ABSTRACT

The Quaternary characterized by two climatic signatures: that of the last 800,000 years, the Upper Pleistocene Climatic Signature (UPCS), and that of the period from 900,000 to 1,800,000 years ago, the Middle Pleistocene Climatic Signature (MPCS). Glacial cycles within the UPCS are 100,000 years long containing interglacials of 10,000-12,000 years duration and a "full" glacial period of 20,000-30,000 years. Cycles of the MPCS range from 20,000-40,000 years duration. Analysis of Miocene-aged Deep Sea Drilling Project cores reveal eight widespread hiatuses. These hiatuses correspond to intervals of cooling as indicated by fauna and flora, ¹⁸0 anomalies and low sea-levels. The Miocene hiatuses may result from decreased polar temperatures and concomitant increased bottom water circulation and corrosiveness. Durations represented by both hiatuses and preserved sediments are approximately one to two million years long. The inferred Miocene glacial epochs are of the same duration as the glacial epochs of the Plio-Pleistocene. Oligocene-aged hiatuses are found in all the world's oceans, indicative of cold bottom-following waters. Evidence (hiatuses, ice rafted material) has demonstrated Eocene continental glaciers in Antarctica. Interaction between the three planetary orbital parameters of eccentricity, tilt, and precession apparently control much of long-term climate change with the dominance of eccentricity dictating glacial cycles. Continuity of climate pattern for the Tertiary is indicated, given the constancy of planetary motion. Gulf Coast hydrocarbon reservoirs of Miocene, Frio, and Wilcox age should be reviewed in terms of a more subtle climatic model to refine interpretation of known depositional sequences.