Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides
The Vrica section in Calabria, southern Italy, was the global stratotype for the Pliocene-Pleistocene boundary until this boundary was redefined in 2009. Several paleomagnetic investigations have been carried out at Vrica to determine the age of the formerly defined Pliocene-Pleistocene boundary, wh...
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/38838 2024-01-14T10:08:38+01:00 Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides Roberts, Andrew Florindo, Fabio Larrasoana, Juan C O'Regan, Matthew A Xiang, Zhao http://hdl.handle.net/1885/38838 https://doi.org/10.1016/j.epsl.2010.01.025 https://openresearch-repository.anu.edu.au/bitstream/1885/38838/5/122._Roberts_et_al._EPSL_2010.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/38838/7/01_Roberts_Complex_polarity_pattern_at_2010.pdf.jpg unknown Elsevier 0012-821X http://hdl.handle.net/1885/38838 doi:10.1016/j.epsl.2010.01.025 https://openresearch-repository.anu.edu.au/bitstream/1885/38838/5/122._Roberts_et_al._EPSL_2010.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/38838/7/01_Roberts_Complex_polarity_pattern_at_2010.pdf.jpg Earth and Planetary Science Letters Keywords: Greigites Magnetostratigraphy Methane hydrates Pleistocene Pliocene Remagnetization Dissolution Gas hydrates Hydration Iron ores Magnetic materials Magnetic polarity Magnetism Methane Minerals Sedimentology Iron compounds gas hydrate gre greigite methane hydrate Olduvai pyrrhotite Vrica Journal article ftanucanberra https://doi.org/10.1016/j.epsl.2010.01.025 2023-12-15T09:35:01Z The Vrica section in Calabria, southern Italy, was the global stratotype for the Pliocene-Pleistocene boundary until this boundary was redefined in 2009. Several paleomagnetic investigations have been carried out at Vrica to determine the age of the formerly defined Pliocene-Pleistocene boundary, which was a key calibration point for the astronomical polarity timescale (APTS). Each study has documented a complex polarity pattern at and above the top of the Olduvai subchron and in relation to the existence of the so-called Vrica subchron. When constructing the APTS, two alternative interpretations for the Vrica section were proposed, neither of which could be conclusively supported. Authigenic growth of magnetic iron sulphide minerals was proposed to explain the complex magnetic polarity record. Availability of a fresh 50-m sediment core enabled us to test this possibility. Our magnetostratigraphic record is similar to that of previous studies, but it is also complex above the Olduvai subchron. We confirm abundant occurrences of authigenic greigite and pyrrhotite, along with detrital titanomagnetite. Authigenic monoclinic pyrrhotite indicates growth significantly later than deposition, and greigite can grow at any time during diagenesis, depending on the availability of dissolved iron and sulphide. The spatially variable magnetic polarity pattern at Vrica is therefore interpreted to have resulted from post-depositional magnetic iron sulphide formation at variable times. Tectonism along the Calabrian arc provides a plausible mechanism for forcing reducing fluids through the sediments, thereby supplying the dissolved ions needed to produce late diagenetic sulphide growth and remagnetization. The complex magnetostratigraphic record at Vrica was taken into account when the APTS was developed, and alternative interpretations result in a maximum age difference of 50 kyr for the upper Olduvai reversal. Our results therefore do not undermine the APTS. Rather, they explain the complex magnetic polarity pattern at this ... Article in Journal/Newspaper Methane hydrate Australian National University: ANU Digital Collections Earth and Planetary Science Letters 292 1-2 98 111 |
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Open Polar |
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Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: Greigites Magnetostratigraphy Methane hydrates Pleistocene Pliocene Remagnetization Dissolution Gas hydrates Hydration Iron ores Magnetic materials Magnetic polarity Magnetism Methane Minerals Sedimentology Iron compounds gas hydrate gre greigite methane hydrate Olduvai pyrrhotite Vrica |
spellingShingle |
Keywords: Greigites Magnetostratigraphy Methane hydrates Pleistocene Pliocene Remagnetization Dissolution Gas hydrates Hydration Iron ores Magnetic materials Magnetic polarity Magnetism Methane Minerals Sedimentology Iron compounds gas hydrate gre greigite methane hydrate Olduvai pyrrhotite Vrica Roberts, Andrew Florindo, Fabio Larrasoana, Juan C O'Regan, Matthew A Xiang, Zhao Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides |
topic_facet |
Keywords: Greigites Magnetostratigraphy Methane hydrates Pleistocene Pliocene Remagnetization Dissolution Gas hydrates Hydration Iron ores Magnetic materials Magnetic polarity Magnetism Methane Minerals Sedimentology Iron compounds gas hydrate gre greigite methane hydrate Olduvai pyrrhotite Vrica |
description |
The Vrica section in Calabria, southern Italy, was the global stratotype for the Pliocene-Pleistocene boundary until this boundary was redefined in 2009. Several paleomagnetic investigations have been carried out at Vrica to determine the age of the formerly defined Pliocene-Pleistocene boundary, which was a key calibration point for the astronomical polarity timescale (APTS). Each study has documented a complex polarity pattern at and above the top of the Olduvai subchron and in relation to the existence of the so-called Vrica subchron. When constructing the APTS, two alternative interpretations for the Vrica section were proposed, neither of which could be conclusively supported. Authigenic growth of magnetic iron sulphide minerals was proposed to explain the complex magnetic polarity record. Availability of a fresh 50-m sediment core enabled us to test this possibility. Our magnetostratigraphic record is similar to that of previous studies, but it is also complex above the Olduvai subchron. We confirm abundant occurrences of authigenic greigite and pyrrhotite, along with detrital titanomagnetite. Authigenic monoclinic pyrrhotite indicates growth significantly later than deposition, and greigite can grow at any time during diagenesis, depending on the availability of dissolved iron and sulphide. The spatially variable magnetic polarity pattern at Vrica is therefore interpreted to have resulted from post-depositional magnetic iron sulphide formation at variable times. Tectonism along the Calabrian arc provides a plausible mechanism for forcing reducing fluids through the sediments, thereby supplying the dissolved ions needed to produce late diagenetic sulphide growth and remagnetization. The complex magnetostratigraphic record at Vrica was taken into account when the APTS was developed, and alternative interpretations result in a maximum age difference of 50 kyr for the upper Olduvai reversal. Our results therefore do not undermine the APTS. Rather, they explain the complex magnetic polarity pattern at this ... |
format |
Article in Journal/Newspaper |
author |
Roberts, Andrew Florindo, Fabio Larrasoana, Juan C O'Regan, Matthew A Xiang, Zhao |
author_facet |
Roberts, Andrew Florindo, Fabio Larrasoana, Juan C O'Regan, Matthew A Xiang, Zhao |
author_sort |
Roberts, Andrew |
title |
Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides |
title_short |
Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides |
title_full |
Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides |
title_fullStr |
Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides |
title_full_unstemmed |
Complex polarity pattern at the former Plio-Pleistocene global stratotype section at Vrica (Italy): Remagnetization by magnetic iron sulphides |
title_sort |
complex polarity pattern at the former plio-pleistocene global stratotype section at vrica (italy): remagnetization by magnetic iron sulphides |
publisher |
Elsevier |
url |
http://hdl.handle.net/1885/38838 https://doi.org/10.1016/j.epsl.2010.01.025 https://openresearch-repository.anu.edu.au/bitstream/1885/38838/5/122._Roberts_et_al._EPSL_2010.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/38838/7/01_Roberts_Complex_polarity_pattern_at_2010.pdf.jpg |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
Earth and Planetary Science Letters |
op_relation |
0012-821X http://hdl.handle.net/1885/38838 doi:10.1016/j.epsl.2010.01.025 https://openresearch-repository.anu.edu.au/bitstream/1885/38838/5/122._Roberts_et_al._EPSL_2010.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/38838/7/01_Roberts_Complex_polarity_pattern_at_2010.pdf.jpg |
op_doi |
https://doi.org/10.1016/j.epsl.2010.01.025 |
container_title |
Earth and Planetary Science Letters |
container_volume |
292 |
container_issue |
1-2 |
container_start_page |
98 |
op_container_end_page |
111 |
_version_ |
1788063043131801600 |