02504nas a2200229   4500008004100000245007200041210006700113260001200180490000800192520178600200100001701986700002202003700002202025700002402047700001502071700002902086700002502115700002102140700002002161700002002181856007302201       2019                        eng d00aThe Geochemistry of Englacial Brine From Taylor Glacier, Antarctica0 aGeochemistry of Englacial Brine From Taylor Glacier Antarctica  c03/20190 v1243 a<p>Blood Falls is a hypersaline, iron‐rich discharge at the terminus of the Taylor Glacier in the McMurdo Dry Valleys, Antarctica. In November 2014, brine in a conduit within the glacier was penetrated and sampled using clean‐entry techniques and a thermoelectric melting probe called the IceMole. We analyzed the englacial brine sample for filterable iron (fFe), total Fe, major cations and anions, nutrients, organic carbon, and perchlorate. In addition, aliquots were analyzed for minor and trace elements and isotopes including δD and δ<sup>18</sup>O of water, δ<sup>34</sup>S and δ<sup>18</sup>O of sulfate, <sup>234</sup>U, <sup>238</sup>U, δ<sup>11</sup>B, <sup>87</sup>Sr/<sup>86</sup>Sr, and δ<sup>81</sup>Br. These measurements were made in order to (1) determine the source and geochemical evolution of the brine and (2) compare the chemistry of the brine to that of nearby hypersaline lake waters and previous supraglacially sampled collections of Blood Falls outflow that were interpreted as end‐member brines. The englacial brine had higher Cl&minus; concentrations than the Blood Falls end‐member outflow; however, other constituents were similar. The isotope data indicate that the water in the brine is derived from glacier melt. The H<sub>4</sub>SiO<sub>4</sub> concentrations and U and Sr isotope suggest a high degree of chemical weathering products. The brine has a low N:P ratio of ~7.2 with most of the dissolved inorganic nitrogen in the form of NH<sub>4</sub><sup>+</sup>. Dissolved organic carbon concentrations are similar to end‐member outflow values. Our results provide strong evidence that the original source of solutes in the brine was ancient seawater, which has been modified with the addition of chemical weathering products.</p>1 aLyons, Berry1 aMikucki, Jill, A.1 aGerman, Laura, A.1 aWelch, Kathleen, A.1 aWelch, Sue1 aGardner, Christopher, B.1 aTulaczyk, Slawek, M.1 aPettit, Erin, C.1 aKowalski, Julia1 aDachwald, Bernd  uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG00441102216nas a2200193   4500008004100000245012200041210006900163260001200232520155300244653001501797653001701812653002101829653002901850653001801879100002101897700001501918700001701933856007201950       2019                        eng d00aThe geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances0 ageochemistry of glacial deposits in Taylor Valley Antarctica Com  c05/20193 a<p>Wet-based glacial deposits have been used traditionally as an analog for upper continental crust (UCC) abundances. To provide more information on the validity of using glacial deposits from wet-based glaciers, samples deposited by the dry-based polar glaciers located in Taylor Valley, Antarctica, were collected. Stream channel sediments, comprised of igneous, metamorphic, and sedimentary rocks initially deposited as glacial tills by polar glaciers, were analyzed by XRF, ICP-MS, and SEM. Based on the Chemical Index of Alteration values and A&ndash;CN&ndash;K ternary diagram, there are low levels of chemical weathering in these tills. Additionally, major and trace element geochemical data are compared to the average UCC values. The observed discrepancies between the mean UCC and Antarctic samples develop from the existence of mafic components, most likely the McMurdo Volcanic Group and Ferrar Dolerite, being present in the Taylor Valley tills. Even though the mafic material typically comprises 3&ndash;7% of the till, the volcanic rocks have a significant influence on the tills&rsquo; bulk geochemistry. The existence of this mafic fraction in the dry-based glacial tills results from the reduced rate of weathering, as compared to wet-based glaciers. Geochemical analyses of the dry-based glacial tills in polar deserts, such as those found in Taylor Valley, may provide a better representative composition of the original material than wet-based glaciers and need to be incorporated into upper continental crust calculations.</p>10aAntarctica10ageochemistry10aglacial deposits10apolar dry-based glaciers10aTaylor Valley1 aDowling, Carolyn1 aWelch, Sue1 aLyons, Berry  uhttps://www.sciencedirect.com/science/article/pii/S0883292719301246