Proterozoic supercontinent, its latest Precambrian rifting, breakup, dispersal into smaller continents, and subsidence of their margins: Evidence from Asia

Several large cratons and numerous smaller blocks, all with Precambrian sialic crust, are seen clearly in the present-day structure of Asia. The outer parts of larger Precambrian terranes and entire smaller ones are covered with Vendian-early Paleozoic shallow-water carbonate sedimentary rocks coupled with the so-called "old" (late Vendian-Early Cambrian) phosphorites in Siberia, southern China, India, Kazakhstan, and Mongolia. These sedimentary rocks are interpreted to represent a global belt of near-equatorial sedimentation on passive continental margins of numerous Vendian-early Paleozoic continents with free access to the world ocean. Later Precambrian rifting is recorded clearly in many Precambrian terranes of Asia; rifting was repeated during Cenozoic time, with the same pattern and in the same places. It was preceded and accompanied by various magmatic activity from 750 to 600 Ma. Tillites filling rifts are about 650 Ma, and are believed to be a feature of a single Proterozoic super-continent. Rift-to-drift transition, as attested by the beginning of thick and laterally continuous carbonate sedimentation on passive margins, seems to be diachronous; it started in early Vendian time or even earlier in some places, but not earlier than Cambrian in others.