The formation of supercontinents has been a topic of wide interest over many years. The supercontinent cycle and its recognition, by which Earth history is seen as having been disturbed by the episodic assembly and breakup of super-huge masses of continents, is one of the most important advances in present-day Earth Science. Relicts of these former continental amalgamations are now dispersed amongst the present-day continents, and correlations between these fragments are used to reconstruct supercontinents palaeogeographically. Since the amalgamation of supercontinents requires continents to collide, whereas supercontinent breakup requires them to rift, the evidence of a supercontinent cycle would be documented in the geologic record by episodic peaks in major tectonic activities such as collisional orogenesis and rift-related mafic magmatism. Using the available isotope data for such events (e.g. isotopic systematics of U-Pb, Rb/Sr, Sm-Nd, Lu-Hf etc), it could be distinguished that global episodes of tectonic activities had punctuated Earth’s history at relatively regular intervals of about few hundred million years, for at least the past 2.5 billion years. In this talk, a synthesis of isotopic data on rocks and sediments from various regions of the world is examined with respect to Supercontinent Cycle.
コロキウム問い合わせ先： 大鳥 範和