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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 Kryvorozh’e), 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
163,8–184,7 m as well as amphibolite of kryvorozhskaya suite within
194,8–257,6 m; 336,0–433,4 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
2615±20–2625±15 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
“Ob’edinennaya” well of Pervomayskoe MD pegmatites are observed as
veinlet with thikness 0,5–1,5 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 75–80° 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 35–40 %, in the form of prismatic, oblong
pink-grey and light-grey cristalls in dimensions of 0,8–1,5 sm.
Plagioclases (10–15 %) in the form of prismatic, tabular or irregular
light-grey cristalls in dimensions of 1 sm or less. Muscovite (10–15 %)
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 (30–35 %) is spread irregularly in the form of xenomorphic grains
that fill space between rock forming minerals or veinlet of various
thicknesses. Tourmaline (5–7 %) are marked as oblong-prismatic
bluish-grey crystals in length 1–2 sm, cross section is 0,5–0,8 mm.
Apatite is usually occurred as short-columnar or irregular form crystals
with dimensions of 0,5–2 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 741,3–748,2 m and 754,3–755,3 m. The structure of
rocks is pegmatoid, texture is massive. Pegmatites consist of
orthoclases (30–35 %), acid plagioclases (10–15 %), quartz (30–35 %),
muscovite (10–15 %), tourmaline (6–8 %), 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. – ¹ 4.
– P. 89–92 (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. 148–149. (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. – ¹ 2. – P. 30–35. (in Russian) |