A COMPARISON OF THE BIOLOGICAL, GEOLOGICAL EVENTS AND ENVIRONMENTAL BACKGROUND BETWEEN THE NEOPROTEROZOIC-CAMBRIAN AND PERMIAN-TRIASSIC TRANSITIONS

The Neoproterozoic-Cambrian (N-C) and Permian-Triassic (P-T) transitions have been regarded as the two most critical transitions during the earth history because of the explosive biological radiation in the Early Cambrian (the Cambrian Explosion) and the largest mass extinction happened at the end-Permian. However, recent various studies suggest that a couple of biological and geological events happened in the N-C transition occurred repeatedly in the P-T transition. Those events include the continental re-configuration, large-scale glaciations and deglaciations, large C-, Sr- and S- isotope perturbations, abnormal precipitation of carbonates and associated multiple biological radiations and mass extinctions. The coupling of all those events in both N-C and P-T transitions suggests that deep mantle activities could be a mechnism causing dramatic changes of surface environment on the earth. A detailed comparison of those two critical transitions indicates that significant differences are present in tempo although both transitions experienced some similar events. The recurrent biological, geological and geochemical events during the two transitions may provide new clues to understand the interplays among the earth-life system.