Applications of the Sedimentary Record of Astronomically-Driven Paleoclimate Oscillations and Trends

Linda A. Hinnov¹ and James Ogg^2
1Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD
²Department of Atmospheric and Earth Sciences, Purdue University, West Lafayette, IN

Paleoclimate research has led to the realization that quasi-periodic oscillations in the Earth’s orbit and axial tilt have been a major driving factor in past climate variations. In addition to their role in governing the Quaternary glacial episodes, these astronomical-forced oscillations have left their record in variations of surface climate and weathering, ocean circulation and productivity, and other features captured in the sedimentary record. Resolving this sedimentary ‘metronome’ from outcrops and cores has enabled a revolution in Earth system science. Global marine sequences, ocean anoxic events, and even biotic extinctions are connected with long-period astronomical modulations. Precise prediction of the superimposed fine-scale oscillations into the distant past is the basis for high-resolution calibration of the Cenozoic timescale, and is rapidly becoming the foundation for Mesozoic-Paleozoic scaling. With a 0.02-0.4 myr resolving power, the ‘astronomical timescale’ offers orders of magnitude improvement over previous geologic timescale estimates and significantly broadens the issues that can be addressed in Earth systems research. For example, paleoclimatologists now know the rate of increase in warming and pCO₂ associated with the Paleocene/Eocene Thermal Maximum, thereby constraining causation mechanisms and feedbacks. Cyclic stratigraphy enables precise scaling of Oxfordian-Kimmeridgian and Aptian-Albian biozones, hence calculation of formation rates of associated source rocks for the majority of the world's oil and gas. In modern climate change research, past climates that experienced astronomical forcing similar to the present are being investigated as potential predictors of future climate. These and other developments testify to the impressive transformative power of the astronomical paleoclimate record in the modern study of the Earth system.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas