The Contribution of Synchrotron Light for the Characterization of Atmospheric Mineral Dust in Deep Ice Cores: Preliminary Results from the Talos Dome Ice Core (East Antarctica)

Abstract

The possibility of finding a stratigraphically intact ice sequence with a potential basal age exceeding one million years in Antarctica is giving renewed interest to deep ice coring operations. But the older and deeper the ice, the more impactful are the post-depositional processes that alter and modify the information entrapped within ice layers. Understanding in situ post-depositional processes occurring in the deeper part of ice cores is essential to comprehend how the climatic signals are preserved in deep ice, and consequently how to construct the paleoclimatic records. New techniques and new interpretative tools are required for these purposes. In this respect, the application of synchrotron light to microgram-sized atmospheric dust samples extracted from deep ice cores is extremely promising. We present here preliminary results on two sets of samples retrieved from the Talos Dome Antarctic ice core. A first set is composed by samples from the stratigraphically intact upper part of the core, the second by samples retrieved from the deeper part of the core that is still undated. Two techniques based on synchrotron light allowed us to characterize the dust samples, showing that mineral particles entrapped in the deepest ice layers display altered elemental composition and anomalies concerning iron geochemistry, besides being affected by inter-particle aggregation.

XANES Iron Geochemistry in the Mineral Dust of the Talos Dome Ice Core (Antarctica) and the Southern Hemisphere Potential Source Areas

“…The possible role played by in situ oxidation of Fe minerals within ice is not discussed here, despite preliminary results showed its relevance only in very deep ice, in agreement with what already observed in the EPICA Dome C ice core [53] and, in the case of TALDICE below 1400 m [54].…”

“…Figure 4. (a) the TD stable isotope record indicating the climatic changes between MIS2 and Holocene (pink line, [54]). (b) the TD dust mass concentration record (blue line [22,34]) and the Fe K-edge energy positions obtained through from the XANES analysis (circles, square, diamonds for Holocene, Termination I and MIS2 samples, respectively).…”

Impurity Analysis and Microstructure Along the Climatic Transition From MIS 6 Into 5e in the EDML Ice Core Using Cryo-Raman Microscopy

“…The spectra showed a very good match with the reference spectra of jarosite. Jarosite was curiously identified by Baccolo et al (2018) within dust particles in deep ice from Talos Dome. The formation of jarosite in icy environments on Mars was discussed by Michalski and Niles (2011).…”

“…This could result from the insufficient number of measured spectra in the "dusty" MIS 6 sample. However, another explanation could be that postdepositional changes in the composition of mineral dust occurred as suggested by Baccolo et al (2018), e.g., due to exposure to strong acids like H 2 SO 4 . The abundant gypsum particles could be a byproduct of such changes.…”

Condensed Matter Researches in Cryospheric Science

“…Finally, important changes also occurred during the deglaciation and in the Holocene, when the influence of Antarctic local sources seems to become progressively more important in more recent times. Baccolo et al [19] investigate the possibility of finding a stratigraphically intact ice sequence with a potential basal age exceeding one million years in Antarctica, and present here preliminary results on two sets of samples retrieved from the TALDICE ice core. A first set is composed of samples from the stratigraphically intact upper part of the core, the second by samples retrieved from the deeper part of the core that remains undated.…”