Geochemistry of microtektites from Victoria Land Transantarctic Mountains

We extended the petrographic and geochemical dataset for the recently discovered Transantarctic Mountain microtektites in order to check our previous claim that they are related to the Australasian strewn field. Based on color and composition, the 465 microtektites so far identified include two groups of transparent glass spheres less than ca. 800 µm in diameter: the most abundant pale-yellow, or normal, microtektites, and the rare pale-green, or high-Mg, microtektites. The major element composition of normal microtektites determined through electron microprobe analysis is characterized by high contents of silica (SiO2 = 71.5 ± 3.6 (1 sigma) wt%) and alumina (Al2O3 = 15.5 ± 2.2 (1 sigma) wt%), low total alkali element contents (0.50-1.85 wt%), and MgO abundances <6 wt%. The high-Mg microtektites have a distinctly higher MgO content >10 wt%. Transantarctic Mountain microtektites contain rare silica-rich (up to 93 wt% SiO2) glassy inclusions similar to those found in two Australasian microtektites analyzed here for comparison. These inclusions are interpreted as partially digested, lechatelierite-like inclusions typically found in tektites and microtektites. The major and trace element (by laser ablation - inductively coupled plasma - mass spectrometry) abundance pattern of the Transantarctic Mountain microtektites matches the average upper continental crust composition for most elements. Major deviations include a strong to moderate depletion in volatile elements including Pb, Zn, Na, K, Rb, Sr and Cs, as a likely result of severe volatile loss during the high temperature melting and vaporization of crustal target rocks. The normal and high-Mg Transantarctic Mountain microtektites have compositions similar to the most volatile-poor normal and high-Mg Australasian microtektites reported in the literature. Their very low H2O and B contents (by secondary ion mass spectrometry) of 85 ± 58 (1 sigma) ?g/g and 0.53 ± 0.21 ?g/g, respectively, evidence the extreme volatile loss characteristically observed in tektites. The Sr and Nd isotopic compositions of multigrain samples of Transantarctic Mountain microtektites are 87Sr/86Sr ~ 0.71629 and 143Nd/144Nd ~ 0.51209, and fall into the Australasian tektite compositional field. The Nd model age calculated with respect to the chondritic uniform reservoir (CHUR) is TNdCHUR ~ 1.1 Ga, indicating a Meso-Proterozoic crustal source rock, as was derived for Australasian tektites as well. Coupled with the Quaternary age from the literature, the extended dataset presented in this work strengthens our previous conclusion that Transantarctic Mountain microtektites represent a major southward extension of the Australasian tektite/microtektite strewn field. Furthermore, the significant depletion in volatile elements (i.e., Pb, B, Na, K, Zn, Rb, Sr and Cs) of both normal and high-Mg Transantarctic Mountain microtektites relative to the Australasian ones provide us with further confirmation of a possible relationship between high temperature-time regimes in the microtektite-forming process and ejection distance.

Langue tarasque; grammaire, dictionnaire--textes traduits et analyses,

"Dictionnaire tarasque-espagnol (d'après le dictionnaire de Gilberti, Mex. 1559)" p. [99]-253. French equivalents are substituted for the Spanish words of the original work.

Langue zoque et langue mixe; grammaire, dictionnaire,

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Le régime de la liberté des cultes dans le département du Calvados, pendant la première séparation (1795-1802)

Bibliographical footnotes.

Collection complète des œuvres /

Livr. [44] without t.p. and preliminary commentaries.

De la nostalgie et des instincts contraires : comme facteurs psychologiques et sociaux.

"Extrait de la Revue internationale de sociologie."

La révolution dans une petite ville,

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The comparative efficiency of current methods and types of equipment used for receiving field boxes of apples at storage houses in the Pacific northwest area.

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König Rudolf von Frankreich,

Issued also as inaugural dissertation, Leipzig, 1885, under title: Geschichte des Westfränkischen Reiches unter König Rudolf.

Journaliste, sans-culotte et thermidorien : le fils de Fréron (1754-1802) d'après des documents inédits /

Bibliographical footnotes.

The true story of the Empress Eugénie,

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Dissertation sur l'incertitude des signes de la mort, et l'abus des enterremens, & embaumemens précipités /

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Noticias sobre las aguas minerales naturales, sales minerales para baños y pastillas digestivas de Vichy...

Datos tomados del colofón.

Urologie : les angusties ou rétrécissements de l'urètre et de leur traitement rationel /

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