Finding the VOICE:organic carbon isotope chemostratigraphy of Late Jurassic-Early Cretaceous Arctic Canada
A new carbon isotope record for two high-latitude sedimentary successions that span the Jurassic-Cretaceous boundary interval in the Sverdrup Basin of Arctic Canada is presented. This study, combined with other published Arctic data, shows a large negative isotopic excursion of organic carbon (δ 13...
| Published in: | Geological Magazine |
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| Main Authors: | , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://curis.ku.dk/portal/da/publications/finding-the-voice(2b0f9da9-f2bc-4091-a003-bfe12fa26ce3).html https://doi.org/10.1017/S0016756819001316 https://curis.ku.dk/ws/files/287609652/Galloway_etal_2019_4_18.pdf |
| Summary: | A new carbon isotope record for two high-latitude sedimentary successions that span the Jurassic-Cretaceous boundary interval in the Sverdrup Basin of Arctic Canada is presented. This study, combined with other published Arctic data, shows a large negative isotopic excursion of organic carbon (δ 13 C org ) of 4‰ (V-PDB) and to a minimum of-30.7‰ in the probable middle Volgian Stage. This is followed by a return to less negative values of c.-27‰. A smaller positive excursion in the Valanginian Stage of c. 2‰, reaching maximum values of-24.6‰, is related to the Weissert Event. The Volgian isotopic trends are consistent with other high-latitude records but do not appear in δ 13 C carb records of Tethyan Tithonian strata. In the absence of any obvious definitive cause for the depleted δ 13 C org anomaly, we suggest several possible contributing factors. The Sverdrup Basin and other Arctic areas may have experienced compositional evolution away from open-marine δ 13 C values during the Volgian Age due to low global or large-scale regional sea levels, and later become effectively coupled to global oceans by Valanginian time when sea level rose. A geologically sudden increase in volcanism may have caused the large negative δ 13 C org values seen in the Arctic Volgian records but the lack of precise geochronological age control for the Jurassic-Cretaceous boundary precludes direct comparison with potentially coincident events, such as the Shatsky Rise. This study offers improved correlation constraints and a refined C-isotope curve for the Boreal region throughout latest Jurassic and earliest Cretaceous time. |
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