THE MAGMATIC PULSE OF THE EARTH: A POWERFUL RECORD OF GEODYNAMIC AND TECTONIC INDICATORS, THROUGH TIME AND SPACE, AND THE ULTIMATE KEY TO PALEOGEOGRAPHIC RECONSTRUCTIONS OF ANCIENT CONTINENTS BACK TO 2.6 GA

Short-lived mantle-derived magmatic events, preserved through time and space, in the continental record and on extant ocean floor, harbour an amazingly diverse array of high-quality information critical to understanding and ground-truthing the dynamic behaviour of planet Earth.

Coupled with precise ages, and an average frequency of ~4-12 events per 100 my, these events could provide a relatively complete time series of numerous first-order geodymanic and tectonic indicators back to 2.5 Ga, and with lesser resolution well into the Archean: significant mantle melting events, mantle plumes through time, mantle geochemistry, the state of the lithosphere, core-mantle boundary processes and the geodynamo, rifting and break-up events, stress fields, relative uplift of crustal blocks, paleo-latitudes and azimuthal orientation of ancient continents and cratons, and with sufficiently dense sampling, well-defined apparent polar wander paths and relative paleo-longitudes.

Yet, in an age where highly capable robotic rovers are dispatched to distant planets, this superb terrestrial record remains severely under-sampled. Currently existing ages alone suggest a strongly episodic record—“the pulse of the Earth”—that appears synchronized with the supercontinent cycle. Normalizing this record to the amount of crust present (preserved) at any time suggests significantly higher peak frequencies of magmatic activity in the Proterozoic, while the ~2.7 Ga event is “off-scale” and in a class of its own (the “2.7 Ga cataclysm”).

With rapid advances in high-precision geochronology of mafic rocks (and allied ultramafic and alkaline rocks), barriers to dating such events are disappearing. Hence, the proposition to date and characterize all significant mafic magmatic events through time and space is becoming realistic. It would allow the synthesis of all continental geology by providing numerous robust constraints for reconstructions of pre-Pangaea supercontinents and supercratons: ca. 1 Ga Rodinia, ca. 1.8-1.5 Ga Nuna, and the large late Archean supercratons such as Superia and Sclavia.

Together with integrated paleomagnetic data, we could track the movements of continental blocks through time and provide ground truth for geodynamic models. With a concerted effort, this could be achieved in less than a decade, finally fulfilling the ultimate promise of the plate tectonic revolution.