Researchers from the University of Copenhagen have developed a method that can accurately
Tectonic theory believes that lithospheric platescover the Earth's surface like massive puzzle pieces. Every year they shift by several centimeters at approximately the same speed. But from time to time, these plates can suddenly speed up or slow down.
Researchers have developed a method for estimating speedmovement of the lithospheric plates, which uses geological data with high resolution. They are usually used to calculate the movement of plates relative to each other. The researchers used the same data to calculate changes in plate movement relative to the planet itself. The result provides estimates with unprecedented accuracy, the authors say.
Map of lithospheric plates. Image: Hasterok et al., Earth Science Reviews
Using this estimation method, scientists calculated,that the S American Plate slowed down by 13% during a period that occurred 10–14 mya and by 20% during another period from 5 to 9 mya. The researchers believe that the interaction between the expansion of the mountains and the lower plate speed was due to a phenomenon called delamination. A large amount of unstable material under the Andes was released and plunged into the mantle, causing major changes in the configuration of the plate.
This process caused the Andes to change shape andgrow to the side. It was during these periods that the mountain range expanded to Chile in the west and Argentina in the east. As the plate accumulated more rock material and became heavier, its movement slowed down. The Andes is the longest surface mountain range on Earth. It extends 8,900 km along the western periphery of South America, is up to 700 km wide, and in some places rises almost seven km into the sky.
In addition to modeling changes in the Andes, researchersalso tested their method on six other areas of the lithospheric plates. The results confirm the correctness of the simulation. The new method can be used for all plates for which high resolution geological data is available. It can be used to refine historical models of tectonics and reconstruct geological phenomena that remain obscure.
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