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, Sölvegatan 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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