Plate Tectonic Development of Late Proterozoic Paired Metamorphic Complexes in Eastern Queen Maud Land, East Antarctica
- Garry D. Mckenzie
Published Online: 21 MAR 2013
Copyright 1987 by the American Geophysical Union.
Gondwana Six: Structure, Tectonics, and Geophysics
How to Cite
Shiraishi, K., Hiroi, Y., Motoyoshi, Y. and Yanai, K. (1987) Plate Tectonic Development of Late Proterozoic Paired Metamorphic Complexes in Eastern Queen Maud Land, East Antarctica, in Gondwana Six: Structure, Tectonics, and Geophysics (ed G. D. Mckenzie), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM040p0309
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1987
Print ISBN: 9780875900643
Online ISBN: 9781118664483
Two Proterozoic metaraorphic complexes of the East Antarctic Shield are exposed in eastern Queen Maud Land: Yamato-Belgica and Lützow-Holm to the southwest and northeast, respectively. In the Yamato-Belgica Complex, igneous activity is widespread. The metamorphic portions of this complex consist mainly of amphibolite facies rocks. Granulite facies rocks occur locally and are partly included in a syenitic intrusive. The granulite facies rocks belong to the low-pressure type. On the other hand, the regional metamorphism of the dominantly metasedimentary Lützow-Holm Complex is of the medium-pressure type, grading progressively from upper amphibolite facies to granulite facies toward the southwest. There is textural evidence of prograde recrystallization. The prograde P-T-time(t) paths of the rocks from different metamorphic zones differ from each other and also from the regional metamorphic geotherm based on the mapping of metamorphic zones. High P/T-type metamorphism in the early stage of regional metamorphism is suggested by garnet porphyroblasts rimmed with symplectic intergrowth of spinel, orthopyroxene, and plagioclase in troctolitic rocks. We thus infer that the Yamato-Belgica and Lützow-Holm complexes form paired metamorphic complexes and that the latter was formerly situated in a subduction zone. Moreover, chemical compositions of metamorphosed ultrabasic and basic rocks occurring mainly in the western part of the Lützow-Holm Complex resemble those of cumulate rocks associated with ophiolites. Therefore, they are possibly fragments of oceanic crust which were tectonically fractured and emplaced into the sedimentary pile prior to regional metamorphism. Consequently, a plate tectonics model would be the most suitable interpretation for the development of the late Proterozoic metamorphic complexes in the region.