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Mass extinctions are times in Earth's past when large proportions of life suddenly and catastrophically died. These have occurred periodically over . The exact causes of these extinctions are not fully understood, but there appears to be a remarkable coincidence .

LIPs are in a . They are much bigger in scale than the famous super eruptions——which typically release less than 5,000 cubic kilometers of magma.

The magma from LIPs can release enough gases during eruption, such as carbon dioxide (a greenhouse gas) or sulfur-based compounds, . This climate change in turn affects the composition of the oceans and quickly leads to .

While huge volcanic eruptions have been linked to mass extinctions on Earth, our research shows that one of the world's largest known LIPs may have had no effect on climate or caused any extinctions. Before our study, the precise age of the LIP was not really known; with our improved dataset and higher precision analysis, we were able to show that these things did not occur at the same time.

Not just eruptions

Research has also suggested that basalt from LIPs, which intrude into the crust, , compounds that vaporize readily. This metamorphism can release huge amounts of gases , which .

Both of these mechanisms have been blamed for causing the climate change which resulted in mass extinctions. However, there are also cases of . The relationship between these huge LIP volcanic eruptions and mass extinctions may not be as clear as previously thought. Disentangling the exact mechanisms involved has been the focus of .

One extremely important factor to consider is the exact age of the LIP relative to the mass extinction. If the ages of the climate change, associated mass extinction and the LIP do not overlap, then the volcanism is not the cause.

Brazilian eruption

To investigate whether one of the world's largest LIPs caused massive climate change and a mass extinction, our research team generated . We dated the mineral zircon that crystallized within the erupted lava flows using the U-Pb system allowing us to precisely determine the eruption age of the lavas. .

Numerous studies had linked this LIP to . The first thing we wanted to know was when did this LIP erupt, and for how long. Once we had this information, we could determine if it occurred at exactly the same time as the mass extinction event.

Our study focused on the Paraná Magmatic Province—the South American portion of the LIP in Brazil—which is by far the largest, and produced approximately one million cubic kilometers of magma.

When this LIP erupted, 140 million years ago, South America and Africa were connected and . This LIP erupted in Brazil and Namibia, when both of these areas were neighbors .

Many studies have suggested that this LIP caused global climate change which led to a small mass extinction and also a reduction in the oxygen concentration in the oceans. This period is called .

No environmental effects

Our research shows that that the Paraná LIP erupted extremely quickly, around one million years after the mass extinction and so it is unlikely to have been the cause. There is one older part of the Paraná LIP that we did not work on which could have caused the Valanginian event. But most LIPs erupt over a , so it is unlikely that the older portion is more than one million years older than the rest of the province.

We also did not work on the . However this part of the province is extremely small in comparison to the South American part, and we expect that it erupted coincidentally with the Paraná, (and therefore may be younger).

Our study of the Paraná LIP proves that the eruption of huge volumes of LIP magma alone may not be enough to cause mass extinctions. The question that remains is why this huge eruption of magma had almost no effect on the climate; our theory is that the lack of volatile-rich sediments around the Paraná LIP meant that no extra volatiles were released due to metamorphism during the positioning, or emplacement, of the LIP. Perhaps the metamorphism of sediments by LIP magmas, and the gas released associated with this, is the main driver of climate change leading to mass extinctions?

Earth's largest mass extinction event occurred at the , . This LIP intruded large volatile rich sedimentary basins which likely caused .

Our findings for the Paraná LIP also depend on the . Currently, the age estimation for this event is based on cyclic analysis of ocean sediments, but it is possible that with greater precision, we may find it overlaps with the Paraná LIP. While huge volcanic eruptions have been linked to mass extinctions on Earth, our research shows that one of the world's largest known LIPs may have had no effect on climate or caused any extinctions. But for now, it seems that the Paraná LIP had almost no environmental effect on our planet.

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