We associate variations from sea level with climate evolution. If it is certain that this is a major element of influence, it is not the only one. Geological and tectonic processes can also interfere. Thus, a new study shows how the decline in marine layer production can lead to significant decline in sea levels 15 million years ago.
During the history of the surface, the surface is changing. Often these variations are associated with the evolution of the climate. Due to the melting of hot periods of polar hats and glaciers, attract the height of the sea level, but especially because of GameGame Thermal of seawater. On the contrary, during the cold periods, sea levels usually decrease, a large part of the water is then protected in the form of ice, and VolumeVolume This time the oceans are low due to thermal contraction of water.
Variation in sea level: it is not necessary to have a climate question
However, in the sea level (we also use the term Eustatic), these variations can be linked to other factors, completely different. The most clearly changed in the volume of the marine basin. However, it should be clear that the area of the continents remain relatively stable over time (and therefore the accumulated surfaces of the oceans), these variations in the amount of marine basins are mainly through the evolution of the depth of these basins.
If we observe a sea basin cut, for example, the Atlantic Ocean, we realize that the depth is not the same. In the extraordinary plains near the continents, the background of the sea is deep and leads to the center of the basin.
The minimum deep zone is thus at the level of marine doses, where the new LayerLayer By Magnetic process. This evolution of BathroomBathroom Which number marks the sea basin LithosfireLithosfire Marine, in fact, lathefer made at the axis level ofAcreAcre Hot, and therefore is less dense and thicker than the old lithosphir (cold, denser and thick) that we find away from the spinal cord. In fact, the background of the sea is high on the axis and is deeply far away. However, of this trendIsostatic adjustmentIsostatic adjustment A marine basin will directly affect the total volume. In this way, we understand that a large part of the young layer will have less volume than the same extension of the basin, made of a large part of the old layer.
Layer production speed can also play a role
Regardless of climate development, it is possible to observe the surface change in the sea in relation to the dynamics of the maritime action. A team of researchers discovered that a significant slowdown in its preparation SeaSea Between 15 and 6 million years of age, levels can be due to a significant decline.
A recent research has actually shown that its migration during this period Tetonic platesTetonic plates The decrease of 35 % decreased, which includes a slowdown in the marine durassal, even the ultra -listed act. Based on this figure, a team of researchers calculated that this situation causes the sea to deepen the sea, in fact reducing the level of the oceans by 26 to 32 meters! The second phenomenon could also be included, which brings the fall of the sea. In fact, the slow maritime activation features are a significant importance to the tricktoon expansion process. VolcanoVolcano Then diminishes to the durassal level, which has the effect of reducing the quantity Green HouseGreen House Excludes the layer of external and unusual sea.
This last point will deepen the background of the sea and reduce the level of about two meters. Decline ProgramProgram Gas may have participated in the cooling of the climate, which also affected the volume of the oceans. Overall, the results published in the journal Geo Chemistry, Geo Physics, Geo Systems Recommend that sea levels may decrease more than 60 meters.
