Re-Os geochronology for the Cambrian SPICE event : Insights into euxinia and enhanced continental weathering from radiogenic isotopes
(2022) In Geology 50(6). p.716-720- Abstract
The late Cambrian Steptoean positive carbon isotope excursion (SPICE) represents a major perturbation to the global carbon cycle and was associated with trilobite extinctions and expansion of anoxic and/or euxinic water masses during episodes of eustatic sea-level change. We present a new Re-Os age together with Os and Nd isotope stratigraphy and major and trace-element data from the Alum Shale Formation (Scania, Sweden). The Re-Os age of 494.6 ± 2.9 Ma is from the interval of peak δ13Corg values, providing the first radiometric age constraint for this Cambrian carbon isotope excursion, interpreted as a possible pre-Mesozoic ocean anoxia event, and the timing of biomere-level extinctions. The Os isotope... (More)
The late Cambrian Steptoean positive carbon isotope excursion (SPICE) represents a major perturbation to the global carbon cycle and was associated with trilobite extinctions and expansion of anoxic and/or euxinic water masses during episodes of eustatic sea-level change. We present a new Re-Os age together with Os and Nd isotope stratigraphy and major and trace-element data from the Alum Shale Formation (Scania, Sweden). The Re-Os age of 494.6 ± 2.9 Ma is from the interval of peak δ13Corg values, providing the first radiometric age constraint for this Cambrian carbon isotope excursion, interpreted as a possible pre-Mesozoic ocean anoxia event, and the timing of biomere-level extinctions. The Os isotope chemostratigraphic profile can be explained by an increase in terrigenous weathering prior to the SPICE, potentially driven by sea-level fall, and in agreement with enhanced nutrient supply, primary productivity, and organic matter burial as the driver of the SPICE event. Post-SPICE, the Os isotopes become increasingly unradiogenic; however, invariant εNd(t) values argue against a change in provenance and instead support a decrease in the continental weathering flux, possibly related to eustatic sea-level rise.
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- author
- Rooney, Alan D. ; Millikin, Alexie E.G. and Ahlberg, Per LU
- organization
- publishing date
- 2022-06
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Geology
- volume
- 50
- issue
- 6
- pages
- 716 - 720
- publisher
- Geological Society of America
- external identifiers
-
- scopus:85131078402
- ISSN
- 0091-7613
- DOI
- 10.1130/G49833.1
- language
- English
- LU publication?
- yes
- additional info
- Funding Information: We thank S. Anseeuw and D. Skarzynski for laboratory and field assistance. This manuscript was greatly improved after constructive criticism from Ben Gill, David van Acken, Jim Schiffbauer, and an anonymous reviewer. Publisher Copyright: © 2022. Geological Society of America. For permission to copy, contact editing@geosociety.org.
- id
- 9945dd6d-7b4c-44a5-9c47-50cf9c7981cd
- date added to LUP
- 2022-12-30 12:57:49
- date last changed
- 2023-03-21 16:39:18
@article{9945dd6d-7b4c-44a5-9c47-50cf9c7981cd, abstract = {{<p>The late Cambrian Steptoean positive carbon isotope excursion (SPICE) represents a major perturbation to the global carbon cycle and was associated with trilobite extinctions and expansion of anoxic and/or euxinic water masses during episodes of eustatic sea-level change. We present a new Re-Os age together with Os and Nd isotope stratigraphy and major and trace-element data from the Alum Shale Formation (Scania, Sweden). The Re-Os age of 494.6 ± 2.9 Ma is from the interval of peak δ<sup>13</sup>C<sub>org </sub>values, providing the first radiometric age constraint for this Cambrian carbon isotope excursion, interpreted as a possible pre-Mesozoic ocean anoxia event, and the timing of biomere-level extinctions. The Os isotope chemostratigraphic profile can be explained by an increase in terrigenous weathering prior to the SPICE, potentially driven by sea-level fall, and in agreement with enhanced nutrient supply, primary productivity, and organic matter burial as the driver of the SPICE event. Post-SPICE, the Os isotopes become increasingly unradiogenic; however, invariant εNd<sub>(t)</sub> values argue against a change in provenance and instead support a decrease in the continental weathering flux, possibly related to eustatic sea-level rise.</p>}}, author = {{Rooney, Alan D. and Millikin, Alexie E.G. and Ahlberg, Per}}, issn = {{0091-7613}}, language = {{eng}}, number = {{6}}, pages = {{716--720}}, publisher = {{Geological Society of America}}, series = {{Geology}}, title = {{Re-Os geochronology for the Cambrian SPICE event : Insights into euxinia and enhanced continental weathering from radiogenic isotopes}}, url = {{http://dx.doi.org/10.1130/G49833.1}}, doi = {{10.1130/G49833.1}}, volume = {{50}}, year = {{2022}}, }