Research Journal of Chemical Sciences ______________________________________________ISSN 2231-606XVol. 4(5), 85-90, May (2014) Res.J. Chem. Sci. International Science Congress Association 85 Termite mound as an Effective Geochemical Tool in Mineral Exploration: A Study from Chromite Mining Area, Karnataka, India L.Chandra Sekhar Reddy Department of Geology, Loyola Degree College, Pulivendula-516390, Kadapa District, Andhra Pradesh, INDIAAvailable online at: www.isca.in, www.isca.me Received 14thMarch2014, revised22nd April 2014, accepted16thMay 2014Abstract In Byrapur chromite mining area, the ore element Cr and other associated trace elements Viz., Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo were determined for termite mounds and their adjoining surface soils unaffected by termites. A biogeochemical parameter called “Biological Absorption Co-efficient” (BAC) of these mounds is computed which helps in the evaluation of the mounds in the geochemical orientation surveys and in mineral exploration. The maximum BAC value 19,090 for Cr element in termite mounds is attributed to the influence of chromite mineral zone in the study area. Since the BAC values of Cr element in all termite mounds are classified as “positive” reflecting the enrichment of the chromium element in the termite mound with reference to the surface soil. The concentration of ore element Cr in termite soils is from 1400 to 4500 ppm, and that of soils it is from 220 to 960 ppm reflecting the element Cr in the termite soils in the study area. These studies reveal that the mounds exhibit indicator characteristics especially for Cr element and also for other associated elements viz., Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo. Hence termite mound may be considered as a tool in mineral exploration. Keywords: Termite mound, mineral exploration, chromium, BAC, Byrapur. IntroductionTermites popularly known as “white ants” exist throughout the tropical and most of the warm temperature countries. They are the most dominant macro invertebrates in many tropical and subtropical ecosystems. They often build earthen mounds of various sizes and shapes forming important features of tropical landscape. Termites are often mentioned as an example of ecosystem engineers. They drastically alter the physical, chemical and biological characteristics of the soil environment. They have been considered as objects of worship in India since the time immemorial. Termites decent through subterranean galleries ramified over wide tract, and sample the sub surface geological formations for their construction material. They may form large, stable nest and can concentrate the organic materials they collect as forage in the vicinity of the nest, in the form of inedible debris, and stored food. In a mineralized area, termites bring up partly dissolved mineralized water from the water table to maintain the required high humidity and they precipitate the mineral matter carried jaws to the site and cemented with a mixture of clay and saliva for the construction of the mounds. When these mounds are sampled and subjected to trace element analysis the evidence of mineralization can readily be obtained and geochemical anomalies can be easily rapidly and effectively determined to locate the concealed ore deposits. Termite mounds in the study area are generally found in association with different types of vegetation, soil and rock. They have varied shapes (figure-1) as conical, elongated, bald and rounded even irregular. The mounds under study area from 45cm to more than 2.5 meters in height with the base diameter varying from 0.7 meters to 3.5 meters. In Byrapur chromite mining area the mounds occurring on amphilobites are dark reddish brown those occurring on tremolite schist are brown colour. Termite Mound in Mineral Prospection Varahamihira’s Brihat Samhita describes termite mound as one of important bioindicators in exploration mineral resources1-4.In Russia, geochemical features of termite mounds have been studied. Biogeochemical studies have demonstrated that in tropical parts of India these mounds can be used as tool in the exploration for copper, tin, lead, gold4,9 and barite10,11 deposits. Similarly modern works also deal with termite mounds in geoexploration12. Earlier workers have studied ecological13,14, biological15,16 and geological17-21 aspects of the termite mounds. Comparative studies of termite mound and the adjacent soils had been carried out in previous researches 22-24. In the present study, termite soils and their adjoining surface soils were studied tin the chromite mining area of Byrapur, Hassan district to examine the potential of the termite mounds as an indicator in mineral exploration. In the study area the mounds are barren, monophytic, and polyphytic vegetation. Area of the Study Byrapur (Lat. 13 06’ 20’ to 13 06’ 56” N; Long 76 24’ 30” to 76 24’40” E) is located in Hassan District, Karnataka. It is included in the Survey of India Toposheet No 57 C/8. Byrapur chromite area is an important mineralized zone in the Nuggihalli schist belt. The chromite ore bodies in and around Byrapur is a linear and narrow band of metamorphic basic and ultrabasic rocks and occur as lensoid bodies. The ultra-basic rocks are Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 85-90, May (2014) Res. J. Chem. Sci. International Science Congress Association 86 intrusive into Dharwar schistose rocks. The Nuggihalli schist belt is one of the ultramafics rich ancient belts in the Dharwar craton25. These deposits are mainly fissure type. In this area the important rock types are amphibolite, dolerite, serpentinite talc, tremolite schist, dunite, pyroxinite, peridotite and titaniferrous magnetite. The chromite mineralization usually occurs as lenses, tabular or irregular bodies in the Nuggihalli Schist Belt. In this mineral zone, the ore have been mined by underground method. Earlier workers studied the oxidation character of chlorite26, and chemical studies chromo chlorite27, 28 of Byrapur chromite area. Sample Preparation Termite Soils and Soils: Samples were collected from 8-10 spots from different parts of the exterior of the termite mound and were combined to form a composite sample. Similarly the adjoining surface soils occurring in a radius of 8-10 m were collected and combined to represent a composite sample. Thus, a total of 10 pairs of termite soils and their adjoining surface soils unaffected by termites were collected in and around the mining area. All the samples were oven dried at 110C to expel moisture. These dry soils were lightly disintegrated with porcelain mortar and pestle to break lumps if any with care to avoid the breaking of individual and were then sieved to pass through 2mm sieve mesh. From this material required quantity of each representative sample was obtained by coning and quartering. These samples thus obtained were finely powdered in an agate mortar and ignited at 500c in a muffle-furnace for six hours. Then the samples were digested in aquaregia and analyzed for Cr and other associated elementsCo, Ni, Pb, Zn, Cu, Fe, Mn, and Mo by atomic absorption spectrophotometry (AAS). The elemental data is shown in table 1. Figure-1 Termite Mounds in the Byrapur Chromite Mining Area, Karnataka Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 85-90, May (2014) Res. J. Chem. Sci. International Science Congress Association 87 Elemental Analysis of Soils and Termite Soils: From the data (table 1) it is revealed that generally, concentration of Cr and other associated elements Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo are higher in thermite soils than those of their adjoining surface termite free soils. The concentration of ore element Cr in termite soils is from 1400 to 4500 ppm, and that of soils it is from 220 to 960 ppm reflecting the element Cr in the termite soils in the study area. Raghu and Prasad10 stated that the termites continuously modify the trace elements distribution within their mound habitat, as consequences of this cultivation of appropriate plant species as an important adaptation to maintain homeostatic equilibrium. The elemental concentration Cu and Zn of the termite mounds are influenced by the presence of vegetation on the mounds and suggested barren and monophytic mounds for mineral exploration29. Due to biogeochemical cycling of elements, the ore element Cr and other associated element shave migrated into sub-soil horizons depleting the concentration of these elements in the surface soil30. From these subsoil horizons termites bring mineral particles for their mound construction and incorporate in the mound, thus enriching these elemental concentrations in the termite mound10. Biological Absorption Co-efficient (BAC) A biogeochemical parameter, Biological Absorption Co-efficient (BAC), which is the ratio of concentration of the element in termite mound (CTs) to that of its adjoining surface soil (CSs) can be applied while using termite mounds in the mineral exploration.Thus, it may be written as: BAC= CTs/CSs Classification of Termite Mounds Based on BAC Biological Absorption Co-efficient (BAC) values of elements in termite mounds are classified as positive and negative. The BAC Value of unity is taken as the datum line. If the value is more than one it is treated as positive reflecting an enrichment of the element in the mound with reference to its adjoining surface soils; similarly if the value is less than one it is treated as negative reflecting depletion of the element in the mound.In the present study BAC has been calculated for the termite mounds. On this basis the BAC of various elements viz., Cr, Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo in the termite mounds has been classified. The BAC values for various elements are shown in table 2. Table- 1 Concentration of trace elements (in ppm) in termite soils (Ts) and in surface soils (Ss) Sample Cr Co Ni Pb Zn Cu Fe Mn Mo No Ts Ss Ts Ss Ts Ss Ts Ss Ts Ss Ts Ss Ts Ss Ts Ss Ts Ss 1 1850 650 15 10 60 25 30 12 42 30 25 18 150 110 50 25 8 3 2 3600 890 20 13 72 18 45 26 55 40 32 22 130 90 100 76 6 2 3 1400 530 13 10 45 32 25 18 40 26 24 20 80 64 75 40 8 5 4 4500 470 25 16 38 28 42 35 46 19 50 38 125 80 40 22 4 2 5 2300 590 18 12 64 50 34 24 38 22 32 26 145 120 30 15 5 3 6 4200 220 20 10 40 34 19 16 52 38 24 18 75 68 25 18 4 3 7 1900 300 35 20 44 20 22 15 60 44 40 34 140 125 80 55 6 2 8 3150 730 24 19 55 38 18 14 35 30 15 12 200 160 60 52 8 3 9 2920 960 31 27 46 26 20 16 50 26 35 20 120 100 70 55 10 7 10 1640 710 18 15 52 40 15 12 54 32 12 10 95 60 90 78 5 3 Table-2 Biological Absorption Co-efficient (BAC) values for various elements Sample No BAC value of Cr BAC value of Co BAC value of Ni BAC value of Pb BAC value of Zn BAC value of Cu BAC value of Fe BAC value of Mn BAC value of Mo 1 2.846 1.500 2.400 2.500 1.400 1.388 1.363 2.000 2.66 2 4.044 1.538 4.000 1.730 1.375 1.454 1.444 1.315 2.00 3 2.641 1.300 1.406 1.388 1.538 1.200 1.250 1.875 1.60 4 9.754 1.562 1.357 1.200 2.421 1.315 1.562 1.818 2.00 5 3.898 1.500 1.280 1.416 1.727 1.230 1.208 2.000 1.666 6 19.090 2.000 1.176 1.187 1.368 1.333 1.102 1.388 1.333 7 6.333 1.750 2.200 1.466 1.363 1.176 1.120 1.454 3.0 8 4.315 1.263 1.447 1.285 1.166 1.250 1.250 1.153 2.666 9 3.041 1.148 1.769 1.250 1.923 1.750 1.200 1.272 1.428 10 2.309 1.200 1.300 1.250 1.687 1.200 1.583 1.153 1.666 Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 85-90, May (2014) Res. J. Chem. Sci. International Science Congress Association 88 The distribution of BAC of termite mounds for various elements in different classes is shown in table 3. From the data (table 3), it has been observed that in all the termite mounds, BAC values are consistently positive trend. It is significant and interesting to note that Cr is almost dispersed in “positive” category throughout the enriched scale. BAC for the Cr element majority mounds fall in 2, and 3 categories and few mounds are also fall in 4, 5, and 6 categories of enrichment. The elements Co, Pb, Zn Cu, Mn and Mo fall in 1and 2 categories of enrichment; and Ni fall in 1, 2, and 3 categories of enrichment. It is significant to note that no element fall under depletion side. In general, it may be noted that the elements are more mobile in termite soils when compared to those of the surface soils due to the activity of the termites. Since the BAC values of Cr element in all termite mounds are classified as “Positive” reflecting the enrichment of the chromium element in the termite mound with reference to the surface soil. The maximum BAC value of chromium (19.090) in termite mounds is attributed to the influence of chromite mineral zone in the study area. The rest of the elements viz., elements Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo have less values of BAC when compared to the ore element chromium. Earlier Raghu and Prasad10 reported that Ba, Sr, Cu, Mn and Zn showing more than unity in termite mounds. Raghu11 reported the average BAC values for Al, Ca, K, Na, Ti, B, Cr, La, Li, Ni, V, Y and Zr showing more than unity in termite mounds. Conclusion In the study area the concentrations of the elements viz.,Cr, Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo are higher in termite soils than those that of adjoining surface soils, suggesting indicator characteristics of the mounds for these elements, especially for chromium in geochemical prospecting. In the study area, amongst all the elements, Cr concentration (14500 ppm) was much greater in the termite mounds reflecting the enrichment of chromium. Similarly the maximum BAC value 19.090 for Cr element in termite mounds is attributed to the influence of chromite mineral zone in the study area. Thus, termite mounds are useful indicators and find application in mineral exploration. The Cr in termite mounds may derive from the soil carried by termites from the sub-soil in the course of construction their mounds. Thus, the concentration of trace elements viz.,Co, Ni, Pb, Zn, Cu, Fe, Mn, and Mo may be utilized to monitor the levels of soil pollution. Metal concentration in termite mounds may depends on the chemical speciation of metals in soil and soil solutions. Therefore, based on these geochemical investigations termite mounds can be ideally used as possible application in mineral exploration; agricultural reconnaissance surveys; and monitoring of the state of pollution levels of the mining environment. Acknowledgement The author is gratefully acknowledged to University Grants Commission, New Delhi for providing financial support for this study (F No 33-44/2007 (SR), dated 6.3.2008). Table -3 Distribution of Termite Mounds Based on classification of Biological Absorption of Co-efficient (BAC) for various elements Category Class intercals BAC Range Cr Co Ni Pb Zn Cu Fe Mn Mo 6. Hyper �15.59 1 Enrichment 5.Intensively strong 9.00- 15.59 1 4. Very strong 5.20-9.00 1 3. Strong 3.00- 5.20 4 1 2. Moderate 1.73- 3.00 3 2 3 1 2 1 4 5 1. 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