Are Mantle Plumes Periodic?



In the past few years, researchers have uncovered evidence that several kinds of geological and biological events seem to show regular cycles of similar lengths. For example, Rohde and Muller [2005] looked at the record of diversity of marine organisms over the past 540 million years and found evidence for two cycles in the data—a roughly 62-million-year cycle and a longer cycle of about 140 million years. This was followed by reports of an approximately 56-million-year cycle in long-term stratigraphic sequences in sedimentary basins [Meyers and Peters, 2011] and a 59-million-year period in the marine strontium-isotope record [Melott et al., 2012]. A similar period may even exist in atmospheric carbon dioxide over the past 542 million years of the Phanerozoic [Franks et al., 2012]. A cycle of about 140 million years was reported by Veizer et al. [2000] and Mayhew et al. [2008] in long-term fluctuations in global climate.