The Archaean geological evolution of Enderby Land, Antarctica

S. L. Harley*, L. P. Black

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The Napier Complex of Enderby Land, Antarctica, is a major terrain exhibiting Archaean granulite-facies metamorphism at extreme PT conditions. Combined Rb-Sr, Sm-Nd and U-Pb zircon isotope systematics define an age of 3070 Ma for initial granulite-facies metamorphism and intense D 1 deformation. Orthogeneissic sheets intruded into the tectonically thickened crust at times up to 3070 Ma resulted in the attainment of peak regional metamorphic conditions of 950°C and 7-10 kb subsequent to D 1. These high-grade conditions prevailed through a second, less intense, deformation (D 2) after which the Napier Complex became a stable craton for some 500 Ma. The presently exposed granulites record a near-isobaric cooling path over this time interval prior to reactivation at 700-650°C and 5-8 kb in a deformation event (D 3) at c. 2450 Ma. The D 3 event resulted in open dome-and-basin folding of the pre-existing recumbent- and isoclinally-folded pile. Protolith ages for some granulite-facies gneisses, obtained from conventional and ion-microprobe investigation of zircons and deduced from Sm-Nd modelling, are in the range 3750-3950 Ma, some 700-900 Ma prior to the first recognized metamorphism.

Original languageEnglish
Pages (from-to)285-296
Number of pages12
JournalGeological Society Special Publication
Volume27
DOIs
Publication statusPublished - 1987

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