Ait-Itto, Fatima-Zahra

Batenburg, Sietske

Huber, Brian T.

Jones, Matthew M.

Martinez, Mathieu

National audienceAn exceptional record of Cretaceous climate and carbon cycle perturbations wasrecovered at Site U1513 in the Mentelle Basin, southwest of Australia at a paleolatitudeof 60°S, during IODP Expedition (Huber et al., 2019). However, sediments across theAlbian–Cenomanian transition (307.10 to 282.61 m) are barren of microfossils, andthis lack of biostratigraphic indicators limits our ability to study paleoenvironmentalchange. Here we present results from cyclostratigraphic analyses, which provide newage constraints for the Albian-Cenomanian boundary. Time series analysis of highresolution(2 cm) elemental data obtained through XRF core-scanning and naturalgamma radiation confirm the influence of orbital forcing. Filtering the 3.5 m periodicity,which likely corresponds to the short (100 kyr) component of eccentricity-modulatedprecession, leads to a duration estimate of 64*100= 6.4 Myr for the interval coveringthe Albian–Cenomanian transition (from 387m to 285.45 m). Independently derivedlogging data of natural gamma radiation reveal a similar number of short eccentricitycycles. The barren interval contain 23 cyles of short eccentricity suggesting a durationof 23*100=2.3 Myr. The clear expression of short eccentricity cycles allows us toestimate the duration of the barren interval at 2.3 Myr. This astronomical time scaleprovides an age model to reconstruct the timing of changes in Cretaceous oceanographyand sedimentation in the Mentelle Basin, and highlights the sensitivity of southern highlatitude paleoclimate to eccentricity forcing

Batenburg, Sietske J.

Huber, Brian

Jones, Matthew, R

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Orbital Turning of the upper Albian from the site U1513D– Palaeoenvironmental implications

Orbital Turning of the upper Albian from the site U1513D - Palaeoenvironmental implications

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Orbital Turning of the upper Albian from the site U1513D - Palaeoenvironmental implications

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