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Kristin Doering

Kristin Doering

Researcher

Kristin Doering

The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific : Implications for silicate cycling during the Last Glacial Maximum

Author

  • Zhifang Xiong
  • Tiegang Li
  • Thomas Algeo
  • Kristin Doering
  • Martin Frank
  • Mark A. Brzezinski
  • Fengming Chang
  • Sophie Opfergelt
  • Xavier Crosta
  • Fuqing Jiang
  • Shiming Wan
  • Bin Zhai
Show all

Summary, in English

The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (δ30SiE. rex) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, δ30SiE. rex varies from -1.23‰ to -0.83‰ (average -1.04‰), a range that is atypical of marine diatom δ30Si and that corresponds to the lower limit of reported diatom δ30Si values of any age. A binary mixing model (upwelled silicon versus eolian silicon) accounting for silicon isotopic fractionation during DSi uptake by diatoms was constructed. The binary mixing model demonstrates that E. rex dominantly utilized DSi from eolian sources (i.e., Asian dust) with only minor contributions from upwelled seawater sources (i.e., advected from Subantarctic Mode Water, Antarctic Intermediate Water, or North Pacific Intermediate Water). E. rex utilized only ∼24% of available DSi, indicating that surface waters of the EPS were eutrophic with respect to silicon during the LGM. Our results suggest that giant diatoms did not always use a buoyancy strategy to obtain nutrients from the deep nutrient pool, thus revising previously proposed models for the formation of E. rex LDMs.

Publishing year

2015-07-01

Language

English

Pages

803-823

Publication/Series

Paleoceanography

Volume

30

Issue

7

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Oceanography, Hydrology, Water Resources

Keywords

  • deep chlorophyll maximum
  • eolian dust
  • giant diatoms
  • marine productivity
  • seawater silicon
  • silicon isotopes

Status

Published

ISBN/ISSN/Other

  • ISSN: 0883-8305