geologists also associate the formation of the richest deposits of copper, lead, zinc, gold, tin, platinum and other valuable metals in the Urals and Tien Shan with the Hercynian era of tectogenesis.
The relief of the Hercynian folding corresponds to the following mountaincountries and facilities:
- Appalachians.
- Ural Mountains.
- Tien Shan.
- Kunlun.
- Altai.
- Sudet.
- Donetsk Ridge and others.
Most traces of this era of mountain building left in Southern Europe, in particular on the Apennine, Iberian, Balkan Peninsulas. It also affected and transformed the structures of the previous, Caledonian orogeny. We are talking about the structures of central Kazakhstan, the northern part of Transbaikalia and Mongolia. In general, the distribution of Hercynidae on the Earth map is shown on the map below.
Ural Mountains
Ural is a mountain range 2,000 kilometers long and no more than 150 kilometers wide. The conditional border between Europe and Asia runs along its eastern foot. Geographically, the mountain system is divided into five parts: the Southern, Middle, Northern, Subpolar and Polar Urals. The mountains are relatively low, the maximum point is Narodnaya Peak (1895 meters).
The process of formation of the Ural mountain system began in the late Devonian, and ended only in the Triassic. Within its limits, rocks of Paleozoic age come to the surface - limestones, dolomites, sandstones. At the same time, the layers of these rocks are often severely deformed, crumpled into folds and broken by ruptures.
The Ural Mountains are a real treasure trove of minerals, primarily ore. There are large deposits of copper ores, bauxite, tin, oil, coal and gas. The bowels of the Urals are also famous for variousgems: emeralds, amethysts, jasper and malachite.
Appalachian Mountains
Another major structure of the Hercynian era is the Appalachians. The mountain system is located in the eastern part of North America, in the United States and Canada. It is a hilly gentle hill with wide valleys and well-marked traces of glaciation. Maximum height - 2037 meters (Mount Mitchell).
Appalachians were formed in the Permian period in the zone of collision of two continents (during the formation of Pangea). The northern part of the mountain system began to form in the Caledonian era of folding, and the southern part - in the Hercynian. The main mineral we alth of the Appalachian Mountains is coal. The total mineral reserves here are estimated at 1600 billion tons. Coal seams occur at shallow depths (up to 650 meters) and are covered from above by sedimentary rocks of the Mesozoic and Cenozoic age.
