Lower oceanic crust

The lower oceanic crust is the lower part of the oceanic crust and represents the major part of it (volumetrically biggest part).[1] It is generally located 4–8 km below the ocean floor and the major lithologies are mafic (ultramafic and gabbroic rocks) which derive from melts rising from the Earth's mantle.[2] This part of the oceanic crust is an important zone for processes such as melt accumulation and melt modification (fractional crystallisation[3] and crustal assimilation). And the recycling of this part of the oceanic crust, together with the upper mantle has been suggested as a significant source component for tholeiitic magmas in Hawaiian volcanoes.[4] Although the lower oceanic crust builds the link between the mantle and the MORB, and can't be neglected for the understanding of MORB evolution, the complex processes operating in this zone remain unclear and there is an ongoing debate in Earth Sciences about this. It is 6KM long.

  1. ^ Winter, J.D., 2010. An introduction to igneous and metamorphic petrology. New York: Prentice Hall.
  2. ^ Coogan, L., 2003. The lower oceanic crust.
  3. ^ Grove, T.L., Kinzler, R.J. and Bryan, W.B., 1993. Fractionation of mid‐ocean ridge basalt (MORB). Mantle flow and melt generation at mid-ocean ridges: 281–310.
  4. ^ Sobolev, A.V., Hofmann, A.W., Soboloev, S.V., and Nikogosian, I.K., 2005, An olivine-free mantle source of Hawaiian shield basalts: Nature, v. 434, no. 7033, pp. 590–597, doi:10.1038/nature03411.