Paper in PNAS proposes repeated glaciation-deglaciation limit cycles driven by Franklin LIP weathering explain the 56-million-year Sturtian glacial period.
Key Takeaways
Standard Snowball and Slushball Earth models conflict with geological evidence: oxygen should deplete long before 56 million years, yet life persisted.
The Franklin Large Igneous Province (~717 Ma, Canadian Arctic) triggered CO2 drawdown via silicate weathering, initiating the Sturtian glaciation.
Researchers used a coupled box model simulating carbon, oxygen, and weathering cycles across a range of volcanic activity and LIP size parameters.
Limit cycling model: glaciation halts LIP weathering, volcanic CO2 accumulates, ice melts, weathering resumes, repeat until Franklin basalt is exhausted.
The ~4 million year cycle timescale matches the shorter Marinoan period; repeated cycles stack to explain the longer Sturtian duration.
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Notable Comments
@wglb: Links directly to the PNAS paper at doi 10.1073/pnas.2525919123.
