Impact events

A Tale of Clusters: No Resolvable Periodicity in the Terrestrial Impact Cratering Record

By Keith Cowing
Press Release
February 1, 2017
Filed under
A Tale of Clusters: No Resolvable Periodicity in the Terrestrial Impact Cratering Record

Rampino & Caldeira (2015) carry out a circular spectral analysis (CSA) of the terrestrial impact cratering record over the past 260 million years (Ma), and suggest a ~26 Ma periodicity of impact events. For some of the impacts in that analysis, new accurate and high-precision (“robust”; 2SE<2%) 40Ar-39Ar ages have recently been published, resulting in significant age shifts. In a CSA of the updated impact age list, the periodicity is strongly reduced. In a CSA of a list containing only impacts with robust ages, we find no significant periodicity for the last 500 Ma. We show that if we relax the assumption of a fully periodic impact record, assuming it to be a mix of a periodic and a random component instead, we should have found a periodic component if it contributes more than ~80% of the impacts in the last 260 Ma. The difference between our CSA and the one by Rampino & Caldeira (2015) originates in a subset of “clustered” impacts (i.e., with overlapping ages). The ~26 Ma periodicity seemingly carried by these clusters alone is strongly significant if tested against a random distribution of ages, but this significance disappears if it is tested against a distribution containing (randomly-spaced) clusters. The presence of a few impact age clusters (e.g., from asteroid break-up events) in an otherwise random impact record can thus give rise to false periodicity peaks in a CSA. There is currently no evidence for periodicity in the impact record. Matthias M. M. Meier (1), Sanna Holm-Alwmark (2) ((1) ETH Zurich, Institute of Geochemistry and Petrology, Clausiusstrasse 25, 8092 Zurich, Switzerland, (2) Lund University, Department of Geology, S√∂lvegatan 12, 22362 Lund, Sweden)
(Submitted on 31 Jan 2017)

Comments: Accepted for Publication in Monthly Notices of the Royal Astronomical Society
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
DOI: 10.1093/mnras/stx211
Cite as: arXiv:1701.08953 [astro-ph.EP] (or arXiv:1701.08953v1 [astro-ph.EP] for this version)
Submission history
From: Matthias M. M. Meier
[v1] Tue, 31 Jan 2017 09:12:47 GMT (1032kb)

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