Carbonate sediments can be subdivided into two end-member realms, heterozoan and photozoan, that in many cases relate to “cool water” and “warm water” conditions respectively. Between these end members are “subtropical” carbonates that can include a mix of both realms. In this paper, Bensing et al. describe Lower Permian strata from Arctic Canada that include a temporally changing, sedimentologically mixed assemblage. The sediments suggest a gradual cooling and decrease in seawater temperature, but that changes in sea level and oceanographic conditions complicated trends. The results represented a refinement of criteria for recognizing and interpreting heterozoan carbonates in Paleozoic strata.
Carbonate Deposition During a Time of Mid-Latitude Ocean Cooling: Early Permian Subtropical Sedimentation in the Sverdrup Basin, Arctic Canada by Joel P. Bensing, Noel P. James, and Benoit Beauchamp