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Noble gases in shocked igneous rocks from the 380 Ma-old Siljan impact structure (Sweden) : A search for paleo-atmospheric signatures

Cattani, Fanny ; Avice, Guillaume ; Ferrière, Ludovic and Alwmark, Sanna LU (2024) In Chemical Geology 670.
Abstract

Finding direct records of the ancient Earth's atmosphere is key to understand the evolution of the entire planet. Nevertheless, such records are scarce, and only a few geological samples with preserved paleo-atmospheric signatures are available today. In this study, we analyzed noble gases contained in shocked granitic and volcanic rocks collected across the 380 Ma-old Siljan impact structure (in Sweden) to investigate the potential of shocked quartz crystals with planar deformation features (PDFs), often decorated by fluid inclusions, to preserve atmospheric signatures. Our results reveal that most of the investigated samples show relative elemental abundances of noble gases falling between those of air and meteoric water values.... (More)

Finding direct records of the ancient Earth's atmosphere is key to understand the evolution of the entire planet. Nevertheless, such records are scarce, and only a few geological samples with preserved paleo-atmospheric signatures are available today. In this study, we analyzed noble gases contained in shocked granitic and volcanic rocks collected across the 380 Ma-old Siljan impact structure (in Sweden) to investigate the potential of shocked quartz crystals with planar deformation features (PDFs), often decorated by fluid inclusions, to preserve atmospheric signatures. Our results reveal that most of the investigated samples show relative elemental abundances of noble gases falling between those of air and meteoric water values. Atmospheric gases are present in the samples but excesses in radiogenic, nucleogenic, and fissiogenic noble gas isotopes highlight interactions of fluids with crustal rocks during the impact-generated hydrothermal circulation of fluids after the impact. Such fluid circulation event(s) could also have remobilized older fluids originally present in fluid inclusions preserved in the mineral lattices. Furthermore, results obtained on the two pure quartz fractions highlight a stronger atmospheric signature correlated with the presence of PDFs. The atmospheric component detected in this study could represent either a paleo-atmospheric signature trapped shortly after the Siljan impact event, or it may result from modern atmospheric contamination. Future studies of noble gases contained within shocked quartz crystals from other impact structures will unveil if such samples present advantages compared to other paleo-atmospheric proxies.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fluid inclusion, Geochemistry, Impact crater, Noble gases, Paleo-atmosphere, Shocked quartz
in
Chemical Geology
volume
670
article number
122440
publisher
Elsevier
external identifiers
  • scopus:85206252972
ISSN
0009-2541
DOI
10.1016/j.chemgeo.2024.122440
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 The Authors
id
b1d4806a-1f4f-4ec7-b771-f226fdbe4de0
date added to LUP
2024-11-26 13:18:07
date last changed
2025-04-04 14:30:12
@article{b1d4806a-1f4f-4ec7-b771-f226fdbe4de0,
  abstract     = {{<p>Finding direct records of the ancient Earth's atmosphere is key to understand the evolution of the entire planet. Nevertheless, such records are scarce, and only a few geological samples with preserved paleo-atmospheric signatures are available today. In this study, we analyzed noble gases contained in shocked granitic and volcanic rocks collected across the 380 Ma-old Siljan impact structure (in Sweden) to investigate the potential of shocked quartz crystals with planar deformation features (PDFs), often decorated by fluid inclusions, to preserve atmospheric signatures. Our results reveal that most of the investigated samples show relative elemental abundances of noble gases falling between those of air and meteoric water values. Atmospheric gases are present in the samples but excesses in radiogenic, nucleogenic, and fissiogenic noble gas isotopes highlight interactions of fluids with crustal rocks during the impact-generated hydrothermal circulation of fluids after the impact. Such fluid circulation event(s) could also have remobilized older fluids originally present in fluid inclusions preserved in the mineral lattices. Furthermore, results obtained on the two pure quartz fractions highlight a stronger atmospheric signature correlated with the presence of PDFs. The atmospheric component detected in this study could represent either a paleo-atmospheric signature trapped shortly after the Siljan impact event, or it may result from modern atmospheric contamination. Future studies of noble gases contained within shocked quartz crystals from other impact structures will unveil if such samples present advantages compared to other paleo-atmospheric proxies.</p>}},
  author       = {{Cattani, Fanny and Avice, Guillaume and Ferrière, Ludovic and Alwmark, Sanna}},
  issn         = {{0009-2541}},
  keywords     = {{Fluid inclusion; Geochemistry; Impact crater; Noble gases; Paleo-atmosphere; Shocked quartz}},
  language     = {{eng}},
  month        = {{12}},
  publisher    = {{Elsevier}},
  series       = {{Chemical Geology}},
  title        = {{Noble gases in shocked igneous rocks from the 380 Ma-old Siljan impact structure (Sweden) : A search for paleo-atmospheric signatures}},
  url          = {{http://dx.doi.org/10.1016/j.chemgeo.2024.122440}},
  doi          = {{10.1016/j.chemgeo.2024.122440}},
  volume       = {{670}},
  year         = {{2024}},
}