Central Antarctic provenance of Permian sandstones in Dronning Maud Land and the Karoo Basin

integration of U-Pb and T-DM ages and host-rock affinity from detrital zircons

J. J. Veevers*, Ayesha Saeed

*Corresponding author for this work

Research output: Contribution to journalReview article

32 Citations (Scopus)

Abstract

In conjugate SE Africa and Antarctica, Early Permian sandstones of the Swartrant Formation of the Ellisras Basin, Vryheid Formation of the Karoo Basin, and Amelang Plateau Formation of Dronning Maud Land (DML) were deposited after Gondwanan glaciation on a westward paleoslope. We analysed detrital zircons for U-Pb ages by a laser ablation microprobe-inductively coupled plasma mass spectrometer (LAM-ICPMS) and attached age significance only to clusters of three or more overlapping analyses. We analysed Hf-isotope compositions by a multi-collector spectrometer (LAM-MC-ICPMS) and trace elements by electron microprobe (EMP) and ICPMS. These analyses indicate the rock type and source (whether crustal or juvenile mantle) of the host magma, and a "crustal" model age (T-DM(C)). The integrated analysis gives a more distinctive, and more easily interpreted, picture of crustal evolution in the provenance area than age data alone.

Zircons from the Ellisras Basin are aged 2700-2540 Ma with minor populations about 2815 Ma and 2040 Ma, which correspond with the ages of the upslope parts of the proximal Kaapvaal Craton and Limpopo Belt. Mafic rock is the dominant host rock, and it reflects the Archean granite-greenstone terrane of the Kaapvaal Craton.

The three Karoo Basin samples and the two DML samples have zircons with these common properties: (1) 1160-880 Ma, host magma mafic granitoid (<65% SiO2) derived from juvenile depleted mantle sources (epsilon(Hf) positive) at 1.65 Ga and 1.35 Ga, with T-DM(C), of 2.0-0.9 Ga; (2) 760 to 480 Ma, host magma granitoid and low-heavy rare earth element rock (?alkaline rock-carbonatite), derived from mixed crustal and juvenile depleted mantle sources (epsilon(Hf) positive and negative) at 1.50 Ga and 1.35 Ga, with T-DM(C) of 2.0-0.9 Ga. Together with similar detrital zircons in Triassic sandstone of SE Australia, these properties reflect those in upslope central Antarctica, indicating a provenance of similar to 1000 Ma (Grenville) cratons embedded in 700-500 Ma (Pan-Gondwanaland) fold belts. Detrital zircons in Cambrian sediments of the Ellsworth-Whitmore Mountains block and Cambrian metasediments of the Welch Mountains with comparable properties suggest that the central Antarctic provenance operated also in the similar to 500 Ma Cambrian. (c) 2007 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)653-676
Number of pages24
JournalSedimentary Geology
Volume202
Issue number4
DOIs
Publication statusPublished - 15 Dec 2007

Keywords

  • U-Pb ages
  • Hf-isotopes
  • Early Permian sandstone
  • Karoo Basin
  • Dronning Maud Land
  • Central Antarctic provenance
  • NATAL METAMORPHIC PROVINCE
  • ELLSWORTH-WHITMORE MOUNTAINS
  • HF ISOTOPE GEOCHEMISTRY
  • CAPE-MEREDITH COMPLEX
  • EAST ANTARCTICA
  • SOUTH-AFRICA
  • GRENVILLE-AGE
  • KAAPVAAL-CRATON
  • TECTONIC SIGNIFICANCE
  • PALEOMAGNETIC DATA

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