Metal induced chitinozoan malformations link the Mid-Ludfordian OAE to the venting of metalliferous hydrothermal basin brines into the Silurian Ocean

De Backer T, Emsbo P, McLaughlin PI, Vancoppenolle I, Klock C, Munnecke A, Vandenbroucke TR (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Global and Planetary Change Elsevier

Book Volume: 259

Article Number: 105303

DOI: 10.1016/j.gloplacha.2026.105303

Abstract

The mechanisms driving Silurian Ocean Anoxic Events (OAEs) and their impact on marine biota remain poorly understood. Previous studies linked chitinozoan (fossil zooplankton) malformations to heavy metal toxicity under expanding reducing oceanic conditions during the onset of some of these events. Importantly, these malformations represent in vivo reactions to changing paleoenvironmental stress and may serve as a sensitive indicator of marine metal loading and the geochemical processes driving Silurian extinction events. In the current study this hypothesis is tested for the prominent Mid- Ludfordian (upper Silurian) OAE. The onset of the event is examined using the thick and well preserved stratigraphic records in outcrop at Bodudd 1 (Gotland, Sweden). A bed-by-bed collection of 101 samples were analyzed for their whole rock geochemistry with chitinozoan malformations quantified in 66 samples. A total of 587.241 specimens were counted with 133 confirmed malformations and 87 potentially malformed, occurring in two intervals that correlate with Mn enrichments. Notably, malformations appear in the lowermost sample in the section, below the carbon isotope excursion, indicating that biotic stress preceded perturbations to the global carbon cycle. In addition to Mn, anomalies in Zn and Pb are present, alongside minor enrichments in Hg, Co, and Sb. The stratigraphic position of metal anomalies corresponds with an extraordinarily rapid rise in marine Sr isotope compositions. The pulsed nature of trace metal enrichments, the distinct elemental suite, and diagnostic spikes in radiogenic 87Sr/86Sr support the emerging model that episodic venting of metalliferous hydrothermal brines was the primary trigger for this and other Silurian OAEs.

Authors with CRIS profile

Axel Munnecke Lehrstuhl für Paläoumwelt

Involved external institutions

Universiteit Gent (UGent) / Ghent University BE Belgium (BE) United States Geological Survey (USGS) US United States (USA) (US) Illinois State Geological Survey ISGS US United States (USA) (US)

How to cite

APA:

De Backer, T., Emsbo, P., McLaughlin, P.I., Vancoppenolle, I., Klock, C., Munnecke, A., & Vandenbroucke, T.R. (2026). Metal induced chitinozoan malformations link the Mid-Ludfordian OAE to the venting of metalliferous hydrothermal basin brines into the Silurian Ocean. Global and Planetary Change, 259. https://doi.org/10.1016/j.gloplacha.2026.105303

MLA:

De Backer, Tim, et al. "Metal induced chitinozoan malformations link the Mid-Ludfordian OAE to the venting of metalliferous hydrothermal basin brines into the Silurian Ocean." Global and Planetary Change 259 (2026).

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