Chapter 7 - Evolution of the Crust-Formation Processes in Earth's History

Abstract

Publisher Summary This chapter discusses the evolution of the crust-formation processes in earth's history. The oldest stage of Earth's formation (the pre-geological or Katarchaean stage) lasted approximately 600 MMY from the moment of Earth's emergence 4.6 BY ago through the beginning of its tectonic activity in Early Archaean, about 4.0 BY ago. Earth at that time was a relatively cold celestial body. All matter within it was at temperatures way below its melting temperature. There was no tectonomagmatic activity. Nevertheless, Earth during Katarchaean was not a tectonically dead planet. First, its insides at that time were gradually warmed up by the radioactive element decay energy and by the energy of tidal interaction with the Moon. These events were preparing the conditions for Earth transitioning to tectonically active evolution. Second, the exogenous tectonics of the tidal origin played a significant role in Katarchaean (especially in Early Katarchaean). This evolutionary stage may be called the “crypto-tectonic stage.” First clear and intense manifestations of the endogenous tectonomagnetic activity on Earth are reliably identified in the beginning of Archaean close to 3.8 BY ago. The beginning of Earth's tectonomagmatic activity was prepared by the radiogenic and tidal heating of the primordial Earth's matter to the temperature when the primary melts appeared within the upper mantle. That was followed by a drastic and maybe even “shock” activation of the tectonomagnetic activity. First, it happened due to “pumping” into the then formed asthenosphere of the tidal energy from the Moon–Earth interaction. Later, it proceeded because of the energy release from gravity differentiation of Earth matter.