A rise in global temperature and humidity occurred during the Late Triassic Carnian Pluvial Episode (CPE), which had a significant influence on the evolution of animal and plant life and coincided with the emergence of contemporary conifers.
Researchers studied sediment and fossil plant records from a lake in northern China’s Jiyuan Basin, tying volcanic activity pulses to important climatic shifts like as the CPE’s “mega monsoon” climate, which occurred between 234 million and 232 million years ago.
The international research team, which included experts from the University of Birmingham, published their findings today in the Proceedings of the National Academy of Sciences (PNAS), revealing four distinct episodes of volcanic activity during this time period, with the most likely source being major volcanic eruptions from the Wrangellia Large Igneous Province, whose remnants can still be seen in western Australia.
“Within the space of two million years, the world’s animal and plant life underwent major changes, including selective extinctions in the marine realm and diversification of plant and animal groups on land,” said co-author Jason Hilton, Professor of Palaeobotany and Palaeoenvironments at the University of Birmingham’s School of Geography, Earth and Environmental Sciences. These occurrences occur during the Carnian Pluvial Episode, a period of unusually heavy rainfall.
“Our research reveals that this era may really be resolved into four separate episodes, each driven by discrete pulses of strong volcanic activity accompanied with large carbon dioxide emissions into the atmosphere, as evidenced by a precise record from a lake in North China. A rise in global temperature and humidity resulted as a result of these events.”
The researchers discovered that each phase of volcanic eruption was accompanied by significant disruptions to the global carbon cycle, significant climatic shifts to more humid circumstances, and the lake’s depth, which resulted in a reduction in oxygen and animal life.
Increased rainfall led in extensive extension of drainage basins converging into lakes or swamps, rather than rivers or seas, according to geological occurrences in Central Europe, East Greenland, Morocco, North America, and Argentina, among other places.
“Our findings show that large volcanic eruptions can occur in multiple, discrete pulses, demonstrating their potent ability to disrupt the global carbon cycle, cause climate and hydrological disruption, and drive evolutionary processes,” said co-author Dr Sarah Greene, Senior Lecturer in the University of Birmingham’s School of Geography, Earth and Environmental Sciences.
Dr. Emma Dunne, a Paleobiologist from the University of Birmingham who was not engaged in the research, had this to say about it:
“For terrestrial animals, this relatively long period of volcanic activity and environmental upheaval would have had significant implications. The dinosaurs had just recently begun to diversify at this time, and it’s likely that they would never have achieved the ecological domination that they did over the following 150 million years if not for this event.”
“Aside from dinosaurs, this remarkable period in Earth history was also important for the rise of modern conifer groups and had a major impact on the evolution of terrestrial ecosystems, animal and plant life — including ferns, crocodiles, turtles, insects, and the first mammals,” Professor Hilton added.
The researchers looked at terrestrial sediments from the ZJ-1 borehole in North China’s Jiyuan Basin. They correlated terrestrial conditions in the region with simultaneous large-scale volcanic activity in North America using uranium-lead zircon dating, high-resolution chemostratigraphy, palynological, and sedimentological data.