Dynamics of the geomagnetic field during the last glacial
Geomagnetic paleosecular variations (PSVs) are an expression of geodynamo processes inside the Earth’s liquid outer core. These paleomagnetic time series provide insights into the properties of the Earth’s magnetic field, from normal behavior with a dominating dipolar geometry, over field crises, su...
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_4330899 2023-05-15T16:30:11+02:00 Dynamics of the geomagnetic field during the last glacial Liu, J. 2019 https://gfzpublic.gfz-potsdam.de/pubman/item/item_4330899 unknown Universität Potsdam info:eu-repo/semantics/altIdentifier/doi/10.25932/publishup-42946 info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:kobv:517-opus4-429461 https://gfzpublic.gfz-potsdam.de/pubman/item/item_4330899 info:eu-repo/semantics/doctoralThesis 2019 ftgfzpotsdam https://doi.org/10.25932/publishup-42946 2022-09-14T05:57:19Z Geomagnetic paleosecular variations (PSVs) are an expression of geodynamo processes inside the Earth’s liquid outer core. These paleomagnetic time series provide insights into the properties of the Earth’s magnetic field, from normal behavior with a dominating dipolar geometry, over field crises, such as pronounced intensity lows and geomagnetic excursions with a distorted field geometry, to the complete reversal of the dominating dipole contribution. Particularly, long-term high-resolution and high-quality PSV time series are needed for properly reconstructing the higher frequency components in the spectrum of geomagnetic field variations and for a better understanding of the effects of smoothing during the recording of such paleomagnetic records by sedimentary archives. In this doctorate study, full vector paleomagnetic records were derived from 16 sediment cores recovered from the southeastern Black Sea. Age models are based on radiocarbon dating and correlations of warming/cooling cycles monitored by high-resolution X-ray fluorescence (XRF) elementary ratios as well as ice-rafted debris (IRD) in Black Sea sediments to the sequence of ‘Dansgaard-Oeschger’ (DO) events defined from Greenland ice core oxygen isotope stratigraphy. In order to identify the carriers of magnetization in Black Sea sediments, core MSM33-55-1 recovered from the southeast Black Sea was subjected to detailed rock magnetic and electron microscopy investigations. The younger part of core MSM33-55-1 was continuously deposited since 41 ka. Before 17.5 ka, the magnetic minerals were dominated by a mixture of greigite (Fe3S4) and titanomagnetite (Fe3-xTixO4) in samples with SIRM/κLF >10 kAm-1, or exclusively by titanomagnetite in samples with SIRM/κLF ≤10 kAm-1. It was found that greigite is generally present as crustal aggregates in locally reducing micro-environments. From 17.5 ka to 8.3 ka, the dominant magnetic mineral in this transition phase was changing from greigite (17.5 – ~10.0 ka) to probably silicate-hosted titanomagnetite ... Doctoral or Postdoctoral Thesis Greenland Greenland ice core ice core GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Greenland |
institution |
Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
op_collection_id |
ftgfzpotsdam |
language |
unknown |
description |
Geomagnetic paleosecular variations (PSVs) are an expression of geodynamo processes inside the Earth’s liquid outer core. These paleomagnetic time series provide insights into the properties of the Earth’s magnetic field, from normal behavior with a dominating dipolar geometry, over field crises, such as pronounced intensity lows and geomagnetic excursions with a distorted field geometry, to the complete reversal of the dominating dipole contribution. Particularly, long-term high-resolution and high-quality PSV time series are needed for properly reconstructing the higher frequency components in the spectrum of geomagnetic field variations and for a better understanding of the effects of smoothing during the recording of such paleomagnetic records by sedimentary archives. In this doctorate study, full vector paleomagnetic records were derived from 16 sediment cores recovered from the southeastern Black Sea. Age models are based on radiocarbon dating and correlations of warming/cooling cycles monitored by high-resolution X-ray fluorescence (XRF) elementary ratios as well as ice-rafted debris (IRD) in Black Sea sediments to the sequence of ‘Dansgaard-Oeschger’ (DO) events defined from Greenland ice core oxygen isotope stratigraphy. In order to identify the carriers of magnetization in Black Sea sediments, core MSM33-55-1 recovered from the southeast Black Sea was subjected to detailed rock magnetic and electron microscopy investigations. The younger part of core MSM33-55-1 was continuously deposited since 41 ka. Before 17.5 ka, the magnetic minerals were dominated by a mixture of greigite (Fe3S4) and titanomagnetite (Fe3-xTixO4) in samples with SIRM/κLF >10 kAm-1, or exclusively by titanomagnetite in samples with SIRM/κLF ≤10 kAm-1. It was found that greigite is generally present as crustal aggregates in locally reducing micro-environments. From 17.5 ka to 8.3 ka, the dominant magnetic mineral in this transition phase was changing from greigite (17.5 – ~10.0 ka) to probably silicate-hosted titanomagnetite ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Liu, J. |
spellingShingle |
Liu, J. Dynamics of the geomagnetic field during the last glacial |
author_facet |
Liu, J. |
author_sort |
Liu, J. |
title |
Dynamics of the geomagnetic field during the last glacial |
title_short |
Dynamics of the geomagnetic field during the last glacial |
title_full |
Dynamics of the geomagnetic field during the last glacial |
title_fullStr |
Dynamics of the geomagnetic field during the last glacial |
title_full_unstemmed |
Dynamics of the geomagnetic field during the last glacial |
title_sort |
dynamics of the geomagnetic field during the last glacial |
publisher |
Universität Potsdam |
publishDate |
2019 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_4330899 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Greenland ice core ice core |
genre_facet |
Greenland Greenland ice core ice core |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.25932/publishup-42946 info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:kobv:517-opus4-429461 https://gfzpublic.gfz-potsdam.de/pubman/item/item_4330899 |
op_doi |
https://doi.org/10.25932/publishup-42946 |
_version_ |
1766019900330999808 |