Geochemistry of microtektites from Victoria Land Transantarctic Mountains

• Main Authors: Folco, L, D'Oratio, M, Tiepolo, Massimo, Tonarini, Sonia, Ottolini, L, Perchiazzi, N, Rochette, Pierre, Glass, B P
• Format: Dataset
• Language: English
• Published: PANGAEA 2009
• Subjects: 124-769A; 184-1143A; 22-213; Antarctic; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Frontier_Mountain; Glomar Challenger; HAND; Indian Ocean//BASIN; Joides Resolution; Leg124; Leg184; Leg22; McMurdo Dry Valleys; southern Victorica Land; Antarctica; Miller_Butte; Mistake_Peak; Mount_Aeolus; Mount_Fleming; Ocean Drilling Program; ODP; PC; Pian_delle_Tectiti; Piston corer; RC08; RC08-52; Robert Conrad; Sampling by hand; South China Sea; Sulu Sea; Trap; micrometeorite; TRAPMET; V28; V28-239; Vema; Victoria Land; Transantarctic Mountains; Indian; Antarc*
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.783473; https://doi.org/10.1594/PANGAEA.783473

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 ...