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TitleFinding the VOICE: organic carbon isotope chemostratigraphy of Late Jurassic - Early Cretaceous Arctic Canada
AuthorGalloway, J MORCID logo; Vickers, M L; Price, G D; Poulton, T; Grasby, S EORCID logo; Hadlari, TORCID logo; Beauchamp, B; Sulphur, K
SourceGeological Magazine 2019., Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190596
PublisherCambridge University Press
Mediapaper; on-line; digital
File formatpdf
ProgramGEM: Geo-mapping for Energy and Minerals Sverdrup Sedimentary Basin
Released2019 12 20
AbstractA 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 (delta-13Corg) of 4 per mille (V-PDB) and to a minimum of -30.7 per mille in the probable middle Volgian Stage. This is followed by a return to less negative values of c. -27 per mille. A smaller positive excursion in the Valanginian Stage of c. 2 per mille, reaching maximum values of -24.6 per mille, is related to the Weissert Event. The Volgian isotopic trends are consistent with other high-latitude records but do not appear in delta-13Ccarb records of Tethyan Tithonian strata. In the absence of any obvious definitive cause for the depleted delta-13Corg anomaly, we suggest several possible contributing factors. The Sverdrup Basin and other Arctic areas may have experienced compositional evolution away from open-marine delta-13C 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 delta-13Corg 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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