Additional supporting information can be found in the online version of this article:

jqs2649-sm-0001-SuppFig-S1.eps7621KFig. S1. Valve chart of the laser fluorination line (Chapligin et al., 2010) with a detailed description of the new SiF4 separation line.
jqs2649-sm-0001-SuppFig-S2.eps910KFig. S2. Cross-plot of δ29Si and δ30Si of PS1772-8bsis and BFC, showing a mass-dependent fractionation of the silicon isotopes and the high purity of the SiF4 samples.
jqs2649-sm-0001-SuppFig-S3.eps1311KFig. S3. Test for memory effects and required minimum sample weight for the whole instrumentation set-up.
jqs2649-sm-0001-SuppFig-S4.tif18090KFig. S4. SEM and light microscopic pictures of C. oculus-iridis and C. marginatus from the subarctic NW Pacific.
jqs2649-sm-0001-SuppTab-S1.xls46KTable S1 Elemental compositions, determined by EDS and ICP-OES analysis.
jqs2649-sm-0001-SuppTab-S2.xls52KTable S2 Composition of purified diatom samples determined by light microscopy.

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