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

Xiong, Zhifang, Li, Tiegang, Algeo, Thomas, Doering, Kristin, Frank, Martin , Brzezinski, Mark A., Chang, Fengming, Opfergelt, Sophie, Crosta, Xavier, Jiang, Fuqing, Wan, Shiming and Zhai, Bin (2015) The silicon isotope composition of Ethmodiscus rexlaminated diatom mats from the tropical West Pacific: Implications for silicate cycling during the Last Glacial Maximum. Open Access Paleoceanography, 30 (7). pp. 803-823. DOI 10.1002/2015PA002793.

[img]
Preview
Text
Xiong et.al.pdf - Published Version

Download (5Mb) | Preview

Supplementary data:

Abstract

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.

Document Type: Article
Additional Information: WOS:000360058100001
Keywords: giant diatoms; silicon isotopes; eolian dust; seawater silicon; marine productivity; deep chlorophyll maximum
Research affiliation: OceanRep > SFB 754
Kiel University
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2015PA002793
ISSN: 0883-8305
Projects: SFB754
Date Deposited: 23 Jul 2015 08:36
Last Modified: 19 Dec 2017 12:51
URI: http://oceanrep.geomar.de/id/eprint/29294

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...