Natural sampling and aliasing of marine geochemical signals.

It is well known that the sedimentary rock record is both incomplete and biased by spatially highly variable rates of sedimentation. Without absolute age constraints of sufficient resolution, the temporal correlation of spatially disjunct records is therefore problematic and uncertain, but these effects have rarely been analysed quantitatively using signal processing methods. Here we use a computational process model to illustrate and analyse how spatial and temporal geochemical records can be biased by the inherent, heterogenous processes of marine sedimentation and preservation.

Sea level controls on Ediacaran-Cambrian animal radiations.

The drivers of Ediacaran-Cambrian metazoan radiations remain unclear, as does the fidelity of the record. We use a global age framework [580-510 million years (Ma) ago] to estimate changes in marine sedimentary rock volume and area, reconstructed biodiversity (mean genus richness), and sampling intensity, integrated with carbonate carbon isotopes (δC) and global redox data [carbonate Uranium isotopes (δU)]. Sampling intensity correlates with overall mean reconstructed biodiversity >535 Ma ago, while second-order (~10-80 Ma) global transgressive-regressive cycles controlled the distribution of different marine sedimentary rocks.

Dynamic redox and nutrient cycling response to climate forcing in the Mesoproterozoic ocean.

Controls on Mesoproterozoic ocean redox heterogeneity, and links to nutrient cycling and oxygenation feedbacks, remain poorly resolved. Here, we report ocean redox and phosphorus cycling across two high-resolution sections from the ~1.4 Ga Xiamaling Formation, North China Craton.

Cambrian radiation speciation events driven by sea level and redoxcline changes on the Siberian Craton.

The evolutionary processes of speciation during the Cambrian radiation and their potential extrinsic drivers, such as episodic oceanic oxygenation events, remain unconfirmed. High-resolution temporal and spatial distribution of reef-associated archaeocyath sponge species on the Siberian Craton during the early Cambrian [ca. 528 to 510 million years ago] shows that speciation was driven by increased endemism particularly ca.

Increases in reef size, habitat and metacommunity complexity associated with Cambrian radiation oxygenation pulses.

Oxygenation during the Cambrian Radiation progressed via a series of short-lived pulses. However, the metazoan biotic response to this episodic oxygenation has not been quantified, nor have the causal evolutionary processes been constrained. Here we present ecological analyses of Cambrian archaeocyath sponge reef communities on the Siberian Platform (525-514 Ma).

The tempo of Ediacaran evolution.

The rise of complex macroscopic life occurred during the Ediacaran Period, an interval that witnessed large-scale disturbances to biogeochemical systems. The current Ediacaran chronostratigraphic framework is of insufficient resolution to provide robust global correlation schemes or test hypotheses for the role of biogeochemical cycling in the evolution of complex life. Here, we present new radio-isotopic dates from Ediacaran strata that directly constrain key fossil assemblages and large-magnitude carbon cycle perturbations.