Estimation of chemical weather indices of sediments using R program

Abstract

For estimating major elemental geochemistry of sedimentary packages, various Weathering Indices (WIs) are utilized by researchers involved in geochemical evolution of sediments. Through developing a computer program, GeoChem, based on ‘R’ programming environment, we intend to simplify the evaluation and implementation of various Weathering Indices (WIs), including CIW, CPA, PIA, CIX, CIA, WIP, R, ICV, V, MWPI and STI. Additionally, it generates plots of input data used to quantify chemical weathering of clastic sediments in various compositional space diagrams, such as Al2O3 – CaO – Na2O, Al2O3 – K2O – CaO – Na2O, Al2O3 – CaO + Na2O – K2O, Al2O3 – CaO + Na2O + K2O – Fe2O3 + MgO and M – F – W compositional space diagram. Using GeoChem, one can do all the calculations and artwork associated with the finished report without having to use Microsoft Excel, CorelDraw or similar software. Input data source files and output calculations results data files are in CSV format. Data plots are produced in vector as well as in raster formats, providing additional flexibility to the user. Also, we are trying to figure out the associated statistical parameters, their correlation and specially restricting the major elemental geochemistry in a variety of compositional space diagrams to constrain sediment and rock composites, demonstrating chemical weathering profiles and mineralogical composition of the parent rock. By altering different arguments in the code, the ‘R’ programming environment allows the investigator to change the code, depending on the dataset under consideration and the user requirement to generate user-defined, customized plots. To demonstrate the applicability of the tool, its performance was tested, evaluating the major elemental geochemical data of diverse geological settings and sedimentary provenance different in kind. For the same, sediments selected include channel, suspended and overbank sediments of the Peninsular rivers of Ganga basin; Surma group and Barail group of sandstones; lake sediments of Manasbal, Kashmir; Mizoram Foreland Basin, India.