Tectonics and Surface Environments on Early Earth.

Abstract

The mode of tectonics that governed early Earth is controversial. This makes it challenging to infer surface environments relevant to the origin of life. The majority of the literature published in the past two decades was inclined to favor the appearance of plate tectonics sometime around the mid-Archean (∼3 Ga), with the operation of stagnant lid convection (or its variants) dominant in the earlier part of Earth's history. However, the available and increasing geological record from early Earth is actually equivocal, and there is no theoretical basis to prefer stagnant lid convection over plate tectonics. In fact, such a delayed onset of plate tectonics would inhibit the emergence of life in the Archean, let alone in the Hadean. On the contrary, rapid plate tectonics in the early Hadean, enabled by the fractional crystallization of a magma ocean, could quickly transform inclement young Earth into a habitable planet, with formation of multiple surface environments potentially conducive to abiogenesis.