Study Links 11 Archean Cratons to Milky Way Spiral-Arm Passages in Earth's Continental Growth
Updated
Updated · ScienceAlert · Jul 25
Study Links 11 Archean Cratons to Milky Way Spiral-Arm Passages in Earth's Continental Growth
2 articles · Updated · ScienceAlert · Jul 25
Summary
Researchers led by Chris Kirkland argue Earth's earliest continents may have grown during repeated Milky Way spiral-arm crossings, not solely through internal geology.
Data from 11 Archean cratons showed recurring hafnium and oxygen isotope shifts in zircon crystals that aligned with predicted galactic passages and peaks in Earth and Moon impact ages.
The proposed mechanism is that spiral-arm gravity disturbed the Oort Cloud, sending more comets into the inner Solar System; those impacts may have helped create stable crustal "seeds" for continents.
The team said the pattern matters more than any single zircon age peak, because a galaxy-scale trigger could affect widely separated cratons at roughly the same time.
Published in Earth and Planetary Science Letters, the study stops short of proof because ancient galactic orbits and comet delivery are hard to reconstruct, and calls for checks in Moon and Mars mineral records.