QUATERNARY FOURIER STRATIGRAPHY - ORBITAL TEMPLATES AND MILANKOVITCH ANOMALIES

A simple template-generating algorithm using summer insolation at 65-degrees-N as input provides a time-series for the last 2 million years that can be compared directly with the oxygen isotope record in deep-sea sediments. Discrepancies between template and record are diminished by representing both series as Fourier expansions, and importing the power spectrum of the record to the template, without changing phase. The remaining differences between the hybrid template and the record contain messages about time spans of unusual behavior of the system. The most striking anomalies in the Quaternary are the unusually cold period following the mid-Pleistocene climate shift at 900 ka (Stage 22) and much of Stage 11 near 400 ka, representing excess warming. The present interglacial also is too warm, compared with expectations. Anomalies are thought to be the result of stabilization of unusually cold periods (by albedo feedback) and unusually warm periods (by carbon dioxide feedback). It is proposed that there is a connection between surplus ice buildup (after the mid-Pleistocene climate shift at 900 ka) on marine shelves and subsequent extra-large transgressions, which stabilize warm periods by shallow-water carbonate production (coral reef hypothesis).