The assessment of the weathering intensity of Emeishan basalt based on rock blocks（Ⅲ）：Assessment of existing chemical weathering indices

Abstract：The suitability of main weathering indices has been studied based on 13 weathered basalt blocks with core-shell structure from 7 rock mass sections in the core area of Emeishan basalt. Poor correlation has been observed between 18 chemical weathering indices and the early-stage weathering grade of the Emeishan basalt. The indices that can be used to evaluate mid-late period weathering degree of the Emeishan basalt include Parker’s index, BA1, BA, BA3, BA2, alkali/alumina ratio, alkali/R2O3 ratio, WPI, SA, SF, Kr, silicate/R2O3 ratio, CIW, CIA and LOI, in which, alkali/alumina ratio, alkali/R2O3 ratio and silicate/R2O3 ratio are more reasonable, while A, B and B1 are the worst. Fe2O3 that controls the alkali/R2O3 ratio, SF, Kr and silicate/R2O3 ratio in the initial weathering stage of Emeishan basalt should be regarded as an important factor to evaluate the weathering degree of Emeishan basalt.