Based on a series of models considering how continents have come together over time, a team of researchers from the University of Adelaide have created an updated map of Earth’s tectonic plates. The map will help provide a better understanding of natural hazards such as earthquakes and volcanoes that occur along plate boundaries.
“We reviewed current knowledge about the configuration of plate boundary zones and the past construction of continental crust,” said Dr. Derrick Hasterok, Department of Earth Scienceswho led the team that produced the models.
The cratons of our modern continents – the continental cores with the oldest and thickest crust – formed more than 3.2 billion years ago. Over time, more and more crustal fragments formed, pushed together by convection currents in the Earth’s mantle, forming the first supercontinent called Vaalbara. These collisions were accompanied by processes of mountain formation along the boundaries of tectonic plates. Eventually Vaalbara split apart, forming a subset of smaller continents. Over the past 3 billion years a number of supercontinents have formed and split apart again, the most recent being Pangea, a supercontinent existing 335 to 65 million years ago.
“The continents were put together a few pieces at a time, much like a jigsaw puzzle, but each time the puzzle was completed, it was cut up and rearranged to produce a new image. Our study helps illuminate the different components so that the geologists can reconstruct the previous images,” explains Hasterok.
To create the map, the team used three new geological models: a plate model (considering the shape and structure of the Earth’s tectonic plates), a province model (considering the geology of large areas of the Earth’s surface Earth) and an orogeny model (simulating mountain formation processes).
“There are 26 orogenies – the process of mountain formation – that have left their imprint on the current architecture of the Earth’s crust. Many, but not all of them, are related to the formation of supercontinents.
Our work allows us to update the maps of tectonic plates and the formation of continents found in school textbooks. These plate models, which were assembled from topographic models and global seismicity, 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 wide areas,” Hasterok said.
The most significant changes to the plate model have been in western North America, which often has the boundary with the Pacific plate drawn as the San Andreas and the Queen Charlotte Faults. But the newly demarcated border is much wider, around 1,500 kilometers, than the previously drawn narrow zone.
The other big change concerns Central Asia. The new model now includes all deformation zones north of India as the plate pushes its way towards Eurasia.
The team’s work provides a more accurate representation of Earth’s structure and has other important practical 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.
The plate model can be used to improve geohazard hazard models; the orogeny model helps to understand geodynamic systems and better model the Earth’s evolution and the province model can be used to improve mineral prospecting,” concludes Hasterok.
The paper “New maps of the world’s geological provinces and tectonic plates” is published in the journal Earth Science Reviews (2022). Material provided by the University of Adelaide.
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