Life on earth has a long, but also extremely turbulent history. On more than one occasion, the majority of all species became extinct and an already highly developed biodiversity shrank to a minimum again, whereby the course of evolution changed each time. The most extensive mass extinction occurred around 252 million years ago. It was the end of the Permian Era and the beginning of the Triassic Era. About three quarters of all land life and about 95 percent of life in the ocean disappeared within a few thousand years.
Gigantic volcanic activity in what is now Siberia and the release of large amounts of methane from the sea floor have long been discussed as possible triggers for the extinction of the Permian Triassic. However, the exact cause and sequence of events that led to the mass extinctions remained highly controversial. Now scientists from Germany, Italy and Canada as part of the EU-funded BASE-LiNE Earth project under the direction of Prof. Dr. Anton Eisenhauer from GEOMAR Helmholtz Center for Marine Research Kiel in cooperation with the Helmholtz Center Potsdam GFZ German Research Center For the geosciences it was possible for the first time to finally reconstruct the entire cascade of events with the help of the most modern analysis techniques and innovative geochemical modeling. The study was published today in the international journal Natural geosciences.
For their study, the BASE-LiNE Earth team used a previously often neglected environmental archive: the shells of fossil brachiopods. “These are shell-like organisms that have existed on Earth for more than 500 million years. We were able to use well-preserved brachiopod fossils from the Southern Alps for our analyzes. These mussels were deposited at the bottom of the shallow shelf seas of the Tethys Ocean 252 million years ago and recorded environmental conditions just before and at the start of extinction, “explains Dr. Hana Jurikova. She is the first author of the study that she carried out as part of the BASE-LiNE Earth project and her doctoral thesis at GEOMAR.
By measuring different isotopes of the element boron in the fossil shells, the team was able to follow the evolution of the pH values in the ocean 252 million years ago. Because the pH of the seawater is closely linked to the CO2 Concentration in the atmosphere, the reconstruction of which was also possible. For the analyzes, the team used high-precision isotope analyzes at GEOMAR as well as high-resolution micro-analyzes with the state-of-the-art secondary ion mass spectrometer (SIMS) with large geometry at the GFZ.
“With this technology, we can not only reconstruct the development of atmospheric CO2 Concentrations, but also clearly attributable to volcanic activity. The dissolution of methane hydrates, which was suggested as a possible further cause, is highly unlikely based on our data, “explains Dr. Marcus Gutjahr from GEOMAR, co-author of the study.
As a next step, the team fed its data from the investigations based on boron and additional carbon isotopes into a computer-aided geochemical model that simulated the earth processes at that time. The results showed that ocean warming and acidification are linked to the immense volcanic CO2 Injection into the atmosphere was already fatal and led to the extinction of marine calcification organisms right at the beginning of extinction. The CO2 Release also had other consequences; With the increased global temperatures caused by the greenhouse effect, chemical weathering on land also increased.
Over thousands of years, more and more nutrients found their way into the oceans via rivers and coasts, which were then overfertilized. The result was a large-scale lack of oxygen and the change in entire elementary cycles. “This domino-like collapse of the interconnected life-sustaining cycles and processes ultimately led to the catastrophic extent of the mass extinction observed at the border between Permian and Triassic,” summarizes Dr. Jurikova together.
The study was carried out as part of the EU-funded ITN project BASE-LiNE Earth, in which the use of brachiopods as an environmental archive was systematically investigated for the first time and relevant analysis methods were improved and newly developed. “Without these new technologies, it would be difficult to reconstruct environmental processes more than 250 million years ago as detailed as they are now,” emphasizes Prof. Dr. Anton Eisenhauer from GEOMAR, the former project coordinator of BASE-LiNE Earth and co-author of the new study: “In addition, the new methods can be used for other scientific applications.”
New insights into the great dying
More information:
Hana Jurikova et al., Permian Triassic Mass Annihilation Pulses Driven by Major Ocean Carbon Disruptions, Natural geosciences (2020). DOI: 10.1038 / s41561-020-00646-4
Provided by the Helmholtz Association of German Research Centers
Quote: Drivers of the largest mass extinction in the history of the earth identified (2020, October 19), accessed on October 19, 2020 from https://phys.org/news/2020-10-driver-largest-mass-extinction-history. html
This document is subject to copyright. Except for fair trade for the purpose of private study or research, no part may be reproduced without written permission. The content is provided for informational purposes only.
These were the details of the news Identified drivers of the largest mass extinction in Earth history for this day. We hope that we have succeeded by giving you the full details and information. To follow all our news, you can subscribe to the alerts system or to one of our different systems to provide you with all that is new.
It is also worth noting that the original news has been published and is available at de24.news and the editorial team at AlKhaleej Today has confirmed it and it has been modified, and it may have been completely transferred or quoted from it and you can read and follow this news from its main source.
