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© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Farrell, U. C., Samawi, R., Anjanappa, S., Klykov, R., Adeboye, O. O., Agic, H., Ahm, A.-S. C., Boag, T. H., Bowyer, F., Brocks, J. J., Brunoir, T. N., Canfield, D. E., Chen, X., Cheng, M., Clarkson, M. O., Cole, D. B., Cordie, D. R., Crockford, P. W., Cui, H., Dahl, T. W., Mouro, L. D., Dewing, K., Dornbos, S. Q., Drabon, N., Dumoulin, J. A., Emmings, J. F., Endriga, C. R., Fraser, T. A., Gaines, R. R., Gaschnig, R. M., Gibson, T. M., Gilleaudeau, G. J., Gill, B. C., Goldberg, K., Guilbaud, R., Halverson, G. P., Hammarlund, E. U., Hantsoo, K. G., Henderson, M. A., Hodgskiss, M. S. W., Horner, Tristan J., Husson, J. M., Johnson, B., Kabanov, P., Brenhin K. C., Kimmig, J., Kipp, M. A., Knoll, A. H., Kreitsmann, T., Kunzmann, M., Kurzweil, F., LeRoy, M. A., Li, C., Lipp, A. G., Loydell, D. K., Lu, X., Macdonald, F. A., Magnall, J. M., Mänd, K., Mehra, A., Melchin, M. J., Miller, A. J., Mills, N. T., Mwinde, C. N., O'Connell, B., Och, L. M., Ossa Ossa, F., Pagès, A., Paiste, K., Partin, C. A., Peters, S. E., Petrov, P., Playter, T. L., Plaza-Torres, S., Porter, Susannah M., Poulton, S. W., Pruss, S. B., Richoz, S., Ritzer, S. R., Rooney, A. D., Sahoo, S. K., Schoepfer, S. D., Sclafani, J. A., Shen, Y., Shorttle, O., Slotznick, S. P., Smith, E. F., Spinks, S., Stockey, R. G., Strauss, J. V., Stüeken, E. E., Tecklenburg, S., Thomson, D., Tosca, N. J., Uhlein, G. J., Vizcaíno, M. N., Wang, H., White, T., Wilby, P. R., Woltz, C. R., Wood, R. A., Xiang, L., Yurchenko, I. A., Zhang, T., Planavsky, N. J., Lau, K. V., Johnston, D. T., Sperling, E. A., The Sedimentary Geochemistry and Paleoenvironments Project. Geobiology. 00, (2021): 1– 12,https://doi.org/10.1111/gbi.12462., Geobiology explores how Earth's system has changed over the course of geologic history and how living organisms on this planet are impacted by or are indeed causing these changes. For decades, geologists, paleontologists, and geochemists have generated data to investigate these topics. Foundational efforts in sedimentary geochemistry utilized spreadsheets for data storage and analysis, suitable for several thousand samples, but not practical or scalable for larger, more complex datasets. As results have accumulated, researchers have increasingly gravitated toward larger compilations and statistical tools. New data frameworks have become necessary to handle larger sample sets and encourage more sophisticated or even standardized statistical analyses. In this paper, we describe the Sedimentary Geochemistry and Paleoenvironments Project (SGP; Figure 1), which is an open, community-oriented, database-driven research consortium. The goals of SGP are to (1) create a relational database tailored to the needs of the deep-time (millions to billions of years) sedimentary geochemical research community, including assembling and curating published and associated unpublished data; (2) create a website where data can be retrieved in a flexible way; and (3) build a collaborative consortium where researchers are incentivized to contribute data by giving them priority access and the opportunity to work on exciting questions in group papers. Finally, and more idealistically, the goal was to establish a culture of modern data management and data analysis in sedimentary geochemistry. Relative to many other fields, the main emphasis in our field has been on instrument measurement of sedimentary geochemical data rather than data analysis (compared with fields like ecology, for instance, where the post-experiment ANOVA (analysis of variance) is customary). Thus, the longer-term goal was to build a collaborative environment where geobiologists and geologists can work and learn together to, We thank the donors of The American Chemical Society Petroleum Research Fund for partial support of SGP website development (61017-ND2). EAS is funded by National Science Foundation grant (NSF) EAR-1922966. BGS authors (JE, PW) publish with permission of the Executive Director of the British Geological Survey, UKRI.

The extent to which Paleozoic oceans differed from Neoproterozoic oceans and the causal relationship between biological evolution and changing environmental conditions are heavily debated. Here, we report a nearly continuous record of seafloor redox change from the deep-water upper Cambrian to Middle Devonian Road River Group of Yukon, Canada. Bottom waters were largely anoxic in the Richardson trough during the entirety of Road River Group deposition, while independent evidence from iron speciation and Mo/U ratios show that the biogeochemical nature of anoxia changed through time. Both in Yukon and globally, Ordovician through Early Devonian anoxic waters were broadly ferruginous (nonsulfidic), with a transition toward more euxinic (sulfidic) conditions in the mid–Early Devonian (Pragian), coincident with the early diversification of vascular plants and disappearance of graptolites. This ~80-million-year interval of the Paleozoic characterized by widespread ferruginous bottom waters represents a persistence of Neoproterozoic-like marine redox conditions well into the Phanerozoic.

The extent to which Paleozoic oceans differed from Neoproterozoic oceans and the causal relationship between biological evolution and changing environmental conditions are heavily debated. Here, we report a nearly continuous record of seafloor redox change from the deep-water upper Cambrian to Middle Devonian Road River Group of Yukon, Canada. Bottom waters were largely anoxic in the Richardson trough during the entirety of Road River Group deposition, while independent evidence from iron speciation and Mo/U ratios show that the biogeochemical nature of anoxia changed through time. Both in Yukon and globally, Ordovician through Early Devonian anoxic waters were broadly ferruginous (nonsulfidic), with a transition toward more euxinic (sulfidic) conditions in the mid–Early Devonian (Pragian), coincident with the early diversification of vascular plants and disappearance of graptolites. This ~80-million-year interval of the Paleozoic characterized by widespread ferruginous bottom waters represents a persistence of Neoproterozoic-like marine redox conditions well into the Phanerozoic.

The Trezona carbon isotope excursion is recorded on five different continents in platform carbonates deposited prior to the end-Cryogenian Marinoan glaciation (>635 Ma) and represents a change in carbon isotope values of 16–18‰. Based on the spatial and temporal reproducibility, the excursion previously has been interpreted as tracking the carbon isotopic composition of dissolved inorganic carbon in the global ocean before the descent into a snowball Earth. However, in modern restricted shallow marine and freshwater settings, carbon isotope values have a similarly large range, which is mostly independent from open ocean chemistry and instead reflects local processes. In this study, we combine calcium, magnesium, and strontium isotope geochemistry with a numerical model of carbonate diagenesis to disentangle the degree to which the Trezona excursion reflects changes in global seawater chemistry versus local shallow-water platform environments. Our analysis demonstrates that the most extreme carbon isotope values (∼-10‰ versus +10‰) are preserved in former platform aragonite that was neomorphosed to calcite during sediment-buffered conditions and record the primary carbon isotope composition of platform-top surface waters. In contrast, the downturn and recovery of the Trezona excursion are recorded in carbonates that were altered during early fluid-buffered diagenesis and commonly are dolomitized. We also find that the nadir of the Trezona excursion is associated with a fractional increase in siliciclastic sediments, whereas the recovery from the excursion correlates with a relative increase in carbonate. This relationship suggests that the extreme negative isotopic shift in platform aragonite occurred in concert with periods of increased input of siliciclastic sediments, changes in water depth, and possibly nutrients to platform environments. Although the process for generating extremely negative carbon isotope values in Neoproterozoic platform carbonates remai

The rise of animals occurred during an interval of Earth history that witnessed dynamic marine redox conditions, potentially rapid plate motions, and uniquely large perturbations to global biogeochemical cycles. The largest of these perturbations, the Shuram carbon isotope excursion, has been invoked as a driving mechanism for Ediacaran environmental change, possibly linked with evolutionary innovation or extinction. However, there are a number of controversies surrounding the Shuram, including its timing, duration, and role in the concomitant biological and biogeochemical upheavals. Here we present radioisotopic dates bracketing the Shuram on two separate paleocontinents; our results are consistent with a global and synchronous event between 574.0 ± 4.7 and 567.3 ± 3.0 Ma. These dates support the interpretation that the Shuram is a primary and synchronous event postdating the Gaskiers glaciation. In addition, our Re-Os ages suggest that the appearance of Ediacaran macrofossils in northwestern Canada is identical, within uncertainty, to similar macrofossils from the Conception Group of Newfoundland, highlighting the coeval appearance of macroscopic metazoans across two paleocontinents. Our temporal framework for the terminal Proterozoic is a critical step for testing hypotheses related to extreme carbon isotope excursions and their role in the evolution of complex life.

The timing of Svalbard's assembly in relation to the mid-Paleozoic Caledonian collision between Baltica and Laurentia remains contentious. The Svalbard archipelago consists of three basement provinces bounded by N-S-trending strike-slip faults whose displacement histories are poorly understood. Here, we report microstructural and mineral chemistry data integrated with Ar-40/Ar-39 muscovite geochronology from the sinistral Vimsodden-Kosibapasset Shear Zone (VKSZ, southwest Svalbard) and explore its relationship to adjacent structures and regional deformation within the circum-Arctic. Our results indicate that strike-slip displacement along the VKSZ occurred in late Silurian-Early Devonian and was contemporaneous with the beginning of the main phase of continental collision in Greenland and Scandinavia and the onset of syn-orogenic sedimentation in Silurian-Devonian fault-controlled basins in northern Svalbard. These new-age constraints highlight possible links between escape tectonics in the Caledonian orogen and mid-Paleozoic terrane transfer across the northern margin of Laurentia.

The beginning of the Ediacaran Period (∼635 Ma) is marked by conspicuous dolostone units that cap Marinoan glacial deposits worldwide. The extent and sedimentary characteristics of the cap dolostones indicate that anomalous carbonate over-saturation coincided with deglacial sea-level rise and ocean warming. However, the geochemical variability within cap dolostones, both between continents, across single continental margins, and within individual stratigraphic sections has been difficult to reconcile with depositional models. Using a compilation of new calcium and magnesium isotope measurements in Marinoan cap dolostone successions worldwide, we show that the geochemical variability can be explained by early diagenetic dolomitization of aragonite along a spectrum of fluid- and sediment-buffered conditions. Dolostones from the outer platform formed under fluid-buffered conditions, whereas dolostones on the inner platform and foreslope environment formed under sediment-buffered conditions. This spatial pattern of dolomitizing conditions is consistent with buoyant recirculation of glacial seawater within carbonate platforms driven by the deglacial sea-level rise and development of a meltwater surface ocean. Using a numerical diagenetic model to evaluate the geochemical differences between sediment- and fluid-buffered cap dolostone units, we constrain the chemical and isotopic composition of both the dolomitizing fluid (glacial seawater [δ13C ∼ 0–2‰]), the meltwater lens (δ13C ∼−11‰), and the primary aragonite sediment (δ13C ∼−6 to −3‰). These model end-members do not imply that primary geochemical variability did not exist but demonstrates that it is not necessary to change the chemistry of seawater to explain the global stratigraphic variability in the geochemistry of basal Ediacaran cap dolostones. Our results provide a novel framework for understanding the geochemical variability of cap dolostone units, including large excursions

SIMS U-Pb zircon dating of metaigneous rocks of the Nordbreen Nappe from the West Ny-Friesland terrane (Eastern Basement Province of Svalbard) yields crystallization ages of 1,761 +/- 4 Ma for a felsic metatuff and 1,373 +/- 4 Ma for a metagabbro dyke. The Palaeoproterozoic age of the metatuff is similar to previously obtained ages for various felsic rocks from the study area, whereas the Mesoproterozoic age of the metagabbro has not been thus far documented on Svalbard. However, a similar age pattern has been reported from Northeast Greenland. Therefore, we conclude that the West Ny-Friesland terrane can be correlated with age equivalent units of Northeast Greenland. We also explore similarities and dissimilarities between the study area and other terranes of Svalbard and speculate on regional-scale correlations. Together, the presented new ages provide critical piercing points in palaeogeographic reconstructions of the relatively poorly understood circum-Arctic region.

Microfossils, stromatolites, preserved lipids and biologically informative isotopic ratios provide a substantial record of bacterial diversity and biogeochemical cycles in Proterozoic (2500-541 Ma) oceans that can be interpreted, at least broadly, in terms of present-day organisms and metabolic processes. Archean (more than 2500 Ma) sedimentary rocks add at least a billion years to the recorded history of life, with sedimentological and biogeochemical evidence for life at 3500 Ma, and possibly earlier; phylogenetic and functional details, however, are limited. Geochemistry provides a major constraint on early evolution, indicating that the first bacteria were shaped by anoxic environments, with distinct patterns of major and micronutrient availability. Archean rocks appear to record the Earth’s first iron age, with reduced Fe as the principal electron donor for photosynthesis, oxidized Fe the most abundant terminal electron acceptor for respiration, and Fe a key cofactor in proteins. With the permanent oxygenation of the atmosphere and surface ocean ca 2400 Ma, photic zone O2 limited the access of photosynthetic bacteria to electron donors other thanwater,while expanding the inventory of oxidants available for respiration and chemoautotrophy. Thus, halfway through Earth history, the microbial underpinnings of modern marine ecosystems began to take shape., Massachusetts Institute of Technology, Harvard University (Junior Fellowship)

After nearly a billion years with no evidence for glaciation, ice advanced to equatorial latitudes at least twice between 717 and 635 Mya. Although the initiation mechanism of these Neoproterozoic Snowball Earth events has remained a mystery, the broad synchronicity of rifting of the supercontinent Rodinia, the emplacement of large igneous provinces at low latitude, and the onset of the Sturtian glaciation has suggested a tectonic forcing. We present unique Re-Os geochronology and high-resolution Os and Sr isotope profiles bracketing Sturtian-age glacial deposits of the Rapitan Group in northwest Canada. Coupled with existing U-Pb dates, the postglacial Re-Os date of 662.4 ± 3.9 Mya represents direct geochronological constraints for both the onset and demise of a Cryogenian glaciation from the same continental margin and suggests a 55-My duration of the Sturtian glacial epoch. The Os and Sr isotope data allow us to assess the relative weathering input of old radiogenic crust and more juvenile, mantle-derived substrate. The preglacial isotopic signals are consistent with an enhanced contribution of juvenile material to the oceans and glacial initiation through enhanced global weatherability. In contrast, postglacial strata feature radiogenic Os and Sr isotope compositions indicative of extensive glacial scouring of the continents and intense silicate weathering in a post–Snowball Earth hothouse., Agouron Institute