ИСТИНА

Long-lived connections among Proterozoic cratons, if they can be demonstrated, form important keys to pre-Pangean supercontinent reconstructions. As an example, increasing paleomagnetic support of a connection between Laurentia and Baltica, between 1.8 and 1.2 Ga, allows those two cratons to be juxtaposed confidently within the Nuna supercontinent. Here we address various hypothesized Proterozoic connections between Laurentia and Siberia, which range from various tight geometric fits of differing relative orientations, mainly based on aligning tectonic provinces or sedimentary basins, to a more distal arrangement that was based primarily on 1.1-1.0 Ga paleomagnetic data from the Aldan region in southeast Siberia. We present three new paleomagnetic poles from 1.7-1.5 Ga unmetamorphosed clastic sedimentary rocks and mafic intrusions surrounding the Anabar Shield in northern Siberia, and compare those results to the Proterozoic apparent polar wander path (APWP) from Laurentia. We find that a tight connection between the southern margin of Siberia and the northern margin of Laurentia, which is favored by several Proterozoic tectonostratigraphic datasets, is compatible with our new results, as well as other paleomagnetic data from the interval 1.9-0.7 Ga. The earlier 1.1-1.0 Ga paleomagnetic poles are brought into line with the Laurentian APWP largely through restoration of Devonian rotations between the Anabar and Aldan regions, across the Vilyuy graben. We propose that Laurentia+Baltica+Siberia formed a large, internally stable component of the Nuna supercontinent, and that the Laurentia+Siberia connection persisted until mid-Neoproterozoic breakup of Rodinia.