Relation between the forms of the Earth relief and the structure of the lithosphere
The lithosphere is the hard shell of the Earth, consisting of the earth’s crust and the upper layer of the mantle. Forty years ago, a scientific theory of lithospheric plates arose. According to this theory, the lithosphere is broken by giant cracks into separate blocks – lithospheric plates. The boundaries of the plates pass along the mid-ocean ridges of the ocean floor or deep-sea gutters, and on land – along mountain belts, such as the Himalayas, Carpathians, Alps, Andes. Scientists distinguish 7 large plates and about 20 smaller ones.
The lithospheric plates very slowly move along the soft layer of the mantle – the asthenosphere – at a speed of 1-6 cm per year, it is impossible to notice such movement without special instruments. Due to the motion of the lithospheric plates in the horizontal direction, in some places on the earth’s surface their collision occurs, in others the discrepancy. This leads to the formation of folds in the earth’s
Features of the structure of the lithosphere and the movement of lithospheric plates are studied by the science of tectonics. Different parts of the lithosphere are called tectonic structures.
The basis of each lithospheric plate is a platform – an ancient relatively stable aligned section of the earth’s crust. Platforms in their structure are basically two-layered. The lower layer – the crystalline basement – consists of hard rocks of magmatic and metamorphic origin, and the upper one – sedimentary cover – from loose sedimentary rocks. If a crystalline basement leaves the earth’s surface, shields form on the platform.
At the edges of plates of the lithosphere are folding belts – mobile parts of the earth’s crust. Belt folds refer to seismically active areas, so they are also called seismic belts. Volcanism is widespread within them, earthquakes often occur. The largest and seismically active belt is the folding belt along the edges of the oceanic Pacific lithospheric plate, the so-called Pacific
Tectonic structures are shown on the map of the structure of the earth’s crust. It depicts the corresponding color of the platform, as well as areas of folding of different periods of mountain building.
In nature, there is a clear pattern of the distribution of tectonic structures and forms of relief. Thus, in ancient plains, large plains most often correspond to ancient platforms, and mountain systems to folding zones. For example, within the Eastern European platform, which occupies a significant part of Europe, the East European Plain extends, and in the areas of the Alpine folding of Eurasia are the highest mountains of the mainland – the Himalayas. Caucasus, Alps.
Knowledge of the structure of the lithosphere is of great practical importance. After all, with the tectonic structures associated with the location of deposits of different origin minerals. For example, knowing the boundaries of lithospheric plates, one can predict the presence there of deposits of minerals of igneous origin. Marine geologists, lifting special samples of rocks from the seabed at the boundary of lithospheric plates, found many deposits of iron ores and other metals. The shields of the ancient platforms also search for rocks of magmatic and metamorphic origin. And in the cover of the platform there are sedimentary minerals: oil, natural gas, coal, etc.
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