The degree of chemical weathering in the Ba River basin, South Central Vietnam: Major-element geochemistry investigations of morden river sediments and sedimentary rocks

Abstract

Major-element geochemistry of Miocene sedimentary rock and modern river sediment samples in the Ba River basin, South Central Vietnam are utilized to assess the degree of chemical weathering in the Miocene and the present time. Sediment samples were analysed by X-ray fluorescence (XRF) spectrometer show that Miocene sedimentary rocks contain higher SiO2 and K2O, but lower Fe2O3, TiO2, MgO, Na2O, MnO, CaO, P2O5 than modern river sediment. Major-element geochemistry indicates that Miocene sedimentary rocks and modern river sediment are characterized by stronger depliption of Ca, Na and Mg than K and Si during the chemical weathering in this river basin. The similar relative depleption of Na, Ca, Mg, Si and K between modern river sediments and sedimentary rocks indicate not much deffirent the intensity of chemical weathering in the Miocene and the present time. The chemical index of alteration (CIA) alter from 69 to 93 in Miocene sedimentary rocks (average 74) and from 69 to 78 (average 77) in morden river sediments, indicating moderate chemical weathering in the Ba River basin in the Miocene and the present time