Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield

Sheared sedimentary clay was found in a faulted fracture in crystalline bedrock in a tunnelling site at 60 m depth in southern Finland. Brittle faults are numerous in the Fennoscandian Palaeoproterozoic bedrock, but only some of them have relative age constraints, while absolute ages are nearly lack...

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Published in:Precambrian Research
Main Authors: Elminen, Tuija, Zwingmann, Horst, Kaakinen, Anu
Other Authors: Department of Geosciences and Geography
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier Scientific Publ. Co 2019
Subjects:
Clay
Fault
K-Ar dating
Neoproterozoic
Thermal event
Sveconorwegian orogeny
K-AR
RB-SR
OROGENIC DEFORMATION
SOUTHWESTERN FINLAND
AGE CONSTRAINTS
SHALLOW FAULTS
CLAY-MINERALS
GOUGES
ILLITE
SITE
1171 Geosciences
Fennoscandian
Online Access:http://hdl.handle.net/10138/308825
id ftunivhelsihelda:oai:helda.helsinki.fi:10138/308825
record_format openpolar
spelling ftunivhelsihelda:oai:helda.helsinki.fi:10138/308825 2024-01-07T09:43:12+01:00 Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield Elminen, Tuija Zwingmann, Horst Kaakinen, Anu Department of Geosciences and Geography 2019-12-31T22:52:33Z 15 application/pdf http://hdl.handle.net/10138/308825 eng eng Elsevier Scientific Publ. Co 10.1016/j.precamres.2017.10.014 Andrew Todd and Mark Raven at CSIRO, and Sari Lukkari, Mia Tiljander and Lassi Pakkanen in the Research Laboratory, GTK, are thanked for technical assistance during the study. Piri Harju of Poyry, Finland, is thanked for providing the samples of clay material. Anneli Uutela, University of Helsinki, is thanked for the fossil analysis and Philip Stickler for drafting the Figs. 10 and 11. The Academy of Finland is acknowledged for partial support of this research (AK). We are grateful to the editor G. Zhao and reviewer G. Viola for their constructive and helpful reviews. Elminen , T , Zwingmann , H & Kaakinen , A 2018 , ' Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield ' , Precambrian Research , vol. 304 , pp. 110-124 . https://doi.org/10.1016/j.precamres.2017.10.014 ORCID: /0000-0002-4654-0665/work/41847722 85034579774 7177134b-fdb7-4060-9d94-0998a7516c13 http://hdl.handle.net/10138/308825 000423651500009 cc_by_nc_nd openAccess info:eu-repo/semantics/openAccess Clay Fault K-Ar dating Neoproterozoic Thermal event Sveconorwegian orogeny K-AR RB-SR OROGENIC DEFORMATION SOUTHWESTERN FINLAND AGE CONSTRAINTS SHALLOW FAULTS CLAY-MINERALS GOUGES ILLITE SITE 1171 Geosciences Article acceptedVersion 2019 ftunivhelsihelda 2023-12-14T00:06:04Z Sheared sedimentary clay was found in a faulted fracture in crystalline bedrock in a tunnelling site at 60 m depth in southern Finland. Brittle faults are numerous in the Fennoscandian Palaeoproterozoic bedrock, but only some of them have relative age constraints, while absolute ages are nearly lacking. Sedimentary rocks altogether are uncommon in Finland and only sparsely dated by micropaleontological studies. This study reports K-Ar data of fresh, non-weathered authigenic illite and constrains a time framework for the local faulting and sedimentation. The Neoproterozoic Tonian to Cryogenian ages derived from the grains in diminishing grain-size order are c. 967, 947, 809 and 697 Ma. Results indicate that the formation of the extension fracture is related to the collapse of Sveconorwegian orogeny c. 1000 Ma; clay and mature quartz sand were deposited in this extension fracture in shallow water in an intracratonic basin followed by early diagenetic processes and neocrystallization of illite around 967-947 Ma. The Neoproterozoic 1000-700 Ma sedimentation documented in this study is rare in the Fennoscandian shield as a whole. Neocrystallization of authigenic illite in the finest 0.4 and <0.1 pm fractions c. 809-697 Ma ago is interpreted as resulting from reactivation in the fault due to the continental break-up on the western side of the craton as documented by arenite crosscutting relationships. The younger ages may also be attributed to a Caledonian thermal overprint ca. 410 Ma ago that would influence the 967 Ma age if sufficient thermal energy had been present. Peer reviewed Article in Journal/Newspaper Fennoscandian HELDA – University of Helsinki Open Repository Precambrian Research 304 110 124
institution Open Polar
collection HELDA – University of Helsinki Open Repository
op_collection_id ftunivhelsihelda
language English
topic Clay
Fault
K-Ar dating
Neoproterozoic
Thermal event
Sveconorwegian orogeny
K-AR
RB-SR
OROGENIC DEFORMATION
SOUTHWESTERN FINLAND
AGE CONSTRAINTS
SHALLOW FAULTS
CLAY-MINERALS
GOUGES
ILLITE
SITE
1171 Geosciences
spellingShingle Clay
Fault
K-Ar dating
Neoproterozoic
Thermal event
Sveconorwegian orogeny
K-AR
RB-SR
OROGENIC DEFORMATION
SOUTHWESTERN FINLAND
AGE CONSTRAINTS
SHALLOW FAULTS
CLAY-MINERALS
GOUGES
ILLITE
SITE
1171 Geosciences
Elminen, Tuija
Zwingmann, Horst
Kaakinen, Anu
Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield
topic_facet Clay
Fault
K-Ar dating
Neoproterozoic
Thermal event
Sveconorwegian orogeny
K-AR
RB-SR
OROGENIC DEFORMATION
SOUTHWESTERN FINLAND
AGE CONSTRAINTS
SHALLOW FAULTS
CLAY-MINERALS
GOUGES
ILLITE
SITE
1171 Geosciences
description Sheared sedimentary clay was found in a faulted fracture in crystalline bedrock in a tunnelling site at 60 m depth in southern Finland. Brittle faults are numerous in the Fennoscandian Palaeoproterozoic bedrock, but only some of them have relative age constraints, while absolute ages are nearly lacking. Sedimentary rocks altogether are uncommon in Finland and only sparsely dated by micropaleontological studies. This study reports K-Ar data of fresh, non-weathered authigenic illite and constrains a time framework for the local faulting and sedimentation. The Neoproterozoic Tonian to Cryogenian ages derived from the grains in diminishing grain-size order are c. 967, 947, 809 and 697 Ma. Results indicate that the formation of the extension fracture is related to the collapse of Sveconorwegian orogeny c. 1000 Ma; clay and mature quartz sand were deposited in this extension fracture in shallow water in an intracratonic basin followed by early diagenetic processes and neocrystallization of illite around 967-947 Ma. The Neoproterozoic 1000-700 Ma sedimentation documented in this study is rare in the Fennoscandian shield as a whole. Neocrystallization of authigenic illite in the finest 0.4 and <0.1 pm fractions c. 809-697 Ma ago is interpreted as resulting from reactivation in the fault due to the continental break-up on the western side of the craton as documented by arenite crosscutting relationships. The younger ages may also be attributed to a Caledonian thermal overprint ca. 410 Ma ago that would influence the 967 Ma age if sufficient thermal energy had been present. Peer reviewed
author2 Department of Geosciences and Geography
format Article in Journal/Newspaper
author Elminen, Tuija
Zwingmann, Horst
Kaakinen, Anu
author_facet Elminen, Tuija
Zwingmann, Horst
Kaakinen, Anu
author_sort Elminen, Tuija
title Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield
title_short Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield
title_full Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield
title_fullStr Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield
title_full_unstemmed Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield
title_sort constraining the timing of brittle deformation and sedimentation in southern finland : implications for neoproterozoic evolution of the eastern fennoscandian shield
publisher Elsevier Scientific Publ. Co
publishDate 2019
url http://hdl.handle.net/10138/308825
genre Fennoscandian
genre_facet Fennoscandian
op_relation 10.1016/j.precamres.2017.10.014
Andrew Todd and Mark Raven at CSIRO, and Sari Lukkari, Mia Tiljander and Lassi Pakkanen in the Research Laboratory, GTK, are thanked for technical assistance during the study. Piri Harju of Poyry, Finland, is thanked for providing the samples of clay material. Anneli Uutela, University of Helsinki, is thanked for the fossil analysis and Philip Stickler for drafting the Figs. 10 and 11. The Academy of Finland is acknowledged for partial support of this research (AK). We are grateful to the editor G. Zhao and reviewer G. Viola for their constructive and helpful reviews.
Elminen , T , Zwingmann , H & Kaakinen , A 2018 , ' Constraining the timing of brittle deformation and sedimentation in southern Finland : Implications for Neoproterozoic evolution of the eastern Fennoscandian shield ' , Precambrian Research , vol. 304 , pp. 110-124 . https://doi.org/10.1016/j.precamres.2017.10.014
ORCID: /0000-0002-4654-0665/work/41847722
85034579774
7177134b-fdb7-4060-9d94-0998a7516c13
http://hdl.handle.net/10138/308825
000423651500009
op_rights cc_by_nc_nd
openAccess
info:eu-repo/semantics/openAccess
container_title Precambrian Research
container_volume 304
container_start_page 110
op_container_end_page 124
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