Low volcanic temperature ushered in global cooling and the thriving of dinosaurs

Date:
January 31, 2022
Source:
Tohoku University
Summary:
Dinosaurs came to flourish during the Jurassic period after a
volcanic eruption roughly 201 millions years ago wiped out many
marine and land animals, leaving them able to evolve and grow. Now,
further details about this eruption and the mass extinction
have been revealed. A group of researchers demonstrated how low
temperature magma slowly heated sedimentary rocks, causing high
sulfur dioxide and low carbon dioxide emissions, a process which
cooled the earth.



FULL STORY ========================================================================== Researchers in Japan, Sweden, and the US have unearthed evidence that
low volcanic temperatures led to the fourth mass extinction, enabling
dinosaurs to flourish during the Jurassic period.


========================================================================== Large volcanic eruptions create climatic fluctuations, ushering in
evolutionary changes. Yet it is the volcanic temperature of the eruption
that determines whether the climate cools or warms.

Since the emergence of early animals, five mass extinctions have taken
place.

The fourth mass extinction occurred at the end of the Triassic Period -
- roughly 201 million years ago. This mass extinction saw many marine
and land animals go extinct, especially large-body, crocodilian-line
reptiles known as pseudosuchia. Approximately 60-70% of animal species disappeared. As a result, small bodied dinosaurs were able to grow
and prosper.

Scientists think the fourth mass extinction was triggered by the eruptions
in the Central Atlantic Magmatic Province -- one of the largest regions
of volcanic rock. But the correlation between the eruption and mass
extinction has not yet been clarified.

Using analysis of sedimentary organic molecules and a heating experiment, current professor emeritus at Tohoku University, Kunio Kaiho and his team demonstrated how low temperature magma slowly heated sedimentary rocks,
causing high sulfur dioxide (SO2) and low carbon dioxide emissions (CO2).

The SO2 gas was distributed throughout the stratosphere, converting to
sulfuric acid aerosols. The instantaneous increase of global albedo caused short-term cooling, which could have contributed to the mass extinction.

Kaiho and his team took marine sedimentary rock samples from Austria
and the United Kingdom and analyzed the organic molecules and mercury
(Hg) in them.

They found four discrete benzo[e]pyrene + benzo[ghi]perylene + coronene
-Hg enrichments.

The discovery of low coronene in the first enrichment was particularly revealing. The second, third, and fifth mass extinction had high coronene concentrations. A low concentration indicates that low temperature
heating caused high SO2 release and global cooling.

"We believe the extinction was the product of large volcanic eruptions
because the benzo[e]pyrene + benzo[ghi]perylene + coronene anomaly could
only be seen around the time frame of the mass extinctions," said Kaiho.

Kaiho's team is now studying other mass extinctions with the hopes of
further understanding the cause and processes behind them.

========================================================================== Story Source: Materials provided by Tohoku_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Kunio Kaiho, Daisuke Tanaka, Sylvain Richoz, David S. Jones, Ryosuke
Saito, Daichi Kameyama, Masayuki Ikeda, Satoshi Takahashi, Md.

Aftabuzzaman, Megumu Fujibayashi. Volcanic temperature changes
modulated volatile release and climate fluctuations at the
end-Triassic mass extinction. Earth and Planetary Science Letters,
2022; 579: 117364 DOI: 10.1016/j.epsl.2021.117364 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220131110505.htm

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