Skip to Main content Skip to Navigation
Journal articles

Rapid intensity decrease during the second half of the first millennium BCE in Central Asia and global implications

Abstract : Recent paleomagnetic studies have shown that important short‐lived intensity fluctuations occurred during the first millennium BCE. However, the knowledge of the spatial and temporal extension of these features is still limited by the scarce availability of robust data. In this study we focus on the study of the intensity decrease that took place in Central Asia during the second half of the 1st millennium BCE after the high intensities that characterized the Levantine Iron Age Anomaly. Since previous archeointensities available for this period and region were obtained without accomplishing modern standards of quality, we present here new archeointensities that are derived from classical Thellier and Thellier experiments, including partial thermoremanent magnetization (pTRM) checks, thermoremanent magnetization (TRM) anisotropy and cooling rate corrections at the specimen level. The new 51 archeointensities, together with previous archeointensities, have been used to present a new local paleosecular variation curve for Central Asia. The results confirm the existence of an important geomagnetic field intensity decrease in South Uzbekistan from the 4th century BCE to the end of the 1st century BCE associated with rates of changes up to ‐15 µT/century. A critical analysis of the archeointensity global database indicates that this feature was present at continental scale, from Western Europe to Central Asia. However, this trend is not identified in other regions such as Japan or Mexico. Finally, the comparison with the dipole moment derived from recent global geomagnetic field reconstructions suggests a strong influence of non‐dipolar sources upon this continental intensity feature.
Document type :
Journal articles
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03388201
Contributor : Isabelle Dubigeon Connect in order to contact the contributor
Submitted on : Wednesday, October 20, 2021 - 11:55:16 AM
Last modification on : Tuesday, October 26, 2021 - 3:14:25 PM

File

 Restricted access
To satisfy the distribution rights of the publisher, the document is embargoed until : 2022-04-20

Please log in to resquest access to the document

Identifiers

Collections

Citation

Raquel Bonilla Alba, Myriam Gómez‐paccard, F. Pavón‐carrasco, J. Del Río, E. Beamud, et al.. Rapid intensity decrease during the second half of the first millennium BCE in Central Asia and global implications. Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2021, 126 (10), pp.e2021JB022011. ⟨10.1029/2021jb022011⟩. ⟨insu-03388201⟩

Share

Metrics

Record views

62