Geology, geochronology, and S-Pb-Os geochemistry of the Alastuo gold deposit, West Tianshan, NW China

Zhang, Bo; Xue, Chunji; Seltmann, Reimar; Dolgopolova, Alla; Chi, Guoxiang; Li, Chao

doi:10.1007/s00126-019-00948-7

Cited by 21 publications

(4 citation statements)

References 75 publications

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“…In the eastern Kyrgyz Tien Shan, the presence of a Precambrian microcontinent with Palaeoproterozoic basement and Neoproterozoic to Early Palaeozoic passive margin sediments similar to that of the Tarim Craton has been demonstrated along the southern margin of the Northern Tien Shan (Alexeiev et al, 2016; Alexeiev, Biske, et al, 2019; Alexeiev, Kröner, et al, 2019). The Middle Tien Shan overlies a continental fragment rifted off the Tarim Craton and accreted to the Northern Tien Shan; in the eastern Kyrgyz Tien Shan, it is separated from the Northern Tien Shan by the ‘Nikolaev Line’ (Kröner et al, 2017; Ma et al, 2014; Zu et al, 2020). In the Middle–Late Palaeozoic, this continental fragment was in part overprinted by a continental arc formed along the northern margin of the Turkestan palaeoocean (Dolgopolova et al, 2017).…”

Section: Regional Tectonic and Metallogenic Settingmentioning

confidence: 99%

“…The ‘Main Structural Line of Tien Shan’, or the ‘Nikolaev Line’, extends for over 500 km in Kyrgyzstan, and continues farther east into the Chinese Tien Shan as the North Narati Fault (Ma et al, 2014; Zu et al, 2020; Figures 1 and 2). This fault system was initially recognized by V. A. Nikolaev (Nikolaev, 1933) and later named after this researcher.…”

Section: Tectonic and Metallogenic Setting Of The ‘Nikolaev Line’mentioning

confidence: 99%

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Late Palaeozoic potassic igneous rocks of the Molo‐Sarychat pluton in the eastern Kyrgyz Tien Shan: Geochemistry, U–Pb zircon geochronology and implications for related skarn‐porphyry Mo‐W‐Cu‐Au mineralization

Soloviev,

Kryazhev,

Semenova

et al. 2024

Geological Journal

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The Molo‐Sarychat multiphase pluton is situated along the fault systems of the ‘Main Structural Line of Tien Shan’ (known also as the ‘Nikolaev Line’). It comprises mafic to intermediate (monzodiorite, monzonite) and silicic (quartz monzonite, monzogranite and leucogranite‐alaskite) rocks, followed by the late mafic (monzodiorite‐porphyry to lamprophyre) dikes. Isotopic U‐Pb zircon dating of quartz monzonite and monzogranite indicates their Early Permian age (ca. 293 to 286 Ma). The rocks appear to have been produced by remelting of a partially crystallized (mush) magma batch at deeper levels, which is evident by the presence of zircon antecrysts dated at some 306 to 320 Ma. These geochronological data are consistent with a post‐collisional setting of the pluton that occurred after the cessation of subduction, which affected the Middle Tien Shan in the Late Palaeozoic. Geochemical signatures of the igneous rocks from the Molo‐Sarychat pluton correspond to high‐K calc‐alkaline to shoshonitic series intrusions emplaced in a post‐collisional setting. An initial shoshonitic magma was produced by a low‐degree partial melting of the metasomatically enriched upper mantle, with amphibole fractionation in a deep (lower crustal) magma chamber. In this evolution, a generation, under the influence of mantle‐supplied fluids and heat, granitic magmas in the crustal protolith can be suggested, with further mixing/mingling of the mantle‐derived mafic (shoshonitic) magma and mantle‐induced crustal granitic magma, followed by the magma fractionation and emplacement at shallower crustal levels. The skarn‐porphyry Mo‐Cu‐W(‐Au) mineralization associated with the Molo‐Sarychat pluton complements the group of similar deposits associated with high‐K calc‐alkaline to shoshonitic series intrusions in the Middle Tien Shan and globally. The characteristic Mo‐W‐Cu‐Au metal assemblage and the high endowment in W and particularly Mo can be related to the fertilization of subduction‐modified subcontinental mantle in these metals, and its subsequent involvement in the magma generation in post‐collisional setting. A certain role of crustal magma sources in the strong Mo endowment can be considered that would be consistent with some A‐type granitoid affinity of the igneous rocks. The Early Permian age of these high‐potassic intrusions supporting their post‐collisional emplacement is remarkably similar to the age of hydrothermal alteration assemblages, previously reported for the super‐large Kumtor Au deposit situated in a similar post‐collisional setting nearby.

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Section: Regional Tectonic and Metallogenic Settingmentioning

confidence: 99%

Section: Tectonic and Metallogenic Setting Of The ‘Nikolaev Line’mentioning

confidence: 99%

Late Palaeozoic potassic igneous rocks of the Molo‐Sarychat pluton in the eastern Kyrgyz Tien Shan: Geochemistry, U–Pb zircon geochronology and implications for related skarn‐porphyry Mo‐W‐Cu‐Au mineralization

Soloviev,

Kryazhev,

Semenova

et al. 2024

Geological Journal

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“…Chlorite group minerals from Tuwu were commonly intergrown with or occur later than the hydrothermal rutile of stage II (Figure 4). The major elements in chlorite coexisting with rutile were determined in this study, and the results are presented in Table 3 [56][57][58]. The chemical formula of the analyzed chlorite was calculated based on 14 oxygen atoms per formula unit (a.p.f.u).…”

Section: Chlorite Geothermometrymentioning

confidence: 99%

Rutile and Chlorite Geochemistry Constraints on the Formation of the Tuwu Porphyry Cu Deposit, Eastern Tianshan and Its Exploration Significance

et al. 2021

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The chemical composition of rutile has been used as an indicator in magmatic and metamorphic-related diagenetic systems, but rarely in porphyry-style ore systems. The Tuwu deposit (557 Mt at 0.58% Cu) is a large porphyry-style Cu mineralization in Eastern Tianshan, Xinjiang, with typical disseminated, stockwork mineralized veins hosted in tonalite and diorite porphyry, and to a lesser extent in volcanic rocks of the Qi’eshan Group. We first present determination of rutile minerals coupled with chlorite identified in mineralized porphyries from Tuwu to reveal their geochemical features, thus providing new insights into the ore-forming processes and metal exploration. Petrographic and BSE observations show that the rutile generally occurs as large crystals (30 to 80 µm), in association with hydrothermal quartz, chlorite, pyrite, and chalcopyrite. The rutile grains display V, Fe, and Sn enrichment and flat LREE-MREE patterns, indicating a hydrothermal origin. Titanium in rutile (TiO2) is suggested to be sourced from the breakdown and re-equilibration of primary magmatic biotite and Ti-magnetite, and substituted by Sn4+, high field strength elements (HFSE; e.g., Zr4+ and Hf4+), and minor Mo4+ under hydrothermal conditions. The extremely low Mo values (average 30 ppm) in rutile may be due to rutile formation postdating that of Mo sulfides (MoS2) formation in hydrothermal fluids. Chlorite analyses imply that the ore-forming fluids of the main stage were weakly oxidized (logfO2 = −28.5 to −22.1) and of intermediate temperatures (308 to 372 °C), consistent with previous fluid inclusion studies. In addition, Zr-in-rutile geothermometer yields overestimated temperatures (>430 °C) as excess Zr is incorporated into rutile, which is likely caused by fast crystal growth or post crystallization modification by F-Cl-bearing fluid. Thus, application of this geothermometer to magmatic-hydrothermal ore systems is questionable. Based on the comparison of rutile characteristics of porphyry Cu with other types of ore deposits and barren rocks, we suggest that porphyry Cu-related rutile typically has larger grain size, is enriched in V (average 3408 ppm, compared to <1500 ppm of barren rocks) and to a lesser extent in W and Sn (average 121 and 196 ppm, respectively), and has elevated Cr + V/Nb + Ta ratios. These distinctive signatures can be used as critical indicators of porphyry-style Cu mineralization and may serve as a valuable tool in mineral exploration.

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“…Это не только затрудняет металлогенические построения, но и является критическим для установления связи минерализации с тектоно-магматическими событиями в регионе. Одним из решений этой проблемы является использование Re-Os изотопных систем рудных минералов (пирит, арсенопирит, антимонит, халькопирит, молибденит) [4,54,58,60,61,63,68,71,72] и золота [9,[51][52][53] для определения возраста и вклада вещества разноглубинных резервуаров в рудообразующий процесс. Участие разноглубинных источников в генерации рудных флюидов можно оценить по начальному изотопному составу Os золота ( 187 Os/ 188 Os) i на предполагаемое время формирования месторождений [9,41,62].…”

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Age of Gold Mineralization in the Yana-Kolyma Metallogenic Belt, Northeast Russia: First Data of Re-Os Isotope Geocronology of Native Gold

Fridovsky¹,

Goryachev²,

Krymsky³

et al. 2021

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Presented are the first results of studying the Re-Os isotope system of native gold from the orogenic Malo-Taryny, Khangalas, and Bazovsky deposits located in the central part of the Yana-Kolyma metallogenic belt. Re concentration in the sampled gold varies from 0.168 to 6.997 mg/t while that of Os changes from 0.068 to 1.443 mg/t. The data obtained enabled calculation of the isochrone age which is consistent, within the limits of error, with 40Ar-39Ar and К-Аr dates of sericite from the above deposits. The results obtained indicate that gold deposits under study were formed in the interv of 147.8–137.1 Ma synchronously with Late Jurassic – Early Cretaceous orogenic processes in the Yana-Kolyma metallogenic belt and the eastern margin of the Siberian continent. The initial Os isotope ratios ((187Os/188Os)i= 0.1844–0.2475) in the studied samples and fractions of gold from the Malo-Tarynsky, Khangalas and Bazovsky deposits suggest a significant role of a non-radiogenic component, normally associated with mantle sources.

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Geology, geochronology, and S-Pb-Os geochemistry of the Alastuo gold deposit, West Tianshan, NW China

Cited by 21 publications

References 75 publications

Late Palaeozoic potassic igneous rocks of the Molo‐Sarychat pluton in the eastern Kyrgyz Tien Shan: Geochemistry, U–Pb zircon geochronology and implications for related skarn‐porphyry Mo‐W‐Cu‐Au mineralization

Late Palaeozoic potassic igneous rocks of the Molo‐Sarychat pluton in the eastern Kyrgyz Tien Shan: Geochemistry, U–Pb zircon geochronology and implications for related skarn‐porphyry Mo‐W‐Cu‐Au mineralization

Rutile and Chlorite Geochemistry Constraints on the Formation of the Tuwu Porphyry Cu Deposit, Eastern Tianshan and Its Exploration Significance

Age of Gold Mineralization in the Yana-Kolyma Metallogenic Belt, Northeast Russia: First Data of Re-Os Isotope Geocronology of Native Gold

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