Continental crust

Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial because its bulk composition is richer in aluminium silicates (Al-Si) and has a lower density compared to the oceanic crust,^[1]^[2] called sima which is richer in magnesium silicate (Mg-Si) minerals. Changes in seismic wave velocities have shown that at a certain depth (the Conrad discontinuity), there is a reasonably sharp contrast between the more felsic upper continental crust and the lower continental crust, which is more mafic in character.^[3]

Most continental crust is dry land above sea level. However, 94% of the Zealandia continental crust region is submerged beneath the Pacific Ocean,^[4] with New Zealand constituting 93% of the above-water portion.

^ Fairbridge, Rhodes W., ed. (1967). The Encyclopedia of Atmospheric Sciences and Astrogeology. New York: Reinhold Publishing. p. 323. OCLC 430153.
^ Davis, George H.; Reynolds, Stephen J.; Kluth, Charles F. (2012). "Nature of Structural Geology". Structural Geology of Rocks and Regions (3rd ed.). John Wiley & Sons. p. 18. ISBN 978-0-471-15231-6.
^ McGuire, Thomas (2005). "Earthquakes and Earth's Interior". Earth Science: The Physical Setting. AMSCO School Publications Inc. pp. 182–184. ISBN 978-0-87720-196-0.
^ Mortimer, Nick; Campbell, Hamish J. (2017). "Zealandia: Earth's Hidden Continent". GSA Today. 27: 27–35. doi:10.1130/GSATG321A.1. Archived from the original on 17 February 2017.

[1] Fairbridge, Rhodes W., ed. (1967). The Encyclopedia of Atmospheric Sciences and Astrogeology. New York: Reinhold Publishing. p. 323. OCLC 430153.

[2] Davis, George H.; Reynolds, Stephen J.; Kluth, Charles F. (2012). "Nature of Structural Geology". Structural Geology of Rocks and Regions (3rd ed.). John Wiley & Sons. p. 18. ISBN 978-0-471-15231-6.

[3] McGuire, Thomas (2005). "Earthquakes and Earth's Interior". Earth Science: The Physical Setting. AMSCO School Publications Inc. pp. 182–184. ISBN 978-0-87720-196-0.

[mortimer-4] Mortimer, Nick; Campbell, Hamish J. (2017). "Zealandia: Earth's Hidden Continent". GSA Today. 27: 27–35. doi:10.1130/GSATG321A.1. Archived from the original on 17 February 2017.

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