405,000 year cycle in Earth Eccentricity found in 215 million years of climate
First published: 2020
Brief summary
CRI blog post on geochronology, magnetostratigraphy and the 405-kyr eccentricity cycle.
Article
One of the four main Milankovitch cycles is a 405,000 year fluctuation in the Earth’s orbital eccentricity. This means that the Earth’s orbit gets more and less circular over that period, affecting the extremes of climate. The variation is due to the effects of Jupiter and Venus which are the two planets with the greatest tidal effect.
“The Newark–Hartford astrochronostratigraphic polarity timescale (APTS) was developed using a theoretically constant 405-kiloyear eccentricity cycle linked to gravitational interactions with Jupiter–Venus as a tuning target and provides a major timing calibration for about 30 million years of Late Triassic and earliest Jurassic time.
While the 405-ky cycle is both unimodal and the most metronomic of the major orbital cycles thought to pace Earth’s climate in numerical solutions, there has been little empirical confirmation of that behavior, especially back before the limits of orbital solutions at about 50 million years before present.
To test the validity of the dangling APTS and orbital periodicities, we recovered a diagnostic magnetic polarity sequence in the volcaniclastic-bearing Chinle Formation in a scientific drill core from Petrified Forest National Park (Arizona) that provides an unambiguous correlation to the APTS.
Additional summary
The article continues with quoted material from the PNAS source and discussion of the cycle’s use in geological timescale calibration.
Source details and credits
- Source / publisher: CRI Blog / Ray Tomes
- Source type: Blog post
- URL type: WWW
- Credits: CRI Blog / Ray Tomes
- URL: https://cyclesresearchinstitute.wordpress.com/2020/04/03/405000-year-cycle-in-earth-eccentricity-found-in-215-million-years-of-climate/