T135 Building Bridges between Modern and Deep-Time Critical Zones

Monday, 23 September 2019
1:30 PM - 5:30 PM
Room 222BC, North Building

WEATHERING OF GLAUCONITE IN SOILS OF TEMPERATE CLIMATE

Paper number: T135-11
Program: Technical Sessions
Time: 4:10 PM – 4:25 PM

Authors

Abstract

The aim of the present research was to investigate the processes of glauconite weathering in soils of temperate climate. Five soil profiles from eastern Poland, each developed on glauconite-bearing sediments of Oligocene to Miocene age, were sampled. Basic physical and chemical properties of bulk soil samples (<2 mm) were analyzed, such as color, texture, pH, carbonates and soil organic carbon contents. Clay fractions (<2 µm and <0.2 µm) were separated using centrifuge after application of Na-acetate buffer treatment to remove carbonates and divalent exchangeable cations. Obtained clays were analyzed using X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy. Glauconite pellets were separated magnetically and analyzed using XRD. Selected clays and pellets were also analyzed using Mössbauer spectroscopy and energy-dispersive spectroscopy. Thin sections were prepared from undisturbed soil material from selected horizons, and observed under optical microscope.

The pH conditions of the studied soils varied from 4.3 to 8.6. Three of the soils were acidic and two of them were alkaline. Chemical composition of parent glauconite pellets did not vary significantly between the profiles; however, Fe(II) constituted from 4% to 13% of total Fe in primary glauconite. Glauconite weathering products were observed mostly in clay fractions, which contained, except for glauconite, also rich in smectite glauconite-smectite mixed layered minerals, kaolinite, and goethite or lepidocrocite. At least in three cases the weathering products were also present in the pellets. They were glauconite-smectite, kaolinite, goethite and/or lepidocrocite. Fe-oxy/hydroxides likely occurred also in XRD-amorphous phases (nano-phases). No major differences in the weathering effects were observed between soils having different pH conditions. Content of Fe(II) in primary glauconite did not seem to influence the weathering processes either.

Acknowledgements:

This study was financed by the National Science Centre, Poland [grant number: UMO-2016/23/B/ST10/02000]

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-338409

© Copyright 2019 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.