ABSOLUTE RECONSTRUCTIONS OF THE PALEOZOIC OCEANS

Abstract

The orientation of three intraplate magmatic belts—the Mongolian (from 130 to 280 m.y.), South Siberian (from 320 to 400 m.y.) and Baltic (from 365 to 400 m.y.) belts—which can be considered as hot spot tracks, are used together with apparent paleomagnetic pole wander paths to reconstruct true motions of continents during Paleozoic times. The reconstructions obtained show that the old, Late Precambrian Pangea continued to exist in the Early Paleozoic with an inner arrangement of constituent continents strongly different from that of the Late Paleozoic Pangea. The continents were constantly located in the eastern hemisphere only. The western hemisphere was occupied by the Paleo-Pacific oceans. Four oceans existed in Paleozoic times between the continents in the eastern hemisphere: (1) the Iapetus which originated in the Late Precambrian and closed before Devonian times (400 m.y.), (2) the Asiatic paleo-ocean which originated in the Late Precambrian and closed 450 m.y. ago, (3) the Uralian paleo-ocean which opened around 500 m.y. ago and closed in the latest Permian (240–230 m.y.), (4) the Paleo-Tethys which opened in the Ordovician (480–450 m.y.) and became the Mesozoic Tethys. Life duration of the oceans was 200–400 m.y. The main trend in the Earth's evolution during the Paleozoic was a break up of the old, Precambrian Supercontinent and construction of the new, Late Paleozoic Pangea.