© Russell Pysklywec, Philip Heron, Randell StephensonA proposed perennial plate tectonic map. Present-day plate boundaries (white lines), with hidden ancient plate boundaries that may reactivate to control plate tectonics (yellow lines). Regions where mantle lithosphere heterogeneities have been located are given by yellow crosses.
Super-computer modelling of Earth's crust and upper-mantle suggests that
ancient geologic events may have left deep 'scars' that can come to life to play a role in earthquakes, mountain formation, and other ongoing processes on our planet. This changes the widespread view that only interactions at the boundaries between continent-sized tectonic plates could be responsible for such events.A team of researchers from the University of Toronto and the University of Aberdeen have created models indicating that former plate boundaries may stay hidden deep beneath the Earth's surface. These multi-million-year-old structures, situated at sites away from existing plate boundaries, may trigger changes in the structure and properties at the surface in the interior regions of continents.
"This is a potentially major revision to the fundamental idea of plate tectonics," says lead author Philip Heron, a postdoctoral fellow in Russell Pysklywec's research group in U of T's Department of Earth Sciences. Their paper, "Lasting mantle scars lead to perennial plate tectonics," appears in the June 10, 2016 edition of
Nature Communications.
Heron and Pysklywec, together with University of Aberdeen geologist Randell Stephenson have even proposed a 'perennial plate tectonic map' of the Earth to help illustrate how ancient processes may have present-day implications.
"It's based on the familiar global tectonic map that is taught starting in elementary school," says Pysklywec, who is also chair of U of T's Department of Earth Sciences. "What our models redefine and show on the map are dormant, hidden, ancient plate boundaries that could also be enduring or "perennial" sites of past and active plate tectonic activity."
Comment: See also: Southern California shaken by 5.2 earthquake