Palaeomagnetism of Upper Precambrian rocks of the La Tinta Formation, Argentina

Summary Palaeomagnetic data from 77 hand samples collected in sequences of marine sediments of Late Precambrian age (709 ± 24 Myr) exposed at two zones (Olavarria—Sierras Bayas and Barker) in central Argentina (37.3° S 59.8° W, La Tinta Formation) are given. After thermal cleaning and chemical leaching, the samples show normal and reversed polarity and yield a palaeomagnetic pole at 300.9° E 79.3° S (α95=4.8°). The position of this pole supports the interpretation that Gondwana was a unit in Late Precambrian times and is consistent with the Late Precambrian glaciation (Marinoan) of south-eastern Australia. The direction and polarity of the stable RM of samples and the change of direction of the stable RM for adjacent samples along a sequence are used to correlate La Tinta rocks within a zone and between the two zones.