In the geosciences, a trench system is a coherent geological weak zone in the earth's crust that leads to the total or partial sinking of the earth's crust.
These subsidence - which are often associated with large sedimentary basins - can be exposed, but in the course of the earth's history they can also be covered with sediments or later tectonics .
On Earth and Mars , trenches can be found primarily in those places where two large-scale lithospheres - plates adjoin (or have bordered) each other - e.g. B. in the deep sea trenches of the earth or the Valles Marineris on Mars. These plates can drift towards each other or move apart; in the first case, mountain folds usually occur , in the second, subsidence and rift formations occur .
When a continent breaks apart as a result of large tectonic processes, the slow formation of trenches in the lithosphere represents the first stage of this process, which usually lasts for millions of years. Among other things, new ocean basins can arise on Earth .
One of the largest rift systems in Africa can be found on earth , but not on today's continental margin, but running across East Africa . The East African Rift System is part of the Great Rift Valley , which extends from Lebanon to Mozambique . In terms of geological history, the Upper Rhine Graben in southwest Germany is probably connected with it ; Another striking example on earth is the Jordan Valley .
Up to now, no clear features of plate tectonics have been found on Venus , which is almost the same size .
The much smaller Mars, on the other hand, has probably the largest rift system in the planetary system in Valles Marineris . The huge, hundreds of kilometers wide and heavily rugged valley would stretch over 4000 km from Gibraltar to Moscow .
There can also be trench systems on other planets , as we know from the success of space travel and modern sensor technology or astronomical remote sensing . Whether larger moons can also have such structures depends on their predominant rock and its density .
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