216 / 2025-04-15 10:28:54

Coral reefs survived the mid-Carboniferous extinction

Coral reef,extinction,refuge,climate cooling,Qaidam Block,Palaeotethys Ocean

Theme 3: Earth-Life Co-evolution Through Time > Session 3e: Mass extinctions and lesser calamities in the marine realm

Under the influence of significant global climate cooling during the mid-Carboniferous, a second-order mass extinction event occurred in the Serpukhovian Stage, associated with ~30% marine genera loss. The mid-Carboniferous extinction was ecologically ranked as the fifth among the Phanerozoic mass extinctions, characterized by the collapse of coral reef ecosystems. To date, coral reefs have rarely been documented during and after the mid-Carboniferous extinction event, resulting in limited understanding of their evolutionary pattern in response to global cooling and biotic crisis during this time. In this study, abundant coral reefs were discovered from the Huaitoutala Formation in the Da Qaidam area, Qinghai Province, northwestern China. In the mid-Carboniferous, the Da Qaidam was located on the northeastern margin of the Qaidam Block, which was situated at low latitudes of northeastern Palaeotethys Ocean. The Da Qaidam reefs exhibit mound-shaped morphology, with outcrops ranging from several meters to tens of meters in width and several meters in height. Based on fusulinid biostratigraphy, the age of the Da Qaidam coral reefs is constrained to the Bashkirian Stage of the Early Pennsylvanian Subperiod. However, systematic palaeontologic studies reveal that the generic and species composition of the reef-building corals represents a typical Mississippian (late Visean to Serpukhovian) coral assemblage. This suggests that the Da Qaidam coral reefs survived the mid-Carboniferous extinction, and the Qaidam Block may have served as a refuge during this time. Through a comparison of the mid-Carboniferous coral composition between the Qaidam and other regions globally, it is suggested that the reef-building corals in Da Qaidam may have migrated from the western Paleotethys. This is consistent with records of ocean-current direction shifts triggered by the collision between the Gondwana and Laurussia continents, as well as intensified ocean-current circulation driven by climate cooling during the mid-Carboniferous.