Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations
The limestones of the upper Katian Boda mud mounds (Ordovician) of the Siljan district in central Sweden are deeply fractured. The fissures were partly synsedimentary and are often lined with stromatolite-like crusts. These crusts thus far are the only known subaerial Ordovician speleothems. They re...
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ftgeosoclonfig:oai:figshare.com:article/3453896 2023-05-15T16:40:38+02:00 Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations Björn Kröger Jan Ove R. Ebbestad Oliver Lehnert Clemens V. Ullmann Christoph Korte Robert Frei Christian M. Ø. Rasmussen 2016-06-21T11:45:03Z https://doi.org/10.6084/m9.figshare.3453896.v1 https://figshare.com/articles/Subaerial_speleothems_and_deep_karst_in_central_Sweden_linked_to_Hirnantian_glaciations/3453896 unknown doi:10.6084/m9.figshare.3453896.v1 https://figshare.com/articles/Subaerial_speleothems_and_deep_karst_in_central_Sweden_linked_to_Hirnantian_glaciations/3453896 CC BY 4.0 CC-BY Geology soil horizon brachiopod shell isotope data subaerial exposure Hirnantian Isotopic Carbon Excursion C isotope values Hirnantian glaciations subaerial Ordovician speleothems crust karst surfaces record time window Subaerial speleothems karst surfaces West Gondwana ice sheet extent Siljan district Boda mud mounds Katian Boda mud mounds Text Journal contribution 2016 ftgeosoclonfig https://doi.org/10.6084/m9.figshare.3453896.v1 2020-02-21T07:23:54Z The limestones of the upper Katian Boda mud mounds (Ordovician) of the Siljan district in central Sweden are deeply fractured. The fissures were partly synsedimentary and are often lined with stromatolite-like crusts. These crusts thus far are the only known subaerial Ordovician speleothems. They reach depths of up to 30 m below the former mound top. Macroscopically the crusts form decimetre-sized, cone-shaped domal aggregates, stalactites and stalagmites. Microfabric and morphology identify them as microbially mediated speleothems in a dark environment. Combined Sr and C isotope values indicate a formation of the speleothems from meteoric waters without influence of a significant soil horizon. For the first time the age of the speleothems can be precisely constrained by δ 13 C whole-rock and brachiopod shell isotope data to the mid-Hirnantian. Repeated and/or prolonged subaerial exposure of the Boda mud mounds during the Hirnantian is evident from karst surfaces and early cements in the mound capping carbonates. The speleothems and the karst surfaces record an estimated sea-level fall in the range of 80–130 m within the time window of the Hirnantian Isotopic Carbon Excursion. This massive regression coincides with maximum ice sheet extent inferred from sections in West Gondwana. Other Non-Article Part of Journal/Newspaper Ice Sheet Geological Society of London: Figshare Boda ENVELOPE(48.867,48.867,-68.083,-68.083) |
institution |
Open Polar |
collection |
Geological Society of London: Figshare |
op_collection_id |
ftgeosoclonfig |
language |
unknown |
topic |
Geology soil horizon brachiopod shell isotope data subaerial exposure Hirnantian Isotopic Carbon Excursion C isotope values Hirnantian glaciations subaerial Ordovician speleothems crust karst surfaces record time window Subaerial speleothems karst surfaces West Gondwana ice sheet extent Siljan district Boda mud mounds Katian Boda mud mounds |
spellingShingle |
Geology soil horizon brachiopod shell isotope data subaerial exposure Hirnantian Isotopic Carbon Excursion C isotope values Hirnantian glaciations subaerial Ordovician speleothems crust karst surfaces record time window Subaerial speleothems karst surfaces West Gondwana ice sheet extent Siljan district Boda mud mounds Katian Boda mud mounds Björn Kröger Jan Ove R. Ebbestad Oliver Lehnert Clemens V. Ullmann Christoph Korte Robert Frei Christian M. Ø. Rasmussen Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations |
topic_facet |
Geology soil horizon brachiopod shell isotope data subaerial exposure Hirnantian Isotopic Carbon Excursion C isotope values Hirnantian glaciations subaerial Ordovician speleothems crust karst surfaces record time window Subaerial speleothems karst surfaces West Gondwana ice sheet extent Siljan district Boda mud mounds Katian Boda mud mounds |
description |
The limestones of the upper Katian Boda mud mounds (Ordovician) of the Siljan district in central Sweden are deeply fractured. The fissures were partly synsedimentary and are often lined with stromatolite-like crusts. These crusts thus far are the only known subaerial Ordovician speleothems. They reach depths of up to 30 m below the former mound top. Macroscopically the crusts form decimetre-sized, cone-shaped domal aggregates, stalactites and stalagmites. Microfabric and morphology identify them as microbially mediated speleothems in a dark environment. Combined Sr and C isotope values indicate a formation of the speleothems from meteoric waters without influence of a significant soil horizon. For the first time the age of the speleothems can be precisely constrained by δ 13 C whole-rock and brachiopod shell isotope data to the mid-Hirnantian. Repeated and/or prolonged subaerial exposure of the Boda mud mounds during the Hirnantian is evident from karst surfaces and early cements in the mound capping carbonates. The speleothems and the karst surfaces record an estimated sea-level fall in the range of 80–130 m within the time window of the Hirnantian Isotopic Carbon Excursion. This massive regression coincides with maximum ice sheet extent inferred from sections in West Gondwana. |
format |
Other Non-Article Part of Journal/Newspaper |
author |
Björn Kröger Jan Ove R. Ebbestad Oliver Lehnert Clemens V. Ullmann Christoph Korte Robert Frei Christian M. Ø. Rasmussen |
author_facet |
Björn Kröger Jan Ove R. Ebbestad Oliver Lehnert Clemens V. Ullmann Christoph Korte Robert Frei Christian M. Ø. Rasmussen |
author_sort |
Björn Kröger |
title |
Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations |
title_short |
Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations |
title_full |
Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations |
title_fullStr |
Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations |
title_full_unstemmed |
Subaerial speleothems and deep karst in central Sweden linked to Hirnantian glaciations |
title_sort |
subaerial speleothems and deep karst in central sweden linked to hirnantian glaciations |
publishDate |
2016 |
url |
https://doi.org/10.6084/m9.figshare.3453896.v1 https://figshare.com/articles/Subaerial_speleothems_and_deep_karst_in_central_Sweden_linked_to_Hirnantian_glaciations/3453896 |
long_lat |
ENVELOPE(48.867,48.867,-68.083,-68.083) |
geographic |
Boda |
geographic_facet |
Boda |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_relation |
doi:10.6084/m9.figshare.3453896.v1 https://figshare.com/articles/Subaerial_speleothems_and_deep_karst_in_central_Sweden_linked_to_Hirnantian_glaciations/3453896 |
op_rights |
CC BY 4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.6084/m9.figshare.3453896.v1 |
_version_ |
1766031036544712704 |