The Neoproterozoic and Snowball Earth

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The Neoproterozoic era (1.0-0.54 Ga) was a time of profound changes in the lithosphere, hydrosphere, atmosphere, cryosphere and biosphere. Earth’s lithosphere records the separation of Rodinia, the pre-Pangean supercontinent, with extensional tectonism on most continents. Evidence that indicate that this was a time of dramatic change comes from well-dated stratigraphic sections that record tectonic, biogeochemical and paleontological information. The Chuar Group, exposed only in the Grand Canyon, accumulated in an intracratonic rift basin. The Chuar group has been indicated that it was deposited at the same time with normal faulting on the north-trending Butte fault from structural and stratigraphic studies. This can be shown by intraformational faults and development and tightening with depth of a Neoproterozoic growth syncline. This evidence along with other global rifting events that show widespread mafic magmatism and sedimentation within extensional basins can conclude the breakup of Rodinia. Each of these rift-related packages provide glaciogenic sedimentary rocks and display large carbon isotope variations, underscoring the close interrelationships among global extensional tectonics, the carbon cycle, and Neoproterozoic climatic fluctuations. The stratigraphy of the Chuar group consists of multicolored mudrocks interbedded with laterally extensive meter-scale dolomite and sandstone beds. The mudrocks are organic rich and contain abundant marine microfossils. The dolomites display microbial laminae, domal to columnar stromatolites, flat-pebble conglomerates, ripple cross- laminae, and various sizes of desiccation cracks. The sandstones contain asymmetric and symmetric ripple marks with mudcracks, planar-tabular cross-beds with local reverse-flow indicators, and planar horizontal laminae. These characteristics suggest deposition in shallow subtidal to

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