ODP 926

ODP Site 926 was drilled at the Ceara Rise in the western equatorial Atlantic Ocean (3°43’N, 42°54’W) during Leg 154 to investigate late Cenozoic changes in the Atlantic Ocean (Curry et al., 1995). The site has been extensively analyzed using cyclostratigraphy (Shackleton & Crowhurst, 1997; Shackleton et al., 1999; Zeeden et al., 2013; Wilkens et al., 2017), and its astronomically tuned timescale serves as a key reference for several bioevents in the Geological Time Scale 2020 (Backman & Raffi, 1997; Wade et al., 2011; Raffi et al., 2020).

This study focuses on the 5–10 Ma interval, where the sedimentary record shows a clear astronomical imprint and minimal uncertainty in orbital parameters, making it ideal for comparing extracted eccentricity curves with established astronomical solutions (Laskar et al., 2004; Laskar et al., 2011a).

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Files in the data Folder

• ODP_926.txt: Data of the ODP 926 site.

• U926_AgeModel_Wilkens_etal_2017.txt: Age model data extracted from Revisiting the Ceara Rise, equatorial Atlantic Ocean: Isotope stratigraphy of ODP leg 154 from 0 to 5Ma (Wilkens et al., 2017).

• La2010d_ecc3L.txt: Astronomical solution data (eccentricity component).

• data_926.csv: Information about the data, age-depth model and eccentricity solution used for the ODP_926 results.

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Data Used

File	Description	Reference	Transformations / Pre-Processing	Version
ODP926.txt	L* color reflectance proxy from ODP Site 926 (145–250 rmcd), representing high-resolution shipboard measurements used to extract astronomical cyclicity in the 4.7–10.9 Ma interval.	missing origin	Detrended with 10% LOWESS; normalized to zero mean and unit variance.	1.0
U926_AgeModel_Wilkens_etal_2017.txt	Age–depth model for ODP 926 based on Zeeden et al. (2013) and revised by Wilkens et al. (2017), defining the chronology and sedimentation rates (0.46–3.15 cm/kyr) for the 145–250 rmcd interval.	Wilkens et al. (2017)	Used directly without modification.	1.0
La2010d_ecc3L.dat	La2010 eccentricity astronomical solution used for tuning.	Laskar et al. (2004, 2011)	Used directly without modification.	1.0

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Execute the Example

Note

• The folder examples has to bee in the same directory as the AstroGeoFit_tool.py file. If not, this will not work.

To run the example, open a terminal in the AstroGeoFit folder. Once this is open execute the following

python AstroGeoFit_tool.py --odp_926

This command will execute the significance test, the genetic algorithm fitting, the MCMC, and the MCMC weights calculation.

If you only want to run specific components (e.g., the genetic algorithm fitting and the MCMC), you can use:

python AstroGeoFit_tool.py --odp_926 -fit -mcmc

The full list of execution options can be found in AstroGeoFit Script Execution.

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Visualization of the Results

To visualize the results, you can use the two Jupyter notebooks provided. To obtain the results of the ODP_926 data, just modify the variable configuration_file_path in the following way:

configuration_file_path = "odp_926"

And then the visualization notebook will be ready to be executed.

For a detailed guide on using the notebooks and interpreting the figures, please refer to Visualization of the Results Guide.