Ellsworth-Whitmore Mountains Crustal Block, Western Antarctica: New Paleomagnetic Results and Their Tectonic Significance

  1. Garry D. Mckenzie
  1. A. M. Grunov,
  2. I. W. D. Dalziel and
  3. D. V. Kent

Published Online: 21 MAR 2013

DOI: 10.1029/GM040p0161

Gondwana Six: Structure, Tectonics, and Geophysics

Gondwana Six: Structure, Tectonics, and Geophysics

How to Cite

Grunov, A. M., Dalziel, I. W. D. and Kent, D. V. (1987) Ellsworth-Whitmore Mountains Crustal Block, Western Antarctica: New Paleomagnetic Results and Their Tectonic Significance, in Gondwana Six: Structure, Tectonics, and Geophysics (ed G. D. Mckenzie), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM040p0161

Author Information

  1. Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1987

ISBN Information

Print ISBN: 9780875900643

Online ISBN: 9781118664483

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Keywords:

  • Gondwana(Geology)—Congresses;
  • Geology,Structural—Congresses

Summary

Preliminary paleomagnetic study of granitic and sedimentary rocks from the Ellsworth-Whitmore Mountains crustal block (EWM), West Antarctica, leads to the following conclusions: (1) The EWM has a paleopole for the Middle Jurassic located at 235°E, 41°S, (α9.5 = 5.3, N = 8 sites) assuming that no widespread regional tilting has occurred since the magnetization measured was acquired. A Middle Jurassic paleolatitude of 47°S is indicated for the sites and precludes an original location for the EWM block south of the Antarctic Peninsula crustal block (AP). (2) This pole is not significantly different from the previously published Middle Jurassic paleopole obtained from rocks of the northern Antarctic Peninsula. The combined AP-EWM paleopole, compared to the Middle Jurassic mean paleopole obtained from igneous rocks of the Ferrar Supergroup in East Antarctica, suggests about 15° tectonic clockwise rotation of the AP and EWM. Since the AP and EWM poles coincide, these two crustal blocks may have moved as one unit since the Middle Jurassic. (3) The new data are compatible with two different Gondwanaland reconstructions. The first considers the AP and EWM as separate entities. The second is based on the movement of the AP and EWM as one block. For the Middle Jurassic, both reconstructions would locate the EWM west of Coats Land and south of the Falkland Plateau, with the adjacent AP located south of southernmost South America. (4) Enigmas concerning the structural trend and isolation of the thick Ellsworth Mountains Paleozoic succession persist.