Rise of major subaerial landmasses about 3.0 to 2.7 billion years ago
Chun‐Tao Liu, Yixiang He
Abstract
The emergence of subaerial landmasses should have inevitably modulated the chemical composition of the atmosphere-ocean and long term climate. However, it remains controversial when major subaerial landmasses first emerged in Earth's history. Here we show that the mean K/La of globally continental mafic volcanic rocks declined from a fairly high value (2125) to a magmatic background (582, indicated by continental mafic plutonic rocks) during 3.0-2.7 Ga. It can only be explained by a progressive reduction in the proportion of submarine hydrothermally altered mafic volcanic samples and thus records a gradual rise of major subaerial landmasses from 3.0 to 2.7 Ga, likely to a present day level since 2.7 Ga. The rise and maintaining of major subaerial landmasses were intrinsically controlled by a dynamic balance of mountain building processes dominantly driven by plate tectonics and subsidence due to weathering erosion and thermal relaxation.