U-TH-PB DETRITAL ZIRCON GEOCHRONOLOGY FROM THE SOUTHERN PRINCE CHARLES MOUNTAINS, EAST ANTARCTICA-DEFINING THE ARCHAEAN TO NEOPROTEROZOIC RUKER PROVINCE

Abstract

Laser ablation inductively coupled mass spectrometry (LA-ICPMS) dating of detrital zircon has been employed to tighten geochronological constraints from the southern Prince Charles Mountains, East Antarctica. The grains of detrital zircon are from extensive metasedimentary units that define different stratigraphic levels. Provenance information from this study has identified three lithostratigraphic units that range in age from Archaean to Neoproterozoic times. The newly defined Tingey Complex contains the oldest known strata, and consists of an Archaean felsic basement overlain by three stratigraphic layers, distinguished by ca. 3200 Ma, ca. 2800 Ma and ca. 2500 Ma detrital zircon grains. The Lambert Complex consists of a metasedimentary package, characterised by ca. 2100 Ma, ca. 1900-1800 Ma and ca. 2600 Ma detrital zircon grains that possibly overlies late Palaeoproterozoic orthogneiss. The Neoproterozoic Sodruzhestvo Group comprises the youngest exposed unit and consists of a thick, clastic-dominated sequence that is distinguished by ca. 1170-970 Ma grains. This study suggests that the isotopic differences reported from the southern Prince Charles Mountains are a result of stratigraphic stacking, rather than due to juxtaposition via collision and accretion tectonics. The discovery of ca. 2500 Ma detrital zircon grains within the Palaeoproterozoic metasedimentary rocks of the Tingey Complex strengthens correlations with Archaean fragments exposed in neighbouring regions of East Antarctica. Constraining the deposition of the Sodruzhestvo Group to the mid-Neoproterozoic period suggests a prominent period of basin development occurred within the southern Prince Charles Mountains at this time. © 2006 Elsevier B.V. All rights reserved.