A SULFUR ISOTOPE EVENT AT THE END OF THE PERMIAN

Abstract

A hypothesis of light sulfur injection to the ocean-atmosphere system at the end of the Permian was presented by Kaiho et al. [Kaiho, K., Kajiwara, Y.,Nakano, T., Miura, Y., Kawahata, H., Tazaki, K., Ueshima, M., Chen, Z.Q., Shi, G.R., 2001. End-Permian catastrophe by a bolide impact: evidence of a gigantic release of sulfur from the mantle. Geology 29, 815-818] based on a negative shift of 34S/32S ratio of carbonate-associated sulfate in South China. This hypothesis was discussed in some papers with additional data in other areas. However, the cause and distribution of the negative shift has not been clarified. Here we show that a significant decrease in the 34S/32S ratio of carbonate-associated sulfate occurred simultaneously in South China and Hungary at the end of the Permian, coincident with the end-Permian mass extinction. The cause of the abrupt negative shift of 34S/32S in these two distant sites is the injection of light sulfur to the surface ocean from the deep ocean rich in H2S, or deposits rich in sulfide, or the mantle. This sulfur isotope event was likely caused by either an abrupt warming, a bolide impact to the ocean, mantle plume-induced volcanism, or a harmonizing of these. Possible direct causes are (1) massive release of H2S gas from the euxinic surface and intermediate waters due to abrupt warming by volcanic CO2 or impact shock wave in the ocean, (2) a huge volcanism penetrated sediments or ore rich in sulfide, (3) an extraterrestrial impact to sulfide-rich sediments or ore deposit, and (4) release of mantle origin sulfur by an impact of > 70 km asteroid to the ocean. These are four possible causes for a mass extinction. There is also a possibility of a local oceanic event, only in the Tethys. © 2006 Elsevier B.V. All rights reserved.