{"id":11320,"date":"2017-01-25T22:05:59","date_gmt":"2017-01-25T21:05:59","guid":{"rendered":"http:\/\/karmaka.de\/?p=11320"},"modified":"2017-02-01T06:59:05","modified_gmt":"2017-02-01T05:59:05","slug":"a-tale-of-clusters-no-resolvable-periodicity-in-the-terrestrial-impact-cratering-record","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=11320","title":{"rendered":"A tale of clusters: No resolvable periodicity in the terrestrial impact cratering record<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"<p>Matthias M. M. Meier, Sanna Holm-Alwmark<\/p>\n<p>MNRAS (2017) stx211.<br \/>\nDOI:https:\/\/doi.org\/10.1093\/mnras\/stx211<br \/>\nPublished: 25 January 2017<\/p>\n<p><a href=\"http:\/\/arxiv.org\/pdf\/1701.08953\" target=\"_blank\"><strong>PDF (OPEN ACCESS)<\/strong><\/a> (updated: 1 Feb)<br \/>\n<a href=\"https:\/\/academic.oup.com\/mnras\/article-abstract\/2957029\/A-tale-of-clusters-No-resolvable-periodicity-in\" target=\"_blank\"><strong>LINK<\/strong><\/a><\/p>\n<p>&#8220;Rampino &#038; 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 \u223c26 Ma periodicity of impact events. For some of the impacts in that analysis, new accurate and high-precision (\u201crobust\u201d; 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 \u223c80% of the impacts in the last 260 Ma. The difference between our CSA and the one by Rampino &#038; Caldeira (2015) originates in a subset of \u201cclustered\u201d impacts (i.e., with overlapping ages). The \u223c26 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.\"\n<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Matthias M. M. Meier, Sanna Holm-Alwmark MNRAS (2017) stx211. DOI:https:\/\/doi.org\/10.1093\/mnras\/stx211 Published: 25 January 2017 PDF (OPEN ACCESS) (updated: 1 Feb) LINK &#8220;Rampino &#038; Caldeira (2015) carry out a circular spectral analysis (CSA) of the terrestrial&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,112,90,96],"tags":[3259,313],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11320"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=11320"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11320\/revisions"}],"predecessor-version":[{"id":11378,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11320\/revisions\/11378"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11320"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11320"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11320"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}