Answer
Oceanic lithosphere subducts while continental lithosphere does not primarily due to differences in their density and composition.
Oceanic lithosphere is denser than continental lithosphere. This density difference arises from the composition and age of the lithospheric material. Oceanic lithosphere is primarily composed of dense basaltic rocks, which are formed at mid-ocean ridges and are relatively young. The newly formed oceanic lithosphere is hot and less buoyant compared to the older and cooler lithosphere. As a result, it tends to sink into the underlying asthenosphere when subjected to compressional forces at convergent plate boundaries.
In contrast, continental lithosphere is composed of less dense granitic and sedimentary rocks. These rocks have a lower density compared to the underlying asthenosphere. Additionally, continental lithosphere is thicker and more buoyant than oceanic lithosphere due to its composition and continental crust's higher thickness. Consequently, it resists subduction and tends to remain on the Earth's surface during tectonic interactions.
The buoyancy of continental lithosphere prevents it from subducting beneath other lithospheric plates. Instead, when continental plates collide at convergent boundaries, they typically undergo a complex process of crustal deformation, mountain building, and intense compression, resulting in the formation of large mountain ranges such as the Himalayas.
In summary, the differences in density, composition, and thickness between oceanic and continental lithosphere contribute to the contrasting behavior observed at convergent plate boundaries. Oceanic lithosphere, being denser and thinner, is prone to subduction beneath other plates, while continental lithosphere, being less dense and thicker, resists subduction and undergoes different deformation processes during plate collisions.
Work Step by Step
Oceanic lithosphere subducts while continental lithosphere does not primarily due to differences in their density and composition.
Oceanic lithosphere is denser than continental lithosphere. This density difference arises from the composition and age of the lithospheric material. Oceanic lithosphere is primarily composed of dense basaltic rocks, which are formed at mid-ocean ridges and are relatively young. The newly formed oceanic lithosphere is hot and less buoyant compared to the older and cooler lithosphere. As a result, it tends to sink into the underlying asthenosphere when subjected to compressional forces at convergent plate boundaries.
In contrast, continental lithosphere is composed of less dense granitic and sedimentary rocks. These rocks have a lower density compared to the underlying asthenosphere. Additionally, continental lithosphere is thicker and more buoyant than oceanic lithosphere due to its composition and continental crust's higher thickness. Consequently, it resists subduction and tends to remain on the Earth's surface during tectonic interactions.
The buoyancy of continental lithosphere prevents it from subducting beneath other lithospheric plates. Instead, when continental plates collide at convergent boundaries, they typically undergo a complex process of crustal deformation, mountain building, and intense compression, resulting in the formation of large mountain ranges such as the Himalayas.
In summary, the differences in density, composition, and thickness between oceanic and continental lithosphere contribute to the contrasting behavior observed at convergent plate boundaries. Oceanic lithosphere, being denser and thinner, is prone to subduction beneath other plates, while continental lithosphere, being less dense and thicker, resists subduction and undergoes different deformation processes during plate collisions.
