The Quaternary System: precision and reliability in global correlation
The Quaternary System, beginning 2.58 million years ago, provides unequalled access to marine and terrestrial sediments and ice-core archives, and offers unique opportunities for testing chronostratigraphic utility. Marine isotope stages form the backbone of Quaternary stratigraphy. Along with their substages, they are often treated as if strictly synchronous, but small leads and lags between different marine basins should be expected and will hinder precise temporal correlation. Most marine isotope stages for the past one million years have been divided into substages. While these substages potentially increase stratigraphic precision, they not always recognized reliably or at global extent. Paleomagnetic reversals represent critical datums in Quaternary chronostratigraphy: the Gauss-Matuyama and Matuyama-Brunhes boundaries, for example, are important guides respectively for the base of the Quaternary and Early-Middle Pleistocene boundary; and the Blake Event should prove useful within the Upper Pleistocene. However, lock-in depth and remagnetization can lower reliability, and the duration of polarity reversals and even their precise timing are questioned. Mediterranean sapropels, loess-paleosol sequences, ice cores, speleothem archives, micropaleontological records, and radiometric dating all have inherent limitations for fine-scale global correlation. With the increasing need to distinguish cause from effect in Quaternary processes, this symposium aims to explore precision and reliability in global correlation.