Sam Bowring (front) and former graduate student Seth Burgess inspecting the End-Permian extinction horizon at Penglaitan. Credit: Shuzhong Shen
Phys.org has a story about new research into the Permian Mass Extinction. The research was detailed in a paper in the GSA Bulletin. The study was a collaboration between scientists at MIT, the Chinese Academy of Sciences, the National Museum of Natural History, and the University of Calgary.
For over two decades, scientists have tried to pin down the timing and duration of the end-Permian mass extinction to gain insights into its possible causes. Most attention has been devoted to well-preserved layers of fossil-rich rocks in eastern China, in a place known to geologists as the Meishan section. Scientists have determined that this section of sedimentary rocks was deposited in an ancient ocean basin, just before and slightly after the end-Permian extinction. As such, the Meishan section is thought to preserve signs of how Earth's life and climate fared leading up to the calamitous event.
"However, the Meishan section was deposited in a deep water setting and is highly condensed," says Shuzhong Shen of the Nanjing Institute of Geology and Palaeontology in China, who led the study. "The rock record may be incomplete." The whole extinction interval at Meishan comprises just 30 centimeters of ancient sedimentary layers, and he says it's likely that there were periods in this particular ocean setting when sediments did not settle, creating "depositional gaps" during which any evidence of life or environmental conditions may not have been recorded.
In 1994, Shen took Bowring, along with paleobiologist Doug Erwin, now curator of paleozoic invertebrates at the National Museum of Natural History and a co-author of the paper, looking for a more complete extinction record in Penglaitan, a much less-studied section of rock in southern China's Guangxi province. The Penglaitan section is what geologists consider "highly expanded." Compared with Meishan's 30 centimeters of sediments, Penglaitan's sedimentary layers make up a much more expanded 27 meters that were deposited over the same period of time, just before the main extinction event occurred.
