Сорское Cu-Mo-порфировое месторождение расположено в Кузнецком Алатау, на северо-западе Алтае-Саянской складчатой области. Промышленное Cu-Mo оруденение тесно ассоциирует с малыми интрузиями (штоки, дайки) порфировых пород, локализованными в Уйбатском плутоне. Плутон и малые интрузии сложены породами габброидной, монцонитоидной и гранит/лейкогранитной ассоциаций. Однотипные породы плутона и малых порфировых интрузий близки по минеральному составу, металлогенической специализации, петрогеохимическим и изотопным характеристикам. Магматиты габброидной ассоциации являются производными плавления литосферной мантии, метасоматизированной субдукционными флюидами. Породы монцонитоидной ассоциации сформировались вследствие фракционной дифференциации мафической магмы и ассимиляции нижнекорового материала. Геохимические характеристики свидетельствуют об отсутствии генетической связи между породами повышенной основности и гранит/лейкогранитной ассоциации. По-видимому, породы гранит/лейкогранитной ассоциации кристаллизовались из расплава, сформировавшегося в результате частичного плавления ювенильной мафической коры под воздействием на нее тепла мафической магмы. Согласно U-Pb геохронологическим исследованиям, становление плутона произошло ~478, а внедрение малых интрузий от ~467 до ~457 млн лет назад. Предполагается, что породы плутона и малых интрузий генерировали расплавы разновозрастных средне-верхнекоровых очагов, формировавшиеся в связи с неоднократным поступлением магмы из глубинного крупнообъемного долгоживущего магматического резервуара. На месте раннего очага кристаллизовались породы Уйбатского плутона. Становление малых интрузий произошло на фоне многократного поступления магмы из позднего очага. На Сорском месторождении магматизм малых интрузий не является продолжением плутоногенного, как это часто отмечается на Cu-Mo-порфировых месторождениях. Связь магматизма плутона и малых интрузий опосредована через общий глубинный очаг. Внедрению малых интрузий предшествовало изменение тектонической обстановки, которое благоприятствовало подъему порфировой магмы, концентрированию и отделению флюидов и формированию богатого оруденения.

The Sorskoe (Sorsk, Sora) porphyry Cu–Mo deposit is located in the Kuznetsk Alatau, in the northwest of the Altai-Sayan folded region. Commercial Cu–Mo mineralization is closely associated with small porphyry intrusions (stocks, dikes) localized in the Uibat pluton. The magmatites of the pluton and small intrusions are composed of rocks of the gabbroid, monzonitoid, and granite/leucogranite associations. The rock associations of the pluton and small porphyry intrusions are similar in mineral composition, type of metallogenic specialization, petrogeochemical and isotopiс characteristics. The gabbroic and monzonitic rocks were probably generated by fractionation of the mafic magma and assimilation of lower crustal material. The geochemical characteristics indicate the absence of a genetic relationship between basic/intermediate rocks and the granite/leucogranite association. The rocks of the granite/leucogranite association were probably derived from the silicic magma generated by partial melting of the juvenile lower mafic crust due to the heat released from the mafic magma. U-Pb geochronological data indicate a time gap between the completion of pluton formation (∼478 Ma) and emplacement of small porphyry intrusions (from ∼467 to ∼457 Ma). Age differences between pluton and small intrusions suggest they are not coeval and were probably sourced from independent upper-middle crust magma chambers, which were formed by ascending melts derived from a deep large long-lived magma reservoir. The rocks of the Uibat pluton represent the remnant of the earlier solidified and eroded magma chamber. Periodic episodes of magma supply from a late shallow magma chamber resulted in the formation of small porphyry intrusions. Together these observations suggest that the magmatites of the pluton and small intrusions are not comagmatic. Their magmas may have been derived from a common deep-seated source, but possibly evolved independently, that is, they do not represent a single magma lineage, as often noted for porphyry Cu–Mo deposits. Changing tectonic environment before the emplacement of small intrusions triggered porphyry magma ascent, fluid saturation and exsolution and provided favorable conditions for large-scale mineralization.

The Siberian and Mongolian porphyry Cu-Mo deposits were generated from Devonian to late Mesozoic in subduction- and collision-related environments. On the continental margin of the Paleo-Tethys, magmatic rocks of the deposits are characterized generally by low H-isotope ratios. Mantle-derived variably D-depleted magma is supposed to have been responsible for formation of magmatic wallrock complexes of these deposits. At the Chubachi deposit that occurs on the continental margin of the Pacific ocean, the host and porphyry complexes are drastically different in δD values. The variation of H-isotopes in magmatic rocks of this deposit is assumed to be accounted for by an important role of old crust in magma generation. The collision-related deposits are characterized by higher δD values of magmatic rocks. From Paleozoic to Mesozoic, the H-isotope composition of these deposits became lighter due to an increasingly higher contribution of the crustal component to their formation.

––Two stages are recognized in the evolution of the Aksug ore-magmatic system (OMS): (1) formation of the Aksug granitoid pluton and (2) emplacement of small ore-bearing intrusions. Intrusive bodies of the two stages are composed of rocks of the same type and bear copper mineralization: poor dispersed and large-scale veinlet-disseminated, respectively. The pluton and small intrusions are formed by gabbroid and granitoid rocks, with similar petrogeochemical characteristics of igneous rocks of the same type. The plutonic gabbroic association includes gabbro, gabbrodiorites, and pyroxene–amphibole diorites/quartz diorites. The small subvolcanic gabbroic intrusions are gabbrodiorite and diorite porphyrites. The trace element patterns of the gabbroids are similar to those of igneous rocks in subduction zones. The gabbroids are characterized by isotope parameters εNd(500) = +6.1 to +7.2 and (87Sr/86Sr)500 = 0.7022–0.7030 and model age TNd(DM) = 0.85–0.74 Ga. As follows from the geochemical parameters, the depleted mantle metasomatized by subduction fluids was the source of basaltic magma. The plutonic granitoid association includes tonalites, plagiogranites, and amphibole diorites/quartz diorites; the small subvolcanic granitoid intrusions are tonalite porphyry and quartz diorite porphyrites. The trace element patterns and Nd and Sr isotope compositions of the granitoids are much similar to those of the gabbroids. According to the geochemical parameters, tonalitic and plagiogranitic magmas formed through the melting of juvenile mafic crust, and dioritic magma resulted from the mixing of basaltic and tonalitic/plagiogranitic magmas. In the course of the OMS formation, metals and volatiles were introduced by basaltic and granitoid magmas from the metasomatized mantle and juvenile mafic crust. The compression setting during the pluton formation hampered the separation of ore-bearing fluids, which led to poor dispersed mineralization. The extension setting during the emplacement of small intrusions favored the intense separation of ore-bearing fluids. The interaction of magma and fluids of the small intrusions with rocks of the pluton was accompanied by the removal of metals from the latter and their involvement in the ore-forming process. This increased the ore potential of the magmatic system and favored the formation of rich mineralization at the final stage of its evolution.

—The Aksug porphyry Cu–Mo deposit is located in a region of long-lasting magmatic activity. Gabbroids of the Khoito-Oka complex are the earliest intrusive rocks, in which the Aksug granitoid pluton hosting ore-bearing small porphyry intrusions is localized. The intrusive activity was terminated with emplacement of late leucogranite dikes. There are different viewpoints on the age of magmatism and mineralization of the Aksug deposit, with the concept of their Devonian age prevailing. To solve the debatable issue, we performed isotope geochronological studies and analyzed new results of U–Pb (SHRIMP-II) zircon dating and previously published Re–Os molybdenite dates (518 ± 2, 516 ± 2, and 511 ± 2 Ma). The concordant U–Pb zircon ages for igneous rocks are younger than the Re–Os age for mineralization. New U–Pb dating of Khoito-Oka gabbro-diorites has yielded an age of 503 ± 2 Ma. The U–Pb SHRIMP zircon age of tonalites from the Aksug pluton has been estimated at 504 ± 5 Ma. The U–Pb zircon ages for ore-related tonalite porphyry I and tonalite porphyry II are 500 ± 6 and 499 ± 6 Ma, respectively. The obtained SHRIMP age for leucogranite dike is 509 ± 4 Ma. Two groups of U–Pb dates have been obtained for each of the analyzed zircon samples: close to the Re–Os dates (518–511 ± 2 Ma) and younger (507–486 Ma). The weighted average zircon ages calculated for early and late populations from post-ore leucogranites are 515 ± 4 and 500 ± 4 Ma, respectively. We suggest that zircons with an age close to the Re–Os dates found in post-ore leucogranites were assimilated from the underlying substrate and zircons with an age of 500 ± 4 Ma crystallized from melt. The oldest U–Pb dates (509–515 Ma) of individual zircon grains from ore-bearing tonalite porphyry are consistent with the Re–Os molybdenite ages. Zircons from tonalite, tonalite porphyry, and Khoito-Oka gabbroids sometimes show internal textures indicating secondary alteration. The younger U–Pb concordia zircon ages relative to the Re–Os dates might be due to the influence of late thermal processes on the U–Pb isotopic system. The younger dates (486–507 Ma) of individual zircon grains probably reflect the time of the impact of a thermal fluid process. The weighted average of these younger dates (502 ± 2 Ma) falls within the weighted average age of post-ore leucogranites (500 ± 4 Ma). According to the Re–Os dates, the Aksug deposit formed at the end of the early Cambrian. Ore occurrences similar in magmatism and mineralization to the Aksug ore deposit are widespread in Tuva and in the Lake Zone in Mongolia. Therefore, it is necessary to reassess the role of the Cambrian and Devonian magmatism in the development of porphyry Cu–Mo mineralization both in Tuva and in the Altai–Sayan orogenic area.

Two intrusive complexes are recognized in the Zhireken deposit: Amanan and ore-bearing porphyry. According to the ages obtained by U-Pb zircon dating (Amanan complex-162.6 +/- 1.4 Ma, granites and monzonite-porphyry of the ore-bearing complex-159.0 +/- 1.6 and 157.5 +/- 2.9 Ma), the Amanan complex formed at the end of collision, and the ore-bearing porphyry complex, during the change of the geodynamic regime by the postcollisional (rift) one. The rocks of two complexes have high contents of LILE and LREE and low contents of HFSE and HREE. The (Sr-87/Sr-86)(0) ratio in the gabbro and granites of the Amanan complex is 0.70501 and 0.70534, respectively, and that in the rocks of the porphyry complex is within 0.70451-0.70633. The Amanan gabbro, gabbro-diorites, and granites are characterized by epsilon(Nd)(T) = -1.4, -1.8, and -10.3, respectively, and the rocks of the ore-bearing complex, by epsilon(Nd)(T) = -3.7 to + 1.0. The model T-Nd(DM) age of the Amanan granites is 1.5 Ga, and that of the granites and porphyry of the ore-bearing complex is 1.0-0.8 Ga. The Pb isotope ratios in the rocks of the Amanan and porphyry complexes are: Pb-206/Pb-204 = 18.086-18.136 and 18.199-18.442, Pb-207/Pb-204 = 15.487-15.499 and 15.506-15.545, and Pb-208/Pb-204 = 38.046-38.256 and 38.230-38.456. The results of geological, geochemical, and isotope studies admit that magmas were generated from juvenile and ancient crusts. Melts probably ascended from a depth of no less than 55 km during the melting of crust thickened as a result of tectonic deformations (in the upper horizons) and during the basic-magma supply (in the lower horizons). Juvenile mafic crust is considered to be the major source of fluid components and metals. Favorable conditions for the ore generation in the magmatic system during the formation of the porphyry complex arose at the previous stage, during the formation of the Amanan complex, which we regard as a preparatory stage in the evolution of the long-living ore-magmatic system. (C) 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Acta Geologica Sinica - English EditionVolume 88, Issue s2 p. 494-496 Meeting Abstracts The Zhireken Porphyry Mo-Cu Deposit, Eastern Transbaikalia, Russia: Isotope Geochemistry, Geochronology and Implications for Magma Sources A.P. BERZINA, Corresponding Author A.P. BERZINA Institute of Geology and Mineralogy SB RAS, Novosibirsk, RussiaCorresponding author. E-mail: anberzina@gmail.comSearch for more papers by this authorA.N. BERZINA, A.N. BERZINA Institute of Geology and Mineralogy SB RAS, Novosibirsk, RussiaSearch for more papers by this authorV.O. GIMON, V.O. GIMON Institute of Geology and Mineralogy SB RAS, Novosibirsk, RussiaSearch for more papers by this author A.P. BERZINA, Corresponding Author A.P. BERZINA Institute of Geology and Mineralogy SB RAS, Novosibirsk, RussiaCorresponding author. E-mail: anberzina@gmail.comSearch for more papers by this authorA.N. BERZINA, A.N. BERZINA Institute of Geology and Mineralogy SB RAS, Novosibirsk, RussiaSearch for more papers by this authorV.O. GIMON, V.O. GIMON Institute of Geology and Mineralogy SB RAS, Novosibirsk, RussiaSearch for more papers by this author First published: 29 December 2014 https://doi.org/10.1111/1755-6724.12374_1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume88, Issues2Special Issue: Meeting Abstracts: The 14th Quadrennial International Association on the Genesis of Ore Deposits Symposium. August 19–22, 2014, Kunming, ChinaDecember 2014Pages 494-496 RelatedInformation

In the Eurasian continent there are three huge metallogenic belts of Cu and Mo porphyry deposits, comprising the Paleozoic Central Asian Ore Belt in the north, the Tethyan Eurasian Ore Belt of Jurassic to Cenozoic age in the southwest, and the East Margin Ore Belt of the Eurasian Continent of Jurassic to Cretaceous age in the east. The latter is considered to be part of the vast Circum-Pacific ore belt. Some of the main features of the spatial-temporal distribution of Cu and Mo porphyry systems and related geodynamic processes of the three metallogenic belts are described. In particular, the key role of post-subduction - related porphyry ore systems is emphasized, comprising collisional and post-collisional Cu-Mo porphyry deposits during the geological history of the Eurasian continent. The recurrent feature of these ore systems and related felsic rocks is their derivation from partial melting of stagnant or residual oceanic slabs, and mixing with a variable amount of crustal material during magma ascent to shallower levels. (C) 2013 Published by Elsevier Ltd.

The Shakhtama Mo-Cu porphyry deposit is located within the eastern segment of the Central Asian Orogenic Belt, bordering the southern margin of the Mongol-Okhotsk suture zone. The deposit includes rocks of two magmatic complexes: the precursor plutonic (J(2)) and ore-bearing porphyry (J(3)) complexes. The plutonic complex was emplaced at the final stages of the collisional regime in the region; the formation of the porphyry complex may have overlapped with a transition to extension. The Shakhtama rocks are predominantly metaluminous, I-type high K calc-alkaline to shoshonitic in composition, with relatively high Mg#, Ni, Cr and V. They are characterized by crustal-like I-Sr (0.70741-0.70782), relatively radiogenic Pb isotopic compositions, epsilon(Nd)(T) values close to CHUR (-2.7 to +2.1) and Nd model ages from 0.8 to 1.2 Ga. Both complexes are composed of rocks with K-adakitic features and rocks without adakite trace element signatures. The regional geological setting together with geochemical and isotopic data indicate that both juvenile and old continental crust contributed to their origin. High-Mg# K-adakitic Shakhtama magmas were most likely generated by partial melting of thickened lower crust during delamination and interaction with mantle material, while magmas lacking adakite-like signatures were probably generated at shallower levels of lower crust. The derivation of melts, related to the formation of plutonic and porphyry complexes involved variable amounts of old Precambrian lower crust and juvenile Phanerozoic crust. Isotopic data imply stronger contribution of juvenile mantle-derived material to the fertile magmas of the porphyry complex. juvenile crust is proposed as an important source of fluids and metals for the Shakhtama ore-magmatic system. (C) 2013 Elsevier Ltd. All rights reserved.

Two intrusive complexes are recognized at the Shakhtama deposit: Shakhtama and ore-bearing porphyry. The U–Pb zircon dates (SHRIMP II) are 161.7 ± 1.4 and 161.0 ± 1.7 Ma for the monzonites and granites of the Shakhtama complex and 159.3 ± 0.9 and 155.0 ± 1.7 Ma for the monzonite- and granite-porphyry of the ore-bearing complex. The igneous complexes formed in a complex geodynamic setting in the late Middle Jurassic and early Late Jurassic, respectively. The setting combined the collision of continents during the closure of the Mongol-Okhotsk ocean and the influence of mantle plume on the lithosphere of the Central Asian orogenic belt. The intrusion of the Shakhtama granitoids took place at the end of the collision, and the intrusion of porphyry of the ore-bearing complex, during the change of the geodynamic setting by a postcollisional (rifting) one. The complexes are composed of monzonite–granite series with similar geochemical characteristics of rocks. The performed geological, geochemical, and isotope-geochemical studies suggest that the sources of magmas were juvenile crust and Precambrian metaintrusive bodies. The juvenile mafic crust is considered to be the predominant source of fluid components and metals of the Shakhtama ore-magmatic system. The granitoids of both complexes include calc-alkalic high-K rocks with typical geochemical characteristics and with characteristics of K-adakites. These geochemical features indicate that the parental melts of the former rocks were generated at depths shallower than 55 km, and the melts of the latter, at depths of 55–66 km. K-adakite melts resulted from the melting of crust submerged into the mantle during the lithosphere delamination, which was caused by the crust thickening as a result of the repeated inflow of basic magma into the basement of the crust and tectonic deformations in its upper horizons. The high-Mg monzonitic magma produced under these conditions ascended and was mixed with melts generated in the upper horizons, which accounts for the high Mg contents of the Shakhtama granitoids. The similar compositions and petrogeochemical characteristics of the granitoids of the Shakhtama and porphyry complexes point to the same sources, transport paths, and evolution trend of their parental melts. This indicates that the igneous rocks of both complexes are products of the same long-living magmatic system, which produced Mo mineralization at the final stage. The favorable conditions for the ore production in the magmatic system during the formation of the porphyry complex appeared as early as the preceding stage—during the formation of the Shakhtama complex, which we regard as a preparatory stage in the evolution of the ore-magmatic system.

The concentrations of platinum-group elements（PGE） have been analyzed in primary magmatic magnetite samples from the Zhireken,Shakhtama and Aksug porphyry Cu-Mo deposits（Siberia,Russia） by laser ablation-inductively coupled plasma mass spectrometry to determine the range of PGE contents in magnetites and to check whether magnetite from two main rock suites（barren plutonic suite and mineralized porphyry suite） has distinct PGE composition.The results presented here indicate that magnetites are enriched in PGE relative to whole-rocks.Comparison of ore-related porphyry and barren plutonic suites shows that magnetite exhibit relatively similar PGE distribution patterns in both suites.Variations in Rh and Ru contents were controlled by the oxygen fugacity during magma crystallization.

The Erdenetuin-Obo porphyry Cu-Mo deposit was formed at the final stage of development of magmatic activity occasionally manifested in the Late Permian-Early Triassic in the period of at least 40 Ma. Early plutonic (host) and late ore-bearing porphyry intrusive complexes were formed in that period. The plutonic complex is multiphase, while the porphyry complex is polyrhythmical and multiphase within rhythms. The obtained data on the U-Pb isotopic composition (SHRIMP II) of zircons from unaltered rocks of the ore field are discussed: gabbro, diorite, and granodiorite of the plutonic complex and granodiorite-porphyry I and II of the first and second rhythms of the ore-bearing complex, respectively. Zircons of different age levels and genotypes were identified in the course of performed investigations. Gabbro are dominated by postmagmatic (superimposed) zircons with the datings of 239–225 Ma. The age of xenogenic zircon brought out from the basement rocks is estimated at 1146 ± 11 Ma. Zircons occur as magmatic and postmagmatic (superimposed) minerals dated 252–247, 244–233 Ma in diorite and 244–242, 239–224 Ma in granodiorite. The ages of postmagmatic zircons from diorite are partially overlapped by datings of magmatic zircons from granodiorite and granodiorite-porphyry. In the porphyry complex, the datings of magmatic zircons are 240–234 and 222–220 Ma in granodiorite-porphyries I and II, respectively. There are also inherited zircons with datings coinciding with those of magmatic zircons from precursor intrusive rocks. Datings of such zircons are 249–241 and 257–231 Ma for granodiorite-porphyries I and II, respectively. As a whole, zircon datings in all studied igneous rocks forming a virtually uninterrupted range in the period of 257–220 Ma allow us to suggest the relation of the ore magmatic system to the long-living constantly active deep source occasionally delivering melt to the upper levels.

We studied the isotopic composition of lead in feldspars from the intrusive rocks of enclosing, ore-bearing porphyry, and post-ore complexes and in sulfides from the Sora magmatic center including the Sora porphyry Cu-Mo deposit. The arrangement of the isotopic composition points below the orogen evolution curve on the uranogenic lead diagram evidences a predominance of lead of mantle genesis in the igneous rocks and a minor content of crustal lead. On the 207Pb/204Pb–206Pb/204Pb diagram, the lead of magmatites form a linear sequence (trend), which is interpreted as mixing of lead from different sources. According to the geochemical parameters, weakly depleted mantle metasomatized by subduction fluids was a source of magmatism. The linear correlation between the ratios of Pb isotopes in the igneous rocks of the Sora magmatic center is explained by the mixing of lead of the mantle and subduction fluids. Mantle lead is predominant in the basites of the enclosing, porphyry, and post-ore complexes and in the leucogranites of the enclosing complex. According to lead isotopy data, the differentiated magmatites (enclosing monzonitoids, ore-bearing porphyry, and post-ore syenite-porphyry) contain a subduction component, whose content increases in passing from early to late complex. The Pb-isotopic composition of sulfides suggests the mantle source of Pb in molybdenite of the breccia ores and the heterogeneous source (mantle and subduction fluids) of Pb in chalcopyrite of the veinlet ores.

Several complexes are recognized within the Sora porphyry Cu-Mo deposit: plutonogenic, porphyry (ore-bearing), and dike. They formed since Ordovician till Devonian at the collision, postcollisional, and rift stages of the regional evolution, respectively. Magmatism was manifested at the deposit synchronously with intraplate magmatism, which was widespread within Kuznetsk Alatau and was initiated by the Altai–Sayan mantle plume. In structural position and geochemical characteristics the dike complex is similar to the intraplate complexes in adjacent regions. It formed after the development of the Sora ore-magmatic system including the plutonogenic and porphyry complexes with similar geochemistry and metallogeny. According to the models for the relationship of mantle plumes with ore-magmatic systems, the plutonogenic and porphyry complexes of the Sora deposit developed at the stage of the thermal plume effect on lithosphere, which caused its melting and, as a result, calc-alkalic magmatism. A change of the collision and postcollisional geodynamic regime by the rift one favored the ascent of plume melts, which then participated in the formation of intraplate structures, in particular, the dike complex of the Sora deposit.

The Sm-Nd isotopic results are reported for two magmatic suites (plutonic and porphyry), represented by compositionally variable mafic to felsic rocks from the Early Devonian Sora porphyry Mo-Cu deposit, Russia. The obtained data, combined with a number of earlier geochronological studies suggest a genetic link between granites and basic rocks through partial melting.

The Erdenetiyn-Ovoo magmatic center (EMC) with a porphyry Cu-Mo deposit includes the following intrusive complexes: Selenga, Shivota, ore-bearing porphyry, and post-ore dike. The EMC formed at 260-200 Ma. The geologic evolution of northern Mongolia in that period was much determined by the effect of a mantle plume, which showed two periods of activity: Late Paleozoic and Early Mesozoic. The long multistage evolution of the EMC was due to its localization on the periphery of the Late Paleozoic and Early Mesozoic areas of the plume's influence. The Shivota and post-ore basites are considered to be comagmatic to the Late Permian-Early Triassic trachyandesite-basalt and Late Triassic-Early Jurassic trachyandesite series, respectively, which are similar to the products of Late Paleozoic and Early Mesozoic within-plate magmatism in northern Mongolia. The Selenga complex, which formed before the Shivota one, and the porphyry complex, which formed before the post-ore dike one, are differentiated gabbro-granite series. Gabbro-granitoid magmatism was initiated by the melting of rocks of continental lithosphere under the action of a plume. Later on, as the plume ascended to the surface and the lithosphere became thinner, the conditions were created favoring the lithosphere breakthrough and within-plate basaltoid magmatism.In geochemical features (high contents of LILE and LREE, low contents of HFSE and HREE) the studied basites are similar to the products of subduction magmatism. But this contradicts the geologic position of basites formed after the completion of subduction during the transition of the region to the rifting stage and during the rifting. The mantle metasomatized during the preceding subduction is regarded as the main source of basites. The high contents of alkalies and LREE in the volcanics of the post-ore dike complex and the REE patterns similar to the OIB ones evidence the influence of the plume on the magma formation. The high contents of incompatible trace elements and the Nd isotope composition corresponding to the weakly depleted mantle do not exclude a possible plume effect during the formation of the Selenga complex gabbroids. The geochemical features of the Shivota gabbros, comagmatic to volcanics produced during the Late Paleozoic within-plate activity, are partly transformed during the melt evolution in crustal chambers.The REE patterns of the EMC basites evidence that the evolution of ascending magma was accompanied by the fractionation of amphibole. During this process, ore elements were redistributed into mineral and concentrated in amphibole-containing rocks, from which metals were later mobilized by late melts and fluids. The evolution of basaltoid magmatism of the Selenga, Shivota, and porphyry complexes is regarded as a preliminary stage of ore formation, which was considerably responsible for the EMC productivity. (C) 2009, IGM, Siberian Branch of the RAS. Published by Elsevier B. V. All rights reserved.

The Aksug deposit, located in Altay-Sayan region of Russia, is one of the largest porphyry Cu-Mo deposits in Southern Siberia. The ore-bearing porphyries of the Aksug porphyry Cu-Mo system were formed in post-collisional environment. Geochemically they belong to talk-alkaline and high K-calk-alkaline series. Rocks are characterized by enrichment of LILE and depletion of HSFE and HREE, showing the importance of subduction-related components in magma generation. Large plutonic intrusions that host porphyry systems have been formed during collision. The origin of porphyritic rocks is dominantly the mantle with lower crustal contribution. The mainly economically important Cu-Mo mineralization is closely related to a porphyry series in time and space., being emplaced towards the end of magmatic activity. Though the emplacement of plutonic kind ore-bearing porphyry complexes took place in different geodynamic environments, both complexes are characterized by certain similarity in geochemical composition, alkalinity, trace element content, Sr isotopic composition. This fact evidently indicates a common deep-seated magmatic source (at the lower crust - upper mantle level). Low initial Sr-87/Sr-86, sulfur isotopic characteristics and presence of PGE-Co-Ni mineralization in associated pyrite-chalcopyrite ores suggest that mantle source of chalcophile elements was of high importance in porphyry Cu-Mo mineralization of the Aksug deposit.