Fig. 3: Geochemical classification and discrimination of the MFAB sandstones.
From: Final closure of the Paleo Asian Ocean basin in the early Triassic
a log(Na2O/K2O) vs log(SiO2/Al2O3) and b ICV vs CIA for studied sandstones; the index of chemical alteration, CIA = [Al2O3/(Al2O3 + CaO*+Na2O + K2O)] ×100, where CaO* is the content of CaO in silicate minerals only, is given after ref. 44 and the Index of Compositional Variability, ICV = (CaO+K2O + Na2O + Fe2O3 + MgO + MnO + TiO2)/Al2O3 is given after ref. 45. c La vs Th; d La/Th vs Hf after ref. 130; sources: Mesoproterozoic crust. 131, PAAS46, ref. for average graywacke compositions132. e, f spider and REEs pattern diagrams of studied sandstones; values of primitive mantle133, chondrite133, and PAAS46 are used for normalization and comparison.
