John Marshall

Cecil and Ida Green Professor of Oceanography, MIT

Reply to comment by Roberta M. Hotinski, Lee R. Kump, and Karen L. Bice on “Could the Late Permian deep ocean have been anoxic?”

Reply to comment by Roberta M. Hotinski, Lee R. Kump, and Karen L. Bice on “Could the Late Permian deep ocean have been anoxic?”.

(Zhang, R and Follows, MJ and Marshall, J), PALEOCEANOGRAPHY, vol. 18, no. 4, 2003.

Abstract

Two recent studies [Hotinski et al., 2001; Zhang et al., 2001] have modeled and discussed Late Permian ocean circulation and oxygenation. These studies have reached significantly different conclusions. Zhang et al. [2001] find that a ‘‘thermal mode’’ ocean circulation driven by cooling in polar latitudes is unlikely to support deep-sea anoxia, but a ‘‘haline mode’’ ocean circulation, a shallow overturning cell driven by enhanced evaporation from the subtropics, perhaps could lead to global-scale deep-sea anoxia. Hotinski et al. [2001], using a different model, find that a ‘‘thermal mode’’ ocean circulation with a high equator-to-pole gradient gives well-oxygenated Permian deep water, while a ‘‘thermal mode’’ ocean circulation with a very low equator-to-pole gradient leads to global deep-sea anoxia. This discrepancy prompted a comment by Hotinski et al. [2002].

doi = 10.1029/2002PA000851