Tectonic Geography
Mapping the ancient Earth
Mawson Geo Centre researchers are mapping the Earth, right back to the Archean. By using geology to find proxies for ancient plate margins, we are figuring out how plate tectonics has changed the map of the world over the past few billion years. For example, where and when did continents split apart and then came back together? How did the world look 1 billion or even 3 billion years ago?
Mapping the ancient Earth is very helpful for the resources industry. It tells you where a part of the basin that you want to examine might be found now and how that evolved from another part of a continent in the past. More fundamentally, it shows where plate margins were located through time, and plate margins are the drivers for mineral deposit formation.
The below image shows the Earth’s tectonic geography at 1000 million years ago. You can also watch our animation of the moving plate margins from about 1000 to 500 million years ago.
A-A = Afif-Abas Terrane; Am = Amazonia; Az = Azania; Ba = Baltica; Bo = Borborema; By = Bayuda; Ca = Cathaysia (South China); C = Congo; Ch = Chortis; G = Greenland; H = Hoggar; I = India; K = Kalahari; L = Laurentia; Ma = Mawson; NAC = North Australian Craton; N-B = Nigeria-Benin; NC = North China; Pp = Paranapanema; Ra = Rayner (Antarctica); RDLP = Rio de la Plata; SAC = South Australian Craton; SF = São Francisco; Si = Siberia; SM = Sahara Metacraton; WAC = West African Craton. Shaded grey area is inferred extent of Rodinia and is meant as a guide only. The longitude is arbitrary and unconstrained, and used here as a relative reference. Cratonic crust is coloured by present day geography: North America = red; South America = dark blue; Baltica = green; Siberia = grey; India and the Middle; East = light blue; China = yellow; Africa = orange; Australia = crimson; Antarctica = purple Source: Merdith, A.S., Collins A.S., Williams, S.E., Pisarevsky, S., Foden, J.F., Archibald, D.A., Blades, M.L., Alessio, B.L., Armistead, S., Plavsa, D.,Clark, C. & Müller, R.D. in press. A Full-Plate Global Reconstruction of the Neoproterozoic. Gondwana Research.
An animation of moving plate margins from about 1000-500 million years ago.
Explaining Earth systems
Tectonic geography is also vital for making observations about the bigger Earth system. It helps us predict and model the effects on the Earth of phenomena such as:
- the amount of solar radiation the Earth bounces back from the sun due to the changing distribution of the continents and oceans
- the effects on the carbon, sulphur and oxygen cycles due to varying rates and amounts of subduction over time
- the idea that sea level changes are not only due to changes in climate, they are also due to how much oceanic crust is being produced at any one time.