New models that show how the continents were put together provide new insights into Earth’s history and help better understand natural hazards such as earthquakes and volcanoes.
“We reviewed current knowledge of the configuration of plate boundary zones and the past construction of continental crust,” said Dr Derrick Hasterok, Senior Lecturer, Department of Earth Sciences, University of Adelaide, who led the team that produced the new models.
“The continents were put together a few pieces at a time, much like a jigsaw puzzle, but each time the jigsaw was completed, it was cut and rearranged to produce a new image. Our study sheds light on the different components so that geologists can reconstruct previous images.
“We found that plate boundary zones make up almost 16% of the Earth’s crust and an even higher proportion, 27%, of the continents.”
The team produced three new geological models: a plate model, a province model and an orogeny model.
“There are 26 orogenies – the process of mountain formation – that have left their imprint on the current architecture of the crust. Many of them, but not all, are related to the formation of supercontinents,” said the Dr Hasterok.
“Our work allows us to update maps of tectonic plates and the formation of continents found in school textbooks. These plate models, which were assembled from topographic and global seismicity models, have not been updated since 2003.
The new plate pattern includes several new microplates, including the Macquarie microplate which lies south of Tasmania and the Capricorn microplate which separates the Indian and Australian plates.
“To further enrich the model, we added more precise information about the boundaries of the deformation zones: previous models showed them as discrete areas rather than broad areas,” Dr Hasterok said.
“The biggest changes to the plate model have taken place in western North America, which often has the boundary with the Pacific plate drawn like the San Andreas and Queen Charlotte faults. But the newly demarcated border is much wider, around 1500 km, than the previously drawn narrow zone.
“The other big change is in Central Asia. The new model now includes all deformation zones north of India as the plate pushes its way towards Eurasia.
Published in the journal Earth Science Reviewsthe team’s work provides a more accurate representation of Earth’s architecture and has other important applications.
“Our new model of tectonic plates better explains the spatial distribution of 90% of earthquakes and 80% of volcanoes over the past two million years, whereas existing models only capture 65% of earthquakes,” said said Dr. Hasterok.
“The plate model can be used to improve geohazard hazard models; the orogeny model helps to understand geodynamic systems and to better model the evolution of the Earth and the province model can be used to improve mineral prospecting.
The work included researchers from the universities of Adelaide, Tasmania, Nevada-Reno and Geoscience Australia.
https://youtu.be/BYdX6_Y-S5g — New models showing the architecture of the Earth. Video: Dr Derrick Hasterok, University of Adelaide.
https://youtu.be/N — HPPmcG-o — Orogenies: A story told by the continents. Video: Dr Derrick Hasterok, University of Adelaide.