COMPARISON OF NEOPROTEROZOIC HISTORY BETWEEN THE TARIM AND YANGZI CRATONS OF CHINA

A number of supercontinental events are developed from the terminal Mesoproterozoic to early Paleozoic period (mainly in the Neoproterozoic). The most important events include the assembly and breakup of the Rodinia, the extreme cold climate (Snowball), biota development and formation of the Gondwanaland, which resulted in the great change of the earth system, such as lithosphere, biosphere, hydrosphere and atmosphere at that time. The supercontinental events are not only preserved at the larger cratons, such as Laurentia, Baltica, East Gondwana, Kalahari, Amazonia et al, but in some smaller block, for example the Tarim and Yangzi Cratons. There is a marvellous similarity of the Neoproterozic history between the Tarim and Yangzi blocks based on a number of stratigraphic and event geological data, especially new U-Pb ages. The similarity is illustrated by the feature, sequence and ages of thermo¨Ctectonic events of the Neoproterozoic, the cratonic progress, bi-layer structure composed of pre-Nanhua metamorphic basement and sedimentary cover£¬the stratigraphic sequence from the Nanhua to Sinian System of Neoproterozoic, and the stratigraphic marker-glaciogenic beds within the Nanhua System. The features, sequence and time framework of the Neoproterozoic thermo-tectonic events of the Tarim and Yangzi Cratons are quite similar and the events took place from the terminal Mesoproterozoic to early Neoproterozoic. In addition, rifting basins, dyke swarms, bimodal volcanics, continental flood tholeiites, and A¨Ctype granites during the period between 810Ma to a little older 700Ma are well preserved in the two cratons and their margins. An unconformity between pre-Nanhua metamorphic basement and the Nanhua-Sinian sedimentary cover is preserved in the two blocks. Above the unconformity, the sequence, sedimentary characteristics and date from the Nanhua to Sinian Systems are nearly same in the cratons. Typical tillites are exposed in the Tarim and Yangzi Cratons. They are well exposed in the Nanhua System (0.80¨D0.68Ga, based on the new Chinese Stratigraphic Time Scale). According to the mentioned¨Cabove similarity, a hypothesis on the Yangzi¨CTarim connection or neighborhood is proposed. ( This work is supported by NSFC No.40032010 and CMLR No. 2000305)