New Data on Minerals. 2014. Vol. 49 57 NEW DATA ON MINERALOGY OF DEPOSITS OF PLUTONOGENIC GOLD-QUARTZ FORMATION IN THE NORTHERN CENTRAL KAZAKHSTAN. PART I Ernst M. Spiridonov Moscow State University, Geological Faculty, Moscow, [email protected] The formation history of mineralogy of plutonogenic gold-quartz deposits of the Stepnyak group in the Northern Central Kazakhstan is discussed. Mineral facies referred to the depth of the deposit formation; mi ne - ralogical features of ore shoots, nature of ore-bearing fluids, white micas, quartz, carbonates, scheelite, pyrite, arsenopyrite, pyrrhotite, gersdorffite, sphalerite, berthierite, argentotennantite, argentotetrahedrite, roshchi- nite, bismuth tellurides and sulfotellurides, mattagamite, Co-bearing frohbergite and melonite, montbrayite, calaverite, sylvanite, petzite, petzite-hessite solid solution, and hessite are reported. The deposition sequence from Au to Ag tellurides and affinity for Te: Co > Fe, Ni > Bi, Sb > Pb > Ag, Hg > Au, Cu are improved. 10 figures, 8 tables, 60 references. Keywords: scheelite, mattagamite, frohbergite, melonite, montbrayite, calaverite, krennerite, sylvanite, pet- zite-hessite solid solution, affinity to Te. Despite many reviews, current state of geo - diately predated or accompanied gold minera- logy causes genetic typification of gold de - lization. posits. One of the ways is the detailed study of Plutonogenic hydrothermal gold-quartz specific gold formations, and separate gold formation. The deposits of the plutonogenic provinces and deposits. gold-quartz beresite-listvenite formation are Hydrothermal gold deposits are frequently paragenetically related to tonalite-grano dio rite- referred to the three formations on the basis of plagiogranite, adamellite, and monzo nite-gra- the formating depth: (1) shallow (with abun- nite intrusive complexes of folded areas. These dant sulfides, low-fineness gold, Ag sulfo salts), deposits are formed in closed system under ele- (2) medium (with moderate sulfides and rela- vated pressure (P). The P value is determined by tively low-fineness gold), and (3) deep (low sul- the top of hydrothermal system located close to fides with high-fineness gold) (Petrov skaya et the roof of intrusives or slightly above. The lo- al., 1976). This conventional in our coun try west pressure estimated from fluid inclusions classification is not up to the recent geo logical (FI) in the early quartz and carbonates of the standards. For example, many deep-seated ores ranges from 0.3 to 0.6 kbar (Spiridonov, deposits are enriched in sulfides; low-sulfide 1995; Trumbull et al., 1996) that cor responds to deposits with high-fineness gold are abundant the shallowest formation depth of 1 to 1.5 km; among shallow deposits; some deposits with the highest values reach 3.5–4 kbar (cca. features typical of shallow de posits were for - 12–15 km) (Spiridonov, 1995; Hagemann and med at the depth of 1.5–2 km; the deposits Brown, 1996; Mishra and Panigrahi, 1999; Jia et with features characteristic of deep-seated al., 2000). The P values higher than 4 kbar corre- deposits were formed at the same depth. The spond to the metamorphosed ore. The Early Ar - classification of hydrothermal gold deposits on chean to Ceno zoic plutonogenic gold deposits the basis of host rocks (many US researchers) were formed under relatively stable pressure at or basic formations (groups of large-volume gradual temperature decreasing. Subtle (to dis- deposits of sulfide ores) is un convincing. The appearance) vertical geochemical and mine - classifications of Lindgren (1933), Schnei - ralogical zoning is typical (Smith, 1948; Naz' - derhöhn (1941), Bilibin (1947), Ramdohr (1980), mova et al., 1978; Spiridonov, 1995). Long verti- Smirnov (1982), and similar classifications of cal extension of gold mineralization is typical: Ivensen and Levin (1975), and Spiridonov 4.5 km, cca. 5 km taking into account erosion (1995; 2010) taking into ac count geological fea- level at Kolar, India; cca. 3 km at Moro Velho, tures of gold deposits and in particular mag - Brazil; cca. 2.5 km at Ashanti, Ghana; cca. 2 km matic rocks to which mine ralization is related at dozen deposits in Canada, Africa, Australia, are better argued. Hyd rothermal plutonogenic and Kazakhstan. formations of folded areas, volcanogenic for- North Kazakhstan gold province. The mations of folded areas, arcs, and mid-oceanic North Kazakhstan gold province localized in ridges, volcano-plutonogenic formations, and the western Caledonian megablock of the Nor- amagmatic formations are distinguished on the thern Central Kazakhstan (Bogdanov, 1959, basis of type of magmatic rocks, which imme- 1965; Shul' ga and Bulygo, 1969; Geology…, 58 New Data on Minerals. 2014. Vol. 49 1971) comprises Stepnyak megasinclinorium posits were found here. In addition, mineralogy (East-Kokchetav depression) and adjacent re - and geology of these deposits are studied in gions. In the western megablock, granitoids and detail including geological, petrographic, geo- metamorphic sequences with the Pro terozoic chemical, and mine ralogical survey of 1:4000 to granitic gneiss domes are abundant (Spiridonov, 1:1000 at Step nyak down to 300 m below surface 19821); ultramafic rocks and olistostrome se - (Spirido nov, 1986), and Bestyube and Zho - quences are less common; and gold mineraliza- lymbet down to 600 m (Spiridonov et al., 19861); tion is mainly plutonogenic. The Proterozoic 3D geological, geophysical, mineralogical and metamorphic sequences form "granitic layer" of geochemical survey of 1:25,000 to 1:10,000 in the Earth crust of the region that underlays in the Aksu ore field including deposits Kvar tsi - places the Archean granulite layer according to tovye Gor ki, North and South Aksu, and Buden - xenoliths in the Stepnyak pluton. The outlines novsk down to 900 m below surface (Spirido nov of the ancient continental mass are marked by et al., 2002). the chains of zircon and rutile paleoplacers hos - Geological setting of the deposits. The ted in the Late Riphean to Vendian quartzite- largest Stepnyak-group deposit Bestyube is sandstone in the Kokchetav, Ishke-Ulmes, and located at the joint of the Ishke-Ulmes anti- Erementau Rises (Shlygin, 1962; Spriridonov, clinotium and Selety sinclunorium. Large de- 19871, 1991). At the Caledonian stage, the Earth posits Zholymbet, Kvartsitovye Gorki, and Aksu crust of the region was substantially altered. For are located at the joint of the Stepnyak sinclino- example, in the Kokchetav Rise (middle massif) rium and Ishke-Ulmes anticlinorium in the zone the Zerinda granodiorite-adamellite batholith of meridional transregional Omsk-Tselino grad 86 87 with Sr/ Sr = 0.7035 – (Shatagin, 1994) that is deep fault, it was transected by the NW-tren - age and formation analogue of the Krykkuduk ding faults for example the Atan sor Fault and Complex of the Stepnyak Depression was ari sen others. Large deposits are spatially related to the among metamorphic sequences with 86Sr/87Sr = smallest intrusions of granodiorite formation 0.716. and are distal from large intrusions. In the eastern Maikain megablock, there are The major Caledonian gold deposits in numerous ultramafic bodies and olistostrome North Kazakhstan are related to small intrusions sequences; granitoids are few; gold mineraliza- of the Stepnyak type, which were refer red to the tion is referred to the massive-sulfide type Stepnyak Complex (post-batholite formation of (Geology…, 1971); this area is deve loped on the small gold-bearing diorite intrusions) (Bilibin, crust of ocean type. 1945) that is younger than the Krykkuduk The Caledonian Stepnyak megasinclinori- Complex (tonalite-granodiorite formation). Re- um comprises the Stepnyak and Selety dep - cently it was proved that the Stepnyak-type ressions (sinclinorium) and Ishke-Ulmes Rise intrusions and major gold depo sits are the (anticlinorium) (Shul'ga and Bulygo, 1969). products of the Late Ordovi cian Krykkuduk Gold deposits are located within these struc- Complex (Spiridonov, 1968, 1986, 1995; Spri - tures close to the boundaries between them. As donov et al., 19861, 19863, 2002). Small gold- all over the world (Nesbitt, 1988), meso thermal bearing intrusions and dy kes to which the gold-quartz deposits of the Stepnyak group are deposits are paragenetically related belong to hosted in the upper part of continental crust the inversion stepnyakite-tonalite-granodiorite within the zone of brittle deformation above formation with the age of 445±5 Ma. Low and isotherm 400°С. poor-sulfide deposits of the Stepnyak group Bestyube, Zholymbet, Kvartsitovye Gorki, Step - Gold deposits nyak, and Aksu be longing to the Late Ordo - of the Stepnyak group vician plutonogenic gold-quartz formation with the age of 445 ± 3–5 Ma are opened by mines Why this group of plutonogenic gold down to 450–1100 m below surface and drill deposits is of the greatest interest? Because holes, down to 1200–1700 m. Other types of these deposits are located in non-linear folded hyd rothermal-metasomatic formations are ra- area and are not affected post-ore tectonization ther developed at these deposits. There is a ne - and metamorphism; they are located in the gative correlation between size of ore-bearing Caledonian folded structures. Here, there are intrusion and related ore concentration that extremely shallow to highly deep-seated coeval indicates deep-seated source of gold (Spiri - deposits, which are unusual in Mezo-Cenozoic donov, 1995). and Pre-Paleozoic folded areas. All crucial de - Characteristics of