Composition of continental crust altered by the emergence of land plants


Type
Article
Change log
Abstract

The evolution of land plants during the Palaeozoic Era transformed Earth’s biosphere 1. Because the Earth's surface and interior are linked by tectonic processes, the linked evolution of the biosphere and sedimentary rocks should be recorded as a near-contemporary shift in the composition of the continental crust. To test this hypothesis, we assessed the isotopic signatures of zircon formed at subduction zones where marine sediments are transported into the mantle 2,3, thereby recording interactions between surface environments and the deep Earth. Using oxygen and lutetium-hafnium isotopes of magmatic zircon that respectively track surface weathering (time-independent) 4 and radiogenic decay (time-dependent) 5, we find a correlation in the composition of continental crust after 430 Myr ago, which is coeval with the onset of enhanced complexity and stability in sedimentary systems related to the evolution of vascular plants. The expansion of terrestrial vegetation brought channelled sand-bed and meandering rivers, muddy floodplains, and thicker soils, lengthening the duration of weathering before final marine deposition 6,7. Collectively, our results suggest that the evolution of vascular plants coupled the degree of weathering and timescales of sediment routing to depositional basins where they were subsequently subducted and melted. The late Palaeozoic isotopic shift of zircon indicates that the greening of the continents was recorded in the deep Earth.

Description
Keywords
3709 Physical Geography and Environmental Geoscience, 37 Earth Sciences, 3703 Geochemistry, 3705 Geology, 3706 Geophysics, 14 Life Below Water
Journal Title
Nature Geoscience
Conference Name
Journal ISSN
1752-0894
1752-0908
Volume Title
Publisher
Springer Science and Business Media LLC
Sponsorship
NERC (NE/T00696X/1)