Quartz-pebble-conglomerate (QPC) bearing unconformable zone at the base of Bababudan Group of rocks in Dharwar Craton in southern India is well known for its stratigraphic significance and uraniferous nature. Over thi...Quartz-pebble-conglomerate (QPC) bearing unconformable zone at the base of Bababudan Group of rocks in Dharwar Craton in southern India is well known for its stratigraphic significance and uraniferous nature. Over this QPC zone, soil cover is very thin which is almost devoid of vegetation. A cursory biogeochemical study here indicated poor (170 to 520 ppb) uranium content in the scantily occurring herbs and shrub species as well as in the soil substratum (1.8 - 3.1 ppm). The values in plant species are much below the background values. Almost barren nature of soil surface and stunted growth of herb and shrub species suggested that geobotanical rather than biogeochemical study is more serviceable as a clue for the hidden QPC-type horizons, which quite often bear signatures of uranium mineralization.展开更多
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 distr...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.展开更多
文摘Quartz-pebble-conglomerate (QPC) bearing unconformable zone at the base of Bababudan Group of rocks in Dharwar Craton in southern India is well known for its stratigraphic significance and uraniferous nature. Over this QPC zone, soil cover is very thin which is almost devoid of vegetation. A cursory biogeochemical study here indicated poor (170 to 520 ppb) uranium content in the scantily occurring herbs and shrub species as well as in the soil substratum (1.8 - 3.1 ppm). The values in plant species are much below the background values. Almost barren nature of soil surface and stunted growth of herb and shrub species suggested that geobotanical rather than biogeochemical study is more serviceable as a clue for the hidden QPC-type horizons, which quite often bear signatures of uranium mineralization.
文摘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.
