The Geochemical Methods To Extract The Weak Geochemical Signals From Concealed Deposits

With the development of deep penetration geochemical methods and techniques, the techniques to extract the weak geochemical signals for exploring the concealed mineralization have been paid more attention among global exploration geochemists. However, the technique of extracting mobile elements from soil could not shake off the restriction of traditional methods in China and the technique have been remaining on the level of analysis for mineral phase with sequential selection extraction. According to MMI technique, the characteristics of weak geochemical signals from deeply concealed deposits were studied with the numberless experiments of the extraction of soil samples selected from the known mineralization ore-bodies in different metal deposits lie in semiarid landscape and semi-humid region with extractant A or B. The blank of these kinds of A or B reagent is controlled. A great of geochemical data will be accumulated.Choosing the high resolution of inductively coupled plasma mass, the comparison between the total contents of elements and the contents of elements after sequential selection extraction and extraction with special reagents A or B from soil samples of different deposits, the results about the weak geochemical signals are better with reagent A or B than traditional geochemical method and sequential selection extraction. The soil samples are from Bairendaba polymetallic deposit in semiarid region; and Longjiang porphyry copper deposit in forest-swamp landscape and Wangjiazhuang porphyry copper deposit in alluvial plain. The results of extraction show that the total digest and the sequential selection extraction are ineffective but the extractant of A or B are effective above the mineralization for these landscape areas. The geochemical signals from deep mineralization could be extracted. Different concentration of extractant A or B is fit to different landscape areas, for instance, the concentration of 0.5% is applied for grassland covered, 0.2% is for alluvial plain and 0.1% is for forest-swamp.The temperature, humidity and the value of p H will influence seriously for the extraction results during process of experiments. So, the comparisons of static immersion experiments and dynamic flow experiments have been studies at the same concentration of extractant A or B. The dynamic flow through the soil samples could save the time of extraction, prevent reverse direction of chemical reaction and reduce the matrix interference. The results from all of three studied areas show that the dynamic flow extraction with extractant A or B is better than the static immersion extraction because the anomaly could be shown clearly and the false anomaly from weathered soil could be minimized.According to the above studies, it is necessary to select appropriate concentration of the extractant A or B through the experiments, but the dynamic flow extraction is available and effective.Based on this research, the comparison study is made between the consequence of the extraction with extractant A or B and the geogas measurement. There are these two kinds of geochemical anomaly in soil above the concealed deposit. Even though the patterns and intensity of anomaly have difference, they could be applied in conjunction for exploring the deposits in overburden areas.