Huge volcanic eruptions 230 million years ago changed Earth’s climate, paving the way for the rise of the dinosaurs, a new study suggests.
The Late Triassic Carnian Pluvial Episode (CPE) saw an increase in global temperature and humidity that matches up to the impact of huge volcanic eruptions, the researchers believe.
Before the CPE, the supercontinent Pangea was dry and hostile to life – but the volcanoes sparked a period where life (including the dinosaurs) could flourish, driven by climate change.
Co-author Jason Hilton, professor of palaeobotany and palaeoenvironments at the University of Birmingham, said: "Within the space of 2 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.
“These events coincide with a remarkable interval of intense rainfall known as the Carnian Pluvial Episode.
"Our research shows, in a detailed record from a lake in North China, that this period can actually be resolved into four distinct events, each one driven by discrete pulses of powerful volcanic activity associated with enormous releases of carbon dioxide into the atmosphere. These triggered an increase in global temperature and humidity."
The period also coincided with the establishment of modern conifers.
Researchers analysed sediment and fossil plant records from a lake in northern China's Jiyuan Basin, matching pulses of volcanic activity with significant environmental changes, including the CPE's "mega monsoon" climate, some 234 million to 232 million years ago.
The most likely source of the volcanic eruptions is the Wrangellia Large Igneous Province, the remnants of which are preserved in western North America.
Hilton said: "In addition to 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 and animal and plant life – including ferns, crocodiles, turtles, insects and the first mammals."
Each phase of volcanic eruption coincided with changes in the global carbon cycle and major climatic changes to more humid conditions, as well the lake's deepening with a corresponding decrease in oxygen and animal life.
Co-author Dr Sarah Greene, senior lecturer at the University of Birmingham, said: "Our results show that large volcanic eruptions can occur in multiple, discrete pulses – demonstrating their powerful ability to alter the global carbon cycle, cause climate and hydrological disruption and drive evolutionary processes.”
The research team investigated terrestrial sediments from the ZJ-1 borehole in the Jiyuan Basin of north China.
They used uranium-lead zircon dating, high-resolution chemostratigraphy, palynological and sedimentological data to correlate conditions in the region with volcanic activity in North America.
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