Neoproterozoic glacial origin of the Great Unconformity

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C. Brenhin Keller , Jon M. Husson , Ross N Mitchell, William F Bottke, Thomas Gernon, Patrick Boehnke, Elizabeth A Bell, Nicholas L Swanson-Hysell , Shanan E Peters 


The Great Unconformity, a profound gap in Earths stratigraphic record often evident below the base of the Cambrian system, has remained among the most enigmatic field observations in Earth science for over a century. While long associated directly or indirectly with the occurrence of the earliest complex animal fossils, a conclusive explanation for the formation and global extent of the Great Unconformity has remained elusive. Here we show that the Great Unconformity is associated with a set of large global oxygen and hafnium isotope excursions in magmatic zircon that suggest a late Neoproterozoic crustal erosion and sediment subduction event of unprecedented scale. These excursions, the Great Unconformity, preservational irregularities in the terrestrial bolide impact record, and the first-order pattern of Phanerozoic sedimentation can together be explained by spatially heterogeneous Neoproterozoic glacial erosion totaling a global average of three to five vertical kilometers, along with the subsequent thermal and isostatic consequences of this erosion for global continental freeboard.



Earth Sciences, Geochemistry, Geology, Glaciology, Physical Sciences and Mathematics


Snowball Earth, Zircon, Cambrian explosion, glacial erosion, Great Unconformity


Published: 2019-01-07 12:06

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CC BY Attribution 4.0 International

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