Marie Protin

@article{Blard_etal2023,

title = {Basal debris of the NEEM ice core, Greenland: a window into sub-ice-sheet geology, basal ice processes and ice-sheet oscillations},

author = {P. H. Blard and M. Protin and J. L. Tison and F. Fripiat and D. Dahl-Jensen and J. P. Steffensen and W. C. Mahaney and P. R. Bierman and A. J. Christ and L. B. Corbett and V. Debaille and T. Rigaudier and P. Claeys and ASTER Team.},

doi = {10.1017/jog.2022.122},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Glaciology},

volume = {614},

pages = {1--19},

abstract = {We present new data from the debris-rich basal ice layers of the NEEM ice core (NW Greenland). Using mineralogical observations, SEM imagery, geochemical data from silicates (meteoric 10Be, $epsilon$Nd, 87Sr/86Sr) and organic material (C/N, $delta$13C), we characterize the source material, succession of previous glaciations and deglaciations and the paleoecological conditions during ice-free episodes. Meteoric 10Be data and grain features indicate that the ice sheet interacted with paleosols and eroded fresh bedrock, leading to mixing in these debris-rich ice layers. Our analysis also identifies four successive stages in NW Greenland: (1) initial preglacial conditions, (2) glacial advance 1, (3) glacial retreat and interglacial conditions and (4) glacial advance 2 (current ice-sheet development). C/N and $delta$13C data suggest that deglacial environments favored the development of tundra and taiga ecosystems. These two successive glacial fluctuations observed at NEEM are consistent with those identified from the Camp Century core basal sediments over the last 3 Ma. Further inland, GRIP and GISP2 summit sites have remained glaciated more continuously than the western margin, with less intense ice-substratum interactions than those observed at NEEM.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Protin_etal2016,

title = {Irreversible adsorption of atmospheric helium on olivine: A lobster pot analogy},

author = {M. Protin and P. H. Blard and Y. Marrocchi and F. Mathon},

doi = {10.1016/j.gca.2016.01.032},

year  = {2016},

date = {2016-01-01},

journal = {Geochimica et Cosmochimica Acta},

volume = {179},

pages = {76--88},

abstract = {This study reports new experimental results that demonstrate that large amounts of atmospheric helium may be adsorbed onto the surfaces of olivine grains. This behavior is surface-area-related in that this contamination preferentially affects grains that are smaller than 125 lm in size. One of the most striking results of our study is that in vacuo heating at 900 textdegreeC for 15 min is not sufficient to completely remove the atmospheric contamination. This suggests that the adsorption of helium may involve high-energy trapping of helium through irreversible anomalous adsorption. This trapping process of helium can thus be compared to a textquotelefttextquoteleftlobster pottextquoterighttextquoteright adsorption: atmospheric helium easily gets in, but hardly gets out. While this type of behavior has previously been reported for heavy noble gases (Ar, Kr, Xe), this is the first time that it has been observed for helium. Adsorption of helium has, until now, generally been considered to be negligible on silicate surfaces. Our findings have significant implications for helium and noble gas analysis of natural silicate samples, such as for cosmic-ray exposure dating or noble gas characterization of extraterrestrial material. Analytical procedures in future studies should be adapted in order to avoid this contamination. The results of this study also allow us to propose an alternative explanation for previously described matrix loss of cosmogenic 3He.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}