The original Figures 3B and 3C were missing six data points between hours 18 and 23 in the graphs of 9-C25:1. These modifications in the presentation offer no substantive change. The corrected version of the figure appears below. The authors regret this error. Figure 3. Cuticular Hydrocarbon Accumulation Is Regulated by a per-Dependent Clock and Is Influenced by Exposure to Light
Ocean chemistry and carbonate sedimentation link Earth's climate, carbon cycle, and marine pH. The carbonate system in seawater is complex and there are large uncertainties in key parameters in deep time. Here, we link sedimentary textures formed in arid coastal environments and preserved in the rock record to past seawater carbonate chemistry. Prior to the mid‐Mesozoic, tepee structures and pisoids – features associated with peritidal environments – co‐vary with available shelf area during cycles of supercontinent formation and rifting. In contrast, tepees and pisoids are consistently scarce after the mid‐Mesozoic, which coincides with a radiation in pelagic calcifiers as well as the breakup of Pangea. Numerical models suggest that the global and temporal abundances of tepee structures and pisoids are correlated with secular shifts in seawater chemistry, and that trends likely reflect the underlying influence of tectonics and biotic innovation on marine alkalinity and the saturation states of carbonate minerals. As independent sedimentary proxies, tepees and pisoids serve as benchmarks for global carbon cycle models and provide a new proxy record of seawater chemistry that can help discern links among tectonics, biotic innovation, and seawater chemistry.
In carbonate-forming environments, authigenic minerals can cement surface sediments into centimeter-sized intraclasts that are later reworked into "flat-pebble" or "edgewise" conglomerates. Flat-pebble conglomerates comprise only a small portion of facies in modern marine environments but are common in ancient strata, implying that seafloor cements were more widespread in the past. Flat-pebble conglomerates nearly disappeared after the Ordovician radiation, yet it is unclear if this decline was due to changing seawater chemistry or if increased infaunalization and bioturbation simply worked to break down nascent clasts. We discovered a process analog that produces flat-pebble conglomerates around the Great Salt Lake, Utah, USA, and studied these facies using field observations, wave models, satellite imagery, petrography, and microanalytic chemical data. Clasts were sourced from wave-rippled grainstone that cemented in situ in offshore environments. Lake floor cements formed under aragonite saturation states that are lower than modern marine settings, suggesting that physical processes are at least as important as chemical ones. Results from our wave models showed that coarse sediments near the field site experience quiescent periods of up to 6 months between suspension events, allowing isopachous cements to form. Using a simple mathematical framework, we show that the main difference between Great Salt Lake and modern, low-energy marine settings is that the latter has enough bioturbating organisms to break up clasts. Observations from Great Salt Lake demonstrate how geologic trends in flat-pebble abundance could largely reflect changes in total infaunal biomass and ecology without requiring regional-to-global changes in seawater chemistry. Plain Language Summary Calcium carbonate is a common sedimentary mineral that precipitates quickly under Earth surface conditions. If carbonate sediments are at rest for long periods of time, they may solidify via cementation into flat, pebble-sized clasts. Geologic trends show that flat pebbles are anticorrelated with burrows, suggesting they may tell us about animal evolution and ecology. However, it was unknown if animals disrupt clasts through chemical means, leading to slower rates of mineral growth, or if they physically push sediments apart, breaking up nascent cements. We studied flat pebbles forming in Great Salt Lake, Utah, where the water is too salty for burrowing animals. The composition of lake water should lead to slower growth rates for carbonate minerals, yet clasts still form. We conclude that pebbles form during quiescent intervals with little physical energy to move grains, either from waves or from burrowing organisms. As a result, ancient flat pebbles are probably not unique markers for seawater chemistry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.