Much of the present day Lower Paleozoic strata around the Arctic Ocean can be tied either to the ancestral Laurentian continent or to the ancestral Siberian continent. Correlated with Laurentia (Arctic Laurentian Assemblage) are the Canadian Arctic Islands, northern Alaska and northern Chukotka, including Wrangel Island. Correlated with ancestral Siberia (Arctic Siberian Assemblage) are the Verkhoyansk and Taimyr fold belts on the north and east of the Siberian Plateau, Omolon microcontinent bordered by the Kolyma fold belt on the west, the New Siberian Islands and Omulevka blocks. The New Siberian Islands and elongate Omulevka block appear to have been pieces of Siberia rifted away during the Middle Devonian. The Omolon microcontinent has also been postulated to have rifted away from Siberia during the Devonian but the existence of the Kolyma fold-belt with Phanerozoic and Proterozoic supracrustal strata facing Siberia suggests an older time of separation. Both the Arctic Laurentian and Arctic Siberian assemblages had miogeoclines that opened into ancestral ocean basins towards the modern day Arctic Ocean. Within the Arctic Laurentian Assemblage the Canadian Arctic Islands joined to Alaska-Chukotka at an obtuse angle across a Paleozoic aulacogen (Richardson Trough). In the aulacogen is a thick succession of carbonate-dominated Lower Paleozoic basin facies, while to the northwest on the eastern Arctic Alaskan Plate, equivalent strata are very thin chert and shale miogeoclinal basin facies. The present day angular relationships, are similar to those expected for a triple-rift system with an ocean basin on the north formed from a rift approximately paralleling the modern ocean margin of the Canadian Arctic Islands, and a second rift paralleling the modern coast of northern Alaska-Chukotka. The aulacogen would have been a failed rift. This indicates that there was an ancestral ocean in the position of Canada Basin in the Lower Paleozoic. This paleogeography differs from the popular rotationist plate reconstruction that shows Alaska and Chukotka against the Canadian Arctic Islands in the Paleozoic. In this scenario a narrow trough or ocean would have had to extend from the Richardson Trough north between pre-rotation Alaska and the Canadian Arctic Islands. The present day facies pattern suggests a northward transition from trough to open miogeocline rather than a continuous trough or closed ocean.