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TitleOn the causes of mass extinctions
AuthorBond, D; Grasby, S E
SourcePalaeogeography, Palaeoclimatology, Palaeoecology vol. 478, 2017 p. 3-29
Alt SeriesEarth Sciences Sector, Contribution Series 20160231
Mediapaper; on-line; digital
File formatpdf
Subjectspaleontology; extinctions, biotic; volcanism; carbon isotopes; acid rain; meteorites; atmospheric geochemistry; paleoclimates; marine ecology; marine environments; Large Igneous Province (LIP); mass extinctions; ocean acidification; toxic metal poisoning; photosynthetic shutdown; anoxia; Phanerozoic; Cambrian; Ordovician; Silurian; Devonian; Permian; Jurassic
Illustrationstables; stratigraphic charts; schematic diagrams; location maps
ProgramWestern Arctic, High Arctic LIP, GEM2: Geo-mapping for Energy and Minerals
AbstractThe temporal link between large igneous province (LIP) eruptions and at least half of themajor extinctions of the Phanerozoic implies that large scale volcanism is the main driver of mass extinction. Here we review almost twenty biotic crises between the early Cambrian and end Cretaceous and explore potential causal mechanisms. Most extinctions are associated with global warming and proximal killers such as marine anoxia (including the Early/Middle Cambrian, the Late Ordovician, the intra-Silurian, intra-Devonian, end-Permian, and Early Jurassic crises). Many, but not all of these are accompanied by large negative carbon isotope excursions, supporting a volcanogenic origin. Most post-Silurian biocrises affected both terrestrial and marine biospheres, suggesting that atmospheric processes were crucial in driving global extinctions. Volcanogenic-atmospheric kill mechanisms include ocean acidification, toxic metal poisoning, acid rain, and ozone damage and consequent increased UV-B radiation, volcanic darkness, cooling and photosynthetic shutdown, each of which has been implicated in numerous events. Intriguingly, some of themost voluminous LIPs such as the oceanic plateaus of the Cretaceous
were emplacedwith minimal faunal losses and so volume of magma is not the only factor governing LIP lethality. Themissing link might be continental configuration because the best examples of the LIP/extinction relationship occurred during the time of Pangaea. Many of the proximal kill mechanisms in LIP/extinction scenarios are also potential effects of bolide impact, including cooling, warming, acidification and ozone destruction. However, the absence of convincing temporal links between impacts and extinctions other than the Chicxulub-Cretaceous example, suggests that impacts are not themain driver of extinctions.With numerous competing extinction scenarios,
and the realisation that some of the purported environmental stresses may once again be driving mass extinction, we explore how experimental biology might inform our understanding of ancient extinctions as well as future crises.
Summary(Plain Language Summary, not published)
Mass extinctions have occurred numerous times through Earth history but the causes of these have remained uncertain. Work in the Canadian Arctic has shed new light on some contributing factors which has led to and overview study of major Earth events that cause mass extinction. I leading driving is massive volcanic eruptions known as Large Igneous Provinces (LIP) events. One such is the High Artic Large Igneous Province (HALIP). How these large eruptions drive mass extinction was studied, including factors such as gas generation (CO2, methane, halogens) by emplacement of volcanic rock into sedimentary basins. The impact that these gases have on global climate and environment are seen as main extinction drivers.