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Zircon geochemistry provides a sensitive monitor of its parental magma composition. However, due to the complexity of the uptake of trace elements during zircon growth, identifying source magmas remains challenging, particularly for... more
Zircon geochemistry provides a sensitive monitor of its parental magma composition. However, due to the complexity of the uptake of trace elements during zircon growth, identifying source magmas remains challenging, particularly for detrital grains whose petrological context is lost. We use a machine learning-based approach to explore the classifiers for zircon provenance, based on 3794 published, high-quality zircon trace element analyses compiled from I-, S-, and A-type granites. Three supervised machine learning algorithms, namely, Support Vector Machine (SVM), Random Forest (RF), and Multilayer Perceptron (MLP) were used and trained with 11 features, including 7 trace elements (Ce, Eu, Ho, Nb, Ta, Th, and U) and 4 derived trace element ratios (Th/U, U/Yb, Ce/Ce*, and Eu/Eu*). Our results show that all three trained machine learning methods perform very well with accuracy varying from 0.86 to 0.89, and that input–output relationships captured by different ML methods are nearly co...
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Orogens are major sites for crustal growth on Earth. However, characterizing orogens with stages is challenging. Here we present Nd isotope mapping results of felsic and intermediate igneous rocks from eight well-studied, typical... more
Orogens are major sites for crustal growth on Earth. However, characterizing orogens with stages is challenging. Here we present Nd isotope mapping results of felsic and intermediate igneous rocks from eight well-studied, typical Phanerozoic orogens. The data illustrate the distribution and areas of isotopic domains ranging from highly primitive to highly evolved, which reflects their final preservation from long-term crustal growth. From the data, we calculated the areal proportion of juvenile crust and divided the orogens into (i) highly primitive (with >70% juvenile crust); (ii) primitive (70-50%; e.g., Altaids with ~58%); (iii) slightly primitive (50–30%; e.g., North American Cordillera (~48%), Newfoundland Northern Appalachian Orogen (~40%), Lachlan Orogen (~31%)); (iv) evolved (30–10%); (v) highly evolved (10–0%; e.g., Tethyan Tibet (~4%), Caledonides (~2%), Variscides (~1%), and Qinling-Dabie (<1%)). Those from (i) to (iii) quantitatively characterize and/or correspond ...
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Situated in the heart of the Tien Shan gold province, Unkurtash (3.5 Moz at 1.82 g/t) is a representative lode gold deposit that is hosted within the Carboniferous Andagul granodiorite in the Kassan district, western Kyrgyzstan. The Tien... more
Situated in the heart of the Tien Shan gold province, Unkurtash (3.5 Moz at 1.82 g/t) is a representative lode gold deposit that is hosted within the Carboniferous Andagul granodiorite in the Kassan district, western Kyrgyzstan. The Tien Shan gold province consists of porphyry and epithermal deposits, which are related to magmatic arcs, and lode gold deposits formed in the late stages of continent-continent collision that have been generally classified as mesothermal or orogenic type. Some of the lode gold deposits have been considered to be intrusion-related, but the genetic relationship between gold mineralization and the magmatic intrusions remains ambiguous in most cases due to lack of absolute timing of the gold mineralization. This paper addresses this problem through detailed geologic and petrographic studies of the Unkurtash gold deposit in conjunction with Re-Os, U-Pb, and 40Ar/39Ar dating along with S and Pb isotopes. The paragenesis of the Unkurtash deposit is divided int...
Research Interests: Geology, Geochemistry, Economic Geology, Pyrite, Arsenopyrite, and 3 moreSericite, Lode, and overprinting
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Research Interests: Geology and Metallogeny
This data set derives from a pilot plant campaign for the beneficiation of a complex tin bearing skarn ore, including different separation and classification steps. The aim of the pilot plant test work was to prove a flowsheet that had... more
This data set derives from a pilot plant campaign for the beneficiation of a complex tin bearing skarn ore, including different separation and classification steps. The aim of the pilot plant test work was to prove a flowsheet that had been developed based on detailed geometallurgical analysis and results from the research projects AFK (Aufbereitung feinkörniger Komplexerze, BMBF grant number 033R128) and FAME (European Union grant 641650) to produce a cassiterite concentrate for tin production, and further preconcentrates for iron, zinc, copper, indium, and arsenic. The tin mineralization is partially well localized in cassiterite, but also partially finely disseminated and thus unrecoverable as minor components in other minerals. The iron is located in magnetic and nonmagnetic iron oxides sometimes intergrown with cassiterite. Therefore, iron concentrates are recovered at larger grain sizes but need a further tin recovery step not implemented in the reported experiment. The other elements are mainly deported in sulfides, which are bulk recovered in a flotation step. A subsequent selective flotation is needed to recover them individually. This selective flotation is, however, not part of the reported experiment. The two tin concentrates recovered from the shaking table should be considered as preconcentrates, that can be enriched further e.g. through multi-stage gravity separation. The motivation for this data set is to provide a consistent basis for the application of new particle based geometallurgical methods enabled by automated mineralogy (e.g. Buchmann et al. 2018; Schach et al. 2019; Buchmann et al. 2020; Pereira et al. 2020). In addition, it should also allow for the comparison and evaluation of different analytical methods, which were used during the pilot plant experiments to generate a validated data set for the whole plant and to correlate different result from various methods. This is the basis for further investigations enabling the application of various analyzing methods in a synergetic way. Thos [...]
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Increasing evidence shows that the mantle contributes (directly or indirectly) to Sn-bearing granites worldwide. However, the specific role of mantle in the formation of tin granites and related mineralization remains poorly understood.... more
Increasing evidence shows that the mantle contributes (directly or indirectly) to Sn-bearing granites worldwide. However, the specific role of mantle in the formation of tin granites and related mineralization remains poorly understood. In the world-class Dachang district, South China, tin mineralization is related to the Longxianggai equigranular/porphyritic biotite granites and tin orebodies are cut by granite porphyry dykes hosting mafic microgranular enclaves (MMEs). A combination of zircon U-Pb dating and Hf-O isotopes, mineral chemistry, and whole-rock elemental and Sr-Nd isotopic compositions—for granitic rocks and MMEs, is employed to constrain the petrogenesis and to unravel the link between tin fertility and mantle upwelling. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U-Pb dating indicates that the biotite granites were emplaced at ca. 93 Ma, and the granite porphyry dykes and MMEs were formed at ca. 86 Ma. The biotite granites are silic...
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Research Interests: Geology, Geochemistry, China, Geochronology, Pyrite, and 4 moreGalena, Mineral Paragenesis, Sericite, and Sphalerite
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We consider geochemical features of mafic magmatism manifested during the evolution of a complex nappe-folded structure in Western Sangilen, resulted from the Cambrian–Ordovician collisional tectogenesis. There are abundant... more
We consider geochemical features of mafic magmatism manifested during the evolution of a complex nappe-folded structure in Western Sangilen, resulted from the Cambrian–Ordovician collisional tectogenesis. There are abundant ultramafic–mafic and mafic associations of different types in this region: layered low-Ti low-alkali ultramafic–mafic intrusions, high-Ti medium-alkali gabbroids, gabbro–monzodiorite intrusions, and alkali basalts. Isotope-geochronological data showed that these complexes formed over a wide time interval, from 570 to 440 Ma. At this time, the geodynamic setting in Western Sangilen changed from an island-arc one via a collision one to an intercontinental rift setting. At the early and late stages of the evolution of Western Sangilen, the geochemical features of mafites were typical of their geodynamic settings. The properties of mafites that formed synchronously with the collision are of particular interest. The studies have shown that the chemical composition of ...
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Abstract There is a wide range of controversial tectonic concepts for the final development of the Paleo-Asian Ocean (PAO) in the western Central Asian Orogenic Belt (CAOB), largely due to scarcity of geochronological and geochemical... more
Abstract There is a wide range of controversial tectonic concepts for the final development of the Paleo-Asian Ocean (PAO) in the western Central Asian Orogenic Belt (CAOB), largely due to scarcity of geochronological and geochemical data. Our paper presents first results of U-Pb zircon dating and detailed geochemical studies (major and trace elements, Sr, Nd and Pb isotopes) of subduction-related mafic to felsic igneous rocks of the Char ophiolite belt (East Kazakhstan). The new data shed light on the final stage of the PAO in this region. The igneous assemblages comprise mafic to felsic volcanic rocks and their plutonic varieties. The rocks yield Devonian and early Carboniferous U-Pb zircon ages, which match the previously reported micropaleontological ages of sedimentary rocks of oceanic origin. According to major element composition, the rocks belong to the tholeiitic and tholeiitic to calc-alkaline transitional igneous series. They are characterized by low TiO2 (0.7 wt% in average) and moderately enriched light rare-earth element (LREE) to flat chondrite normalized REE patterns (Lan = 3.5–34.6, La/Smn = 0.8–4.6, La/Ybn = 0.6–9.1). Primitive mantle normalized multi-element spectra show distinct troughs at Nb (Nb/Lapm = 0.1–0.38; Nb/Thpm = 0.04–0.6). Most of the samples have positive eNdt values ranging from +2.9 to +8.8 and 206Pb/204Pb ratios ranging from ~18.0 to ~19.7. The trace element and isotope data and the results of geochemical modeling in the Nb-Yb system suggest high degrees of melting of a strongly depleted mantle source in the spinel stability field. Clinopyroxene (cpx) monomineral thermometry and the calculations based on the composition of cpx hosted melt inclusions suggest that the melts from which the younger samples were derived crystallized at lower temperatures (below 1170 °С) at depths of 12, 6–3 km and in subsurface conditions, while the older samples derived at higher temperatures (up to 1193 °С) crystallized at a depth from 6 to 3 km. Our new data show that the Char ophiolite belt hosts fragments of at least two intra-oceanic arcs, middle Devonian and Early Carboniferous, which existed in the Irtysh-Zaisan branch of the Paleo-Asian Ocean, at the active margin of the Kazakhstan continent.
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Research Interests: Engineering, Earth Sciences, Geology, Geochemistry, Paleozoic, and 3 moreTransactions, Riphean, and Anticline
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Research Interests: Earth Sciences, Geology, Paleontology, Devonian, Ordovician, and 4 moreCarboniferous, Permian, Paleozoic, and Thrust
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Gold and silver mineralogy is studied in ores of the Biksizak base-metal deposit (South Urals, Russia). This is a skarn-related carbonate replacement mineralization typical for marginal zones of porphyry-epithermal systems. The... more
Gold and silver mineralogy is studied in ores of the Biksizak base-metal deposit (South Urals, Russia). This is a skarn-related carbonate replacement mineralization typical for marginal zones of porphyry-epithermal systems. The variability of precious metals minerals is established. Native gold (fineness 853 to 939) in assemblage with chalcopyrite and sphalerite is the most abundant. A telluride assemblage (tetradymite, hessite, stützite, petzite, galena, tellurobismuthite, rucklidgeite, altaite and native gold with a fineness of 830–900) and a silver–pearceite–acanthite assemblage (acanthite/argentite, pearceite–polybasite and gold–silver alloy from native gold with fineness of 747 to native silver) are identified. It is shown the exhibited variability is controlled by decreasing the temperature and variations in the tellurium and sulfur fugacities.
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Research Interests: Geology, Geochemistry, Provenance, Plate Tectonics, Archean, and 3 moreCrust, Continental Crust, and Hadean
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Ten rock samples with unidirectional solidification textures (USTs) from nine Asian and Australian porphyry and intrusion-related Au deposits and prospects were investigated in terms of mineralization sequences, textural and paragenetic... more
Ten rock samples with unidirectional solidification textures (USTs) from nine Asian and Australian porphyry and intrusion-related Au deposits and prospects were investigated in terms of mineralization sequences, textural and paragenetic relationships, melt and fluid inclusion inventory, cathodoluminescence, and trace elements of UST quartz. Despite general similar structural appearance of the investigated UST sequences, each UST locality has its own specific textural features. We provide a structural classification of observed USTs that distinguishes equigranular and heterogranular USTs, which are subdivided according to the UST layer structure into straight, wavy, or contorted/brain-like type. In addition, there is the group of disturbed USTs comprising incompletely developed UST layers, and ductile- or brittle-fragmented UST sequences. Ti-in-quartz-based calculations revealed crystallization temperatures of UST quartz between 590 and 770 °C. Primary silicate melt inclusions found ...
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Research Interests: Geology and Metallogeny
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British Fluorspar Ltd (BFL) operates a lead-fluorite-barite deposit located in the Peak Lake District (Derbyshire, UK) with fluorspar as the main product and lead and barite as by-products. Recent analysis of the CaF2 concentrate showed... more
British Fluorspar Ltd (BFL) operates a lead-fluorite-barite deposit located in the Peak Lake District (Derbyshire, UK) with fluorspar as the main product and lead and barite as by-products. Recent analysis of the CaF2 concentrate showed high values of deleterious elements such as Pb, P, S and As, which affect the quality of the product. Grindability studies showed an overgrinding of material prior to the flotation stage with high liberation of P2O5 mainly to the fluorspar concentrate. Data obtained from bath flotation test indicated an improvement of lead recovery from 2.33 % to 15.03 %, decreasing Na2S to 100g/t and pH to 9 in the lead oxide circuit and a depression of P2O5 in the fluorspar flotation stage from 87 % to 91 % recovered in the tailings using 200 g/t of CaCl-CuSO4 as “depressant” of phosphates related minerals
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The western Tianshan Gold Belt hosts numerous giant and large gold deposits that have been formed during the late Paleozoic amalgamation of the Tianshan orogen. However, little is known about their exhumation histories during the Mesozoic... more
The western Tianshan Gold Belt hosts numerous giant and large gold deposits that have been formed during the late Paleozoic amalgamation of the Tianshan orogen. However, little is known about their exhumation histories during the Mesozoic to Cenozoic intracontinental evolution of the orogen. The Carboniferous Katebasu orogenic gold deposit in northwestern China is a new gold discovery within the western Tianshan Gold Belt, and it shares many similarities with other orogenic gold deposits in the belt. In this contribution, new 40Ar/39Ar and (U–Th)/He ages were combined with previous geochronology and numerical modelling to quantify its post-Carboniferous cooling and exhumation history. The results revealed a three-phase cooling history and two phases of post-mineralization exhumation. We suggest that a large volume (c. 0.8 km) of the mineralized roof parts of the Katebasu deposit might have been removed during uplift and erosion, whereas significant ore reserves could still exist at ...
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The attached document is the authors’ submitted version of these conference proceedings. You are advised to consult the publisher’s version if you wish to cite from it.
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Research Interests: Geology, Geochemistry, Geochronology, Devonian, Zircon, and 3 moreSkarn, Plagioclase, and Trace element
Abstract: The recent discovery of numerous large porphyry Cu deposits in the southern Qinghai-Tibet Plateau shows that porphyry Cu deposits can be hosted in magmatic suites in collisional settings. However, in contrast, only a few small... more
Abstract: The recent discovery of numerous large porphyry Cu deposits in the southern Qinghai-Tibet Plateau shows that porphyry Cu deposits can be hosted in magmatic suites in collisional settings. However, in contrast, only a few small porphyry Cu deposits have so far been discovered in association with collision-related granitoids in the northern Qinghai-Tibet Plateau. This raises questions about the origin of collision-related magmas and their mineralization potential. In this contribution, we comprehensively synthesize whole-rock geochemical and isotopic data on collision-related intrusions from the Qimantagh Metallogenic Belt in the northern Qinghai-Tibet Plateau, which hosts many skarn polymetallic deposits but only a few, small porphyry Cu-Mo deposits. This, combined with newly obtained zircon trace element data, provides a high-quality database that can yield insights on the nature and origin of the magmatic suites as well as their fertility in terms of Cu mineralization. Two volumetrically dominant intrusive suites are identified in the Qimantagh Metallogenic Belt: 435-370 Ma granitoids (Suite I) and 245-196 Ma granitoids (Suite II). They formed during syn- to post-collisional stages of the Caledonian and Hercynian-Indosinian Orogenies, respectively. In contrast, arc magmatic rocks are relatively scarce. Both Suites I and II are characterized by low zircon Ce/Ce* and Eu/Eu* values, low whole-rock Sr/Y and Eu/Eu* values with arc-like features (e.g., depletion of Nb and Ta). Furthermore, both suites display some evolved Sr-Nd-Hf isotopic values (e.g., eNdi = -8.1 to 0.1), with the majority of samples characterized by Paleo- to Meso-Proterozoic two-stage Nd and Hf model ages. These features suggest that the parental magmas of the two suites were probably derived from subduction fluid-modified mantle sources which underwent significant crustal AFC processes during magma ascent. The relative scarcity of arc magmatic rocks and the prevalence of collisional magmatism during the Caledonian and Hercynian-Indosinian Orogenies in the Qimantagh Metallogenic Belt can be explained by pre-collisional, flat-slab subduction and subsequent slab breakoff during collision, the later triggering asthenosphere upwelling and extensive magmatism in collisional settings. Compared to fertile plutons in some large porphyry Cu deposits worldwide, especially those in the Gangdese Metallogenic Belt, the two suites in the Qimantagh Metallogenic Belt have low magmatic oxidation states and low water content which inhibited the formation of large porphyry Cu deposits. Thus, skarn polymetallic deposits (probably as well as small porphyry Cu-Mo deposits) rather than large porphyry Cu deposits should be targeted during future mineral exploration in the northern Qinghai-Tibet Plateau, since such deposits do not necessarily need a parental magma with high oxidation state and water content.