Water-induced mantle overturns leading to the origination of Archean continents and sub continental lithospheric mantle

Abstract

The originations of the Archean continents and sub continental lithospheric mantle (SCLM) were most important events in the early Earth and crucial for understanding how the early Earth worked. The mechanisms for the originations of the Archean continents and SCLM remain unclear. This study suggests that these events were controlled by a deep-water cycle (DWC) in the early Earth. With the solidification of the basal magma ocean (BMO), water in the BMO moved toward the core-mantle boundary and the BMO eventually became gravity unstable because of the enrichment of water. The gravity instability triggered the massive mantle overturns and transported a huge amount of water upward to the shallow part of the Earth. The massive overturn events resulted in the major pulses of the thick SCLM and continental crust generations in the Neoarchean. The DWC model in the early Earth can account for the episodic feature of continental growth and why TTG and thick SCLM basically occurred in the Archean. The DWC model also shows why only the Earth among inner solar system planets was covered with the continental crust. Our results suggest that the DWC played a first-order role in the evolution and dynamics of the early Earth just like the current DWC driven by the plate tectonics on the nowadays Earth.

Mobility of Magmas Within the Earth: Insights From the Elasticity and Transport Properties of Hydrous Albitic Melts

“…The ρ and η of melts also affect the ability of crystals to float or sink, which significantly influences the crystallization of magmatic bodies. It is likely that the evolution of the mantle and continental crust in the early history of the Earth, such as in the Archean, might have been influenced by the ρ and η of melts (Wu et al., 2023).…”