The selection of geochemical anomaly verification methods in forest swamp landscape areas is closely related to the characteristics of secondary landscape conditions and the characteristics of epigenetic geochemistry. Foreign scholars have carried out extensive research work in this research field through various channels.
Northwestern Europe, the former Soviet Union and North America have large areas of forest swamps. The unique soil and organic-matter-rich peat in forest swamps have an impact on the enrichment and dispersion of elements. Exploration geochemists in these areas have their great concern. From the 1960s to the 1970s, they did a lot of research on the existence forms of elements in organic matter and the relationship between organic matter, iron and manganese oxides and elements. Boyle (1977) systematically studied the distribution characteristics of elements in two copper-rich swamps in Canada and concluded that copper mainly exists in the form of humates in the swamps. Some scholars believe that organic complexes are the main forms of metal elements in soils rich in organic matter (R. Ewelett, 1978, etc.). Gleeson and Coope (1966), Chowhurg and Bose (1971, 1972), Baker (1973) and other Western scholars have studied the total amount of elements and organic binding phases in peat, and proposed that the degree of humification affects the combination of organic matter and heavy metal elements. main factors. Jackson (1978) pointed out through experiments on the binding ability of organic acids and elements that pH value and clay content control the binding ability of organic matter and elements. The above studies show that organic matter has an important influence on the migration and enrichment of elements in forest swamp areas. These studies provide a theoretical basis for the formulation of geochemical exploration methods for mineral resources in forest swamp areas.
Through research and field observations, many scholars have proposed that in areas where forest and swamp landscape water systems develop, water system sediments should be used as sampling media to carry out water system sediment measurements. They systematically studied the sampling location, particle size, seasonal changes in element content and sampling density of river sediments. Whitney (1974, 1980) studied the relationship between iron and manganese oxides and metal content, and proposed a geochemical exploration method and technology using hydroxylamine hydrochloride to extract metal elements in the iron and manganese oxide film on the gravel surface.
The former Soviet Union carried out a large amount of research work in the forest swamp area of ??the Be-A Line (Wu Chuanbi et al., 1987), and proposed that iron sediments, soil, etc. can be collected based on local landscape characteristics and different work requirements. Carry out geochemical exploration work using media such as gravel, peat, water and plants in swamps.
In recent years, Canadian exploration geochemist Stewart M. Hamilton and others have carried out fruitful research on the migration mechanism of elements in the epigenetic zone in forest swamp landscape areas, and proposed "reduced chimneys", The concepts of "forest ring", acidic caps and element electrochemical migration model. According to its research results, it is proposed that the sampling layers for soil measurement in the forest swamp landscape area should be the lower part of layer A and the top of layer B; and ammonium acetate or MMI (a confidential patented extractant) or enzyme extraction should be used, and other partial extractants are too strong; only in this way can we achieve better prospecting results. Applying this method to carry out geochemical exploration work in areas covered by thick moraine in Canada has achieved obvious geological prospecting results.
In summary, the current status of research on geochemical exploration methods in forest swamp landscape areas can be summarized as follows:
1) Conduct landscape geochemical research and landscape geochemical zoning ( Б. Ф. Мицкевич , Ю. Я. Сущик, 1981), established a conceptual model of exploration geochemistry (C. R. M. Butt and R. E. Snilh, 1979), and provided basic data for carrying out exploration geochemistry work in different levels of landscape areas (Information Research Institute of the Ministry of Geology and Mineral Resources, 1984) .
2) Carry out research on the element migration mechanism and element geochemical behavior in the epigenetic zone, summarize the activity of elements in the epigenetic environment (Andrews-Jones, 1968), and propose geochemical barriers in the epigenetic zone (A. A. Levinson, 1974).
3) Study the occurrence forms of elements under supergene conditions, and point out that the main forms of trace elements in soil and water sediments are adsorbed ionic states, iron and manganese oxide adsorption phases, and primary sulfide There are 6 forms including physical phase, organic matter adsorption phase, clay adsorption phase and secondary mineral phase (S. Dijkstra et el., 1984).
4) Comprehensive summary of the application of partial extraction technology in geochemical exploration (T. T. Chao, 1984) and hydrochemical measurement (И. С. Ломоносов, 1988), plant geochemical measurement (F. D. Busche, 1987; C. E. Dunn, 1987, 1992; P. J. Rogers, 1993), element activity state measurement (L. V. Antrpovo, 1992; J. R. Clark, 1994; Mann, 1995) and other experimental research results of unconventional geochemical exploration methods. The above results provide important reference materials for the study of large-scale geochemical exploration methods in forest swamp areas.
In short, most people believe that: the 1:50,000 working phase is mainly based on water system sediment measurement (with water chemistry measurement in some areas), and the sampling media include silt sediment, fine-grained sediment between gravels, and peat. materials, washed lime sand materials, etc.; the 1∶10,000 working stage mainly focused on soil measurement, using moss-lichen biogeochemical measurement in the surface stone weathering development area, plant measurement in the stone flow development area, and along the stone flow area. The eroded silt measurement is used at the edge of the stream, and the aquatic moss measurement is used in the swamp development area. At the same time, sampling at the lower part of the A layer and the top of the B layer, testing the content of active elements in the soil with ammonium acetate or MMI or enzyme extraction is expected to achieve better geological prospecting results.