Volcanically driven lacustrine ecosystem changes during the Carnian Pluvial Episode (Late Triassic)

Area of Science:

• Paleoclimatology
• Paleontology
• Geochemistry

Background:

• The Late Triassic Carnian Pluvial Episode (CPE) was marked by increased global humidity and temperature, linked to volcanism.
• This period saw significant terrestrial biological turnover, including dinosaur ascent and conifer evolution.
• A detailed terrestrial record is crucial for understanding CPE cause and effect.

Purpose of the Study:

• To reconstruct the volcanism and environmental changes during the CPE using a lake succession record.
• To establish a high-resolution terrestrial record linking large igneous province (LIP) activity to climate and biological events.
• To investigate the pulsed nature of LIP eruptions and their impact on the global carbon cycle and macroevolution.

Main Methods:

• Multidisciplinary analysis of an expanded Carnian lake succession in the Jiyuan Basin, North China.
• U-Pb zircon dating for precise age constraints.
• High-resolution chemostratigraphy (including C isotopes), palynology, sedimentology, and sedimentary mercury analysis as a proxy for volcanism.

Main Results:

• Terrestrial conditions in the Jiyuan Basin closely tracked large-scale volcanism.
• Four distinct volcanic episodes during the CPE (ca. 234.0–232.4 Ma) were identified using the mercury record.
• Each eruptive phase correlated with negative carbon isotope excursions, increased humidity (hygrophytic plants), lake expansion, and eutrophication.

Conclusions:

• Large igneous province eruptions can occur in discrete pulses, not just a simple decline.
• LIP volcanism significantly altered the global carbon cycle and drove climate change during the Triassic.
• These findings demonstrate the powerful influence of LIPs on macroevolutionary events.