Orbital forcing of Upper Jurassic (Tithonian) shallow-water carbonates, Tethyan Adriatic Platform, Croatia evaluated using synthetic vs. real data sets

Milankovitch Record From Middle Jurassic Platform Supports Moderate Coolhouse Glaciation

“…Although the ASM rates were obtained using a modified La2004 target and empirical data (Table 1), the fact that the estimated ASM accumulation rate is within the range of the estimated long‐term or average rate, suggests that the tuning is valid (cf. Husinec et al., 2023 on real and synthetic Jurassic data sets). Expanding the low‐frequency interval (Figures 8d–8f) yields peaks at 120 kyr, 175 kyr (short obliquity modulation), and 200 kyr (<95%), 420–500 kyr (long eccentricity?…”

“…These include variable accommodation rate, variable duration of nondeposition within parasequences (typically associated with lag depths at bases, and supratidal nondeposition at parasequence tops), variable incremental sedimentation rates, and submarine erosion events. Synthetic models (Husinec et al., 2023; Kemp et al., 2016; Kemp & van Manen, 2019) show that in spite of the variability of these processes, time‐averaging of these processes at the parasequence (10 4 year) scale allows the sediment system to capture a fairly accurate Milankovitch record down to the precession level. This occurred in synthetic successions even with a considerable random walk of sea level, and randomly chosen sedimentation rates/time slice.…”

“…Because facies on modern platforms have strongly overlapping water depth ranges and thus poor discrimination between water depth and facies type (Geyman et al., 2021; Harris et al., 2015; Kaczmarek & Hasiuk, 2008), we use a proximal (inboard, tidal flat) to distal (shelf margin grainstone) ranking that reflects energy and degree of winnowing of mud (cf., Husinec et al., 2023). The sedimentary facies are described in Husinec et al.…”

“…The relatively short covered intervals in the analyzed section were filled by the lithology at the base of the covered interval. A second time series (Figure 6c) of parasequence (cycle) thickness‐stratigraphic position (m) was constructed plotting the stratigraphic position (m) of parasequence tops against the thickness of each parasequence (Table S2 in Husinec and Read (2023)). This data set was used to examine the bundling of parasequences and the presence of any longer‐term cycles greater than the meter‐scale parasequences.…”