GEOTRACES-PAGES workshop report 2019

GEOTRACES-PAGES Workshop Synthesis Publications

The GEOTRACES-PAGES workshop on geochemical proxies used in paleoceanography was held nearly 3 years ago, from 3-5 December 2018, in Aix-Marseilles France.

The workshop aimed to establish the strength, limits and conditions of application of a given proxy. It was felt there is a vital need for a synthesis of geochemical proxies used in paleoceanography to improve interpretation of commonly used proxies. This synthesis is timely in view of the wealth of new data coming from GEOTRACES and contemporary programs.

Four synthesis papers have since been published as an outgrowth of stimulating discussions that were held during this workshop:  

  • Costa KM et al. have published "230Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean" in Paleoceanography and Paleoclimatology. The authors synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the Late Holocene (0-5000 years ago, or 0-5 ka) and the Last Glacial Maximum (18.5-23.5ka), and investigated the spatial structure of 230Th-normalized mass fluxes:
  • Hayes CT et al. have published "Global Ocean Sediment Composition and Burial Flux in the Deep Sea" in Global Biogeochemical Cycles. Their new compilation of seafloor sedimentary fluxes provides detailed regional and global information, which will help refine the understanding of sediment preservation:
  • Horner TJ et al. have published "Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES-Era Data, Global Biogeochemical Cycles". The authors review the oceanic distributions, driving processes, and depositional archives for nine metals and their isotopes based on GEOTRACES-era datasets. They offer an assessment of the overall maturity of each isotope system to serve as a proxy for diagnosing aspects of past ocean productivity and identify priorities for future research:
  • Farmer JR et al. have published "Assessment of C, N, and Si Isotopes as Tracers of Past Ocean Nutrient and Carbon Cycling" in Global Biogeochemical Cycles. The authors compile water column C, N, and Si stable isotopes from GEOTRACES-era data in four key ocean regions to review geochemical proxies of oceanic carbon and nutrient cycling based on the C, N, and Si isotopic composition of marine sediments. The review highlights opportunities for future research and emphasizes the importance of such applications to reconstructing past changes in the oceans and climate system:

The workshop was funded by the US National Science Foundation (NSF) through the GEOTRACES program, the international PAGES project, which in turn received support from the Swiss Academy of Sciences and NSF, and the French national program LEFE (Les Enveloppes Fluides et l'Environment). Thank you to the GEOTRACES-PAGES workshop organizers, particularly Bob Anderson, Catherine Jeandel, Laurence Vidal, and Kazuyo Tachikawa.