Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains
Pelagic marine carbonates provide important records of past environmental change. We carried out detailed low-temperature magnetic measurements on biogenic magnetite-bearing sediments from the Southern Ocean (Ocean Drilling Program (ODP) Holes 738B, 738C, 689D, and 690C) and on samples containing wh...
Main Authors: | , , , , , , , , |
---|---|
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2013
|
Subjects: | |
Online Access: | https://dspace.library.uu.nl/handle/1874/306530 |
id |
ftunivutrecht:oai:dspace.library.uu.nl:1874/306530 |
---|---|
record_format |
openpolar |
spelling |
ftunivutrecht:oai:dspace.library.uu.nl:1874/306530 2023-11-12T04:26:37+01:00 Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains Chang, L. Winklhofer, M. Roberts, A.P. Heslop, D. Florindo, F. Dekkers, M.J. Krijgsman, W. Kodama, K. Yamamoto, Y. NWO-VICI: The evolution of the Paratethys: the lost sea of Central Eurasia Palaeomagnetism and environmental magnetism of magnetofossils Paleomagnetism 2013-12 application/pdf https://dspace.library.uu.nl/handle/1874/306530 en eng 2169-9313 https://dspace.library.uu.nl/handle/1874/306530 info:eu-repo/semantics/OpenAccess Article 2013 ftunivutrecht 2023-11-01T23:12:40Z Pelagic marine carbonates provide important records of past environmental change. We carried out detailed low-temperature magnetic measurements on biogenic magnetite-bearing sediments from the Southern Ocean (Ocean Drilling Program (ODP) Holes 738B, 738C, 689D, and 690C) and on samples containing whole magnetotactic bacteria cells. We document a range of low-temperature magnetic properties, including reversible humped low-temperature cycling (LTC) curves. Different degrees of magnetite oxidation are considered to be responsible for the observed variable shapes of LTC curves. A dipole spring mechanism in magnetosome chains is introduced to explain reversible LTC curves. This dipole spring mechanism is proposed to result from the uniaxial anisotropy that originates from the chain arrangement of biogenic magnetite, similar to published results for uniaxial stable single domain (SD) particles. The dipole spring mechanism reversibly restores the remanence during warming in LTC measurements. This supports a previous idea that remanence of magnetosome chains is completely reversible during LTC experiments. We suggest that this magnetic fingerprint is a diagnostic indicator for intact magnetosome chains, although the presence of isolated uniaxial stable SD particles and magnetically interacting particles can complicate this test. Magnetic measurements through the Eocene section of ODP Hole 738B reveal an interval with distinct magnetic properties that we interpret to originate from less oxidized biogenic magnetite and enrichment of a biogenic "hard" component. Co-occurrence of these two magnetic fingerprints during the late Eocene in the Southern Ocean indicates less oxic conditions, probably due to increased oceanic primary productivity and organic carbon burial. Article in Journal/Newspaper Southern Ocean Utrecht University Repository Southern Ocean |
institution |
Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
description |
Pelagic marine carbonates provide important records of past environmental change. We carried out detailed low-temperature magnetic measurements on biogenic magnetite-bearing sediments from the Southern Ocean (Ocean Drilling Program (ODP) Holes 738B, 738C, 689D, and 690C) and on samples containing whole magnetotactic bacteria cells. We document a range of low-temperature magnetic properties, including reversible humped low-temperature cycling (LTC) curves. Different degrees of magnetite oxidation are considered to be responsible for the observed variable shapes of LTC curves. A dipole spring mechanism in magnetosome chains is introduced to explain reversible LTC curves. This dipole spring mechanism is proposed to result from the uniaxial anisotropy that originates from the chain arrangement of biogenic magnetite, similar to published results for uniaxial stable single domain (SD) particles. The dipole spring mechanism reversibly restores the remanence during warming in LTC measurements. This supports a previous idea that remanence of magnetosome chains is completely reversible during LTC experiments. We suggest that this magnetic fingerprint is a diagnostic indicator for intact magnetosome chains, although the presence of isolated uniaxial stable SD particles and magnetically interacting particles can complicate this test. Magnetic measurements through the Eocene section of ODP Hole 738B reveal an interval with distinct magnetic properties that we interpret to originate from less oxidized biogenic magnetite and enrichment of a biogenic "hard" component. Co-occurrence of these two magnetic fingerprints during the late Eocene in the Southern Ocean indicates less oxic conditions, probably due to increased oceanic primary productivity and organic carbon burial. |
author2 |
NWO-VICI: The evolution of the Paratethys: the lost sea of Central Eurasia Palaeomagnetism and environmental magnetism of magnetofossils Paleomagnetism |
format |
Article in Journal/Newspaper |
author |
Chang, L. Winklhofer, M. Roberts, A.P. Heslop, D. Florindo, F. Dekkers, M.J. Krijgsman, W. Kodama, K. Yamamoto, Y. |
spellingShingle |
Chang, L. Winklhofer, M. Roberts, A.P. Heslop, D. Florindo, F. Dekkers, M.J. Krijgsman, W. Kodama, K. Yamamoto, Y. Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains |
author_facet |
Chang, L. Winklhofer, M. Roberts, A.P. Heslop, D. Florindo, F. Dekkers, M.J. Krijgsman, W. Kodama, K. Yamamoto, Y. |
author_sort |
Chang, L. |
title |
Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains |
title_short |
Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains |
title_full |
Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains |
title_fullStr |
Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains |
title_full_unstemmed |
Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains |
title_sort |
low-temperature magnetic properties of pelagic carbonates: oxidation of biogenic magnetite and identification of magnetosome chains |
publishDate |
2013 |
url |
https://dspace.library.uu.nl/handle/1874/306530 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
2169-9313 https://dspace.library.uu.nl/handle/1874/306530 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782340530944868352 |