Peculiarities of geomagnetic field behavior near boundary of the mesozoic - cenozoic

TL;DR

This study analyzes paleointensity data from sedimentary rocks spanning 167 to 12 million years, revealing variations linked to geological boundary events and suggesting a connection between Earth's core processes and tectonics.

Contribution

It provides new paleointensity data across the Mesozoic-Cenozoic boundary and links cyclic geomagnetic variations to tectonic transgressive-regressive cycles.

Findings

Paleointensity increased from 167 to 67 Ma.

Maximum paleointensity occurred before the Cretaceous-Paleogene boundary.

Cyclic changes in paleointensity align with T-R cycles.

Abstract

The results of paleointensity determinations of the geomagnetic field, which are obtained by sedimentary rocks in the Middle Jurassic - Neogene (167-12) Ma, are summarized. It was found that in the interval (167-67) Ma (Middle Jurassic - Cretaceous) mean values and amplitudes of paleointensity variations increased. Mean values of paleointensity reached a maximum in front of the Cretaceous-Paleogene boundary. During the Paleogene the mean values and amplitudes of paleointensity variations decreased. In the Cretaceous - the beginning of the Paleogene cyclic changes in the amplitudes of paleointensity variations with characteristic times of several million years have been observed. It is shown that the duration of cycles of the paleointensity changes coincided with transgressive-regressive cycles (T-R cycles). This can be considered as a confirmation of the hypothesis on a relation between processes in the Earth's core and tectonic processes.