Use of insolation as a proxy for high-frequency eustasy in forward modeling of platform carbonate cyclostratigraphy — A promising approach

Eustatic oscillations driven by Milankovitchian astronomical forcing have been interpreted as sea-level drivers for high-frequency carbonate depositional cycles in studies dating from the mid-1960s. Forward modeling of these oscillations with respect to their recorded effects on cyclical stacking patterns has only been attempted using generalized parameters for Milankovitchian forcing. The development of increasingly advanced forward modeling software, coupled with the availability of formulas quantifying insolation (incoming solar radiation) as a function of composite orbital variations allows for the testing of Milankovitchian insolation against measured stratigraphy. In this case, a series of Milankovitchian insolation curves were calculated and used to generate proxy sea-level curves for use in the Carb3D+ forward modeling package in order to synthesize a series of stacked carbonate strata. These synthetic successions are compared against that of the Latemar platform (middleTriassic, northern Italy), which has been interpreted to contain a record of orbital forcing within its stratigraphy. While the timing and nature of periodic drivers that affected Latemar stratigraphy have stirred a vigorous debate, results from this study indicate that use of Milankovitchian insolation as a proxy for high-frequency sea-level oscillations was successful in modeling Latemar-like stratigraphy with both pure Milankovitchian and mixed Milankovitchian–sub-Milankovitchian temporal frameworks.

Research Highlights
► Strengthening the link between Milankovitchian orbital processes and the carbonate depositional record.
► Using Milankovitchian insolation as a proxy for eustasy produces vertical stacking patters consistent with those measured in outcrop.
► Using Milankovitchian insolation as a proxy for eustasy is a way forward for carbonate stratigraphic modeling