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Daily growth and tidal rhythms in Miocene and modern giant clams revealed via ultra-high resolution LA-ICPMS analysis -- A novel methodological approach towards improved sclerochemistry

Warter, Viola ; Muller, Wolfgang

Palaeogeography, Palaeoclimatology, Palaeoecology, Jan 1, 2017, Vol.465, p.362(14) [Rivista Peer Reviewed]

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  • Titolo:
    Daily growth and tidal rhythms in Miocene and modern giant clams revealed via ultra-high resolution LA-ICPMS analysis -- A novel methodological approach towards improved sclerochemistry
  • Autore: Warter, Viola ; Muller, Wolfgang
  • Descrizione: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.palaeo.2016.03.019 Byline: Viola Warter, Wolfgang Muller Abstract: We present a novel approach for ultra-high resolution laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICPMS) analysis, which not only allows us to clearly resolve <10[mu]m (daily) compositional variability in B/Ca, Mg/Ca, Sr/Ca and Ba/Ca, but also to detect long-term tidal and seasonal cycles in both Miocene and modern Tridacna (giant clam) shells. Daily element/Ca variability preserved within microscopically visible growth increments is resolved by utilizing the combined capabilities of a rotating rectangular aperture (spot size on target 4x50[mu]m), the rapid signal washout of a Laurin two-volume laser ablation cell and slow compositional profiling ([less than or equal to]1.5[mu]m/s). Striking co-variation between oscillating cycles in B/Ca, Mg/Ca, Sr/Ca and Ba/Ca is discernible, yet also tantalizingly, sub-daily shifts between these element/Ca ratios can be observed. In comparison to a lower-resolution, seasonally-resolved [delta].sup.18O-Mg/Ca record (Warter et al., 2015), the ~10-20[mu]m element/Ca cycles are determined to be daily in origin, and a further ~14-15day cyclicity is superimposed on the daily cycles. The latter is interpreted to reflect (Miocene) tidal periodicity. Changes in pixel intensity during thin section observation associated with micro- and macroscopically visible low and high density bands have been quantified via image processing analysis. This reveals close correspondence to the measured trace elemental cyclicity, indicating a coupling between the geochemical composition of the shell and the incremental growth pattern. A comparison between the elemental and image processing results reveals that ultra-high-resolution LA-ICPMS analysis surpasses the latter in detecting environmental rhythms, including daily and tidal cycles. Highly-resolved LA-ICPMS analysis is a viable alternative to nanoSIMS and opens up routine investigation of long-term (deep-time) paleoenvironmental records at daily resolution. Article History: Received 3 September 2015; Revised 14 March 2016; Accepted 18 March 2016
  • Fa parte di: Palaeogeography, Palaeoclimatology, Palaeoecology, Jan 1, 2017, Vol.465, p.362(14)
  • Soggetti: Mass Spectrometry – Analysis
  • Lingua: Inglese
  • Identificativo: ISSN: 0031-0182 ; DOI: 10.1016/j.palaeo.2016.03.019
  • Fonte: Cengage Learning, Inc.

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