Making continental crust on water-bearing terrestrial planets

Area of Science:

• Planetary Science
• Geochemistry
• Early Earth History

Background:

• The formation of early Earth's crust, particularly felsic continental crust, remains a key debate in geochemistry.
• Understanding the role of Hadean zircons within an ultramafic environment is crucial for deciphering early planetary evolution.

Purpose of the Study:

• To investigate the generation of felsic melts through interactions between serpentinized peridotite and basaltic magmas.
• To determine the extent and timing of Hadean felsic crust formation on Earth and potentially Mars.

Main Methods:

• Experimental petrology
• Thermodynamic modeling
• Elemental partitioning analysis
• Hafnium isotopic analysis of Hadean zircons

Main Results:

• Felsic melts, the precursors to continental crust, can form from shallow interactions of serpentinized peridotite and basaltic magmas.
• Hadean detrital zircons indicate extensive felsic crust formation between 4.4 and 4.5 billion years ago, potentially comprising up to 50% of current continental crust.
• A similar process is plausible for early Mars.

Conclusions:

• The interaction of primordial magmas with serpentinized peridotite is a viable mechanism for early felsic crust generation on Earth and Mars.
• This process explains the presence of Hadean zircons and the formation of significant early continental crust.
• The serpentinized protocrust played a dual role in providing crustal ingredients and potentially enabling the origin of life.