Efficacy of Some Chemical Extractions in the Recognition of True and False Anomalies in Geochemical Exploration

Various chemical extraction techniques are being employed in exploration geochemistry to identify true and false nature of soil anomalies. The efficacy of hydroxylamine hydrochloride, sodium dithonite and ammonium acetate selective extractions have been evaluated through model experiments on a series of Pb, Zn, Mn and Fe near pure mineral forms. The results obtained suggest that these extractions are not as specific as claimed in literature. Due to its complexing tendency, ammonium acetate extractant cannot be employed to extract ion-exchangeable trace metals either in the selective or sequential extractions. Selective and differential chemical quantities arc useful in designing an interpretative methodology for recognising true and false anomalies. Selective chemical quantities of Zn have provided greater insight into the distribution characteristics. Computation of background, anomalous and highly anomalous components has been accomplished from the Zn selective quantities, which are usable directly in exploration. Evaluation of this nature can assist in taking a decision. whether to carry out detailed exploration or not. Hence practicing of such an approach is strongly recommended.