Geochemical characterization and regional correlation of Youngest Toba Tuff (YTT, 75 ka) glass shards, Purna alluvial basin, Central India

• Published in: Arabian journal of geosciences 2021-10, Vol.14 (19), Article 2013
• Main Authors: Srivastava, Ashok Kumar, Singh, Ajab, Muhammad, Ros Fatihah Binti Haji, Pattan, Jinnappa, Sharma, Natwar, Parthiban, Gopal, Khare, Neloy
• Format: Article
• Language: English
• Subjects: Alluvial basins; Aluminum oxide; Ashes; Composition; Crystallization; Earth and Environmental Science; Earth science; Earth Sciences; Fractional crystallization; Geochemistry; Glass; Isotopes; Lava; Magma; Minerals; Original Paper; Potassium oxides; Rare earth elements; Silica; Silicon dioxide; Strontium; Titanium dioxide; Trace elements; Tuff; Yttrium
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-07848-z

Geochemistry of glass shards belonging to Youngest Toba Tuff (YTT) ash from eight different localities of Purna alluvial basin, Central India have been carried out to interpret magmatic and postdepositional processes led variations. Inter- and intra-basinal correlations of analytical data have also been made. The ash comprise of abundant glass shards, minor quantity of minerals, and fine-grained admixture. EPMA analysis of the glass shards showing high SiO 2 (76.6–80.3 wt%) along with Al 2 O 3 (11.7–13 wt%), K 2 O (3.2–4.4 wt%), and Na 2 O (1.9–2.7 wt%) reveals their rhyolitic composition. ICP-MS analysis of the same depicts enriched LREE and depleted HREE along with strong negative Eu anomaly; elements like Ba, Sr, Rb, Nb, Y, and Ce are also on higher side. Geochemical variations in major, minor, and trace elements exhibit fractional crystallization and post-depositional processes led heterogeneities in the magma constituents and glass shards, respectively. The same have been interpreted through the ratios of immobile elements i.e., FeO/TiO 2 vs. Al 2 O 3 /TiO 2 , Sr/Nb vs. Ce/Y and mobile elements i.e., SiO 2 /Al 2 O 3 vs. Na 2 O/K 2 O, FeO/Al 2 O 3 vs. Na 2 O/K 2 O,Nb vs. Rb. Higher and lower concentrations of LREE and HREE respectively are due to fractional crystallization of magma. Concentrations of major, minor, and rare earth elements including trace are in good agreement with the glass compositions of Toba Caldera and other YTT bearing sites in India and Malaysia.