Impact crises and mass extinctions: A working hypothesis

The Frasnian–Famennian biotic crisis: How many (if any) bolide impacts?

“…A summary of the ìstate of the artî is given by McLaren (1996) and Rampino and Haggerty (1996). The broad, positive δ 13 C excursion ("heavy carbon event") in the prolonged F-F passage interval (~1 m.y.)…”

“…All the known Late Devonian craters are below 100 km in diameter (see McGhee 1996). According to the impact kill curve of Raup (1992), such cosmogenic stimulation could be responsible for elimination of approximately 30% of species (Jansa 1993; Rampino and Haggerty 1996;Poag 1997). As observed by McGhee (1996), to fit the single catastrophe model a far larger crater diameter is expected for this biotic turnover (of the order of 140 km, 65% kill; Raup 1992), or a multiple-impact scenario appears to be inescapable especially when combined with previousgreat-diversity reduction due to Earth-derived factors.…”

“…The following discussion, in several points guided by new data from the reference Permian-Triassic and Cretaceous-Tertiary mass extinctions, concerns primarily different aspects of the assumed impact evidence. It seems to this author that not only Devonian workers, who have followed the current models of impact-induced turning points, are not always aware of the outlined pitfalls; this is visible in attributes of unified theory of impact crises and mass extinctions by Rampino and Haggerty (1996). Furthermore, as an alternative, several Earth-bound mechanisms are re-examined in the key and conflicting points, with emphasis on poorly constrained F-F tectonism and associated volcanic-hydrothermal phenomena (Racki 1998a).…”

Earth's Impact Events Through Geologic Time: A List of Recommended Ages for Terrestrial Impact Structures and Deposits

“…In addition to seemingly clustered impacts, the recognition of an apparent periodic pattern in the timing of impact events has caused a debate that started in the mid-1980s and still continues today. Following Raup and Sepkoski (1984), who found that mass extinctions in the Phanerozoic seem to have a periodic pattern potentially caused by extraterrestrial forces (such as periodic cometary showers), other researchers also recognized through time-series analysis that large impacts occurred in a similar repetitive pattern of predominantly *26 and *30 Myr intervals over the past *250 Myr and may, therefore, be causally linked (e.g., Alvarez and Muller, 1984;Davis et al, 1984;Rampino and Stothers, 1984;Torbett and Smoluchowski, 1984;Muller, 1985;Rampino and Haggerty, 1996;Rampino andCaldeira, 2015, 2017). However, one should keep in mind that those periodicity models were based on the impact crater ages available in the 1980s and 90s, and since then, other workers have called the proposed periodicity into question (e.g., Grieve et al, 1988;Heisler and Tremaine, 1989;Baksi, 1990;Weissman, 1990;Yabushita, 1996;MacLeod, 1998;Montanari et al, 1998;Bailer-Jones, 2011), some of them noting that the apparent periodicity may, in part, be an artificial effect due to the rounding of imprecise impact ages to integer values, often in multiples of 5 or 10 Ma (e.g., Jetsu and Pelt, 2000;Grieve and Kring, 2007).…”

A Unified Theory of Impact Crises and Mass Extinctions: Quantitative Tests

“…We have also tested the robustness of the ∼27 Myr peak by performing Fourier analyses on a series of truncated extinction time series starting from 0 to 540 Myr, and subtracting one extinction at a time back to 253 Myr. As evidence for the robustness of the ∼27 Myr periodicity in the extinction time series, a stable peak between 26.5 and 27.3 Myr remained the dominant feature in the spectra of the truncated extinction data sets [80].…”