『Abstract
Stream sediment geochemical maps serve as a tool for mineral
exploration, identifying pollutant sources and providing information
on weathering and transport processes. This paper presents geochemical
maps of the upper catchment of the Mahaweli River of Sri Lanka,
with interpretations based on geochemistry, geology and environmental
conditions.
For the construction of these maps, stream sediment geochemical
data of 1585 samples, collected from 05 main tributaries of the
Mahaweli River, was used. Elemental concentrations of 19 major
and trace elements were determined by X-ray fluorescence spectrometry.
Geochemical maps were prepared and existing geological maps, discriminant
analysis, factor analysis, and correlation coefficients were used
to recognize the relationship between spatial distribution patterns
and the geological and environmental factors.
These maps and statistical analysis clearly show the identical
geochemical behavior of K, Rb, Ba and Sr. Even Mg and Ca show
a similar distribution in different basins, the lack of correlation
with metacarbonates probably being due to dissolution of Ca-Mg
bearing minerals. The anomalous concentrations of these elements
observed in the Anda Oya of Belihul Oya basin may indicate the
existence of a Fe-Cu ore body and a Ni-Cr deposit in the upstream
tributary of Badulu Oya. This however needs further detailed geological
investigations. High Al levels in some streams seem to be controlled
by high silt and clay contents released due to agricultural soil
erosion in the upstream areas. Similarly, Pb enrichment in the
vicinity of some cities may also be anthropogenic. Na, Mn, Ti,
Nb, Y, Zn, Zr distribution in the stream sediment shows a relationship
with the underlying lithologies of the area.
Keywords: Stream sediment; Geochemistry; Sri Lanka』
1. Introduction
1.1. Physiography and geology
1.2. Drainage and land use
2. Methodology
3. Results and discussion
3.1. Element distribution in different river basins
3.2. Major elements
3.3. Trace elements
3.4. Multivariate analysis
4. Conclusions
Acknowledgments
Appendix A. Supplementary data
References