NEWS & EVENTS

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. 

In this talk, I will present my previous research results of using zircon trace elements to identify those that come from (i) sediment-derived (S-type) melts, and (ii) high-pressure zones of deep mountain roots. Applying to our global database of zircon from major rivers, we show that Nuna (2.0-1.8 Ga) and Gondwana (650-500 Ma) were periods of significant S-type granite production and extensive high mountain (supermountain) formation. Both periods coincide with periods of peak metamorphic pressure and increased seawater Sr isotope, supporting our interpretation that the Gondwana and Nuna amalgamation produced extensive high, Himalaya-like mountains. Rapid erosion of these supermountains is expected to result in (i) high primary production due to an increased nutrient flux into the oceans, and (ii) rapid burial of organic carbon, leading to increases in atmospheric oxygen. Another implication of these supermountains is that large amounts of continental materials may have been lost into the mantle during the Nuna and Gondwana assemblies, based on the results of my recent study of using the Himalayas as an example for mass balance calculations during the continental collisions. 

For additional information, please contact Dr Ziyi Zhu, ziyizhu@hku.hk