Secular Evolution of Continents and the Earth System

Understanding of secular evolution of the Earth system is based largely on the rock and mineral archive preserved in the continental lithosphere. Based on the frequency and range of accessible data preserved in this record, we divide the secular evolution into seven phases: (a) Proto-Earth (ca. 4.57-4.45 Ga); (b) Primordial Earth (ca. 4.45-3.80 Ga); (c) Primitive Earth (ca. 3.8-3.2 Ga); (d) Juvenile Earth (ca. 3.2-2.5 Ga); (e) Youthful Earth (ca. 2.5-1.8 Ga); (f) Middle Earth (ca. 1.8-0.8 Ga); and (g) Contemporary Earth (since ca. 0.8 Ga). Integrating this record with knowledge of secular cooling of the mantle and lithospheric rheology constrains the changes in the tectonic modes that operated through Earth history. Initial accretion and the Moon forming impact during the Proto-Earth phase likely resulted in a magma ocean. The solidification of this magma ocean produced the Primordial Earth lithosphere, which preserves evidence for intra-lithospheric reworking of a rigid lid, but which also likely experienced partial recycling through mantle overturn and meteorite impacts. Evidence for craton formation and stabilization from ca. 3.8 to 2.5 Ga, during the Primitive and Juvenile Earth phases, likely reflects some degree of coupling between the convecting mantle and a lithosphere initially weak enough to favor an internally deformable, squishy-lid behavior, which led to a transition to more rigid, plate like, behavior by the end of the early Earth phases. The Youthful to Contemporary phases of Earth, all occurred within a plate tectonic framework with changes between phases linked to lithospheric behavior and the supercontinent cycle. Plain Language Summary The record of Earth evolution is preserved in the continental rock archive, but is incomplete and our knowledge of it decreases with increasing age and depth of preservation. Based on secular cooling of the mantle and associated changing lithospheric properties, we recognize three dominant tectonic modes that have operated on Earth; stagnant lid, squishy lid, and plate tectonics. After solidification of the Earth's initial magma ocean (>4.45 Ga), the lithosphere was likely dominated by mafic crust that existed until ca. 3.8 Ga. The tectonic mode that operated at this time involved either no lithosphere-mantle coupling (cf., stagnant lid), or coupling between non-rigid lithosphere and convecting mantle (cf., squishy lid). The latter mode likely operated through most of the Archean (ca. 3.8-2.5 Ga), and was associated with the formation of the stable interior of continents, called cratons. The stabilization of these cratons in the latter half of the Archean (ca. 3.2-2.5 Ga) is associated with the development of rigid lithosphere and the transition to a plate tectonic mode that continues to the present day. Further changes, likely in response to the supercontinent cycle, lead to subdivisions of the Earth system between ca. 1.8 and 0.8 Ga.

Automated summary

Understanding the secular evolution of the Earth system is essential for studying the history of our planet. By analyzing the rock and mineral archive in the continental lithosphere, researchers have identified seven phases of secular evolution. Integrating this record with knowledge of mantle cooling and lithospheric rheology provides insights into the changes in tectonic modes throughout Earth's history.