Skip to content

Research at St Andrews

Spatial and temporal trends in Precambrian nitrogen cycling: a Mesoproterozoic offshore nitrate minimum

Research output: Contribution to journalArticle

Author(s)

Matthew C. Koehler, Eva E. Stüeken, Michael A. Kipp, Roger Buick, Andrew H. Knoll

School/Research organisations

Abstract

Fixed nitrogen is an essential nutrient for eukaryotes. As N2 fixation and assimilation of nitrate are catalyzed by metalloenzymes, it has been hypothesized that in Mesoproterozoic oceans nitrate was limited in offshore environments by low trace metal concentrations and high rates of denitrification in anoxic and episodically euxinic deep water masses, restricting eukaryotes to near-shore environments and limiting their evolutionary innovation. To date this hypothesis has only been tested in the Belt Supergroup (∼1.4 Ga), with results that support an onshore-offshore nitrate gradient as a potential control on eukaryote ecology. Here we present bulk nitrogen and organic carbon isotopic data from non-isochronous cross-basinal facies across the Bangemall (∼1.5 Ga) and the Roper (∼1.4-1.5 Ga) basins to better understand the extent and variability of onshore-offshore nitrogen isotope gradients in the Mesoproterozoic. Both basins show an average ∼1-2‰ enrichment in δ15Nbulk from deep to shallow facies, with a maximum range from -1‰ offshore to +7.5‰ onshore. Unlike the Belt basin, the Bangemall and Roper basins show some offshore δ15Nbulk values that are enriched beyond the isotopic range induced by biological N2 fixation alone. This suggests a mixture of aerobic and anaerobic metabolisms offshore. In shallow waters, where δ15Nbulk enrichment peaks, an aerobic nitrogen cycle was evidently operating vigorously. Even though isotopic signatures of aerobic nitrogen cycling are seen in all parts of the Bangemall and Roper basins, our data are consistent with a lateral gradient in nitrate availability within the photic zone, with higher concentrations in near-shore environments than offshore. The variability in δ15Nbulk values in each depositional environment and the consistently low δ15N values from Mesoproterozoic units compared to the Paleoproterozoic and Neoproterozoic suggest that nitrate concentrations in the global ocean were likely low. This trend is now seen in all three Mesoproterozoic basins so far examined, and contrasts with the Paleoproterozoic and Neoproterozoic where nearly all δ15Nbulk data plot above the N2 fixation window. Thus, we propose that the Mesoproterozoic ocean was characterized by a nitrate minimum between the Paleo- and Neoproterozoic, with the lowest concentrations in offshore environments. This inference is consistent with a Mesoproterozoic O2 decline following a temporary Paleoproterozoic O2 peak, and it further supports the idea that nitrate limitation offshore may have contributed to the restriction of photosynthetic eukaryotes to near-shore environments, delaying their rise to ecological dominance until the Neoproterozoic Era.
Close

Details

Original languageEnglish
Pages (from-to)315-337
Number of pages23
JournalGeochimica et Cosmochimica Acta
Volume198
Early online date16 Nov 2016
DOIs
Publication statusPublished - 1 Feb 2017

    Research areas

  • Mesoproterozoic, Nitrogen isotopes, Eukaryote evolution, Onshore-offshore gradients

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Sulphur isotopes of alkaline magmas unlock long-term records of crustal recycling on Earth

    Hutchison, W., Babiel, R., Finch, A. A., Marks, M., Markl, G., Boyce, A. J., Stüeken, E. E., Friis, H., Borst, A. M. & Horsburgh, N. J., 16 Sep 2019, In : Nature Communications. 10, 12 p., 4208.

    Research output: Contribution to journalArticle

  2. Coupled evolution of nitrogen cycling and redoxcline dynamics on the Yangtze Block across the Ediacaran-Cambrian transition

    Chen, Y., Diamond, C. W., Stüeken, E. E., Cai, C., Gill, B. C., Zhang, F., Bates, S. M., Chu, X., Ding, Y. & Lyons, T. W., 18 May 2019, In : Geochimica et Cosmochimica Acta. In press

    Research output: Contribution to journalArticle

  3. Effects of pH on redox proxies in a Jurassic rift lake: implications for interpreting environmental records in deep time

    Stüeken, E. E., Martinez, A., Love, G., Olsen, P. E., Bates, S. & Lyons, T. W., 1 May 2019, In : Geochimica et Cosmochimica Acta. 252, p. 240-267

    Research output: Contribution to journalArticle

  4. Limited oxygen production in the Mesoarchean ocean

    Ossa Ossa, F., Hofmann, A., Spangenberg, J. E., Poulton, S. W., Stüeken, E. E., Schoenberg, R., Eickmann, B., Wille, M., Butler, M. & Bekker, A., 2 Apr 2019, In : Proceedings of the National Academy of Sciences of the United States of America. 116, 14, p. 6647-6652 6 p.

    Research output: Contribution to journalArticle

Related by journal

  1. Coupled evolution of nitrogen cycling and redoxcline dynamics on the Yangtze Block across the Ediacaran-Cambrian transition

    Chen, Y., Diamond, C. W., Stüeken, E. E., Cai, C., Gill, B. C., Zhang, F., Bates, S. M., Chu, X., Ding, Y. & Lyons, T. W., 18 May 2019, In : Geochimica et Cosmochimica Acta. In press

    Research output: Contribution to journalArticle

  2. Decimeter-scale mapping of carbonate-controlled trace element distribution in Neoarchean cuspate stromatolites

    Warke, M. R., Edwards, N. P., Wogelius, R. A., Manning, P. L., Bergmann, U., Egerton, V. M., Kimball, K. C., Garwood, R. J., Beukes, N. J. & Schröder, S., 15 Sep 2019, In : Geochimica et Cosmochimica Acta. 261

    Research output: Contribution to journalArticle

  3. Effects of pH on redox proxies in a Jurassic rift lake: implications for interpreting environmental records in deep time

    Stüeken, E. E., Martinez, A., Love, G., Olsen, P. E., Bates, S. & Lyons, T. W., 1 May 2019, In : Geochimica et Cosmochimica Acta. 252, p. 240-267

    Research output: Contribution to journalArticle

  4. Experimentally determined Si isotope fractionation between zircon and quartz

    Trail, D., Savage, P. S. & Moynier, F., 1 Sep 2019, In : Geochimica et Cosmochimica Acta. 260, p. 257-274

    Research output: Contribution to journalArticle

  5. Isotopic fractionation of zirconium during magmatic differentiation and the stable isotope composition of the silicate Earth

    Inglis, E., Moynier, F., Creech, J., Deng, Z., Day, J., Teng, F-Z., Bizzarro, M., Jackson, M. & Savage, P., 1 Apr 2019, In : Geochimica et Cosmochimica Acta. 250, p. 311-323 13 p.

    Research output: Contribution to journalArticle

ID: 247731285