High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician

Abstract We investigated the paleogeography of Baltica via a paleomagnetic study of 471‐454 Ma limestones from the Siljan (Sweden) impact structure. Stepwise thermal demagnetization isolated a well‐defined magnetization component that unblocks up to the Curie temperature of magnetite and passes fold...

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Main Authors: Nastaran Ahanin, Stuart A. Gilder
Format: Article
Language:English
Published: Wiley 2025-04-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2024GL114204
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author Nastaran Ahanin
Stuart A. Gilder
author_facet Nastaran Ahanin
Stuart A. Gilder
author_sort Nastaran Ahanin
collection DOAJ
description Abstract We investigated the paleogeography of Baltica via a paleomagnetic study of 471‐454 Ma limestones from the Siljan (Sweden) impact structure. Stepwise thermal demagnetization isolated a well‐defined magnetization component that unblocks up to the Curie temperature of magnetite and passes fold and reversal tests, indicative of a primary magnetization. Paleolatitude data show that Baltica experienced an initial stationary phase at approximately 55°S from 471 to 467 Ma, followed by a rapid northward drift (∼35 cm/yr) after 467 Ma. This motion slowed to ∼15 cm/yr at ∼463 Ma until 454 Ma when Baltica reached 33°S. A notable correlation was found between Baltica's latitude and the relative proportion of magnetite and hematite in the carbonates; they are relatively hematite rich at 55°S and magnetite rich by 33°S. Our results provide a high‐precision model how Baltica moved in the Ordovician with potential environmental implications regarding the oxidation state of the ocean at that time.
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spelling doaj-art-1f0360c17b754d76abc4468db064843c2025-08-20T02:30:59ZengWileyGeophysical Research Letters0094-82761944-80072025-04-01527n/an/a10.1029/2024GL114204High‐Resolution Tracking of Baltica's Northward Drift in the OrdovicianNastaran Ahanin0Stuart A. Gilder1Department of Earth and Environmental Sciences Ludwig‐Maximilians‐University Munich GermanyDepartment of Earth and Environmental Sciences Ludwig‐Maximilians‐University Munich GermanyAbstract We investigated the paleogeography of Baltica via a paleomagnetic study of 471‐454 Ma limestones from the Siljan (Sweden) impact structure. Stepwise thermal demagnetization isolated a well‐defined magnetization component that unblocks up to the Curie temperature of magnetite and passes fold and reversal tests, indicative of a primary magnetization. Paleolatitude data show that Baltica experienced an initial stationary phase at approximately 55°S from 471 to 467 Ma, followed by a rapid northward drift (∼35 cm/yr) after 467 Ma. This motion slowed to ∼15 cm/yr at ∼463 Ma until 454 Ma when Baltica reached 33°S. A notable correlation was found between Baltica's latitude and the relative proportion of magnetite and hematite in the carbonates; they are relatively hematite rich at 55°S and magnetite rich by 33°S. Our results provide a high‐precision model how Baltica moved in the Ordovician with potential environmental implications regarding the oxidation state of the ocean at that time.https://doi.org/10.1029/2024GL114204PaleomagnetismBalticapaleogeographyhematiteSiljanOrdovician
spellingShingle Nastaran Ahanin
Stuart A. Gilder
High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician
Geophysical Research Letters
Paleomagnetism
Baltica
paleogeography
hematite
Siljan
Ordovician
title High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician
title_full High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician
title_fullStr High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician
title_full_unstemmed High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician
title_short High‐Resolution Tracking of Baltica's Northward Drift in the Ordovician
title_sort high resolution tracking of baltica s northward drift in the ordovician
topic Paleomagnetism
Baltica
paleogeography
hematite
Siljan
Ordovician
url https://doi.org/10.1029/2024GL114204
work_keys_str_mv AT nastaranahanin highresolutiontrackingofbalticasnorthwarddriftintheordovician
AT stuartagilder highresolutiontrackingofbalticasnorthwarddriftintheordovician