Severe environmental disasters led to major extinction events during the Jurassic 178-186 million years (myr) ago. The disturbance was said to be due to the release of volcanic gases, but the link between the volcano and its eruption has been disputed.
“Our results provide strong support for the idea that episodic magmatism in the Karoo region is related to the faults of Jurassic environments and natural disasters,” said Arto Luttinen from the Finnish Museum of Natural History, lead author of the article published in. Search for Gondwana.
“The period before the volcano in the Karoo region was shown to be a short period of 182-183 myr production. Although these years combined with the greatest destruction of the Jurassic, it is not possible it explains the new natural disasters that began millions of years ago and continued long afterwards. ”said Luttinen, explaining that the symptoms of the length and duration of the volcano were considered unreliable due to methodological problems.
The Uranium-lead route should open up to historical events
Recent measurements were measured at the Nordsim Laboratory in Stockholm using a technique called uranium-lead on sub-millimeter-sized zircon crystals in volcanic rocks. The production of lead from the radioactive decay of uranium provides the most reliable chronometer for recording ancient earth processes.
At the Nordsim Laboratory, the studied crystals were coated with a narrow beam of ionized particles and the age of the small zircons was determined by large spectroscopic measurements of uranium and lead levels.
“This method allows us to capture individual crystals based on different evolutionary features of long -term magma systems,” explains Matti Kurhila, Geological Survey of Finland, and Martin Whitehouse, Swedish Museum of Natural. History.
Examination of samples collected over a 1000 km long magmatic zone in Mozambique shows a height of 182-183 myr activity that took place before the 185-190 myr volcano erupted. past, and was followed by a large magmatic phase 178-181 myr ago, and a decline in activity over the past millions of years.
“These results will pave the way for further research on age -related and magmatic degassing in order to better understand the coincidence between the Karoo volcano and global biosphere problems,” he said. Luttinen concluded.
The first accurate evidence of a basic mantle plume of Jurassic flood basalts in southern Africa
Arto Luttinen et al, The length of the Karoo rift zone magmatism observed from the zircon ages of silicic rocks: Consequences for the cause and effect of the environment of large igneous land, Search for Gondwana (2022). DOI: 10.1016 / j.gr.2022.03.005
Presented by the University of Helsinki
Directions: Volcanoes may have started several times Jurassic extinctions (2022, March 31) captured on March 31, 2022 from https://phys.org/news/2022-03-periodic-volcanism-triggered -multiple-jurassic.html
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