2012

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Abstracts of International conference

Ore potential of alkaline, kimberlite

and carbonatite magmatism

Petrological features and ore content of veined granitoids in Kryvbass

Velikanov Y. F., Velikanova O. Y.

Institute of geochemistry, mineralogy and mineralization n. a. N. P. Semenenko of National Academy of Sciences of Ukraine, Kyiv, Ukraine

olgavelikanova1@rambler.ru

 

The attention of researchers are always being attracted to problems of granitoids study their composition, age, relations with inclosing aqueous-volcanic rock formations of kryvorozhskaya series, petrological-geochemical characteristics and ore content.

Granitoides of demourinskiy and saksaganskiy complexes of Archaean age are developed in eastern framing of Kryvbass (ore basin of Kryvorozhe), the ones of ingulets complex of Archaean age and kyrovograd granits of Proterozoic age are developed in the western framing.

 Age position of granitoides within region as specific formations of defined stage of its development, that carry a typical metallogenic load, is of a great concern to discover condition s and regularities of some minerals formation.

Data of relations of granits and rocks of kryvorozhskaya series are of importance as to be used for doing various structural and stratigraphical maps (constructions) in region.

Nowadays relations of granitoides of framing and volcanic-aqueous rock mass of kryvorozhskaya series are determined in individual case and are not discovered sufficiently.

Active contact of microcline calcigranite and metabasite of novokryvorozhskaya suite is known in mine Olkhovskaya of Eastern Mining and Enrichment Enterprise. Mineralization of Cu, Mo, W, Sn, Zn, and Pb is occurred in aureole.  Zircon is isolated from granites has showed isotopic age of 2650 billion years [2].

Bodies of granite-pegmatite and aplite which crosscut ferruginous formation of saksaganskaya and chemogenic-aqueous rocks of gdantsevskaya suits within the interval 163,8184,7 m as well as amphibolite of kryvorozhskaya suite within 194,8257,6 m; 336,0433,4 m and 467,4 489,0 m are penetrated in Eastern-Annovskaya streak by the well 20873. Veined-shaped bodies of aplites by various thikness are penetrated also by wells 20520, 20525 and others. Age of granitoides of well 20873 determined by zircon is 261520262515 billion years [3].

Zones of silicification and greysening with abnormal content of Mo, Cu, W, Au are determined by the well 20526 in Eastern-Annovskaya streak in aureole of microcline calcigranite and metabasite of novokryvorozhskaya suite [1].

New data about relations of veined granitoides and aqueous-volcanic formation of  kryvorozhskaya series are gained while description of  Pervomaysk Mining Department minings and wells of prospecting-structural profile that was drilled southward MD n. a. Lenin on the latitude of Kryvorozhskaya super-deep well where pegmatites burst enclosing rocks of kryvorozhskaya series.

On various horizons of  Obedinennaya well of Pervomayskoe MD pegmatites are observed  as veinlet with thikness 0,51,5 m and walked out along the strike for some meters on minings. Contacts with enclosing rocks that are represented by breccia metasandstone and quartz-biotite schists of gdantsevskaya suite are sharp, clean, pithes are heavy at a 7580 eastward.

Pegmatites are coarse-grained pink-grey rocks of pegmatoid structure with phenocryst of orthoclases, quartz, muscovite, tourmaline. Textures of rocks are massive, brecciated on some areas. Mineral composition: microcline+orthoclase 3540 %, in the form of prismatic, oblong pink-grey and light-grey cristalls in dimensions of 0,81,5 sm. Plagioclases (1015 %) in the form of prismatic, tabular or irregular light-grey cristalls in dimensions of  1 sm or less. Muscovite (1015 %) are light-grey with bluish-greenish tone in the form of crossicolumnar cristalls of pseudohexagonal habit in dimensions of 1,5 sm or less. Quartz (3035 %) is spread irregularly in the form of xenomorphic grains that fill space between rock forming minerals or veinlet of various thicknesses. Tourmaline (57 %) are marked as oblong-prismatic bluish-grey crystals in length 12 sm, cross section is 0,50,8 mm. Apatite is usually occurred as short-columnar or irregular form crystals with dimensions of 0,52 mm, pale green or greenish-bluish colored. Albite is occurred as prismatic or tabular crystals with dimensions of 0,8 sm or less which replace orthoclases, and fine grains of some millimeters and yellow-grey colored is filled rock fissures. Magnetite is occurred as scarce impregnation of segregation in dimension of some millimeters.

Pink-grey coarse grained pegmatites also were determined while description of core of well 19929 of prospecting structural profile is drilled southward MD n. a. Lenin within the range of 741,3748,2 m and 754,3755,3 m. The structure of rocks is pegmatoid, texture is massive. Pegmatites consist of orthoclases (3035 %), acid plagioclases (1015 %), quartz (3035 %), muscovite (1015 %), tourmaline (68 %), apatite and magnetite. Enclosing rocks are represented by grey garnet-mica schists and dark-grey mica metaaleurolite of gdantsevskaya suite.

Similarity of main parameters of pegmatites of both territories was shown by petrographic and petrochemical research. Representative points of pegmatites chemical composition fill total field.

Study of pegmatites in sections has shown they have been exposed by various processes of metasomatosis was manifested in albitization, greysening, silicification and sandy metasomatosis manifestation.

Filling of orthoclases by albite and healing of joint in pegmatite and enclosing rocks with albite are connected with processes of albitization.

Development of muscovite, apatite and tourmaline in pegmatites is connected with greysening, silicification and sandy metasomatosis.

Abnormal content of Li, Rb, Cs, Be, Zr, W, Mo, Sn, F, Cl, B and other ore elements in pegmatites are determined by processes of metasomatosis.

Absolute age of specified pegmatites of Pervomayskoe MD and prospecting-structural profile is not determined. They are confined to late dislocation with a break in continuity and probably have formed in conditions of establishing of platform regime on Kryvorozhskaya structure territory.

 

References:

1. Velikanov Y. F, Semenenko N. P. Conditions of forming of molybdenum mineralization in rocks of Eastern-Annovskaya streak // Geological magazine 1992. 4. P. 8992 (in Russian)

2. Semenenko N. P., Yaroshchuk E. A., Kourlov N. S. and oth. Isotopic age of saksaganskaya metabasite series and bokovyansko-lozovatskiy complex of Ukrainian Shield // Theses of XXI session. Commission on determination of absolute age of geological formations. Ufa, 1979. P. 148149. (in Russian)

3. Shcherbak N. P., Artemenko G. V., Bartnitskiy E. N. And oth. Age of aqueous-volcanic formations of Eastern-Annovskaya streak // Report of Academy of Sciences of USSR. Series B. 1989. 2. P. 3035. (in Russian)