Knoll Andrew H.
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ArticleThe Sedimentary Geochemistry and Paleoenvironments Project(Wiley, 2021-07-05) Farrell, Úna C. ; Samawi, Rifaat ; Anjanappa, Savitha ; Klykov, Roman ; Adeboye, Oyeleye O. ; Agic, Heda ; Ahm, Anne-Sofie C. ; Boag, Thomas H. ; Bowyer, Fred ; Brocks, Jochen J. ; Brunoir, Tessa N. ; Canfield, Donald E. ; Chen, Xiaoyan ; Cheng, Meng ; Clarkson, Matthew O. ; Cole, Devon B. ; Cordie, David R. ; Crockford, Peter W. ; Cui, Huan ; Dahl, Tais W. ; Mouro, Lucas D. ; Dewing, Keith ; Dornbos, Stephen Q. ; Drabon, Nadja ; Dumoulin, Julie A. ; Emmings, Joseph F. ; Endriga, Cecilia R. ; Fraser, Tiffani A. ; Gaines, Robert R. ; Gaschnig, Richard M. ; Gibson, Timothy M. ; Gilleaudeau, Geoffrey J. ; Gill, Benjamin C. ; Goldberg, Karin ; Guilbaud, Romain ; Halverson, Galen P. ; Hammarlund, Emma U. ; Hantsoo, Kalev G. ; Henderson, Miles A. ; Hodgskiss, Malcolm S. W. ; Horner, Tristan J. ; Husson, Jon M. ; Johnson, Benjamin ; Kabanov, Pavel ; Keller, C. Brenhin ; Kimmig, Julien ; Kipp, Michael A. ; Knoll, Andrew H. ; Kreitsmann, Timmu ; Kunzmann, Marcus ; Kurzweil, Florian ; LeRoy, Matthew A. ; Li, Chao ; Lipp, Alex G. ; Loydell, David K. ; Lu, Xinze ; Macdonald, Francis A. ; Magnall, Joseph M. ; Mänd, Kaarel ; Mehra, Akshay ; Melchin, Michael J. ; Miller, Austin J. ; Mills, N. Tanner ; Mwinde, Chiza N. ; O'Connell, Brennan ; Och, Lawrence M. ; Ossa Ossa, Frantz ; Pagès, Anais ; Paiste, Kärt ; Partin, Camille A. ; Peters, Shanan E. ; Petrov, Peter ; Playter, Tiffany L. ; Plaza-Torres, Stephanie ; Porter, Susannah M. ; Poulton, Simon W. ; Pruss, Sara ; Richoz, Sylvain ; Ritzer, Samantha R. ; Rooney, Alan D. ; Sahoo, Swapan K. ; Schoepfer, Shane D. ; Sclafani, Judith A. ; Shen, Yanan ; Shorttle, Oliver ; Slotznick, Sarah P. ; Smith, Emily F. ; Spinks, Sam ; Stockey, Richard G. ; Strauss, Justin V. ; Stüeken, Eva E. ; Tecklenburg, Sabrina ; Thomson, Danielle ; Tosca, Nicholas J. ; Uhlein, Gabriel J. ; Vizcaíno, Maoli N. ; Wang, Huajian ; White, Tristan ; Wilby, Philip R. ; Woltz, Christina R. ; Wood, Rachel A. ; Xiang, Lei ; Yurchenko, Inessa A. ; Zhang, Tianran ; Planavsky, Noah J. ; Lau, Kimberly V. ; Johnston, David T. ; Sperling, Erik A.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 assess changes in geochemical signatures through Earth history.
PreprintPerspectives on Proterozoic surface ocean redox from iodine contents in ancient and recent carbonate( 2017-01) Hardisty, Dalton S. ; Lu, Zunli ; Bekker, Andrey ; Diamond, Charles W. ; Gill, Benjamin C. ; Jiang, Ganqing ; Kah, Linda ; Knoll, Andrew H. ; Loyd, Sean ; Osburn, Magdalena ; Planavsky, Noah J.The Proterozoic Eon hosted the emergence and initial recorded diversification of eukaryotes. Oxygen levels in the shallow marine settings critical to these events were lower than today’s, although how much lower is debated. Here, we use concentrations of iodate (the oxidized iodine species) in shallow-marine limestones and dolostones to generate the first comprehensive record of Proterozoic near-surface marine redox conditions. The iodine proxy is sensitive to both local oxygen availability and the relative proximity to anoxic waters. To assess the validity of our approach, Neogene-Quaternary carbonates are used to demonstrate that diagenesis most often decreases and is unlikely to increase carbonate-iodine contents. Despite the potential for diagenetic loss, maximum Proterozoic carbonate iodine levels are elevated relative to those of the Archean, particularly during the Lomagundi and Shuram carbon isotope excursions of the Paleo- and Neoproterozoic, respectively. For the Shuram anomaly, comparisons to Neogene-Quaternary carbonates suggest that diagenesis is not responsible for the observed iodine trends. The baseline low iodine levels in Proterozoic carbonates, relative to the Phanerozoic, are linked to a shallow oxic-anoxic interface. Oxygen concentrations in surface waters would have at least intermittently been above the threshold required to support eukaryotes. However, the diagnostically low iodine data from mid-Proterozoic shallow-water carbonates, relative to those of the bracketing time intervals, are consistent with a dynamic chemocline and anoxic waters that would have episodically mixed upward and laterally into the shallow oceans. This redox instability may have challenged early eukaryotic diversification and expansion, creating an evolutionary landscape unfavorable for the emergence of animals.