Glacio-epochs and the supercontinent cycle after ∼ 3.0 Ga: Tectonic boundary conditions for glaciation

Tectonic influences on long-term climate change are of considerable current interest and debate. This paper reviews the relationship between multi-million year periods of glaciation (glacio-epochs) over the last 3 Ga of Earth history and phases of supercontinent breakup and assembly. A preferred but not exclusive relationship is evident between glacio-epochs and their mostly glacially influenced marine record, with rifting. The earliest known glaciation (mid Archean ∼ 2.9 Ga) is recorded in the marine Mozaan Group of South Africa deposited along the passive margin of the Kapvaal Craton then part of the early continent Ur. The Paleoproterozoic glacio-epoch, exemplified by the Huronian Supergroup of Ontario, Canada (∼ 2.4 Ga) and strata in northern Europe and the U.S., is associated with rifting of Kenorland. A long Paleo-Mesoproterozoic non-glacial interval (c. 2.3 Ga to 750 Ma?) coincides with continental collisions and high standing Himalayan-scale orogenic belts marking the suturing of supercontinents Nena-Columbia and Rodinia. A near absence of glacial deposits other than at 1.8 Ga, may reflect lack of preservation. The extensive and prolonged Neoproterozoic glacio-epoch records either diachronous glaciations or discrete pulses of cooling between ∼ 750 and ∼ 580 Ma, and is overwhelmingly recorded by substantial thicknesses (1 km+) of glacially influenced marine strata stored in rift basins. These formed on the mid to low latitude (< 30°) oceanic margins of western (Panthalassa: Australia, China, Western North America) and eastern (Iapetus: Northwest Europe) margins of a disintegrating Rodinia. The youngest glacially influenced deposits formed about 580 Ma along the compressional Cadomian Belt exterior to Rodinia (Gaskiers Formation) possibly correlative with the classic passive margin Marinoan deposits of South Australia. 
 
A short-lived (1 to 15 Ma?) Early Paleozoic ice sheet about 440 Ma grew over highlands on the polar North Africa margin of Gondwana possibly likely triggered by uplift at high paleolatitudes as large terranes (e.g., Meguma, Avalonia) rifted away from North Africa. Incised valleys, coarse glacial fills and thick (1 km +) ‘postglacial’ shales suggest a continuing tectonic influence. Devonian cooling across the Frasnian-Famennian boundary (c. 376 Ma) is recorded by local ice covers in Brazil and Bolivia and is linked to elevated topography and enhanced erosion of continental crust. The Late Paleozoic glacio-epoch (∼ 350 and 250 Ma) coincides with a high paleolatitude positioning of Gondwana and the growth of high standing topography when Gondwana collided with Laurasia to create Pangea. Breakup after 180 Ma moved landmasses into higher northerly latitudes and was the backdrop to global cooling of the Cenozoic glacio-epoch that commenced after the Paleocene–Eocene Thermal Maximum (< 55 Ma). Earliest Antarctic ice at ∼ 40 Ma most likely nucleated on the high shoulders of the Transantarctic Rift coeval with opening of Drake Passage, and coincides with the earliest ice rafting in the Arctic Basin at 43 Ma, followed by another pulse at 34 Ma. Accelerated glacierization in both hemispheres occurred at ∼ 14 Ma during the middle Miocene Transition but Milankovitch-forced continental-scale ice sheets did not nucleate in the northern hemisphere until after 3.5 Ma on uplifted borderlands along North Atlantic passive margins. 
 
A preferred association of the deposits of Proterozoic and Phanerozoic glacio-epochs with rift basins reflects either a causal link between rift-related uplift and regional cooling, or simply enhanced preservation of glacial sediments. Glacial deposits are poorly preserved in areas of compressional tectonics.

Field of study: Environmental science, Geography