World correlations of New Zealand Permian stages

Abstract

New Zealand Permian stages are discussed. Two horizons are recognised below the lowest formally named stage, and the Braxtonian Stage is subdivided into the Barrettian and Flettian substages. Recent advances in the Permian geology of Siberia, and work by the writer on huge collections from the Canadian Arctic, reveal that the pattern of stages proposed for New Zealand also holds true for the Arctic realm. A visit to Tasmania confirmed that the stages can also be recognised there, including a very high Permian fauna in the upper Ferntree beds, equivalent to the New Zealand Waiitian Stage. The persistence over much of the world of brachiopod and bivalve horizons suggests that more stress should be given to these groups in attempting world correlations for the Permian, and therefore correlations for New Zealand stages are adjusted accordingly, bringing the stages into harmony with some fusuline and ammonoid evidence, but conflicting with the views of some workers on fusulinids and ammonoids. Most of the divergence in opinion concerns the relative position of the Kazanian and the Cyclolobus ammonoid zone. The Kazanian is here considered to be relatively low in the New Zealand Permian, and to be followed by three stages, not two as considered by Chao (1965), or one as considered by most ammonoid workers. Cyclolobus is also considered to come low in the upper Permian, and to be followed by two world-wide stages, instead of lying at the top of the Permian. The paleogeographic significance of New Zealand's similarity to Arctic realms is noted, with the suggestion that support is thereby added for continental displacement.