A supercontinent without plume has no less panache
September 7 2016
The aggregation and dispersal of supercontinents control the Earth’s geological history, and influences the Earth’s climate and the evolution of species. But, what is the impact of these supercontinents on the deep Earth interior?
A study published in the journal American Mineralogist, involving a team of researchers from the University of Toulouse (France) and Earthbyte’s Basin Genesis Hub at the University of Sydney, presents a new, global, perspective on the magmatic history of Pangea, the last supercontinent.
The proposition that supercontinents could act as blankets warming up the mantle underneath and leading to intraplate magmatism explains that deep mantle instability are not required to produce thermal anomalies at the Earth’s surface. Although many numerical studies have strengthened this hypothesis no petrological data has been presented in support to supercontinent mantle warming.
In order to track the temperature of mantle-derived magmas through times, the research team has compiled over 16 millions of data including samples’ bulk composition and the composition of their minerals. The statistical analysis shows that over the past 600 millions years, the average temperature of continental magmas has increased before to decrease by up to 100ºC.
The study shows that the warming period is coeval with the aggregation of Pangea from 600 to 200 Ma, whereas the progressive cooling is synchronous with Pangea’s dispersal from 200 myr onwards. This confirms that a link exists between the temperature of the sub-continental mantle and the supercontinent cycle, and suggests that magmas that originate at shallow levels underneath continents are probably linked to tectonic rather than global mantle processes in particular at time of major plate re-organization.
This work opens a suite a questions regarding the formation of continental margins and their associated sedimentary basins. In particular, it suggests that continental margins formed during the dispersal of supercontinents should evolve over a warmer, more buoyant mantle. This may have implication regarding the involvement of magmatic inputs into continental margins, as well as the stratigraphy of sedimentary basins through the margin’s uplift and subsidence history.
Paper Reference: Ganne, J., Feng, X., Rey, P. F., De Andrade, V. (2016). Statistical petrology reveals a link between supercontinents cycle and mantle global climate. American Mineralogist
Check out the paper here.