MESOPROTEROZOIC – TONIAN PALEOGEOGRAPHY: NEW INSIGHTS

Abstract:

Mesoproterozic – Tonian (1600-850 Ma) times are generally associated with a significant part of supercontinental cycle: assembly and breakup of Nuna followed by assembly of Rodinia, The understanding of these processes is hampered by a deficit of reliable geochronological, paleomagnetic and other datasets. Consequently there is a variety of opinions about paleogeographic locations of many Precambrian cratons and terranes and about their kinematics. Almost every new well-dated paleomagnetic pole, or re-dated old paleopole, or discovered LIP event causes significant reconsideration of existing paleogeographic models. Many new exiting results have been reported in last few years from Baltica, Siberia, North China, Australia, Congo-São Francisco and other parts of Nuna and Rodinia. Recent testings of some popular paleogeographic reconstructions (e.g. SAMBA) and re-interpretation of orogenic histories (e.g. Grenville and Sveconorwegian) also require some revisiting of Mesoproterozoic – Tonian paleogeography. This study summarises these new data and new ideas. Proposed updated positions of some continents are now better justified. Most changes are associated with North China and Congo-São Francisco cratons. Kinematics of the transitional period between the breakup of Nuna and the assembly of Rodinia is now better understood and better constrained, but some aspects are still enigmatic and controversial.