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Composition of Continental Crust

Published in Crust Composition 2 mins read

What is Continental Crust Made Of?

Continental crust is primarily composed of granitic rocks, which are rich in silicon and aluminum. These rocks are less dense than the basaltic rocks that make up the oceanic crust. However, continental crust is not solely granitic. It's a complex mix of rock types, including:

  • Igneous rocks: These form from the cooling and solidification of magma or lava. Granite is a prime example, but other igneous rocks are also present.
  • Sedimentary rocks: Formed from the accumulation and cementation of sediments (like sand, silt, and shells), these rocks represent a significant portion of the continental crust.
  • Metamorphic rocks: Created when existing rocks are transformed by heat, pressure, or chemical reactions, these rocks add further diversity to the continental crust's composition.

The most common elements found in continental crust include feldspar, granite, quartz, and pyroxenes. The overall composition is described as felsic, indicating a higher proportion of feldspar and silica.

Density and Compositional Differences

Continental crust, with a density of about 2.7 grams per cubic centimeter, is less dense than the oceanic crust (which is primarily basaltic). This density difference is a key factor in plate tectonics, with the less dense continental crust tending to ride above the denser oceanic crust during plate collisions.

Formation of Continental Crust

While the exact mechanisms are still being researched, a significant amount of continental crust is believed to form through a rock-forming process involving partial melting and differentiation of mantle material. This process creates the felsic rocks characteristic of continental crust. Collisions between tectonic plates also contribute to the building and thickening of continental crust.

The information above incorporates details from several sources, including ScienceDirect, Britannica, and National Geographic.