Abstracts of International conference Geochemistry of magmatic rocks-2009 . School ซGeochemistry of Alkaline rocksป
๓ollision granitoides and sienites of the Urals: Conditions of location, geochemical and metallogenic specialization and practical significance
Sazonov V.N*** ,Ogorodnikov V.N** Polenov Yu.A**
* Institute of
geology geochemistry, Urals branch of RAS,
A collision process in the Urals took place in two time interval: 375 320 and 320 240 Ma.
In early stage quartz diorite, granodiorites, adamellites and granites (Berezovsk, Kochkar, Aidirla, Verkh-Isetsk and others ore fields), specialized on Au, W, As at least measure Mo and fluid phase on CO2, F-Cl, S, were formed. In late stage were formed biotite (normal) granites, leucogranites (Murzinka-Aduy, Djabic, Adamov plutons and s.o.), specialized on rare metals and big spectrum of non metallic mineralizations (asbestos, talc, mica, quartz etc.) and fluid phase on F; gabbro-granite-sienite complexes (Magnitogorsk ore region), specialized on Fe, at least measure Mo, Pb and fluid phase on Cl F; alkaline granites and sienites of the Gumbeysky,
Stepnoy complexes and sienites of the Berzovsk gold field (Fershtater, 1987; Sazonov et al., 20071,2; Kholodnov, 2007).
The Gumbeisk alkaline complex. This complex include some massifs-stocks subalkaline group (boundary between C and P) which consist of sienite-diorite, sienite, quartz sienite, granosienite which controlled by diagonal fault element of suture zone of a duplex character. The massifs host rocks are volcanites and sedimentary formations (D2). In the stocks there are two deposits and some manifestation of W (stockworc and skarn nature). A mineralization besides W include Mo and Au (rare). Complex was formed with participation of mantle substance (Sazonov et al., 20071).
Granitiid massifs of tonalite-granodiorite formation (I-type). They submitted
batholiths or batholith like bodies and consist of
tonalities and granodiorites (prevail), rare gabbro and gabbrodiorites (may be
absence), adamellites and granites. Massifs are
controlled by faults zones (they are duplexes often). In an endocontact of massifs there many henoliths
including gabbroic. In big massifs we can find granitoids,
diorites and lamprophirys dykes and products of
hydrothermal activity. The last conclude quartz veins mainly. They fixed big
Granite massifs of granite formation (S-type). These granites nature is crust. They were formed because silic substrat (gneissic block , R) was partly melting. F-type hydrothermal fluid was formed with such granites. Pegmatites and quartz veins were formed in connection with them. The main value of both formations are rare metals and granulate quartz. And may be mention emeralds and crystals.
Sienite of the Stepnoy complex. Monzodiorites are the main rocks of this complex. Many dykes (granites, granosienites, sienites, sienodiorites) fixed in them. Construction? Composition and metallogeny specialization of these massifs and massifs of Gumbeyka complex (see above) are analogous.
Alkaline rocks of the Berezovsk ore field. These rocks distinguished by M.B.Borodaevskaya (1951year) in the contact of collision granitoid-porphiry dykes with antigorite serpentinite. There following zonation was picket out: granite-porphiry albite quartz-bearing sienite albite sienite (without quartz) albitite serpentinite. In formation of metasomatites a mantle fluid (T > 400 OC, P>2 kbar, specialization on Na, CI F) and components of granitoids and serpentinites took place.
Today metallogenic and geochemistry (including such volatile elements as F, Cl, CO2, S) specialization of complexes rocks of different geodynamic environments are known. So this caused a possibility to pick out in boundaries of structure-formation spots perspective on ore and non ore deposits. Besides a fluid specialization jf collision patterns is important criteria of magmatic specialization and potential ore-bearing. It pre-determine by: spot of melts generation (mantle, crust), nature of substrate and geodynamic regime. A fluid specialization (F, Cl an example) is characteristic for all parts of ore-magmatic system magmatites, ore bodies and associate metasomatites. Thas fluid specialization is a base for formation analyses of magmatites, associated metasomatites and metallogeny.
The spots of localization granitoids both groups
are: a) suture zones, b) zones crossing and conjugated of suture zones
with the faults of NW (diagonal) orientation, c) the Main granite axis of the
Urals (there are some massifs located in the W from the Main suture zones). In the Urals granitoid batholites are located
in such domains where a deep to the basalt strata consist of
There are mach dykes (from acidic to
basic composition) in the Uralian granitoid batholits. Dykes composition pre-determined by poly step anatexis on the basite (gabbro) base and crystallization differentiation (Gold
, 2001; Fershtater
et al., 2007; Kholodnov, 2007). More late granitoids accompanied more acidic dyke complexes. This was
a reason for the next relations which everyone can see in the Shartash granite batholite (
Early granitoides are specialized on Au and W (see Korobeynikov, Mironov, 1992; Gold , 2001; Fershtater et al., 2007). As a rule, there is more gold in more basic granitoides. The dykes complexes more auric then hosted granitoides. Dykes complexes are considerate as a fluid leader (Korobeynikov, Mironov, 1992; Gold , 2001). In apogranitoid fluid relatives F: Cl: S (perhaps and CO2) is such which quite enough for extraction of Au, but of extraction chalkhophile elements and Fe in these conditions is not going on (Kholodnov, 2007). Late collision granites specialized on F (instead of Cl) and rare metals, they are nonauriferous.
Most gold deposits of quartz-veined type conjugated with a bererzite-listvenite formation. Its metasomatites are forming at high active of CO2, low concentration Cl and relatively nigh F in the fluid. During process of berezitization-listvenitization F concentrated in muscovite, so content of F in the fluid increase. Cl take part in a transport Au, evidence appear of this element and its in the nuggets of gold.
Hydroxide minerals of late collision granites poor of Cl (0,0-0,05 Wt.%). But they rich of F: in apatites 4,0, in biotites 1,5 Wt.% and more (Koroteev, Sazonov, 2005). Contents of F and K, Be, Ta, Nb, Li, Rb, Cs in late collision granites are correlated. Active of F in an apogranite fluid essential pre-determine of composition of rare metal (Be, Ta, Nb, Li, Rb, Cs) and W and W-Mo mineralization.
The collision process played a dual role in the Urals. On the one hand, it caused transformation in the previous ore associations (chromites, Fe-quartzites, sulfide ores of massive sulfide deposits and other), on the other hand, in was the reason of formation of different types of mineralizations in suture zones (antigorite serpentnites, talc and talc-carbonate metasovatites, berezites, listvenites with quartz veins with native gold, and goldbearing sulfides).
Thus fluid specialization of collision granitoides is important criteria of magmatic specialization and potential ore-bearing. It pre-determine by: spot of melts generation (mantle, crust), nature of substrate and geodynamic regime. A fluid specialization (F and Cl an example)
is characteristic for all parts of ore-magmatic system - magmatites, ore bodies and associate metasomatites. Thus, fluid specialization is a base for formation analyses of magmatites, associated metasomatites and metallogeny (Korobeynikov, Mironov 1992; Koroteev, Sazonov, 2005; Gold , 2001; Kholodnov, 2007).
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Sazonov V.N., Nedosekova I.L., Ogorodnikov V.N., Polenov Ju.A. Sienite and sienite-miaskite complexes of the Urals // Geodynamics, magmatism, metamorphism and ore-forming. Ekaterinburg, 20071. P. 216-243 (in Rassian).
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