Methods of founds of fields

Hydrochemical method

Hydrochemical methods of looking up of fields are grounded on study of an elemental composition natural surface and underground waters. The principal ground of this method is compounded by capacity of water to dissolution of soils, its involvement in chemical transformations of minerals and property of water as movable environment. Connection between an elemental composition of water and presence near to a water source of reservoirs of minerals does not cause doubts and is one of the reasons of originating of the hydrochemical anomalies having search value.

Conditions of application

Original positions. The most effective is application of a hydrogeochemical method for looking up of the mineral deposits which are in following conditions:

1. on the leases bridged by a thick jacket carried of depositions when the biogeochemical method of looking up is inefficient even
2. in sharply splited high-mountainous areas where because of particular conditions of drain of underground waters the method becomes not only more plutonic, but also more exact interpretation of hydrogeochemical anomalies is possible
3. in platform conditions at interquartile burial those of minerals below domestic bases of erosion

Depending on a task in view hydrochemical and followings it is possible to partition on: 1) - regional (1:200000-1:100000); 2) - actually search (1:50000-1:25000) 3)-detailed (I: 10000 and is larger).

Areal studies. They usually promote finding-out of the communal geochemical both hydrogeochemical performance of region and emanating of the most perspective territories, therefore the esteemed stage has special value in hydrogeochemical studies. In the samples sampleed on it a stage, the maintenance of the max number of detecting instruments of minerals, interquartile for learnt region should be instituted.

Actually basic researches. These operations are held: on the perspective floor spaces for eliciting of hydrogeochemical auras and emanating of leases for posing of detailed operations.

Detailed studies. They are conducted for a contouring of fields, and in certain cases - separate bodies of minerals, on the perspective leases revealed by the previous studies.

Optimum objects for hydrochemical looking up are fields of mineral salts - various natural chlorides and sulphates. The cumulative maintenance of these joints in natural return brines can exceed 350 gm/l, and they are capable to remain steadily in solutions, instituting composition of salt in solution of oceanic water (the sum of salts 35,6 gm/l). Allowing, that communal salinity natural fresh, including fluvial, waters usually compounds 1,0-0,5 gm/l, it is possible to value that range in which one anomalous maintenances of salts in surface and land underground waters can lay.

From ore deposits optimum objects for hydrochemical looking up are sulphidic, mainly kolchedanno-polymetallic, and, specially, copper-sulphide fields rich with disulfides. Natural waters are beneficiated with ore members basically at hypergene acidification of sulphide ores in which one course almost insoluble, but unstable sulphides before transformation into steady and almost insoluble sec minerals drive a stage of readily soluble sulphates.

Despite processes of self-cleaning of natural waters from maintenances of ore members, their raised, anomalous concentration remain in fluvial and underground waters on spacing intervals to 500-1000 m, sometimes to several kilometres from fields. It is instituted by a variety of forms of a finding of ore members in difficult multicomponent systems which one represent natural waters. Migration of ore members in waters proceeds in the form of simple ions, complex inorganic joints with various ligands, in particular in the anionic form, and also in the form of various metalorganic joints of the raised dissolubility. Practice of hydrochemical studies affirms a discovery reality by looking up of aqueous auras and currents of dissipation of ore deposits. The example of a hydrochemical profile is introduced on fig. of 1 appendix.

Results of a hydrochemical method depend on seasonal fluctuation of levels of groundwater, a deposition of an atmospheric precipitation and a mode of a hydrosink of the rivers, for a short interval of time modified in hundreds times. It institutes instability of quantitative arguments of a hydrochemical background - variable values Cf the big or obscure magnitude standard multiplier e, bad reproducibility and small contrast of hydrochemical anomalies.

Very effective range of application of a hydrochemical method - looking up of fields of zones of pore acidification. The ore bodies of these fields which have received the name of "beaters", are reshaped of natural waters on a regenerative barrier. An atmospheric precipitation rich with oxygen, being filtered through soils of a granite massif, is capable to be beneficiated with six-valency uranium though the maintenance in them is only a little this member above the background. Arriving in aquifer of sedimentary depositions of submontane plain, these waters spend the oxygen for acidification of organic matter, ferrous iron and pyrite - customary reductants of the sandy facieses separating in regenerative conditions of seabed. On boundary between the oxidised part of a seam and its source state there is a sharp gang of geochemical conditions and on a regenerative barrier there is a sedimentation of tetravalent uranium, up to forming of commercial ores. The maintenance in local waters, after passing of a regenerative barrier by them, falls on the whole order - to n · 10-6 gm/l.

The problem of hydrochemical looking up includes localisation of a spacing of underground waters in which one there is a gang of oxidising conditions on regenerative, tracked by a decrease of the maintenance of uranium in waters. This problem successfully dares by boring of exploratory tests by a principle of dichotomy with their hydrochemical sampling. Similarly hydrogene fields of molybdenum and selenium - members with the variable basicity, capable to deposition on a regenerative barrier can be reshaped. In these cases the hydrochemical method is irreplaceable at solution of a search problem.

Images of results of the analysis and estimation of anomalies

On materials of regional hydrochemical studies. Maps of communal chemical and microcomponental structure of waters are compounded. On a map of a communal elemental composition genetic types of waters are dedicated and their elemental composition is resulted. This map is compounded on a hydro-geological ground taking into account landscape-geochemical conditions. On a map of microcomponental structure the leases differing on a complex of microcomponents, and in their limits - the floor spaces with anomalous maintenances of one or several members-detecting instruments are dedicated. A result of analysis of allocation of members-detecting instruments in the waters probed at areal studies, is emanating of leases, perspective for looking up of various minerals.

The data received at sredne - and large scale hydrochemical studies, form a ground for emanating of hydrochemical anomalies and an establishment of their dimensional connection with locus of ore bodies.

Calculation of all background and anomalous maintenances is carried out differentiated in relation to probe to types of waters, aquiferous complexes and geochemical landscapes. At considerable variation of salinity of waters sometimes there are handicappings in grading of anomalies. In these cases it is expedient to use following relations of maintenances of separate reductants among themselves and communal salinity of water:

SO4/I; SO4/Сl; В/Сl; SO4/НСО3; Zn/М; B/M

Where M - communal salinity of water in a culling dot.

In case of their essential difference from the similar relations calculated for obviously barren leases, they can be one of indirect search signs.

As a result by results of hydrochemical studies the map of perspective leases at which one big number it is necessary to dedicate prime leases should be compounded.

Atmochemical method

Atmochemical (gaseous) looking up of mineral deposits are grounded on study of structure of underground atmosphere - an elemental composition of the gases sating rocks near to a daylight area. If the gaseous sample drawing is conducted from small depth (1-3), it is accepted to speak about study of subsoil air. Modern gaseous shootings are executed with depth of a sample drawing of 20-600 m. the gaseous structure of ground atmosphere though efficiency of atmochemical shooting essentially increases in this alternative is less often investigated. Aerosol shootings to refer to number of lithochemical methods of looking up more correctly.

Atmosphere basically three gases - nitrogen (about 78 %) compose, oxygen (about 21 %) and argon (nearby 1 %), in the sum components of 99,94 % of its mass. At variable quantities in atmosphere there are water pairs; maintenance CO2 - about 0,03 %, the maintenance of other gases 10-4 - 10-6 % and less. The low geochemical background and high mobility of chemical elements in a gas phase construct favorable conditions for forming of atmochemical auras of dissipation of any mineral deposits.

Conditions of application

The basic amount of works by looking up of mineral deposits is necessary on a fraction of looking up of oil and gas reservoirs. Geologo-geochemical substantiations of an atmochemical method of looking up of these fields are most obvious. The natural oil pool represents a mixture liquid and hydrocarbon gass, metane, naphthenic and aromatic numbers with an impurity of sulphurous, nitrogenous, oxygen joints and the sol rests. The maintenance of hydrocarbons in petroleum gass reaches 80-95 %, and the geochemical background does not exceed 2-4·10-4 %. Such huge differential of concentration institutes process of dissipation of hydrocarbons in surrounding soils. Any rocks possess a gastightness thanks to presence in them of pores and fractures. Under the influence of lithostatic pressure of move of gases in pores and fractures originates towards a daylight area in the form of an effusion.

Gas-mercury shootings - an indirect method of looking up of fields, only for actually mercury fields they are straight lines. In sulphidic minerals and fields of chalcophylic group of members essentially raised concentration of mercury are discovered. The mercury maintenance in a cerussite can reach 0,1 %, that in ten thousand times exceeds a rock sphere clarke. Capacity to mercury upbuilding is marked and for fields of other minerals, including. Oil and gas.

All it, along with very low (1,33·10-9 mg/l) and steady (e =1,02) a geochemical background gas-mercury to shootings provides universality by looking up in the barred territories (fig. of 3 appendices).

Among gases of ore deposits three basic groups are dedicated:

1. gases, idiogenous to ore deposition process
2. gaseous reductants of zones of tectonic disturbances
3. gases of hypergene processes

Gases all three groups in the sum institute forming of multicomponent atmochemical auras of dissipation of ore deposits; field observations affirm a reality of their eliciting

By looking up of ore bodies atmochemical methods should be used on the leases bridged by a strata of young depositions. Their posing is possible only after conducting of the skilled-methodical studies which have demonstrated performance of an atmochemical method of looking up, expected in concrete geologic and landscape-geochemical conditions of certain industrially-genetic type of fields. Application of atmochemical methods of looking up of ore deposits most expediently at a stage “Looking up of mineral deposits” at plotting scale of studies 1: 50000-1: 25000. These studies can be held as independently, and in a complex with other explorations.

Conducting of skilled operations

In all new areas skilled-methodical studies which one should answer on following questions should precede conducting of search operations by atmochemical methods:

1. whether gaseous auras of dissipation are formed over expected bodies of minerals in a concrete geologic and landscape-geochemical situation
2. what detecting instruments form anomalies
3. what is the most expedient depth of a sample drawing
4. what values of the background and anomalous maintenances chosen for looking up of detecting instruments
5. whether are in the given conditions atmochemical looking up more effective and cheap in comparison with other methods of looking up

The image of results of the analysis and an estimation of anomalies

The data received by atmochemical looking up, are represented in the form of profiles, sections on wells and maps of maintenances of gaseous reductants. All plot material make out; according to earlier reviewed requirements. About perspectivity of the revealed atmochemical anomalies for ore bodies it is possible to do deductions after conducting of plutonic lithochemical sampling. Thus wells should reach radical rocks which one are exposed to sampling.

Biogeochemical method

Biogeochemical looking up of mineral deposits are grounded on study of an elemental composition of live matter, as a rule, structure of plants. Between an elemental composition of live organisms and inhabitancy structure there is an indisputable dependence, in limiting cases exhibited by gang of their specific structure, the boosted or oppressed progressing and occurrence of morphological features. Modern biogeochemical looking up are linked to chemical analysis of matter, observations over specific structure and morphological features of vegetation compound a subject of geobotanical studies.

As a result of studies presence of biogeochemical anomalies in an elemental composition of the plants growing over fields of copper, zinc, lead, uranium, molybdenum, nickel, a boron, gold and other minerals was invariably affirmed. Usually these biogeochemical shootings were held by sampling of one or several dominating kinds of plants, an ashing of vegetative matter and spectral analysis of the received ashes.

For the performance of a geologic role of biogene migration of trace elements B.B.Polonov has tendered relation magnitude between member maintenances in sol of a plant and in soil on which one it grows. This index has received the name of coefficient of biological occluding and is designated Ax:

Аx=С2 / С1,

Where C2 - the member maintenance in sol of a plant, %; С1 - the maintenance of this member in soil.

Application conditions

Original positions. Application of a biogeochemical method of looking up expediently when it possesses advantage before more simple lithochemical method of looking up on sec auras of dissipation. It is possible to consider, that the biogeochemical method is one of the most effective methods in following landshaftno-geochemical and climatic zones:

1. a hymid zone at the slowed down denudation if wide progressing was received by processes of leaching of members-detecting instruments from eluvial - deluvial depositions and airing crusts
2. hymid and modestly damp zones if sec lito-chemical auras are bridged by remote brought depositions power to 40 m, and in separate cases-to of 80 m
3. deserts or arid zone semi-deserts if sec lithochemical auras or it is is immediate ore zones are bridged by remote brought depositions power to 20-40 m; 4) boggy plains and peats bog at ebb (2 10) burial of potentially ore - hosting bedrocks; 5) on the leases boarded with a close set moss cover where culling of lithochemical samples is handicapped and linked to the big expenses
4. on the leases boarded with a vegetative cover, and with blind lithochemical auras of dissipation which one high bound is on depth not less than 1 m from a daylight area
5. on the leases bridged largely clumpy large boulders by taluses, the overgrown trees and bushes
6. on bogs (under condition of their frigidness and possibility of winter sampling)

Depending on a task in view biogeochemical studies share on regional (1:200000-1:100000); actually search (1:50000-1:25000) and detailed (1:10000).

Regional operations. They promote finding-out of the communal geochemical and biogeochemical performance of areas ', at their conducting discovery of biogeochemical auras of a part of fields is possible. Conducting of the skilled-methodical studies providing effective conducting of looking up by a biogeochemical method at the subsequent stages should be the basic task at this stage.

Actually search operations These studies should lead to discovery of biogeochemical auras of new mineral deposits and an establishment of communal laws. Their placings. At engineering of plutonic geological mapping with forecasting of minerals biogeochemical looking up should precede boring, and their data - to be allowed for definition of places of location of wells.

Detailed operations. The primary goal of these studies eliciting and a contouring of biogeochemical auras of the fields, separate ore zones and bodies.

Skilled operations

Skilled operations should be held over ore bodies and barren leases and include botanical and biogeochemical studies. At botanical studies institute principal views of the plants growing in given area, and compound a herbarium. By means of biogeochemical skilled operations solve following problems:

1. definition of influencing of phenological phases of progressing and age on the maintenance of members-detecting instruments in the most abundant plants of area
2. an establishment of laws of allocation of members-detecting instruments in parts plants
3. eliciting of features of connection between metals in plants
4. an establishment at the basic plants of area of physiological barriers of occluding of members-detecting instruments
5. definition of plants, the most suitable for sampling
6. eliciting of a complex of members-detecting instruments, which one definition of maintenances is necessary for holding in samples
7. an establishment of morphological and biochemical features of biogeochemical auras depending on structure and the sizes of ore bodies and sec lithochemical auras, from power of friable depositions, landscape - geochemical conditions
8. definition in concrete landshaftno-geochemical conditions of a distance of a method at culling in samples of the basic plants
9. confrontation of results of biogeochemical looking up to the lithochemical
10. an establishment of distinctions in allocation of the basic members-detecting instruments in the same plants growing in various landscape - geochemical conditions

Culling and treating of samples

General provisions. A sample drawing network at conducting of biogeochemical studies, orientation of profiles and succession of rowing of plotting scale of operations should correspond to the requirements shown to production of lithochemical looking up on sec auras. One kind of plants should be probed successively not less than on five dots on a profile. At sampling of grassy plants (the proportion between separate parts in which one always is approximately identical) in sample to take all overground part, except the radical leaves contaminated by parts of soil better. At sampling of long-term bushes and trees in samples always it is necessary to take only the same part of a plant (from bushes and deciduous soils of trees it is expedient to sample leaves in samples, and with coniferous - a gain of last year with needles).

The account of biological barriers at a choice of plants for sampling. Now very big attention at conducting of biogeochemical looking up began to be given to biological barriers of occluding of members, and accordingly - "barrier" and “non-barrier” to plants. Analysis of analyses of many tens thousand biogeochemical samples demonstrates, that a physiological barrier of upbuilding of the metals which are usually being detecting instruments of an orebody, starts to operate after reception by a plant of their such "portion" which one exceeds the anomalistic maintenance of the same members in a plant for the given landscape. However in this connection it is necessary to place emphasis on once again, that for each plant it is necessary to institute background and anomalistic maintenances in each geochemical landscape. Inflow of the raised maintenances of any members in plants causes failure before existing connections between members in an organism. As a result of it in plants it is accumulated in anomalous concentration (raised or slashed) a number of indirect members-detecting instruments.

The basic features of sampling. At sampling it is necessary to pay attention to the botanical signs pointing a possible finding of mineral deposits. Such signs can be:

1. physiological and morphological variations of plants
2. occurrence of peephole and universal plants-detecting instruments
3. gang of vegetative associations, not explainable from the point of view of measuring of ecological conditions
4. essential deflections in the form of progressing of plants (early or later flowering, an early or late leaf fall of leaves, etc.)
5. signs of oppression or not explainable other reasons absence of vegetation

Treating of samples. The sampleed biogeochemical samples in field conditions dry and crushed. In case of a strong dust pollution of sample it is necessary to flush rain or pure fluvial water. In view of hazard of "washing away" of members flushing should be held as soon as possible. Then in sample lab are exposed to an ashing in special boards. The received ashes calcinate in muffle boards within 4-6 hours at temperature 500-600 C°. In such conditions in samples burn out organic matters. The Calcinated zone is pounded and transmitted for spectral analysis conducting

In need of definition in biogeochemical samples of easily volatile members (Hg, As, Sb, etc.) samples dilute in acid (preliminary validated on absence of members spotted in samples) and analyze a solution.

The complex of the members which are subject to obligatory definition at regional biogeochemical studies, is similar to that in the learnt lithochemical samples sampleed by looking up on sec auras of the applicable plotting scale. The members spotted in biogeochemical samples at sredne - and large scale looking up, are erected after conducting of skilled operations.

The image of results of the analysis and an estimation of anomalies

For an exception of influencing of terms of sampling of plants on the maintenance in them of metals within all area of looking up it is necessary to dedicate the floor space sampling in which one limits it is possible to effect in one phenological phase of progressing probe-tested plants (for which one in advance it is erected, what their part is taken in samples). The sizes of such floor spaces depend in each concrete case on speed of gang of phenological phases at probe-tested kinds of plants, from passableness of a lease and from a sample drawing season.

Within isolated the floor spaces leases of comparable samples are erected was immediate. Practically emanating of such leases is held at consecutive laying of the maps of geochemical landscapes made on a tracing-paper and gangs of phenophases probe-tested plants (for each plant the maps of leases of comparable samples become). Usually within the floor space including to 10000 sampling points, it is dedicated from 30 to 70 various leases of comparable samples.

Emanating of anomalies. In the course of mathematical treating separately for each kind of the plants growing on certain leases of comparable samples, anomalous maintenances of members in sol are erected. For eliciting of biogeochemical anomalies on a plane-table special badges or colour take out maintenances, considerably smaller background, anomalous for two and nine correlated samples, and also for individual samples. Then dedicate "below zero" and "positivegoing" anomalies for each member on a separate plane-table. The summary map of anomalies with emanating on it of separate anomalous zones is then compounded.

Estimation of anomalies. Perspectivity of each anomaly is esteemed depending on features of a geological feature, allocation of members-detecting instruments and variation of correlation dependences between them. All anomalies should be examined on terrain for rejection obviously not linked to mineral deposits and for finding-out of features of a geological feature of anomalous leases.

On perspective anomalies necessarily conducting verifying plutonic or surface (depending on power of bridging depositions) lithochemical shooting on friable depositions. After complementary geochemical and geophysical studies mountain or chisel developments for opening of ore zones in radical burial are set.

Data of biogeochemical shootings remain till now at level of qualitative results that does not give the answer to the basic question - about advantages of a biogeochemical method of the looking up instituting expediency of its application instead of other geochemical methods.