I have combination of sulfide minerals without arsenopyrite... commonly pyrite, Chlpyrite, sphalerite, galena.... etc. with some ganugues calcite, Pj, Muscovite and fluorite... Can I use one or some of them for temperature determination?
Dear Mr. El Monsef,
the term geothermometer would be misleading and cannot be used for sphalerite in this case. Nevertheless, there are some elements such as Fe and In, which are abnormally high in sphalerite originating from fluids of elevated T. In pegmatites, near the quartz core (Hagendorf, Pleystein) and in skarn deposits, e.g. Trepca, Fe increases to contents of double-digit values and ZnS is given a name of its own christophite or marmatite. Along with this increase In increases too. By contrast, Hg tends to increase as the temperature of formation of ZnS decreases. You may use these trace elements to approximate the T regime but the approach is far from being called a geothermeter. Also pressure has an impact on the Fe content in ZnS. Combination of In and Cd is also very helpful.
Galena is much better for an approximation of the T regime using the element combination Ag, Sb, Bi which are a function of the presence of miargyrite (AgSbS2) and schapbachite (AgBiS2). The latter used to be conentrated in galena under high-T conditions, whereas the Sb-enriched analogue is concentrated in galena of medium- to low-T conditions.
A more precise description of the mineral association would perhaps allow for a more precise answer as to the use of one or the other trace element or mineral couple to constrain the T of formation.
Best regards
H.G.Dill
Dear Mr. El Monsef,
I completely agree with the concepts of H. D. Dill. Sphalerite can not be called a geothermometer and EPMA studies always give you qualitative results regarding the temperature formation. However, I would to add that the common presence of fluid inclusions in sphalerite will provide to you an excellent tool to know the exact temperature of formation. This method can be applied not only in sphalerite but also in quartz, calcite or fluorite. The latter, minerals that you tells are present in the mineralization.
Regards,
Nilda E. Urbina
Thanks for all, prof. H.G.Dill and prof, Urbina ... I am already working on fluid inclusions inside quartz veins carrying sphalerite mineralization, but i need to combine fluid inclusion study with mineral chemistry for better restriction and accuracy of the P-T condition
Dear Mr. El Mosef,
If you want to improve accuracy of your estimated P and T, certainly EMPA data are not the best, unless you obtain trace elements values (means increasing acquisition time to 100-200 seconds and adjust a few more parameters for analyses acquisition). I suggest to try to get sulfur stable isotope composition of sulfides which appeared to be formed at the same time (i.e., in equilibrium). In such instance you could produce sulphur-isotope geothermometric temperature values (see for example: Gulcan Bozkaya, and David A. Banks, 2015, Ore Geology Reviews). Constraining pressure is even more complicated. Fluid inclusion study and calculation of the correct solute-bearing water isochore is going to be your key tool for pressure.
I also agree with the comments of Dr. Giulio F. Solferino. Studies of fluid inclusions not only allow you to get absolute values of temperature but also the pressure values through P-V-T diagrams. Of course always that you get the correct calculation of the corresponding isochore as suggested by Dr. Solferino.
Regards,
Nilda E. Urbina
Hello. It is possible to estimate pressure using sphalerite-pyrite-pyrrhotite assemblage. Martín JD, Gil AS (2005) An integrated thermodynamic mixing model for sphalerite geobarometry from 300 to 850°C and up to 1 GPa. Geochim Cosmochim Acta 69:995–1006. doi: 10.1016/j.gca.2004.08.009
Also, you can try to estimate equilibrium temperature by measuring concentrations of Cd and Mn in sphalerite and galena. Their distribution constants are known.
Bethke PM, Barton PB (1971) Distribution of some minor elements between coexisting sulfide minerals. Econ Geol 66:140–163. doi: 10.2113/gsecongeo.66.1.140
Hope that helps.
Could you list all of the sulfide minerals present in your assemblage?
Hello.
I thought that the following articles may be of help regarding your question.
-Hutchison M.N. and Scott S.D. 1981. Sphalerite geobarometry in the Cu-Fe-Zn-S system, Economic Geology, 76:143-153.
-Scott S.D. 1983. Chemical behavior of sphalerite and arsenopyrite in hydrothermal and metamorphic environments, Mineralogical magazine, 47:427-435.
Good luck and Salam!
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