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Study of Mineralogy and Weathering of Two Soil Profiles of Undulating Plateau Area of Jumar Subwatershed, Jharkhand, India

2010; Volume: 3; Issue: 3 Linguagem: Inglês

2230-732X

Shovik Deb, Sakti Sankar Sahu,

Groundwater and Isotope Geochemistry

To study the weathering status of two soil series of Jumar subwatershed, Jharkhand, India, soil mineralogy specially the mineralogy of clay fractions have been studied with some basic soil properties. Sugnu and Edalatu soil series developed on lower and upper reach of undulating plateau area respectively. These soils are moderately acidic, low in CEC and silty loam, loam or silty clay loam in texture. After separation of different sized soil fractions, mineralogical investigations of clay were carried out following XRD, SDA, CEC and total elemental chemical analysis. XRD results indicate that soil clay, isolated from surface soil of Sugnu series is dominated by kaolinite type of minerals followed by mica/illite while kaolinite and mica/illite together constitute maximum portion of clay of subsurface soil. Soil clays of both the layers of Sugnu series have significant amount of interstratified minerals and comparatively less amount of smectite and vermiculite. There is no evidence of presence of chlorite. On the other hand, kaolinite, mica/illite, smectite, vermiculite and interstratified minerals are present in a good proportion in Edalatu soil clays of both surface and subsurface layers. Little amount of chlorite is also present which is supported by MgO content of Edalatu soil. The afore said findings are also supported by CEC values accompanied with SiO2/Al2O3 molar ratios. Frequency distribution diagrams along with weathering means indicate that among all soil clays, Sugnu surface soil clay is the most weathered despite aquic moisture regime. This might be due to Sugnu surface soil formation by accumulation of transported soil materials. On the other hand, Edalatu surface soil is more weathered than subsurface soil, indicating in situ soil genesis (ustic moisture regime). SDA analysis depicts presence of a fair amount of amorphous materials in all soil clays. XRDs of primary fractions of both soils indicate presence of quartz and feldspar with little amount of gibbsite, haematite and mica also.