Lomb periodogram of the CENOGRID (Westerhold et al., 2020; Table S34) series. To be noted that the Milankovich cycles do not appear: they need an enlargement of the spectrum in order to outline very low-power Milankovitch cycles, as in figure 3.

The spectral maximum at ~30 Myr has been addressed by e.g. Johnson & Rich (1986): A 30 Million Year Cycle in Arctic Volcanism? where they wrote: If medial times are assigned to those in Table I then the volcanic activity peaks for the Cenozoic-Mesozoic is 27 my, which is remarkably consistent with the approximate 30 my cycle predicted by Fisher (1982).

Fisher (1982) wrote: Fischer and Arthur (1977) suggested that the Mesozoic-Cenozoic part of Earth history is logically subdivided not into four periods as currently practiced but into seven, with a mean duration of 32 m.y., corresponding essentially to Grabau’s (1940) seven pulses: the Triassic, Liassic, “Jurassic”, Comanchean, Gulfian or “Cretaceous,” Paleogene, and Neogene. Each of these corresponds to an expansion of organic diversity in the pelagic marine realm (development of polytaxy) followed by a decline to an “oligotaxic” state. And also: This pattern appears in global counts of coexisting genera and species as well as in the structure of marine communities, ....