Cyclostratigraphy of Early Albian Marine Strata of the Sergipe Basin, Brazil
Abstract
Sedimentary archives with high-resolution chronologies are rare for the Cretaceous period. With the aim to generate an astronomically calibrated chronology for the early Albian, we investigate the stratigraphic interval assigned to the Microhedbergella renilaevis to Ticinella primula planktic foraminiferal zones at Core SER-03, drilled in the Sergipe Basin, northeastern Brazil. The sedimentary succession is lithotologically characterized by intercalations between calcareous and siliciclastic facies, and we used the gamma-ray record measured along the cored sections to assess whether orbital-scale cyclicities were preserved in the sedimentary succession. Spectral power estimation in the stratigraphic domain revealed ratios between significant cycles (confidence level above 99%) that suggest the occurrence of the long and short eccentricity, obliquity and precession cycles. Therefore, we used planktic foraminiferal datums to obtain a first alignment of the gamma-ray record to reconstructed variations of Earth's orbital eccentricity, and performed the orbital tuning of the section by correlating high gamma-ray values to low orbital eccentricity. Our results imply that the sedimentary succession spans about 4 Myr, and sedimentation rates vary between 3 and 8 cm/kyr. Furthermore, spectral power estimation in the time domain corroborates the occurrence of cycles with periods that can be related to long and short eccentricity, obliquity and precession. Our new chronology for the early Albian provides an opportunity to better understand recovery rates of the ocean system, since a global planktic foraminiferal turnover suggests marked environmental changes close to the Aptian-Albian transition. [IODP/CAPES project 88887.091703/2014-01]
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP51D1400K
- Keywords:
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- 1030 Geochemical cycles;
- GEOCHEMISTRY;
- 1165 Sedimentary geochronology;
- GEOCHRONOLOGY;
- 4910 Astronomical forcing;
- PALEOCEANOGRAPHY;
- 4946 Milankovitch theory;
- PALEOCEANOGRAPHY