March 29, 2019
Research Highlight
Cooling an Anoxic, Ancient Ocean
A recent study examines the conditions of Earth’s oceans in the early Triassic over the Smithian/Spathian boundary (SSB). The SSB occurred during the roughly five million years that followed the end-Permian mass extinction. During this time, major changes occurred in Earth’s climate, ocean environments, and biology. The SSB represents a period of climate cooling that followed a ‘hyper-greenhouse’ on Earth. The causes that underlie the SSB are unknown.
(A) Early Triassic palaeogeography of South China (modi fi ed from Feng et al., 1997). B) Early Triassic global paleogeography; base map courtesy of R. Blakey (~rcb7/).Image credit: Song and Algeo (2012) DOI: 10.1016/j.gloplacha.2012.10.023.
The recent study provides a review of current knowledge around the mechanisms that could have been responsible for the dramatic changes in Earth’s ocean environments during the SSB. The team also examined rocks from the western edge of the ‘South China Craton’ (e.g. the ancient, Triassic continent that is now part of southeast Asia). The paper outlines theories for how oxygen became depleted in marine environments, both during the Middle Smithian (when hyperwarming was experienced) and the SSB (global cooling).
The study, “Cooling-driven oceanic anoxia across the Smithian/Spathian boundary (mid-early Triassic),” was published in the journal Earth-Science Reviews. The work was supported by NASA Astrobiology through the Exobiology Program.