Geophysical Processes Influencing the Lower Continental Crust

  1. Robert F. Mereu,
  2. Stephan Mueller and
  3. David M. Fountain
  1. D. L. Turcotte

Published Online: 9 APR 2013

DOI: 10.1029/GM051p0321

Properties and Processes of Earth's Lower Crust

Properties and Processes of Earth's Lower Crust

How to Cite

Turcotte, D. L. (1989) Geophysical Processes Influencing the Lower Continental Crust, in Properties and Processes of Earth's Lower Crust (eds R. F. Mereu, S. Mueller and D. M. Fountain), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM051p0321

Author Information

  1. Department of Geological Sciences, Cornell University, Ithaca, New York

Publication History

  1. Published Online: 9 APR 2013
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780875904566

Online ISBN: 9781118666388

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Keywords:

  • Earth—Crust—Congresses;
  • Geophysics—Congresses

Summary

The primary mechanisms for the addition of material from the mantle to the continental crust at the present time are island arc volcanics and continental rift and hot spot volcanics. We propose as a working hypothesis that these mechanisms have also been responsible for the addition of material to the continental crust in the past. However, since these volcanics have near basaltic compositions, an essential question is how the continental crust develops a silicic composition. Partial melting of the lower continental crust can create magmas with a silicic composition; this volcanism can lead to an internal crustal fractionation with a more silicic upper crust and a more mafic lower crust. In order to achieve a bulk silicic composition for the continental crust it is necessary to remove the mafic lower crust. We propose that this is done by the delamination of substantial portions of the continental lithosphere including the lower continental crust. We suggest that the mean rate of continental delamination is near 0.1 km2/yr. This is about 4% of the present rate of subduction.