[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: [dinosaur] Palacrodon from Arizona + from tracks from Korea + K-Pg seafloor eruptions + more
> John P Staub (2018)
> Paleozoic geomagnetism shapes vertebrate evolution.
> PeerJ Preprints 6:e26490v1
> Background. Despite a fifty-year failure of paleontologists to find a viable
> connection between geomagnetic polarity reversals and evolutionary patterns,
> recent databases show that the early appearance, radiation, and
> diversification of Paleozoic vertebrates tend to occur during periods having
> frequent collapses of the Earthâs geomagnetic field. The transition time
> during the collapse of the Earthâs protective magnetic shield can last
> thousands of years, and the effects on biota are unknown. Solar and cosmic
> radiation, volcanism, weather alteration, low-frequency electromagnetic
> fields, depletion of ozone, and the stripping of atmospheric oxygen have been
> proposed as possible causes, but previous studies have found no effects.
It has been proposed that the multipolar geomagnetic field during a polarity
reversal induces a magnetic field in the ionosphere which takes over the
protective function. I'll have to read the preprint; the rest of the abstract
promises several puzzling results.
> Joseph S. Byrnes & Leif Karlstrom (2018)
> Anomalous K-Pgâaged seafloor attributed to impact-induced mid-ocean ridge
> Science AdvancesÂ 4(2): eaao2994
> Eruptive phenomena at all scales, from hydrothermal geysers to flood basalts,
> can potentially be initiated or modulated by external mechanical
> perturbations. We present evidence for the triggering of magmatism on a
> global scale by the Chicxulub meteorite impact at the Cretaceous-Paleogene
> (K-Pg) boundary, recorded by transiently increased crustal production at
> mid-ocean ridges. Concentrated positive free-air gravity and coincident
> seafloor topographic anomalies, associated with seafloor created at
> fast-spreading rates, suggest volumes of excess magmatism in the range of
> ~105 to 106 km3.
10^5 to 10^6 of course, in case anyone is wondering.