Large perturbations of the carbon and sulfur cycle associated with the Late Ordovician mass extinction in south China
Large perturbations of the carbon and sulfur cycle associated with the Late Ordovician mass extinction in south China
Geology (Boulder) (April 2009) 37 (4): 299-302
- anaerobic environment
- ancient ice ages
- Ashgillian
- Asia
- biostratigraphy
- biozones
- C-13/C-12
- carbon
- carbon cycle
- chemostratigraphy
- China
- deep-water environment
- Far East
- geochemical cycle
- geochemistry
- glaciation
- Graptolithina
- Guizhou China
- Hirnantian
- isotope ratios
- isotopes
- lithostratigraphy
- Lower Silurian
- mass extinctions
- Ordovician
- organic carbon
- paleo-oceanography
- paleoclimatology
- paleoecology
- Paleozoic
- pyrite
- S-34/S-32
- sea-level changes
- Silurian
- stable isotopes
- sulfides
- sulfur
- sulfur cycle
- Upper Ordovician
- variations
- southern China
- Tongzi China
- Honghuayuan China
High-resolution delta (super 13) C data of organic carbon from a continuous section of the Late Ordovician-Early Silurian reveal two positive delta (super 13) C excursions that are associated with the mass extinction in South China. The first stratigraphic delta (super 34) S measurements on pyrite tied to well-established biostratigraphy indicate a large perturbation of the sulfur cycle, consistent with major sea-level changes related to the glaciation. The elevated delta (super 34) S values of pyrites and a large, short-lived negative delta (super 34) S excursion of approximately 20 per mil associated with the decay of the glaciation suggest deep-water anoxia during the Hirnantian Stage, in contrast to the conventional view that the global oceans were oxygenated. We suggest that deep-water anoxia may have contributed to the Late Ordovician mass extinction in South China and possibly elsewhere.
