Strategy of a Geological Orrery
Paul E. Olsen,
Lamont-Doherty Earth Observatory of Columbia University,USA.,
Web Lecture on April 22, 2021 at 3:00 PM (Paris Time)
The Geological Orrery is a network of long geological records of orbitally paced climate and complementary geochronologically-focused coring projects designed to address the inherent limitations of solutions for planetary orbits beyond the 60 million year horizon of reliability imposed by the chaotic nature of Solar System motion (1). “The Geological Orrery,” is named after the mechanical planetaria—Orreries—of the 18th century from the fourth Earl of Orrery, Charles Boyle, and the “Digital Orrery,” a dedicated 1980s parallel-processing computer that was constructed to investigate the long-term motion of the Solar System. I will illustrate the strategy of The Geological Orrery by describing three scientific coring experiments, two completed, and one proposed, as well as how these endeavors are integrated with other ongoing projects. These projects are as follows. 1) The Newark Basin Coring Project (NBCP: cored 1990-1994), designed to core a high-sedimentation rate lake sequence in a tropical rift basin that was known at the time to have a pervasive pattern of lake level cycles reflecting orbital variations. A major outcome was a demonstration of 25 million years of orbital pacing of climate through 6700 m of core and the first empirical determination of the secular fundamental frequencies of the precession of perihelion of the inner planets that proved substantially different than today’s values (2). 2) The Colorado Plateau Coring Project (CPCP-1: cored 2013), was designed to recover a continuous Triassic paleomagnetic polarity sequence with numerous datable ash-rich levels (3). The main result was an independent, zircon U-Pb anchored timescale that can be accurately and precisely correlated to the NBCP cores (4, 5), testing and refining the Triassic Solar System parameters showing that the rather dramatic differences between NBCP-derived values and the present -day values are real and accurate (6). 3) The proposed Colorado Plateau Coring Project phase 2 (CPCP-2: 202x), which seeks to extend the globally exportable U-Pb-calibrated magnetic polarity record through the rest of the Late Triassic and all of the Early Jurassic, again on the Colorado Plateau and its environs. This project will test not only the Jurassic age part of NBCP sequence but also the spectacular cyclical marine records of the JET project for the legacy Mochras and the new Prees cores (cored December 2020) in the UK marine Early Jurassic (7). With completion of CPCP-2 and analysis of the Mochras and Prees records, the Geological Orrery will have provided an empirical, well-tested and accurate map of inner planet solar system evolution spanning nearly 60 million years that can serve as an entirely new empirical basis for exploring solar system evolution, astronomical solutions, and gravitational models, as well as a proof of concept for extending the Orrery approach to both more recent and far more ancient times.
1. J. Laskar, Chaotic diffusion in the Solar System. Icarus 196, 1-15 (2008).
2. P. E. Olsen, D. V. Kent, Long-period Milankovitch cycles from the Late Triassic and Early Jurassic of eastern North America and their implications for the calibration of the early Mesozoic time scale and the long-term behavior of the planets. Philosophical Transactions of the Royal Society of London A 357, 1761-1787 (1999).
3. P. E. Olsen et al., Colorado Plateau Coring Project, Phase I (CPCP-I): A continuously cored, globally exportable chronology of Triassic continental environmental change from Western North America. Scientific Drilling 24, 15-40 (2018).
4. C. Rasmussen et al., U-Pb zircon geochronology and depositional age models for the Upper Triassic Chinle Formation (Petrified Forest National Park, Arizona, USA): Implications for Late Triassic paleoecological and paleoenvironmental change. Geological Society of America Bullentin https://doi.org/10.1130/B35485.1, (2020).
5. D. V. Kent et al., Magnetochronology of the entire Chinle Formation (Norian age) in a scientific drill core from Petrified Forest National Park (Arizona, USA) and implications for regional and global correlations in the Late Triassic. Geochemistry, Geophysics, Geosystems. 20. https://doi.org/10.1029/2019GC008474, (2019).
6. P. E. Olsen et al., Mapping Solar System chaos with the Geological Orrery. Proceedings of the National Academy of Sciences 116, 10664–10673 (2019).
7. S. P. Hesselbo et al., JET: Integrated understanding of the early Jurassic Earth system and Timescale. 2021, https://www.icdp-online.org/projects/world/europe/prees-england/ (2021).