A MPG/SGT seminar presentation by Dr. Alberto Malinverno from MPG.
Title:
A Geomagnetic Polarity Time Scale constrained by marine magnetic anomaly records, radioisotopic dates, and astrochronology
Abstract:
The Geomagnetic Polarity Time Scale (GPTS) dates past reversals of the Earth’s magnetic field, forms the framework of the geological time scale, and is crucial to determine rates of plate motion and the timing of events recorded by sedimentation. The first GPTSs were based on the record of magnetic anomalies created by seafloor spreading, calibrated by a few radioisotopic dates. Recently, GPTS construction shifted to astrochronology, where magnetostratigraphy is dated from astronomical cycles recorded in selected sediment sequences. Rather than using a single type of data from a few locations, this work builds a GPTS that fits a variety of data within their uncertainty: 154 magnetic anomaly ship tracks over the global mid-ocean ridge system, 20 radioisotopic dates, and 97 magnetochron durations estimated by astrochronology. The intent is to improve time scale construction from using a single data type to an integration of a wide range of data that have independent errors. The GPTS is obtained by Monte Carlo sampling, which proceeds by perturbing reversal ages while keeping the sampled GPTSs that fit all the data. The variability of the sampled GPTSs gives a measure of the final time scale uncertainty. The Late Cretaceous-Eocene GPTS (~83-33 Ma) obtained here highlights a global change in spreading rates in the 50-45 Ma interval, when India-Eurasia collision slowed spreading in the Indian Ocean; at the same time, spreading rates increased in the South Atlantic and in the Northern Pacific, coinciding with the bend in the Hawaii‐Emperor seamount chain. Open access paper is at https://doi.org/10.1029/2025JB033130
https://columbiauniversity.zoom.us/j/95770053407?pwd=mQPcv4OZWhVBEKxHyrEFzZIiL4BjY2.1
Meeting ID: 957 7005 3407
