Stream Sediment Geochemistry and Mineral Potential of Lower Walawe and Mau Ara Basins
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Date
2013
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Uva Wellassa University of Sri Lanka
Abstract
Regional geochemical maps are considered to be a national asset for resource evaluation and
environmental management. This project covered a considerable portion of the lower Walawe
Ganga and Mau Ara which represent the geologically and environmentally important Highland -
Vijayanlithotectonic boundary of Sri Lanka Stream sediments remain the dominant sampling
medium in regional geochemical exploration, in areas where relief permits development of
distinct drainage systems (Fletcher, 1997). In addition, human activity can often strongly
influence the stream sediment composition that can be used to identify pollution sources. In this
study, distribution of selected major, trace and rare earth elements (REE) were studied to
identify potential mineral enrichments in the Lower Walawe Basin.
Methodology
44 sample locations were selected within lower Walawe and Mau Ara streams. Chemical
components were analyzed using various analytical methods. Element concentrations in stream
sediments
were
measured
in powdered
using
hand held X-ray Fluorescence
Absorption
Spectrophotometer (AAS) (Ranasinghe et al, 2008). Stream sediment geochemical maps were
prepared using Arc-GIS 9 software and data analysis was done using SPSS 13 software.
Results and Discussions
A comparison of special element concentrations in studied area with upper crustal and mean
stream sediment values are given in Table 1. Results show that Cr, Ni Y, Zr and Pb at some
sampling locations are well above the upper crustal values and mean sediment levels while
other elements are below the above global average values. When examined the individual
distribution maps of above elevated elements, UWG 18 and UWG 20 locations are enriched
with respect to Zr, Y and Cr, Ni elements (Figure 1). However, enrichment of Zr and Y at UWG
18 is mainly due to hydro dynamical heavy mineral accumulation in the area. UWG 20 location
is a confluence point of two streams and enriched Cr and Ni concentrations indicate potential
metallic mineral source upstream of above location., Elevated Pb concentrations at UWG 5-1,
UWG 6, LWG 1 and LWG 2 locations could be due to natural sources because there is very
low potential for anthropogenic Pb pollution in the area. Also these locations are situated at the
vicinity of gem and gold mining areas.
Conclusions
This study reveals the enrichment of Cr, Ni and Pb in several locations in the lower catchment
of the Walawe and Mau Ara basins. Analysis of geographical and geological features of the
locations suggests that these elevated levels could be due to natural sources rather than
anthropogenic or hydrodynamic enrichments. Therefore, detailed high resolution sampling
around these localities is suggested to identify potential mineralization.
Description
Keywords
Mineral Sciences, Mineral, Geochemistry, Materials Sciences, Science and Technology