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A 32-million year cycle detected in sea-level fluctuations over the last 545 Myr

Geoscience Frontiers 2020年第6期11卷 2061-2065页

作者： Michael R.Rampino ken caldeira Departments of Biology and Environmental Studies New York University100 Washington Square EastNew YorkNY10003USA NASA Goddard Institute for Space Studies2880 BroadwayNew YorkNY10025USA Department of Global Ecology Carnegie Institution for Science290 Panama StreetStanfordCA94305USA

Spectral analyses of past relative sea-level oscillations as represented by the ages of 57 Phanerozoic(the last 545 Myr)stratigraphic sequence boundaries from the Canadian Arctic show a strong spectral peak at 32 Myr(>99.9%confidence).These findings concur with previous reports of significant cycles with periods of around 30 Myr in various records of fluctuations of sea level,and in potentially related episodes of tectonism,volcanism,climate,and biotic *** boundaries commonly coincide with stage boundaries based on biostratigraphy,and are correlated with episodes of extinction and times of flood-basalt *** connection between tectonics and sea-level variations may come from changes in rates of ocean-floor spreading and subduction,intraplate stresses from plate-reorganizations,and pulsations of hotspot *** coordinated periodic fluctuations in tectonics,sea level and climate may be modulated by cyclical activity in the Earth’s mantle,although some pacing by astronomical cycles is suspected.

关键词： Sea level Periodicity Sequence boundary

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Correlation of the largest craters,stratigraphic impact signatures,and extinction events over the past 250 Myr

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Geoscience Frontiers 2017年第6期8卷 1241-1245页

作者： Michael R.Rampino ken caldeira Department of Biology New York University100 Washington Square EastNew YorkNY 10003USA NASA Goddard Institute for Space Studies2880 BroadwayNew YorkNY 10025USA Carnegie Institute for Science Department of Global Ecology260 Panama St.StanfordCA 94305USA

The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters),66,and 145 Myr ago,and possibly with two provisional extinction events at 168 and215 Myr *** impact cratering events are accompanied by layers in the geologic record interpreted as impact *** occurrences of impacts and extinctions can be rejected at confidence levels of99.96%(for 4 impact/extinctions)to 99.99%(for 6 impact/extinctions).These results argue that several extinction events over the last 250 Myr may be related to the effects of large-body impacts.

关键词： Extinctions Impact craters Ejecta layers

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A pulse of the Earth: A 27.5-Myr underlying cycle in coordinated geological events over the last 260 Myr

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Geoscience Frontiers 2021年第6期12卷 236-242页

作者： Michael R.Rampino ken caldeira Yuhong Zhu Departments of Biology and Environmental Studies New York University100 Washington Square EastNew YorkNY 10003USA Department of Global Ecology Carnegie Institution for Science290 Panama StreetStanfordCA 94305USA Center for Data Science New York University60 Fifth AvenueNew YorkNY 10011USA

We performed spectral analyses on the ages of 89 well-dated major geological events of the last 260 Myr from the recent geologic literature. These events include times of marine and non-marine extinctions,major ocean-anoxic events, continental flood-basalt eruptions, sea-level fluctuations, global pulses of intraplate magmatism, and times of changes in seafloor-spreading rates and plate reorganizations. The aggregate of all 89 events shows ten clusters in the last 260 Myr, spaced at an average interval of ~ 26.9 Myr, and Fourier analysis of the data yields a spectral peak at 27.5 Myr at the ≥96% confidence level. A shorter period of ~ 8.9 Myr may also be significant in modulating the timing of geologic *** results suggest that global geologic events are generally correlated, and seem to come in pulses with an underlying ~ 27.5-Myr cycle. These cyclic pulses of tectonics and climate change may be the result of geophysical processes related to the dynamics of plate tectonics and mantle plumes, or might alternatively be paced by astronomical cycles associated with the Earth’s motions in the Solar System and the Galaxy.

关键词： Global geological events Fourier analysis Cyclic pulses Tectonics Correlations

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