New palaeomagnetic data from tillites of Neoproterozoic Polarisbreen Group, Nordaustlandet, Svalbard

New demagnetization results of 53 independently oriented palaeomagnetic samples (145 specimens) of diamictite-rich units from 8 sites collected from the Neoproterozoic sequence of Murchisonfjord, Western Nordaustlandet are presented. The palaeomagnetic samples were obtained from 2 distinct stratigraphical units of Polarisbreen Group: Petrovbreen Member of Elbobreen Formation (2 sites) and Wilsonbreen Formation (6 sites) which represent Marinoan Neoproterozoic glaciation (Halverson et al. 2004). The sequence is a part of Eastern Svalbard Caledonian Terrane/Northeastern Basement Province.

Principal component analyses revealed strong contribution of post-folding high-inclination palaeomagnetic component TILL L/M demagnetized up to 320°C (D = 32.3°, I = 83.6°,  α95=6.6, κ=103.7 recognized in 6 sites, in 35 independently oriented samples and in 77 demagnetized specimens). Calculated paleopole TILL L/M (Φ = 83.24°, Λ = 114.0°; Dp/Dm = 12.7°/13.0°) fall into Late Cretaceous – Paleogene – Neogene sector of Baltica Apparent Polar Wander Path (Torsvik et al. 2012). That suggests a possible relation of TILL L/M remagnetization with Late Cretaceous Svalbard magmatism (e.g. Senger et al. 2014). Great circle analyses point to the additional contribution of low-inclination component, potentially related to Caledonian remagnetization (compare Michalski et al. 2023). At this data processing stage, in investigated tillites no pre-Caledonian paleomagnetic record was recognized. Preliminary rock-magnetic results suggest the presence of maghemite and magnetite. Paleomagnetic, rock-magnetic as well as investigations of Anisotropy of Magnetic Susceptibility (AMS) were conducted at the Laboratory of Palaeomagnetism Department of Magnetism Institute of Geophysics, Polish Academy of Sciences.

All investigated tillites were subjected detailed petrographic and mineralogical observations (reflected /transmitted light microscopy, scanning electron microscopy – SEM, electron microprobe) at the University of Warsaw Inter – Institute Analytical Complex, in the Faculty of Geology and at the Uppsala University in the Department of Earth Sciences. Separated detrital zircons is being subjected to U-Pb dating at the Department of Geological Processes, Czech Academy of Sciences.

This study is part of the NEOMAGRATE project 2022–2025: “Rate of tectonic plates movement in Neoproterozoic – verification of Neoproterozoic True Polar Wander hypothesis”, funded by the Polish National Science Centre (NSC); grant number:2021/41/B/ST10/02390.

References:

Halverson, G.P., Maloof, A.C. and Hoffman, P.F. 2004. The Marinoan glaciations (Neoproterozoic) in northeast Svalbard. Basin Research, 16, 297-324.

Michalski, K., Manby, G.M., Nejbert, K., Domańska-Siuda, J. and Burzyński, M. 2023. Palaeomagnetic investigations across Hinlopenstretet border zone: from Caledonian metamorphosed rocks of Ny Friesland to foreland facies of Nordaustlandet (NE Svalbard). Journal of the Geological Society, 180.

Senger, K., Tveranger, J., Ogata, K., Braathen, A. And Planke, S. 2014. Late Mesozoic magmatism in Svalbard: A revive. Earth-Science Revievs, 139, 123-144.

Torsvik, T.H., Van der Voo, R., Preeden, U., Mac Niocaill, C., Steinberger, B., Doubrovine, P.V., van Hinsbergen, D.J.J., Domeier, M., Gaina, C., Tohver, E., Meert, J.G., McCausland, P.J.A. and Cocks, L.R.M. 2012. Phanerozoic polar wander, paleogeography and dynamics. Earth-Science Reviews, 114, 325–368.