Barium isotopes indicate spatiotemporal heterogeneity of marine primary productivity during the toarcian oceanic anoxic event

Journal article

The Toarcian Oceanic Anoxic Event (T-OAE, ~183 Ma) was characterized by globally enhanced 30 organic-carbon burial and a negative carbon-isotope excursion (N-CIE). However, the role of marine productivity at this time, and its spatio-temporal variability, is unclear. We present the first carbonate barium-isotope (δ¹³⁸ Ba_carb) records across the T-OAE from a shallow-water platform (Nianduo, SE Tethys) and a pelagic basin (Dogna, Alpine-Mediterranean Tethys) to reconstruct productivity dynamics. Both sites show positive δ¹³⁸ Ba_carb shifts at the N-CIE onset, indicating supra-regional productivity enhancement. At Nianduo, δ¹³⁸ Ba_carb rises through the onset, consistent with increased export production driven by weathering-derived nutrient inputs. At Dogna, δ¹³⁸ Ba_carb declines within the N-CIE onset due to reduction-driven barite dissolution, followed by a rise during the N-CIE recovery. The Dogna data suggest protracted elevation of pelagic productivity supported by nutrient upwelling and aeolian fertilization. As such, pelagic basins may have acted as an important carbon sink regulating the T-OAE carbon cycle.

Authors: Chen, W; Kemp, DB; Jenkyns, HC; Robinson, SA; Lin, Y

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Geophysical Research Letters
• Volume: 53
• Issue: 10
• Article number: e2026GL121983
• Publication date: 2026-05-20
• Acceptance date: 2026-04-28
• DOI: 10.1029/2026gl121983
• EISSN: 1944-8007
• ISSN: 0094-8276
• Language: English
• Keywords: Toarcian Oceanic Anoxic Event; barium isotopes; primary productivity; pelagic environments