A PALEOGEOGRAPHIC CONTEXT FOR THE EARLY MESOPROTEROZOIC BASINS

The early Mesoproterozoic (ca. 1.6~1.3 Ga) sedimentary strata, including carbonate and siliciclastic rocks, are largely preserved in northern Europe, Siberia, north China, south China, India, Northern and central Australia and western and northern Laurentia, indicating the occurrence of global extension in this geological interval. Due to later modifications, tectonic settings and paleogeographic positions of these extensional basins are poorly known. This presentation displays the basins on the global paleogeographic maps, constructed on the grounds of the recently updated paleomagnetic database and reconstructions of the supercontinent Nuna. Geological records from many cratons may suggest that Nuna had undergone multiple extensional tectonic conditions between 1.60 and 1.30 Ga, but the high quality paleomagnetic signals from these records, which include the sedimentary successions in the basins and dykes widely exposed, are in good agreement to support the existence of a single coherent supercontinent, indicating no significant break-up of Nuna occurred during these extensional events. It is suggested that most early Mesoproterozoic basins mentioned above were cratonic basins or plate interior basins. High quality paleomagnetic poles at 1.59 Ga, 1.50 Ga, 1.45 Ga and 1.38 Ga place Nuna and these basins in low paleolatitudinal regions, that is consistent with the paleoclimatic indicators preserved in the basins.