Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany)
International audience Anisotropy of magnetic susceptibility (AMS) is employed as a tool to unravel the depositional history of the 17 m thick Nussloch P8 Weichselian loess sequence located 10 km south of Heidelberg, Germany. Through an AMS study, the primary aeolian depositional origin of the magne...
Published in: | Journal of Geophysical Research: Solid Earth |
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Online Access: | https://hal-insu.archives-ouvertes.fr/insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755/document https://hal-insu.archives-ouvertes.fr/insu-01351755/file/jgrb-2015-taylor.pdf https://doi.org/10.1002/2014JB011803 |
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ftunivnantes:oai:HAL:insu-01351755v1 2023-05-15T17:58:06+02:00 Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) Taylor, Samuel, Lagroix, France Institut de Physique du Globe de Paris (IPGP) Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS) 2015-05-07 https://hal-insu.archives-ouvertes.fr/insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755/document https://hal-insu.archives-ouvertes.fr/insu-01351755/file/jgrb-2015-taylor.pdf https://doi.org/10.1002/2014JB011803 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1002/2014JB011803 insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755/document https://hal-insu.archives-ouvertes.fr/insu-01351755/file/jgrb-2015-taylor.pdf doi:10.1002/2014JB011803 info:eu-repo/semantics/OpenAccess ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://hal-insu.archives-ouvertes.fr/insu-01351755 Journal of Geophysical Research : Solid Earth, 2015, ⟨10.1002/2014JB011803⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2015 ftunivnantes https://doi.org/10.1002/2014JB011803 2023-02-08T10:05:56Z International audience Anisotropy of magnetic susceptibility (AMS) is employed as a tool to unravel the depositional history of the 17 m thick Nussloch P8 Weichselian loess sequence located 10 km south of Heidelberg, Germany. Through an AMS study, the primary aeolian depositional origin of the magnetic fabrics is evaluated, and overprinting due to postdepositional reworking and/or deformation is identified. Primary fabrics along the P8 sequence are defined by near-vertical K MIN axes and horizontal foliations. Eight intervals display secondary fabrics, characterized by either prolate orientation distributions or oblate orientation distributions with dipping foliation planes. These postdepositional fabrics are associated with laminated loess and tundra gley horizons. It is proposed that increased moisture (due to higher precipitation or enhanced snowmelt) and repeated cryogenic processes were able to reorganize and rework the accumulated loess. Primary aeolian fabrics are archived within 6.45 m of cumulated depth or 38% of the profile and dominantly within the Upper Pleniglacial units. Even though maximum susceptibility axes of primary fabrics are statistically well resolved at the specimen (ε 12 = 10.1° ± 8.6) and population (ε 12 = 6°) level, any inferred paleowind directions from the magnetic lineation remains speculative given the low concentration of ferrimagnetic minerals (<0.03 wt %). Tundra gley horizons upprofile display primary magnetic fabrics and no major changes in the degree of anisotropy or AMS orientation distributions. This suggests a weakening in gley-induced diagenesis and therefore favorable environmental conditions needed (moisture and presence of permafrost active layer) to initiate their formation in loess deposits. Finally, pedogenesis has not played an important role in modifying the magnetic fabric since paleosols display the same magnetic fabrics observed in primary loess. Article in Journal/Newspaper permafrost Tundra Université de Nantes: HAL-UNIV-NANTES Journal of Geophysical Research: Solid Earth 120 5 2859 2876 |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Taylor, Samuel, Lagroix, France Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience Anisotropy of magnetic susceptibility (AMS) is employed as a tool to unravel the depositional history of the 17 m thick Nussloch P8 Weichselian loess sequence located 10 km south of Heidelberg, Germany. Through an AMS study, the primary aeolian depositional origin of the magnetic fabrics is evaluated, and overprinting due to postdepositional reworking and/or deformation is identified. Primary fabrics along the P8 sequence are defined by near-vertical K MIN axes and horizontal foliations. Eight intervals display secondary fabrics, characterized by either prolate orientation distributions or oblate orientation distributions with dipping foliation planes. These postdepositional fabrics are associated with laminated loess and tundra gley horizons. It is proposed that increased moisture (due to higher precipitation or enhanced snowmelt) and repeated cryogenic processes were able to reorganize and rework the accumulated loess. Primary aeolian fabrics are archived within 6.45 m of cumulated depth or 38% of the profile and dominantly within the Upper Pleniglacial units. Even though maximum susceptibility axes of primary fabrics are statistically well resolved at the specimen (ε 12 = 10.1° ± 8.6) and population (ε 12 = 6°) level, any inferred paleowind directions from the magnetic lineation remains speculative given the low concentration of ferrimagnetic minerals (<0.03 wt %). Tundra gley horizons upprofile display primary magnetic fabrics and no major changes in the degree of anisotropy or AMS orientation distributions. This suggests a weakening in gley-induced diagenesis and therefore favorable environmental conditions needed (moisture and presence of permafrost active layer) to initiate their formation in loess deposits. Finally, pedogenesis has not played an important role in modifying the magnetic fabric since paleosols display the same magnetic fabrics observed in primary loess. |
author2 |
Institut de Physique du Globe de Paris (IPGP) Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Taylor, Samuel, Lagroix, France |
author_facet |
Taylor, Samuel, Lagroix, France |
author_sort |
Taylor, Samuel, |
title |
Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) |
title_short |
Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) |
title_full |
Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) |
title_fullStr |
Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) |
title_full_unstemmed |
Magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at Nussloch (Germany) |
title_sort |
magnetic anisotropy reveals the depositional and postdepositional history of a loess-paleosol sequence at nussloch (germany) |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://hal-insu.archives-ouvertes.fr/insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755/document https://hal-insu.archives-ouvertes.fr/insu-01351755/file/jgrb-2015-taylor.pdf https://doi.org/10.1002/2014JB011803 |
genre |
permafrost Tundra |
genre_facet |
permafrost Tundra |
op_source |
ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://hal-insu.archives-ouvertes.fr/insu-01351755 Journal of Geophysical Research : Solid Earth, 2015, ⟨10.1002/2014JB011803⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1002/2014JB011803 insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755 https://hal-insu.archives-ouvertes.fr/insu-01351755/document https://hal-insu.archives-ouvertes.fr/insu-01351755/file/jgrb-2015-taylor.pdf doi:10.1002/2014JB011803 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1002/2014JB011803 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
120 |
container_issue |
5 |
container_start_page |
2859 |
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2876 |
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