Trace Elemental Expression in Soil Substratum and Floral Species in Selected Lateritic Profiles in the Northern Part of Kolar Schist Belt, Dharwar Craton, India ()
ABSTRACT
Extensive laterite cappings are observed in the northern part of Kolar schist
belt and they are underlain by pillowed metabasalt and partially weathered
auriferous cherty intercalations. To appraise the possible distribution of trace
elements in both laterite cappings and in plants growing over there, a geobotanical
study was conducted in the well exposed, almost flat to slightly undulating
lateritic profiles in Jaderi-Holur-Nayakarahalli stretch in the northern
part of Kolar schist belt. Due to humus-poor lateritic soil and scanty rainfall,
the vegetation is sparse and scrubby. Shrub species are relatively more abundant
than herbs and trees. The shrub species studied are Argyreia cuneata,
Dodonaea viscosa, Carissa carandas, Ziziphus species, Barleria buxifolia and
Atylosia scarbiocides. The herb species are mainly represented by Leucas ciliata, Pulicaria wightiana, Hyptis suaveolens, Tephrosia tinctoria, Trichodesma indicum, Stylosanthes fruticosa, Evolvulus alsinoides, Pavonia zeylanica,
Orthosiphon diffusus, Waltheria indica and Stachytarpheta indica. Less frequent
species included Acacia megaladena and Dolichandrone atrovirens.
Geochemical analysis of different plant species and lateritic soil samples has
been carried out. Cu, Cr, Zn, Ni, Co, As, Mn and Mg are in good concentration
in soil but the same are impoverished in the plant species except Mn. A
few analyses for Au show that its values are close to background concentration.
However, plant uptake of Au appears to be better (25 - 86 ppb). The
humic acid activity could have enabled gold to get absorbed by plants. While
all other analyzed metals show higher range of concentration in soil compared
to flora, gold shows a reverse relationship.