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Revisiting Glauconi...
Revisiting Glauconite Geochronology: Lessons Learned from In Situ Radiometric Dating of a Glauconite-Rich Cretaceous Shelfal Sequence
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Scheiblhofer, E. (författare)
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Moser, U. (författare)
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Lohr, S. (författare)
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Wilmsen, M. (författare)
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Farkas, J. (författare)
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Gallhofer, D. (författare)
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- Bäckström, Alice Matsdotter (författare)
- Gothenburg University,Göteborgs universitet,Institutionen för geovetenskaper,Department of Earth Sciences
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- Zack, Thomas, 1968 (författare)
- Gothenburg University,Göteborgs universitet,Institutionen för geovetenskaper,Department of Earth Sciences
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Baldermann, A. (författare)
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(creator_code:org_t)
- 2022-06-27
- 2022
- Engelska.
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Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 12:7
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https://gup.ub.gu.se...
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https://doi.org/10.3...
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Abstract
Ämnesord
Stäng
- The scarcity of well-preserved and directly dateable sedimentary sequences is a major impediment to inferring the Earth's paleo-environmental evolution. The authigenic mineral glauconite can potentially provide absolute stratigraphic ages for sedimentary sequences and constraints on paleo-depositional conditions. This requires improved approaches for measuring and interpreting glauconite formation ages. Here, glauconite from a Cretaceous shelfal sequence (Langenstein, northern Germany) was characterized using petrographical, geochemical (EMP), andmineralogical (XRD) screening methods before in situ Rb-Sr dating via LA-ICP-MS/MS. The obtained glauconite ages (similar to 101 to 97 Ma) partly overlap with the depositional age of the Langenstein sequence (+/- 3 Ma), but without the expected stratigraphic age progression, which we attribute to detrital and diagenetic illitic phase impurities inside the glauconites. Using a novel age deconvolution approach, which combines the new Rb-Sr dataset with published K-Ar ages, we recalculate the glauconite bulk ages to obtain stratigraphically significant 'pure' glauconite ages (similar to 100 to 96 Ma). Thus, our results show that pristine ages can be preserved in mineralogically complex glauconite grains even under burial diagenetic conditions (T < 65 degrees C; <1500 m depth), confirming that glauconite could be a suitable archive for paleo-environmental reconstructions and direct sediment dating.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences (hsv//eng)
Nyckelord
- glauconite
- radiometric dating
- in situ Rb-Sr geochronology
- diagenesis
- illitization
- LA-ICP-MS/MS
- green-clay authigenesis
- volcanic ash
- isotopic constraints
- penganga
- group
- sr
- rb
- fe
- chemistry
- evolution
- origin
- Geochemistry & Geophysics
- Mineralogy
- Mining & Mineral Processing
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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Scheiblhofer, E.
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Moser, U.
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Lohr, S.
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Wilmsen, M.
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Farkas, J.
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Gallhofer, D.
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visa fler...
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Bäckström, Alice ...
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Zack, Thomas, 19 ...
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Baldermann, A.
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visa färre...
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- NATURVETENSKAP
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Minerals
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Göteborgs universitet