Geologic variability of conodont strontium isotopic composition quantified by laser ablation multiple collection inductively coupled plasma mass spectrometry

Details

• Journal Title:
  Palaeogeography, Palaeoclimatology, Palaeoecology
• Personal Author:
  Griffin, Julie M. ; Montañez, Isabel P. ; Glessner, Justin J.G. ; Chen, Jitao ; Willmes, Malte
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service) ; SWFSC (Southwest Fisheries Science Center)
• Description:
  Conodont microfossils record seawater strontium isotope values (87Sr/86Sr), permitting chemostratigraphic correlation for tectonic and climatic reconstructions of the Paleozoic and early Mesozoic (541–201 Ma). Laser ablation multiple collection inductively coupled plasma mass spectrometry (LA MC-ICP-MS) can provide rapid, high spatial resolution 87Sr/86Sr analysis of conodont bioapatite but has not been validated by comparison with solution analysis. Validation of LA MC-ICP-MS should be completed in order to use the conodont 87Sr/86Sr values for age-correlations and environmental interpretations. Here, for the first time, we compare solution and LA MC-ICP-MS 87Sr/86Sr analyses of Carboniferous-age conodonts. Furthermore, we use quadrupole LA ICP-MS to determine concentrations of trace elements potentially responsible for isobaric interferences. Using increased mass resolving power (m/∆m = ~7500) and analyzing conodont tissue with low 85Rb/88Sr (< 0.001), we find laser ablation copacetic with solution 87Sr/86Sr values. The two-standard-deviation of these LA 87Sr/86Sr ratios (average 2SD = 0.00105) are within the two-standard-error uncertainty of solution measurements (average 2SE = 0.00001) on conodonts from the same stratigraphic level. The LA measurements are at a higher spatial resolution and on average 0.00015 higher than solution measurements. Uncertainty of the mean calculations, made on duplicate LA MC-ICP-MS analyses of individual conodonts from the same stratigraphic level, exhibit 87Sr/86Sr variability beyond the precision of reference materials (2SE = 0.00001). This finding suggests that solution 87Sr/86Sr values determined by dissolving multiple conodonts are homogenizing the conodont 87Sr/86Sr signal. As such, the precision of these solution measurements does not capture the geologic variability of conodont 87Sr/86Sr within a stratigraphic level, which may originate from differential diagenetic alteration. Conodont 87Sr/86Sr measurements that do not account for this variability are at risk of false calibrations with the paleo-seawater 87Sr/86Sr curve, which has implications for the timing of geologic events and reconstructions of paleo-environmental changes.
• Keywords:
  Earth-Surface Processes Ecology, Evolution, Behavior And Systematics Oceanography Paleontology Ecology, Evolution, Behavior And Systematics Ecology, Evolution, Behavior And Systematics
• Source:
  Palaeogeography, Palaeoclimatology, Palaeoecology, 568, 110308
• DOI:
  https://doi.org/10.1016/j.palaeo.2021.110308
• ISSN:
  0031-0182
• Format:
  PDF
• Publisher:
  Elsevier BV
• Document Type:
  Journal Article
• License:
  https://creativecommons.org/licenses/by-nc-nd/4.0/
• Rights Information:
  CC BY-NC-ND
• Compliance:
  Library
• Main Document Checksum:
  urn:sha-512:188b209be7c4206af1e6db068b1bfa0decab65720dc6435565d416666c4c6da2c20bb6a6820b4c39a8a849e52e663a3a058a6e6eb09ff8be16fb5c18b7f94d7e
• Download URL:
  https://repository.library.noaa.gov/view/noaa/62815/noaa_62815_DS1.pdf
• File Type:
  [PDF - 2.95 MB ]