甘肃芨岭铀矿床围岩蚀变特征及其与铀矿化的关系

以芨岭地区铀矿床碱交代蚀变岩石为研究对象,对该区碱交代作用蚀变的特征进行详细研究。结果表明:芨岭钠交代岩型铀矿床属断裂碱交代型铀矿床,矿床蚀变种类繁多,主要有钠长石化、绿泥石化、碳酸盐化、赤铁矿化、绢云母化和硅化等。蚀变组合及分布特征较明显,并与铀矿化关系密切。     

新疆哈赞布拉克金铜矿成矿地质特征及成因探讨

哈赞布拉克金铜矿位于博罗科努金铜钼铅锌成矿带.矿化产于华力西中期中酸性侵入岩体内及与围岩接触带内,主要蚀变为围岩地层中的角岩化,闪长岩中的钾化、绢云母化、青盤岩化及含矿岩石中的硅化、碳酸盐化等,矿区发现Ⅰ、Ⅱ、Ⅲ号三个矿化带,以Ⅱ号矿化带规模最大,矿床为铜、金共生矿化,矿化成因类型为石英脉型、矽卡岩型、斑岩型,以石英脉型矿化为主,矿化主要受岩浆岩和构造控制,矿床为先期斑岩型矿化,伴矽卡岩型矿化,经后期热液改造叠加的石英脉型矿床.     

华北克拉通和西澳克拉通金矿床对比研究及其对中国金矿勘查的启示

华北克拉通固结时间较晚,活动性较强,金矿床赋矿围岩以中深变质的镁铁质岩石和花岗岩类岩石为主,大规模金矿床一般产在韧、脆性剪切叠加的构造带中,成矿时代在188~46Ma之间.西澳克拉通固结较早,稳定性较好,金矿床主要产在太古宙花岗岩-绿岩地体中,一般产在韧-脆性剪切过渡带或叠加的构造带中,金矿化年龄在2640~2600Ma之间.华北克拉通金矿床比西澳金矿床形成晚,受剥蚀程度低,许多矿床尚未出露地表,在深部寻找盲矿体前景可观.     

山西原平狐狸山金矿围岩蚀变特征与金矿化的关系

狐狸山金矿是韧性剪切带型金矿床，矿区围岩蚀变发育广泛，类型有碳酸盐化，绢云母化，硅化等，蚀变分带明显，且蚀变强度与金矿化关系密切。围岩蚀变受韧性剪切变形影响，金矿化与围岩蚀变的主要期次同时形成。     

Ore and Alteration Types of the Gold and Copper Mineralization in the Lascogon Project, Surigao del Norte, Mindanao Island, Philippines

Two ore and three alteration types were identified in the Lascogon Project of Philex Gold Philippines, in Surigao del Norte, Mindanao Island, Philippines. The jasperoid ore is the host to the Carlin‐like gold mineralization in the Lascogon and Danao prospects. The ore occurs in a decalcified and silicified horizon, with minor chlorite and goethite, stibnite, pyrite and quartz crystals ranging from cryptocrystalline to botryoidal. The stringer–stockwork type Cu‐Au mineralization in the Suyoc prospect is hosted in argillized andesitic rocks of the Mabuhay Formation. The primary ore minerals are chalcopyrite with minor amounts of sphalerite. The alteration types identified are propylitic alteration, argillic alteration and silicification. The propylitized basaltic and andesitic flows of the Bacuag Formation bound the jasperoid mineralization in the Lascogon prospect. Stratigraphically, the relationship between propylitized basalts and stringer–stockwork Cu‐Au is not clear but a lateral change can be inferred from jasperoid in the center and stringer–stockwork towards the east.     

Characteristics of Element Migration in the Process of Wall-Rock Alteration in the Shibangou Gold Deposit,Western Henan

The Shibangou gold deposit in western Henan is associated with irregular quartz veinlets occurring in altered shear zones dissecting a dioritic intrusion. The altered shear zones are characterized by silicification, pyriti-zation, sericitization, chloritization and K-feldspar alteration. Zoning of altered rocks adjacent to the Au-bearing quartz veins is obviously exhibited. Fine-grained sulphides and quartz veinlets of different ages and small-scale fissures are widely distributed in the central part of the altered zones. Major mineralization types in this gold deposit are Au-bearing quartz vehlets and altered rocks in the shear zones. Samples were collected from drilling cores according to the alteration zoning and mineralization type and all samples were analyzed for major and trace elements. Mass balance, volume change (fv=97.3-71.9%) and major element variation sequences are studied in terms of major elements. The changes of mobile components (SiO2, K.2O, Fe2O3 and CaO) and immobile component (Al2O3     

Gold potential of the volcanoplutonic zones in the southeastern Siberian Platform and physicochemical conditions of the deposit formation

Numerous gold deposits and occurrences were recognized in the regions of tectonomagmatic activation in the southeastern Siberian Platform. They are located in four metallogenic zones: the Ket-Kap (skarns, quartz veins, and stockworks; gold-bearing lodes in silicitolites; and argillisite-sericite metasomatites), Ulkan (clayey-micaceous metasomatites, quartz veins), Preddzhugdzhur (quartz veins, skarns, and sericite-hydromicaceous metasomatites), and Uda (sericite-hydromicaceous metasomatites). The skarn mineralization is of Meosozoic age, while the mineralization in the quartz veins, quartz-hydromicaceous metasomatites, and quartz-sulfide veins may have a Meosozoic, Paleozoic, or Late Paleozoic age. The highest temperatures were determined for the ore formation in the Preddzhugdzhur skarns (500–715 °C) and the hydrothermal-metasomatic rocks of the Ket-Kap zone (510–530 °C). The composition of gas-liquid inclusions in the minerals of these rocks is dominated by aqueous Na, K, and Ca chloride solutions with salinity up to 40 wt % NaCl equiv; fluid contains CO₂. Quartz veins and stockworks of the Ket-Kap zone were formed under high (up to 465°C) and moderate temperatures and salinity up to 32 wt % NaCl equiv. Sometimes, the minerals in these rocks contain inclusions of low-density CO₂. The gold-bearing veins of the Preddzhugdzhur zone formed at 225–230°C and salinity of 1–2 wt % NaCl equiv. The ore-bearing solutions in the gold-bearing veins of the Ulkan zone are characterized by a potassium-sodium-chlorine composition and salinity of 2–10 wt % NaCl equiv., and the temperature of their formation was 220–280 °C.     

河南省商城县汤家坪钼矿围岩蚀变与成矿

文章从矿床地质特征、蚀变岩石的元素含量特征及蚀变分带研究入手,认为硅化和钾长石化岩石的钼含矿性最强,硅化和钾长石化与钼成矿关系密切.研究表明,围岩蚀变始终伴随着钼成矿作用的每个阶段,且不同的成矿期和成矿阶段、不同的围岩,其蚀变类型不同;矿床蚀变分带明显,由岩体中心向外侧依次为钾长石化-硅化带(强蚀变带)、硅化-绢英岩化带(弱蚀变带)、硅化-青磐岩化带,强度由中心向外围逐渐减弱,其蚀变作用的强弱与钼矿体的品位高低相对应,确定硅化和钾长石化是该区最有效的找矿标志之一.     

Nature, origin and evolution of the granitoid-hosted early Proterozoic copper-molybdenum mineralization at Malanjkhand, Central India

At Malanjkhand, Central India, lode-type copper (-molybdenum) mineralization occurs within calcalkaline tonalite-granodiorite plutonic rocks of early Proterozoic age. The bulk of the mineralization occurs in sheeted quartz-sulfide veins, and K-silicate alteration assemblages, defined by alkali feldspar (K-feldspar ≫ albite) + dusty hematite in feldspar ± biotite ± muscovite, are prominent within the ore zone and the adjacent host rock. Weak propylitic alteration, defined by albite + biotite + epidote/zoisite, surrounds the K-silicate alteration zone. The mineralized zone is approximately 2 km in strike length, has a maximum thickness of 200 m and dips 65°–75°, along which low-grade mineralization has been traced up to a depth of about 1 km. The ore reserve has been conservatively estimated to be 92 million tonnes with an average Cu-content of 1.30%. Supergene oxidation, accompanied by limited copper enrichment, is observed down to a depth of 100m or more from the surface. Primary ores consist essentially of chalcopyrite and pyrite with minor magnetite and molybdenite. δ³⁴S (‰) values in pyrite and chalcopyrite (−0.38 to +2.90) fall within the range characteristic of granitoid-hosted copper deposits. δ¹⁸O (‰) values for vein quartz (+ 6.99 to +8.80) suggest exclusive involvement of juvenile water. Annealed fabrics are common in the ore. The sequence of events that led to the present state of hypogene mineralization is suggested to be as follows: fracturing of the host rock, emplacement of barren vein quartz, pronounced wall-rock alteration accompanied by disseminated mineralization and the ultimate stage of intense silicification accompanied by copper mineralization. Fragments of vein quartz and altered wall rocks and striae in the ore suggest post-mineralization deformation. The recrystallization fabric, particularly in chalcopyrite and sphalerite, is a product of dynamic recrystallization associated with the post-mineralization shearing. The petrology of the host rocks, hydrothermal alteration assemblages, ore mineral associations, fluid inclusions and the sulfur and oxygen isotopes of ores are comparable to those in Phanerozoic (and reported Precambrian) porphyry-copper systems, and the Malanjkhand deposit has important implications for both metallogenic models for, and mineral exploration in, Precambrian terrains.     

Rb-Sr age of metasomatism and ore formation in the low-temperature shear zones of the Fenno-Karelian CRATON,Baltic Shield

Manifestations of the main types of metasomatites (beresite, propylite, listwaenite, aceite, and gumbeite) were identified in the shear zones of the Fenno-Karelian craton on the basis of the previously proposed systematics of metasomatic facies. These metasomatites were formed in shear stress environments, which determined their morphological features, in particular, finely banded texture. Comparatively low-temperature conditions of infiltration process and salting out effect (reduction of CO₂ solubility with increasing salt content) lead to the heterogenization of fluid into two phases: aqueous salt solution and almost pure CO₂. This results in more aggressive and mobile behavior of the fluid, and, correspondingly, more intense differentiation of the matter and contrast in metasomatic banding. Relations between metasomatic parageneses indicate an evolution trend of the processes from propylite, beresite and listwaenite to alkaline varieties and their repeated manifestation in the same shear zones. The results of Rb-Sr isochron dating of ore metasomatites from eight deposits and occurrences of the Fenno-Karelian craton (more than 100 samples of rocks and minerals) confirm previous assumptions. In general obtained data show that the shear zones controlling the distribution of the studied occurrences operated as fluid pathways during a long time period, up to 200 Ma, after the Svecofennian orogeny completion and did not show any correlation with Paleoproterozoic and Neoarchean magmatism. Rb-Sr isotope data on the metasomatites indicate three peaks of the post-Svecofennian metallogenic activity: 1700–1780, 1600–1650, and 1400–1500 Ma. Since the studied ore deposits were formed within tectonic structures, which evolved on the Archean crust and have a long prehistory, and fluid flows were subjected to intensive contamination by ancient crustal material, a relatively high initial Sr isotope ratios of formed ore-metasomatic systems were developed. High variablity of this value in the studied rocks ((⁸⁷Sr/⁸⁶Sr)₀ from 0.706 to 0.750) is related to the heterogeneity of crustal protolith and to the relative storage and manifestation of the juvenile component of the fluid, which was responsible for the metasomatic transformation of the Archean and Paleoproterozoic rocks and ore-deposit formation.     

<Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar age of the porphyry Ca(Au) mineralization of the Elna deposit and its relation to magmatism (northeastern part of the Argun superterrane)

The Elna Cu(Au)–porphyry deposit is one of the typical ore objects in the northeastern margin of the Argun superterrane facing the Mongolia–Okhotsk foldbelt. Mineralization includes zones of argillization with fine quartz veins in granodiorite of the Elna massif. The geochronological ⁴⁰Ar/³⁹Ar studies of hydrothermal near-ore metasomatites and magmatic rocks of the deposit show that the age of host granitoids is 126 ± 2 Ma, which corresponds to the upper age boundary of granitoids from the Burinda Complex, whereas the age of overprinted hydrothermal processes is 122–117 Ma. The age of mineralization correlates well with the age of the thermal event in East Asia. An intense stage of magmatism including both volcanic and intrusive forms occurred in this period.     

The mineralogy of propylites of the large Peschanka porphyry copper deposit (West Chukotka)

The Au-Mo-Cu porphyry Peschanka deposit is confined to the Egdygkych Pluton (K₁). The deposit comprises three major types of metasomatic rocks: quartz-K-feldspar-biotite, propylites and quartz-sericite. In their chemical compositions, amphiboles of propylites range from early magnesiohornblende to tremolite-actinolite. Compared to magmatic K-feldspar, the metasomatic K-feldspar is enriched in barium (up to 7.3 wt % BaO). Tourmaline belongs to the intermediate member of the oxydravite-povondraite series. The Al content in chlorite decreases to the outer zones of propylitization, which is caused by a decrease in the temperature of mineralization.     

安徽池州马头铜钼矿地质特征及蚀变分带

安徽池州马头铜钼矿是长江中下游成矿带中安庆—贵池矿集区内一个典型的铜钼矿床。通过野外地质祥查和系统的岩相学、矿相学工作,对该矿床的蚀变特征及分带进行了深入研究。识别出马头铜钼矿的蚀变类型主要有硅化、绢云母化、钾长石化,其次为黏土化、绿泥石化和碳酸盐化等。矿区围岩蚀变在空间上往往重叠,但具有一定的水平及垂向分带特征,自岩体深部至浅部、自内向外总体表现为面型石英钾长石化带、线型石英钾长石化带和石英绢云母化带。矿（化）体以脉状矿化为主,其中分布较广的石英脉带矿化主要产在石英绢云母化带中,以石英细（网）脉为主,受节理和裂隙控制;而品位较富的细脉浸染状矿化则主要产在面型钾长石化带中。通过研究认为,马头铜钼矿在成矿过程的早期阶段,由于高温、富钾和高pH值的热液流体作用,形成大面积的钾长石化,伴生与面型钾长石化有关的细脉、浸染状矿化;热液演化中期阶段,随着温度持续下降、K＋活度和流体pH值的降低,形成硅化、绢云母化等蚀变类型,并伴随范围较大的细脉-网脉状矿化;热液演化晚期阶段,主要形成碳酸盐化,而相应的矿化作用不显著。通过与部分典型斑岩型铜钼矿床的对比研究认为,马头铜钼矿在蚀变类型等方面与斑岩型铜钼矿大体相同,可归至斑岩型成矿体系。     

帕米尔中部含刚玉变质杂岩

刚玉矿化位于穆兹科尔(Muzkol)变质杂岩体内.该杂岩体近纬向展布在帕米尔中部阿尔卑斯褶皱带的东部,属蓝晶石—夕线石型阿尔卑斯带变质杂岩.地质填图发现有4个变质岩区:低绿片岩相(白云母—绿泥石)区,高绿片岩相(黑云母—绿泥石)区,绿帘石—角闪岩相区,角闪岩相区,而刚玉矿化集中在绿帘石—角闪岩及周围角闪岩相变质体内的交代蚀变区.交代蚀变区内的刚玉矿化通常与层面或 大型同倾斜褶皱轴面平行.根据母岩成分可将含刚玉交代岩分为3类,分别位于方解石大理岩内、白云石大理岩内及片岩内.在大理岩内,刚玉成粉红色,与白云母、黑云母、方柱石、钙长石、正长石、金红石、电气石、磷灰石、黄铁矿及石墨共生,以Al含量变化大和Fe含量低为特点.在片岩内,刚玉成蓝色,与黑云母、绿泥石、电气石及磷灰石共生各种类型的含刚玉岩石均以K,Na,Mg的含量较高而Fe含量较低为特点.根据P—T—XCO2图估算含刚玉交代岩的稳定范围在610℃相似文献   

Geochronology of the Xiaodonggou Porphyry Mo Deposit in Northern Margin of North China Craton

The Xiaodonggou porphyry Mo deposit is located in the Mesozoic calc-alkaline Xiaodonggou granitoid within a Palaeozoic fold zone of northern China. The mineralization mainly occurred in an area of 0.54 km² at the south-eastern part of the Xiaodonggou granitoid. The mineralization includes disseminated molybdenite, pyrite, chalcopyrite, magnetite and pyrrhotite and stockwork quartz-sulfide veins. A molybdenite-rich inner core is surrounded by a concentric zone of the sulfide mineral assemblage of pyrite, galena and sphalerite. Intense potassic alteration is overprinted by sericitization and silicification in the mineralized zone. SHRIMP U-Pb data of zircon indicate that the granitoid crystallized at 142 ± 2 Ma (2σ). Re–Os age dating for six molybdenite samples from underground galleries of the deposit constrains the age of porphyry-style Mo mineralization to be 138.1 ± 2.8 Ma (2σ). These data suggest that porphyry-style mineralization was associated with the Xiaodonggou granitoid intrusion and support an Early Cretaceous porphyry-type metallogenic epoch along the northern margin of North China Craton.     

The Pogromnoe deposit as an unconventional commercial type of gold mineralization in Transbaikalia

We studied the mineralogic and geochemical features of metasomatic rocks and ores from the Pogromnoe gold deposit, which is unconventional for Transbaikalia. The deposit, which formed in the Early Cretaceous, at the rifting stage of the regional evolution, is localized in the dynamoclastic strata of the Mongol-Okhotsk suture, along which the Siberian continent joined the Mongolia-China continent in the Early-Middle Jurassic. Gold mineralization occurs as two morphologic types of ores: stockwork quartz-carbonate-arsenopyrite-pyrite ores in altered volcanics (orebody no. 1) and veinlet-vein quartz ones (with disseminated sulfides) in altered carbonaceous shales (orebody no. 10). The host rocks of the deposit are the highly altered volcanosedimentary rocks of the Butorovskii Formation (Shadoron Group, J_2–3), which transformed into metasomatic (by composition) and dynamoclastic (by texture and structure) rocks. It has been found that the formation of the metasomatic rocks and mineralization proceeded in several stages. Propylites formed at the preore stage (J₃); tectonic schists and albitophyres, at the late preore stage; and sericitolites and albite-carbonate-sericite-quartz metasomatic rocks (quartzites), at the synore stage. The ⁴⁰Ar/³⁹Ar age of the stockwork system of ore-bearing fractures and metasomatic rocks which formed at the late preore stage is estimated as 139.5 ± 1.8 Ma. The gold-bearing rocks at the deposit are the late preore and synore metasomatic rocks formed after volcanics with sulfide mineralization (gold concentrators are pyrite II and III and arsenopyrite I and II) and after altered carbonaceous shales (gold concentrators are vein quartz and arsenopyrite II). Gold grade is completely consistent with silicification, saturation with quartz-sulfide and sulfide microveinlets, and fine sulfide dissemination. By genesis, the Pogromnoe deposit belongs to objects which formed in shear zones with the contribution of gold-bearing mantle fluids. The authors presume that the sources of mineralization are the ore-producing granitoids of the Amudzhikan-Sretensk intrusive assemblage within the Aprelkovo ore-magmatic system (OMS) (Os’kina and Urguchan plutons). This is confirmed by Pb isotope compositions (²⁰⁷Pb/²⁰⁴Pb and ²⁰⁶Pb/²⁰⁴Pb) for the pyrite and arsenopyrite of the Pogromnoe gold-bearing ores, which testify to the widespread occurrence of “mantle” Pb isotope signatures. The ⁴⁰Ar/³⁹Ar age of the ore-producing granitoids of the Aprelkovo OMS is 131.0 ± 1.2 Ma. Gold in the orebodies occurs in native form and is fine and very fine. By gold grade, the Pogromnoe deposit deserves very close attention as a new commercial type of gold mineralization in Transbaikalia.     

黑龙江金厂金矿床18号矿体围岩蚀变及短波红外光谱特征

金厂金矿18号矿体围岩蚀变发育顺序从早到晚为:钾化、硅化、绿泥石化、绢云母化、碳酸盐化、高蛉土化,从内往外依次发育青磐岩化带、绢英岩化带和钾化带.矿化出现在泥化和绢英岩化叠加处,以及泥化和青磐岩化叠加处.通过短波红外光谱测试技术,识别出本矿区有26种蚀交矿物,其中白云母含量与金矿体呈正相关,说明绢云母化与金矿化关系密切;青磐岩化带蚀变矿物组合为绿泥石+绿帘石+伊利石±埃洛石±蒙脱石±石英;钾化带蚀变矿物组合为钾长石+高岭石+埃洛石±蒙脱石±石英;绢英岩化带蚀变矿物组合为绢云母+埃洛石±蒙脱石±高岭石±石英.     

New data on the correlation of skarn and gold mineralization at the Tardan deposit (northeastern Tuva)

Gold mineralization of the Tardan deposit is of different spatial occurrences and is related to different hydrothermal-metasomatic formations, the main ones being skarn-magnetite bodies, metasomatites of mineralized crush zones, and metasomatites of argillizitic-rock association. The formation of gold mineralization was a multistage process related to the repeated magmatism of the Tannu-Ola complex. It took place in a wide temperature range (400–150 °C), which determined the diversity of produced mineral assemblages. The gold mineralization associated with magnetite bodies shows a spatial correlation with magnesian and calcareous skarns and is localized in plagiogranites and gabbro-diorites of the Tannu-Ola complex intruded in the Late Ordovician. Gold mineralization that occurs in crush zones and along the fault sutures in moderate- and low-temperature hydrothermal-metasomatic rocks (propylites, beresites, serpentinites, and argillizites) formed somewhat later than skarns as a result of the intrusion of granite dike bodies. Comparative analysis of different types of gold mineralization showed both a change of mineral assemblages of the gold mineralization during the ore formation and some geochemical difference between gold and gold-bearing ores. In passing from early to late occurrences of native gold, its fineness decreases, the contents of admixtures correspondingly increase, and the gold composition changes. Gold of high-temperature rocks is rich in Cu (up to 17%), and gold of low-temperatures rocks has higher contents of Ag and Hg.     

Patterns in the transformation of the composition and properties of volcanogenic rocks in hydrothermal-magmatic systems of the Kuril-Kamchatka island arc

Hydrothermal-magmatic systems of the Kuril-Kamchatka island arc were formed in Neogene-Quaternary volcanic rocks. Acting on host rocks, thermal waters induced their alteration and transformation into hydrothermal-metasomatic rocks, such as propylites, secondary quartzites, zeolitic rocks, argillic rocks, opalites, quartz-adularia metasomatites, etc. The dynamics of changes in rock properties during the hydrothermal process depends on a number of factors, including the features of primary rocks, temperature, pressure and composition of thermal fluids, fluid phase, fluid pH, and duration of fluid-rock interaction. Deep high-temperature fluids cause consolidation and hardening of the rocks, an increase in deformational properties, and a decrease in porosity and permeability, regardless of fluid composition. The chemical composition and acidity-alkalinity of thermal fluids have a significant influence on the alteration of rock properties during low-temperature hydrothermal processes.     

Chronology of hydrothermal and magmatic activity in the Dukat gold-silver ore field

The previously published and newly obtained geological and geochronological (Rb-Sr and Ar-Ar) data show that the igneous rocks and products of hydrothermal alteration in the Dukat ore field pertain to two ore-forming magmatic-hydrothermal systems (OMHSs). The igneous rocks of the Early Cretaceous rift-related OMHS are represented by potassium rhyolites of the Askol’d Formation with Rb-Sr ages of 124 ± 3 and 119.3 ± 3.4 Ma and intercalating amygdaloidal basalts. The products of the hydrothermal activity of this OMHS are the metasomatic anatase-chlorite assemblage of the root zone, which replaces potassium rhyolites, and shallow-seated quartz-adularia and quartz-carbonate-feldspar veinlets retained in rhyolite fragments in Late Cretaceous conglomerate and breccia. The Late Cretaceous OMHS was related to the origination of the Okhotsk-Chukotka volcanic belt and consists of calc-alkaline basaltic andesites of the Tavvatum Formation and moderately silicic K-Na rhyolites of the Nayakhan Formation with a Rb-Sr age of 84 ± 4 Ma. The Late Cretaceous postmagmatic hydrothermal activity in the Dukat ore field resulted in the formation of preore metasomatic rocks and orebodies of the unique Dukat Au-Ag deposit. The first stage of the Late Cretaceous hydrothermal activity gave birth to preore propylites with a Rb-Sr isochron age of adularia samples estimated at 85 ± 1 Ma and quartz-chlorite-sulfide and Ag-bearing quartz-chlorite-adularia orebodies with Rb-Sr isochron ages of adularia estimated at 84 ± 1 and 86.1 ± 4 Ma. The second stage was marked by the formation of garnet-bearing propylites and quartz-rhodonite orebodies with a Rb-Sr age of 73 ± 3 Ma. Further hydrothermal activity occurred after a break related to structural rearrangement of the ore field and was expressed in the replacement of propylites by products of argillin alteration and Ag-bearing Mn hydroxides. Paleogene basaltic dikes and related subeconomic mineralization concluded magmatic and hydrothermal processes in the Dukat ore field.