What can cause over half of the life on Earth to die? In this lesson, we'll check out the Ordovician-Silurian mass extinction, and examine the. Abstract. The Late Ordovician mass extinction (LOME), one of the five largest Phanerozoic biodiversity depletions, occurred in two pulses. The Ordovician–Silurian extinction events, when combined, are the second-largest of the five Sahara Desert. A combination of lowering of sea level and glacially driven cooling were likely driving agents for the Ordovician mass extinction.‎Impact · ‎Possible causes · ‎Glaciation · ‎End of the event.


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He believes such an event occurs about once in a billion years. The intense radiation of a gamma ray burst could have depleted about forty percent of the ozone layer, according to Thomas's recent calculations, presented at the Ordovician mass extinction Meeting.

The ozone layer would take about ten years to recover from such a blast, said Thomas.


ordovician mass extinction In ordovician mass extinction Hirnantian Stage the volcanism ceased, and the continued weathering caused a significant and rapid draw down of CO2. Metal poisoning[ edit ] Toxic metals on the ocean floor may have dissolved into the water when the oceans' oxygen was depleted.

An increase in available nutrients in the oceans may have been a factor.

The toxic metals may have killed life forms in lower ordovician mass extinction levels of the food chaincausing a decline in population, and subsequently resulting in starvation for the dependent higher feeding life forms in the chain.

The rebound of life's diversity with the sustained re-flooding of continental shelves at the onset of the Silurian saw increased biodiversity within the surviving ordovician mass extinction.


These species could not survive in colder, deeper oceans and many died out. Many of these were kinds of corals, ordovician mass extinction, and similar marine organisms.

Brachiopod fossils from the Ordovician period Causes In reality, the Ordovician-Silurian extinction was not a single event.

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  • Ordovician-Silurian extinction

It was a combination of multiple extinction ordovician mass extinction that compounded over a relatively short time period into a massive loss of genetic diversity on Earth. We see two main phases in these extinctions, one that happened as global cooling began and one that occurred as sea levels dropped.

Those seem to be the main causes of ordovician mass extinction Ordovician-Silurian extinction, but why did they occur? There have been several attempts to explain this mass extinction throughout the years.

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Here are some of the leading theories. The sample sets analyzed here are the same as those ordovician mass extinction in Jones et al. Carbonate content of whole-rock powders was determined by mass loss following decarbonation with hydrochloric acid.

Carbon content of insoluble residue was measured with a Costech ECS elemental analyzer. At the Monitor Range Fig. While a diastem could produce such enrichment, field evidence ordovician mass extinction a hiatus at this stratigraphic position is lacking Finney et al.

We argue that ordovician mass extinction Hg enrichments observed in both sections are the products of enhanced environmental loading caused by LIP emplacement. The upper Katian ornatus zone anomaly at the Monitor Range Fig.

End-Ordovician Extinction

Our ornatus zone Ordovician mass extinction data provide indirect geochemical evidence for such a late Katian volcanic event, and we suggest that attendant cooling changed climatic boundary conditions Finnegan et al.

Further LIP emplacement broadly synchronous with the Hirnantian glacial maximum is suggested by Hg records at both sections Fig. Volcanic SO2 emission produces sulfur aerosols that can affect climate by increasing planetary albedo upon reaching the stratosphere Robock, As a result, Silurian brachiopods were far more widely distributed than their Ordovician predecessors.

Other groups of organisms—including conodontsacritarchs a catchall group of various small microfossilsbryozoansand trilobites —that showed this pattern of regional, but not global, distribution were similarly affected by this extinction event.

Despite the intensity of the extinction and the loss of many ordovician mass extinction species, Silurian ecosystems were remarkably similar to those in the Ordovician.