Multiple causes of Earth's earliest global glaciation


Professor Victor A. Melezhik, Geological Survey of Norway, Leiv Eirikssons vei 39, Trondheim N-7491, Norway. Tel.: 00 47 73 90 40 00; fax: 00 47 73 92 16 20; e-mail:


In the context of Earth System evolution, the causal factors driving the Palaeoproterozoic Huronian global glaciations occupy a central position. The rise of O2 at 2320 Ma, which eliminated most of the methane, was not apparently a single cause triggering the glaciation. At c. 2450 Ma mantle-plume-driven continental uplifts led to the emplacement of voluminous continental flood-basalts in low latitudes that were subsequently dissected by rifting. Major topographical features and continental drainage patterns were most likely similar to those in younger continental flood-basalt provinces and would have enabled deep weathering and erosion of extensive basalt-covered continental areas. Intense consumption of atmospheric CO2 by silicate weathering of fresh basaltic surfaces would have been further amplified by a constant organic carbon burial rate. These factors, similar to those of younger glacial periods, in combination with the diminished CH4 greenhouse led to an onset of global cooling at the million-year timescale.