2010 GSA Denver Annual Meeting (31 October 3 November 2010)
Paper No. 230-5
Presentation Time: 9:00 AM-9:15 AM

A 56 MILLION YEAR RHYTHM IN NORTH AMERICAN SEDIMENTATION DURING THE PHANEROZOIC

MEYERS, Stephen R., Department of Geoscience, University of Wisconsin, 1215 West Dayton St, Madison, WI 53076, smeyers@geology.wisc.edu and PETERS, Shanan E., Department of Geology and Geophysics, University of Wisconsin-Madison, 1215 W. Dayton St, Madison, WI 53706

Long-term (>10 Myr) fluctuations in climate, sea-level and sedimentation have been documented in the stratigraphic record, but the lack of well-constrained data series has made it difficult to rigorously evaluate cyclic (periodic or quasi-periodic) changes at this scale. Here we utilize a new compilation of the coverage area of sedimentary rocks in North America to investigate the dominant modes (“orders”) of stratigraphic variability, and to evaluate potential long-period cyclic changes in sedimentation on the continent during the Phanerozoic. Our analysis resolves two principal temporal modes of variability: (1) a strongly sinusoidal mode with a periodicity of 56 Myr +/- 3 Myr, and (2) a longer-term Phanerozoic mode (the “M-curve” or Wilson cycle), which is indistinguishable from a stochastic autoregressive process. The newly identified 56 Myr cycle in sedimentation delineates most of the cratonic sequences that have previously been identified qualitatively in North America, but here we propose a quantitative redefinition that includes nine distinct units and two mega-sequences. The timing of the 56 Myr beat in sedimentation is consistent with an orogenic oscillator source or an oscillatory dynamic in mantle convection, and its tempo is statistically similar to a known rhythm in number of marine animal genera in the global fossil record. Thus, the identification of a significant periodic signal in the sedimentary record of North America provides new evidence for an important tectonic- or mantle-scale cyclic process that links both large-scale biological evolution and physical environmental change.

2010 GSA Denver Annual Meeting (31 October 3 November 2010)
General Information for this Meeting
Session No. 230
Recent Advances in Stratigraphy Geology I
Colorado Convention Center: Room 303
8:00 AM-12:00 PM, Wednesday, 3 November 2010

Geological Society of America Abstracts with Programs, Vol. 42, No. 5, p. 543

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