HIGH-RESOLUTION INTEGRATED CONODONT AND CARBONATE CARBON ISOTOPE CHEMOSTRATIGRAPHY OF THE HANGENBERG EXCURSION FROM THE H-28 AND H-32 CORES BURLINGTON, IOWA

2019 ◽  
Author(s):  
Megan N. Heath ◽  
◽  
Brittany M. Stolfus ◽  
Bradley D. Cramer ◽  
James Day ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Carbonate Carbon

Extending the record of the Lomagundi–Jatuli carbon isotope excursion in the Labrador Trough, Canada

2020 ◽  
Vol 57 (9) ◽  
pp. 1089-1102
Author(s):  
Malcolm S.W. Hodgskiss ◽  
Kelsey G. Lamothe ◽  
Galen P. Halverson ◽  
Erik A. Sperling
Keyword(s):  
High Resolution ◽  
Water Column ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Large Range ◽  
Authigenic Carbonate ◽  
Elemental Ratios ◽  
Carbonate Carbon ◽  
Carbon Isotope Excursion ◽  
Isotope Analyses

The Labrador Trough in northern Québec and Labrador is a 900 km long Rhyacian–Orosirian orogenic belt containing mixed sedimentary–volcanic successions. Despite having been studied intensively since the 1940s, relatively few chemostratigraphic studies have been conducted. To improve our understanding of the Labrador Trough in the context of Earth history, and better constrain the local record of the Lomagundi–Jatuli carbon isotope excursion, high-resolution sampling and carbon isotope analyses of the Le Fer and Denault formations were conducted. Carbonate carbon isotopes (δ13C) in the Le Fer Formation record a large range in values from −4.4‰ to +6.9‰. This large range is likely attributable to a combination of post-depositional alteration and variable abundance of authigenic carbonate minerals; elemental ratios suggest that the most 13C-enriched samples reflect the composition of the water column at the time of deposition. Cumulatively, these data suggest that the Lomagundi–Jatuli Excursion was ongoing during deposition of the Le Fer Formation, approximately 2 km higher in the stratigraphy than previously recognised. However, the possibility of a post-Lomagundi–Jatuli Excursion carbon isotope event cannot conclusively be ruled out. The directly overlying Denault Formation records a range in δ13C values, from −0.5‰ to +4.3‰, suggesting that it was deposited after the conclusion of the Lomagundi–Jatuli Excursion and that the contact between the Le Fer and Denault formations occurred sometime during the transition out of the Lomagundi–Jatuli Excursion, ca. 2106 to 2057 Ma.

scholarly journals Correlation of carbon isotope events in the Danish Upper Cretaceous chalk

2008 ◽  
Vol 15 ◽  
pp. 13-16 ◽  
Author(s):  
Niels H. Schovsbo ◽  
Susanne Lil Rasmussen ◽  
Emma Sheldon ◽  
Lars Stemmerik
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
North Sea ◽  
Research Centre ◽  
Stratigraphic Correlation ◽  
The North ◽  
Carbonate Carbon ◽  
Marine Carbonates ◽  
The North Sea ◽  
The University

A high resolution carbon isotope (δ13C) profile through the upper Campanian to Maastrichtian chalk was recently completed based on material from the Stevns-1 core from the Stevns peninsula, eastern Denmark. The δ13C variation of marine carbonates essentially reflects global perturbations in the carbon cycle, i.e. the burial fluxes of carbonate carbon versus organic carbon. It is widely observed that the δ13C variation broadly tracks the eustatic sea-level curve, and that δ13C curves can be used for stratigraphic correlation (e.g. Jarvis et al. 2002). In the Stevns-1 core, a total of 29 notable isotope changes have been identified in the upper Cam panian to Maastrichtian succession. In order to evaluate the stratigraphic significance of the isotope changes, the variation in δ13C values of the mid-Maastrichtian chalk from cores in eastern Denmark and the Danish North Sea, and from outcrops at Rørdal, northern Jylland has been examined (Fig. 1). The selected interval is characterised by distinct chalk and marl cycles in the Stevns-1 and Karlslunde-1 cores and in the Rørdal quarry (Fig. 2), whereas a non-cyclic clean chalk is found in the M-10X well from the North Sea. In the Rørdal quarry, the chalk–marl unit spans the upper–lower Maa strichtian boundary in the Boreal brachiopod and belemnite stratigraphies (Surlyk 1984; unpublished data, B. Lauridsen & F. Surlyk). In Stevns-1 and Karlslunde-1 the chalk–marl unit was deposited during the younger part of nannofossil subzone UC20b (Sheldon 2006, in press). This paper presents preliminary results of a high-resolution study of carbon isotopes, carried out by the Geological Survey of Denmark and Greenland (GEUS) in co-operation with partners from the Department of Geography and Geology at the University of Copenhagen. This paper is a product of the Cretaceous Research Centre (CRC) at Geo center Denmark.

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