Investigating Ediacaran-Cambrian carbon isotope variability from the Zuun-Arts Formation in southwestern Mongolia
Abstract
The carbonate-rich Zuun-Arts Formation of the Zavkhan terrane, southwestern Mongolia, records a 4-6‰ drop in carbon isotope values over ~150-400 m of stratigraphy, locally reaching values as low as -10‰. This negative carbon isotope excursion has been correlated with the basal Cambrian negative carbon isotope excursion (BACE) recognized in end-Ediacaran strata around the globe, and, along with other relative age constraints, has been used to identify the Ediacaran-Cambrian boundary in Mongolia. However, unlike other BACE excursions, the Zuun-Arts carbon isotope record captures lateral variability between localities, across ~120 kms. This variability complicates chemostratigraphic correlation regionally and globally, particularly when lithostratigraphy and sequence stratigraphy are considered.
Here we present high-resolution (0.5-1.0 m) carbon isotope (δ13Ccarb) records from stratigraphic sections measured across the Zavkhan terrane. To characterize the spatial scale of Zuun-Arts carbon isotope reproducibility, parallel stratigraphic sections were measured meters to hundreds of meters apart. To identify reasons for local carbon isotope record variation, we integrate sedimentological data with carbon isotope data from these sections. We also pair carbon isotope records with proxies for geochemical alteration, including calcium isotope (δ44/40Cacarb) and Sr/Ca records.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMPP0080007L
- Keywords:
-
- 0448 Geomicrobiology;
- BIOGEOSCIENCES;
- 1039 Alteration and weathering processes;
- GEOCHEMISTRY;
- 3022 Marine sediments: processes and transport;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4863 Sedimentation;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL