First Precambrian palaeomagnetic data from the Mawson Craton (East Antarctica) and tectonic implications

J Camilla Stark,Uwe Kirscher,Sergei A Pisarevsky,Yebo Liu,Chris Clark,Zheng-Xiang Li,Martin Hand,Ross N Mitchell

doi:10.1038/s41598-018-34748-2

Abstract

A pilot palaeomagnetic study was conducted on the recently dated with in situ SHRIMP U-Pb method at 1134 ± 9 Ma (U-Pb, zircon and baddeleyite) Bunger Hills dykes of the Mawson Craton (East Antarctica). Of the six dykes sampled, three revealed meaningful results providing the first well-dated Mesoproterozoic palaeopole at 40.5°S, 150.1°E (A95 = 20°) for the Mawson Craton. Discordance between this new pole and two roughly coeval poles from Dronning Maud Land and Coats Land (East Antarctica) demonstrates that these two terranes were not rigidly connected to the Mawson Craton ca. 1134 Ma. Comparison between the new pole and that of the broadly coeval Lakeview dolerite from the North Australian Craton supports the putative ~40° late Neoproterozoic relative rotation between the North Australian Craton and the combined South and West Australian cratons. A mean ca. 1134 Ma pole for the Proto-Australia Craton is calculated by combining our new pole and that of the Lakeview dolerite after restoring the 40° intracontinental rotation. A comparison of this mean pole with the roughly coeval Abitibi dykes pole from Laurentia confirms that the SWEAT reconstruction of Australia and Laurentia was not viable for ca. 1134 Ma.

Highlights

East Antarctica has been a key piece in Precambrian palaeogeographic reconstructions
We present the results of a palaeomagnetic study of these ca. 1134 Ma Bunger Hills mafic dykes, representing the first Precambrian palaeomagnetic pole from the Mawson Craton of East Antarctica, and discuss its tectonic implications
East Antarctica represents the Precambrian portion of Antarctica, and most workers agree that it is divisible into several tectonic domains that have geological affinities with Africa (Kalahari), India, Australia, and some unknown sources[7,8,16,18,41,42]

Summary

Introduction

East Antarctica has been a key piece in Precambrian palaeogeographic reconstructions (e.g., refs[1,2,3,4]). There are only two Precambrian palaeomagnetic poles available from East Antarctica: the ca. The Bunger Hills area of the Wilkes Land district of East Antarctica is commonly considered to be a fragment of the Archaean Yilgarn Craton[13,14,15] (Fig. 1). In this study we dealt with the second group only These non-deformed dykes were classified into five compositionally distinctive sub-groups ranging from olivine tholeiites and slightly alkaline dolerites to picrites–ankaramites[19]. Those five sub-groups were proposed to have www.nature.com/scientificreports/. 1134 Ma Bunger Hills mafic dykes, representing the first Precambrian palaeomagnetic pole from the Mawson Craton of East Antarctica, and discuss its tectonic implications We present the results of a palaeomagnetic study of these ca. 1134 Ma Bunger Hills mafic dykes, representing the first Precambrian palaeomagnetic pole from the Mawson Craton of East Antarctica, and discuss its tectonic implications

Methods

Results

Discussion

Conclusion