Earth’s supermountains as revealed by detrital zircon from modern rivers linked to biological evolution

Zircon is an invaluable accessory mineral found in a wide range of crustal rocks. It can faithfully record its host rock’s composition, over long periods of geological time, leading to its wide use in studies of continental evolution. Detrital zircons collected from Earth’s modern rivers provide a representative sample that can be used to study the evolution of the continental crust on a large scale, aided by long-time sediment-sediment recycling, which results in the efficient mixing of zircons from source rocks of diverse origins.  

We use the Lu contents in zircons to identify those that come from the high-pressure zones of the deep mountain roots. By applying this technique to our global data base of zircon from major rivers, we show that Nuna and Gondwana were periods when Earth’s topography was dominated by high, Himalayan-type mountains, whereas Rodinia was not. The dramatic difference between Rodinia on one hand, and the amalgamation of Nuna and Gondwana on the other, is also manifested in other geological proxies, such as peaks in the average metamorphic pressure, seawater Sr isotope and S-type granite abundance. The two periods of extensive high mountain (supermountain) formation coincide with two major changes in Earth’s evolution: (i) postulated increases in atmospheric oxygen, and (ii) major biological advances. We argue that the big evolutionary changes that occurred during these two periods were potentially driven by dramatic increases in the supply of bio-limiting nutrients into the oceans, which resulted from the rapid erosion of Earth’s two supermountains.