1 AT THE MECHANISM OF ALLOCATION OF MINERALS. 2. |
SULFIDES OF ORE DEPOSITS Makarov V.P. (Geol. Dep. RSGPU, Moscow).
firstname.lastname@example.org; Phone: (495) 433-56-77, Add. 11- 78 1. Studying sulfides of ore deposits helps to specify conditions of their formation. On isotope matter of S sulfur frequently try to determine sources of sulfur. It is more important to emphasize, that formation of isotope structure S is first of all physical and chemical process. According to experiments (EB) sulfides are divided on groups:
a). Sulfides, in particular, biogenic, isotopic equilibrium to the oxide form of sulfur (SO4-2 and so forth). Negative values are typical for them 34S (up to - (30-40) %о), significant ranges of change 34S and simplification S with falling Т.
b). S, for example, in meteorites, it is isotopicaly equilibrium S connections of kind H2S, S-2 and so forth. For them small limits of fluctuation 34S about 0%o (meteoric standard) and enrichment of sulfur by an isotope 34S with falling Т are characteristic. On EB at joint allocation even at very low concerning sulfides concentration of sulfates S of the last takes away overwhelming part heavy S.
Table Deposit Region ПТМ ТРТ Minerals Ion ТизотоС X Y X Y Cerro-de- Peru Py Sph H2S 150 160 Pascо West Shasta USA ПМ СФ Py Q H2S 350 300 Broken Hill Australia КП СФ Gn Sph H2S 200 340 Rex Hill Tasmania Sn ЖЛ Gn Sph H2S 250-300 300-350 Сардана Russia КП СФ Gn Sph S-2 150-200 300-350 Rosebery Tasmania WS ЖЛ Gn Sph S-2* 170 300 Darwin USA КП ЖЛ Gn Sph S-2* 300 300 Cheonbo Korea Au, Ag ЖЛ Gn Sph S-2 150 360 Смирновское Russia ПМ ЖЛ Gn Sph S-2 150 360 Ruakaka Н. Zealand ПМ ЖЛ Gn Sph S-2 250 300 Darwin USA КП СФ Py Sph S-2* 190 300 Левиха Russia КП Py Sph S-2 350 240 Филизчай Russia КП СФ Py Sph S-2 200 300 Rosebery Tasmania WS ЖЛ Py Sph S-2* 350 300 Gaspe Quebec Cu Po Cp S-2 350 150 Горевское Russia ПМ СФ Po Gn S-2 350 250 Филизчай Caucasus КП СФ Po Py S-2 350 Горевское Russia ПМ СФ Gn Sph SO4-2 () 150 Rex Hill Tasmania Sn ЖЛ Gn Sph SO4-2 () 150 Lake Ural КП СФ Gn Sph SO4-2 () 225 Pine Point Canada ПМ СФ Gn Sph SO4-2 () 150 Broken Hill Australia КП СФ Gn Sph SO4-2 () 200 Cleveland Tasmania Mo Po Sph SO4-2 () 350 ЖЛ Rex Hill Tasmania Sn Gn Sph HSO4-1 () 350 ЖЛ Anvil Canada ПМ Py Sph HSO4-1*() 345 СФ The note: ПТМ-industrial type of a deposit. ТРТ - type of ore body. In columns "Minerals" X and Y are axes of coordinates on which values 34S specified in the text of the table of minerals are postponed, and in the column "Temperature" the established Т values of formation of these minerals on the isotope data. (*) are values of Т are coordinated on several mineral pairs.
2. On the literary data distribution of isotopes S between sulfides from 50 deposits of the former USSR and Foreign countries is investigated on the basis of the analysis of 80 minerals samples: Gn-Sph (43 %), Py-Sph (18), Py-Cp (15), Po-Py (8), Po-Cp (8), Py-Mo (5) in pyritaceous-polymetallic (КП-36 %), polymetallic (ПМ-24), copper (10), gold-silveric (Au-Ag-6), tungsten-tinic (WS-6), tin (Sn-4), uraniumic (2), molybdenumic (Мо-1), rock crystal objects with stratiform body (CF - 51 %, as deposits - 3), interspersed (1 %), vein (ЖЛ-25 %) ore bodies (Gn- galena, Sph- sphalerite, Cp- chalcopyrite, Po- pyrrotite, Py-pyrite, Mo- molibdenite, Q- quartz, Сс-calcite). It is revealed: 1). In ores I type (vein and interspersed) with falling Т and distance from an ore body there is a pauperization, 2). In ores of II type (massive) S enrichment by isotope 34S. EB allows to assume, that in ores-II sulfides are equilibrium isotopicaly to substances restored; and in ores-I - oxidized forms S.
3. The technique of an estimation of substance composition (C), isotopic equilibrium to the given mineral (M) is developed on the basis of the theory of new kinds of isotope geothermometers developed by us.
The diagram of isothermal distribution of isotopes S in two coexisted M, described by the equation of a direct line of a kind 34S (М1) = s [34S (М2)] + S is under construction. The angular factor (s) depends from Т formations of minerals and a kind substance, equilibrium isotopicaly М1 and. М2. On size (s) it is calculated Тisot formations of minerals. We believe that the duet «M-C» is a product decomposition of some initial parent substance. Then comparison Тisot with established by a method independent reference Тэт, allows defining composition of substance C (at presence of the known fractionation equations of sulfur isotopes between two minerals).
4. Some results of the analysis are reflected in the table. Sulfides will be equilibrium isotopicaly to ions S-2 (50 %), SO4-2 (14), HSO4-1 (12) and H2S (5) which on a oxidation degree of S are subdivided into groups: restored (H2S and S-2) and oxidized (HSO4-1 and SO4-2) S forms; have no 19 address of % выборок. Earlier for the description of distribution of isotopes S the hypothesis of mixture with participation meteoric or biogenic S was used. Finally, because of methodical mistakes this hypothesis has led a problem of a nature of sulfides up a blind alley. At formation of sulfides meteorites appeared not and besides.
For paragenesis of M- S-2 the following mechanisms of an establishment of these equilibriums are possible on the basis of the following hypothetical reactions:
... … + МеS (or МеS2) + H2S + …. (1)... … + МеS (or МеS2) + S-2 + …. (2)... … + МеS (or МеS2) + SO4-2 (or HSO4-1) + …. (3) In connection with reaction (1) in a seal reactions such as Me (HS)3-1 MeS + HS-1 + H2S [K.Grejndzher, 1976] or Me+x(HS)nx-n MeS + HS-1 + H2S [I.L. Chodakovskij, 1966] are usually discussed. Complexes of metals look like [Zn (HS)3]-1; [Pb(HS)3]-1; Zn(HS)2 and so forth. But ion HS-1 is not established on the isotope data. By Bigeleisen’s rule in a chain (MeS HS-1 H2S) an exchange of isotopes ion HS-1 should not be fixed, and will be observed isotope equilibrium in association [МеS (or МеS2) + H2S]. In conditions of high potential S it corresponds to presence in a hydrothermal solution of polysulfides of a kind [MeS2]-2, [MeS4]-2 etc. [V.V.Scherbina, 1962], soluble in hydrocarbonaten and chloriden solutions [N.I.Govorov etc., 1966].
For low-sulfiden objects for a substantiation of reaction (2) I.G.Ganeeva's hypothesis (1977) is acceptable: in vein deposits minerals are allocated from ansulfiden solutions according to hypothetical reaction of Pb (OH)4 + 2H2S [PbS + S-2] + 4H2O.
On Kizil-Say U-deposit (S. Kazakhstan) is investigated Py of post-ore Q- and Q-Cc veins. For Py low sizes 34S (up to -30%о), reduction 34S with falling Т (homogenization ГЖВ and Cc isotope) are characteristic. It speaks about influence of oxidized forms S according to reaction (3) on formation Py and formation Py as a result of decomposition of tiosulfate or sulphites on hypothetical reactions (a) Fe (S2O3) FeS2 + 2SO3 or (b) Fe (S2O3) + H2O FeS2 + SO4-2 + H2. The opportunity of existence thiosulfates and sulphites in hydrothermal conditions is investigated R.M. Garrels et al (1958), N.G.Tjurinym (1963), V.V.Scherbina (1964), T.M.Sulzhievoj etc. (1982), S.V.Kushnir (1989) and at low concentration of components follows from the analysis of their thermodynamic properties. These reactions are possible at formation Q-Py-of veins. However, their use for analysis Q-Cc- veins is problematic, as in result the sour environment destroying Cc with formation of gypsum or anhydrite can be formed. On an ore field these sulfates are not observed.
References 1. Макаров В.П. Способ определения глубины диффузионного фракционирования изотопов элементов природных соединений. Авт. свид. 1260906 // Бюлл. изобр. откр. 1986. З6. 197.
2. Макаров В.П. Способ определения температуры образования природных соединений. Авт. свид.
1312504. // Бюлл. изобр. откр. 1987. 19. 192.
3. Макаров В.П. Некоторые условия образования сульфидов рудных месторождений по изотопным данным // Конф-ция «Геологическая служба и минерально-сырьевая база России на пороге XXI века. Санкт - Петерб., ВСЕГЕИ, 2000.
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