ALBERT

Description:    Epithermal uranium deposits of the Sierra Peña Blanca are classic examples of volcanic-hosted deposits and have been used as natural analogs for radionuclide migration in volcanic settings. We present a new genetic model that incorporates both geochemical and tectonic features of these deposits, including one of the few documented cases of a geochemical signature of biogenic reducing conditions favoring uranium mineralization in an epithermal deposit. Four tectono-magmatic faulting events affected the volcanic pile. Uranium occurrences are associated with breccia zones at the intersection of fault systems. Periodic reactivation of these structures associated with Basin and Range and Rio Grande tectonic events resulted in the mobilization of U and other elements by meteoric fluids heated by geothermal activity. Focused along breccia zones, these fluids precipitated under reducing conditions several generations of pyrite and uraninite together with kaolinite. Oxygen isotopic data indicate a low formation temperature of uraninite, 45–55°C for the uraninite from the ore body and ∼20°C for late uraninite hosted by the underlying conglomerate. There is geochemical evidence for biological activity being at the origin of these reducing conditions, as shown by low δ 34 S values (∼−24.5‰) in pyrites and the presence of low δ 13 C (∼−24‰) values in microbial patches intimately associated with uraninite. These data show that tectonic activity coupled with microbial activity can play a major role in the formation of epithermal uranium deposits in unusual near-surface environments. Content Type Journal Article Category Article Pages 1-16 DOI 10.1007/s00126-012-0408-5 Authors Samuel Angiboust, Institut des Sciences de la Terre de Paris, UMR 7193 CNRS, Université Pierre et Marie Curie-Paris 6, 4 Place Jussieu, 75252 Paris, France Mostafa Fayek, Department of Geological Sciences, University of Manitoba, 240 Wallace Building, 125 Dysart Road, Winnipeg, MB R3T 2N2, Canada Ian M. Power, Department of Earth Sciences, University of Western Ontario, London, ON N6A 5B7, Canada Alfredo Camacho, Department of Geological Sciences, University of Manitoba, 240 Wallace Building, 125 Dysart Road, Winnipeg, MB R3T 2N2, Canada Georges Calas, Institut de Minéralogie et de Physique des Milieux Condensés, Université Pierre et Marie Curie-Paris 6, UMR CNRS 7590, 4 Place Jussieu, 75252 Paris, France Gordon Southam, Department of Earth Sciences, University of Western Ontario, London, ON N6A 5B7, Canada Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    The Horní Slavkov–Krásno Sn–W ore district is hosted by strongly altered Variscan topaz–albite granite (Krudum granite body) on the northwestern margin of the Bohemian Massif. We studied the fluid inclusions on greisens, ore pockets, and ore veins from the Hub Stock, an apical expression of the Krudum granite. Fluid inclusions record almost continuously the post-magmatic cooling history of the granite body from ∼500 to 〈50°C. Rarely observed highest-temperature (∼500°C) highest-salinity (∼30 wt.% NaCl eq.) fluid inclusions are probably the result of secondary boiling of fluids exsolved from the crystallizing magma during pressure release which followed hydraulic brecciation of the gneissic mantle above the granite cupola. The greisenization was related to near-critical low-salinity (0–7 wt.% NaCl eq.) aqueous fluids with low amount of CO 2 , CH 4 , and N 2 (≤10 mol% in total) at temperatures of ∼350–400°C and pressures of 300–530 bar. Crush-leach data display highly variable and negatively correlated I/Cl and Br/Cl values which are incompatible with both orthomagmatic and/or metamorphic origin of the fluid phase, but can be explained by infiltration of surficial and/or sedimentary fluids. Low fluid salinity indicates a substantial portion of meteoric waters in the fluid mixture that is in accordance with previous stable isotope data. The post-greisenization fluid activity associated with vein formation and argillitization is characterized by decreasing temperature (〈350 to 〈50°C), decreasing pressure (down to ∼50–100 bar), and mostly also decreasing salinity. Content Type Journal Article Category Article Pages 1-13 DOI 10.1007/s00126-012-0400-0 Authors Zdeněk Dolníček, Department of Geology, Palacký University, 17. listopadu 12, 771 46 Olomouc, Czech Republic Miloš René, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 94/41, 182 09 Prague, Czech Republic Walter Prochaska, Department of Geology and Economic Geology, Montanuniversität Leoben, Peter-Tunner-Strasse 5, 8700 Leoben, Austria Michal Kovář, Department of Geology, Palacký University, 17. listopadu 12, 771 46 Olomouc, Czech Republic Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    The ore deposits of the Mesozoic age in South China can be divided into three groups, each with different metal associations and spatial distributions and each related to major magmatic events. The first event occurred in the Late Triassic (230–210 Ma), the second in the Mid–Late Jurassic (170–150 Ma), and the third in the Early–Mid Cretaceous (120–80 Ma). The Late Triassic magmatic event and associated mineralization is characterized by peraluminous granite-related W–Sn–Nb–Ta mineral deposits. The Triassic ore deposits are considerably disturbed or overprinted by the later Jurassic and Cretaceous tectono-thermal episodes. The Mid–Late Jurassic magmatic and mineralization events consist of 170–160 Ma porphyry–skarn Cu and Pb–Zn–Ag vein deposits associated with I-type granites and 160–150 Ma metaluminous granite-related polymetallic W–Sn deposits. The Late Jurassic metaluminous granite-related W–Sn deposits occur in a NE-trending cluster in the interior of South China, such as in the Nanling area. In the Early–Mid Cretaceous, from about 120 to 80 Ma, but peaking at 100–90 Ma, subvolcanic-related Fe deposits developed and I-type calc-alkaline granitic intrusions formed porphyry Cu–Mo and porphyry-epithermal Cu–Au–Ag mineral systems, whereas S-type peraluminous and/or metaluminous granitic intrusions formed polymetallic Sn deposits. These Cretaceous mineral deposits cluster in distinct areas and are controlled by pull-apart basins along the South China continental margin. Based on mineral assemblage, age, and space–time distribution of these mineral systems, integrated with regional geological data and field observations, we suggest that the three magmatic–mineralization episodes are the result of distinct geodynamic regimes. The Triassic peraluminous granites and associated W–Sn–Nb–Ta mineralization formed during post-collisional processes involving the South China Block, the North China Craton, and the Indo-China Block, mostly along the Dabie-Sulu and Songma sutures. Jurassic events were initially related to the shallow oblique subduction of the Izanagi plate beneath the Eurasian continent at about 175 Ma, but I-type granitoids with porphyry Cu and vein-type Pb–Zn–Ag deposits only began to form as a result of the breakup of the subducted plate at 170–160 Ma, along the NNE-trending Qinzhou-Hangzhou belt (also referred to as Qin-Hang or Shi-Hang belt), which is the Neoproterozoic suture that amalgamates the Yangtze Craton and Cathaysia Block. A large subduction slab window is assumed to have formed in the Nanling and adjacent areas in the interior of South China, triggering the uprise of asthenospheric mantle into the upper crust and leading to the emplacement of metaluminous granitic magma and associated polymetallic W–Sn mineralization. A relatively tectonically quiet period followed between 150 and 135 Ma in South China. From 135 Ma onward, the angle of convergence of the Izanagi plate changed from oblique to parallel to the coastline, resulting in continental extensional tectonics and reactivation of regional-scale NE-trending faults, such as the Tan-Lu fault. This widespread extension also promoted the development of NE-trending pull-apart basins and metamorphic core complexes, accompanied by volcanism and the formation of epithermal Cu–Au deposits, granite-related polymetallic Sn–(W) deposits and hydrothermal U deposits between 120 and 80 Ma (with a peak activity at 100–90 Ma). Content Type Journal Article Category Article Pages 1-28 DOI 10.1007/s00126-012-0446-z Authors Mao Jingwen, MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037 China Cheng Yanbo, Faculty of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083 China Chen Maohong, MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037 China Franco Pirajno, MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037 China Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    The Yuchiling Mo deposit is a recently discovered giant porphyry system in the East Qinling Mo belt, China. Its apparent causative intrusion, i.e., the Yuchiling granite porphyry, is the youngest intrusion (phase 4) of the Heyu multiphase granite batholith, which was emplaced between 143 and 135 Ma. New robust constraints on the formation of the Yuchiling porphyry Mo system are provided by combined zircon U–Pb, biotite 40 Ar/ 39 Ar, and molybdenite Re–Os dating. Zircon grains from the Mo-mineralized granite porphyry yield weighted 206 Pb/ 238 U age of 134.0 ± 1.4 Ma ( n  = 19, 2 σ error, MSWD = 0.30). Magmatic biotite from the same sample yield a 40 Ar/ 39 Ar plateau age of 135.1 ± 1.4 Ma (2 σ error), and an inverse isochron age of 135.6 ± 2.0 Ma ( n  = 7, 2 σ error, MSWD = 10.8), which are effectively coincident with the zircon U–Pb age within analytical error. Three pulses of mineralization can be deduced from the molybdenite Re–Os ages, namely: ∼141, ∼137, and ∼134 Ma, which agree well with the zircon U–Pb ages of granitic phases 1, 2, and the Yuchiling porphyry (phase 4), respectively. These well-constrained temporal correlations indicate that Mo mineralization was caused by pulses of granitic magmatism, and that the ore-forming magmatic-hydrothermal activity responsible for the Yuchiling porphyry Mo system lasted about 8 Ma. The Yuchiling Mo deposit represents a unique style of porphyry Mo system formed in a post-collision setting, and associated with F-rich, high-K calc-alkaline intrusions, which differ from convergent margin-associated porphyry Mo deposits. Content Type Journal Article Category Article Pages 1-20 DOI 10.1007/s00126-012-0441-4 Authors Nuo Li, Key Laboratory of Orogen and Crustal Evolution, Peking University, 5 Yiheyuan Road, Beijing, 100871 China Yan-Jing Chen, Key Laboratory of Orogen and Crustal Evolution, Peking University, 5 Yiheyuan Road, Beijing, 100871 China Franco Pirajno, Centre for Exploration Targeting, School of Earth and Environment, University of Western Australia, 35 Stirling Highway, Crawley, WA 6008, Australia Zhi-yong Ni, Key Laboratory of Orogen and Crustal Evolution, Peking University, 5 Yiheyuan Road, Beijing, 100871 China Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    Representing one of the largest known (estimated 〉5 Gt at 1 % Cu and 0.02 % Mo) porphyry system, the Río Blanco-Los Bronces deposit incorporates at least five hypabyssal intrusive and hydrothermal centres, extending for about 5 km from the Río Blanco and Los Bronces mines in the north, through the Don Luis mine, to the Sur Sur mine, La Americana and Los Sulfatos in the south. The new geochronology data, which now include data on different molybdenite vein types, confirm the U–Pb ages of the pre-mineralisation intrusions but slightly increase their age range from 8.8 to 8.2 Ma. The distinct magmatic pulses of the mineralisation-associated porphyritic intrusives (Late Porphyries) indicate an age interval instead of the previously suggested individual ages: the quartz monzonite porphyry ranges from 7.7 to 6.1 Ma (Sur Sur 5.74 ± 0.13 Ma), the feldspar porphyry shows an interval from 5.8 to 5.2 Ma and the Don Luis porphyry from 5.2 to 5.0 Ma. The new Re–Os data on distinct molybdenite vein types confirm the protracted history of Cu(–Mo) mineralisation, inferred previously. The vein development occurred at least from 5.94 to 4.50 Ma, indicating a time-span of 1.5 Ma for the hydrothermal activity. Hydrothermal minerals dated by the 40 Ar/ 39 Ar method are generally too young to record the age of early, high-temperature mineralisation. The majority of the 40 Ar/ 39 Ar data in the Río Blanco porphyry cluster record reheating by either the youngest member of the Late Porphyry suite or the post-mineralisation dacite or rhyolite plug formations at around 4.9–4.7 Ma. Content Type Journal Article Category Article Pages 1-23 DOI 10.1007/s00126-012-0412-9 Authors Katja Deckart, Departamento de Geología, Universidad de Chile, Plaza Ercilla 803, Casilla 12518 Santiago, Chile Alan H. Clark, Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada Patricio Cuadra, Corporación Nacional del Cobre de Chile, Divisíon Andina, Sta. Teresa 513, Los Andes, Chile Mark Fanning, Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description: Chusi Li and Edward M. Ripley (eds) Magmatic Ni–Cu and PGE deposits: geology, geochemistry, and genesis Content Type Journal Article Category Book Review Pages 1-2 DOI 10.1007/s00126-012-0418-3 Authors Christina Yan Wang, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou, China Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    Re–Os isotope compositions of mantle-derived magmas are highly sensitive to crustal contamination because the crust and mantle have very different Os isotope compositions. Crustal contamination may trigger S saturation and thus the formation of magmatic Ni–Cu–(PGE) sulfide deposits. The ∼287-Ma Kalatongke norite intrusion of NW China are hosted in carboniferous tuffaceous rocks and contain both disseminated and massive sulfide mineralization. The Re–Os isotope compositions in the intrusion are highly variable. Norite and massive sulfide ores have γ Os values ranging from +59 to +160 and a Re–Os isochron age of 239 ± 51 Ma, whereas disseminated sulfide ores have γ Os values from +117 to +198 and a Re–Os isochron age of 349 ± 34 Ma. The variability of Os isotope compositions can be explained as the emplacement of two distinct magma pulses. Massive sulfide ores and barren norite in the intrusion formed from the same magma pulse, whereas the disseminated sulfide ores with more radiogenic Os isotopes formed from another magma pulse which underwent different degrees of crustal contamination. Re–Os isotopes may not be suitable for dating sulfide-bearing intrusions that underwent variable degrees of crustal contamination to form magmatic sulfide deposits. Content Type Journal Article Category Letter Pages 1-8 DOI 10.1007/s00126-012-0414-7 Authors Jian-Feng Gao, Department of Earth Sciences, The University of Hong Kong, Hong Kong, China Mei-Fu Zhou, Department of Earth Sciences, The University of Hong Kong, Hong Kong, China Peter C. Lightfoot, Vale, Highway 17 West, Sudbury, ON P0M 1N0, Canada Wenjun Qu, National Research Center of Geoanalysis (NRCG), Chinese Academy of Geological Sciences, Beijing, China Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    The Mississippi Valley-type Pb-Zn deposits of the Pine Point district (Northwest Territories, Canada) are located close to the eastern edge of the present day Western Canadian Sedimentary Basin. The deposits are thought to have formed as the result of basin-wide fluid flow in the Presqu’ile Barrier, the host to the ore deposits. A laser ablation multi-collector inductively coupled plasma mass spectrometric study of 87 Sr/ 86 Sr ratios of ore-related dolomites from the N81 deposit at Pine Point indicates that at least two sources of Sr were present in the mineralizing system. One fluid has a range in Sr isotopic values from 0.07073 to 0.71200 and is interpreted to be derived from Middle Devonian seawater that interacted with clastic units in the basin. The second fluid has higher Sr isotopic values (up to 0.71520), similar to those found in some Canadian Shield brines, and is interpreted to represent an evaporated seawater-derived brine which has interacted with crystalline basement rocks. Reactivation of old structures in the basement may have provided a pathway for cross-formation fluid flow to the site of mineralization. The data suggest that the stratigraphic location of the Pine Point District, near the interface between the Western Canadian Sedimentary Basin and its basement, may have exerted a fundamental control on the formation of these deposits. Content Type Journal Article Category Letter Pages 1-6 DOI 10.1007/s00126-012-0435-2 Authors Paulina Gromek, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada Sarah A. Gleeson, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada Antonio Simonetti, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    Mineral supply is controlled by a feedback mechanism. When there is a shortage of a commodity in a market economy, prices will rise, triggering this mechanism. The expectation of high financial returns will encourage inventiveness and creativity in the quest for new solutions. On the supply side, for primary resources, the appropriate response is to cut losses in the mining process, to lower the cut-off grade, to improve recoveries in the beneficiation and smelting processes, to expand existing production facilities, and to discover and bring into production new deposits. For secondary resources, the key to increasing the supply lies in improving recycling rates by better technology, reprocessing lower-grade scrap which becomes economic because of increased prices, and reducing downgrading to optimize the usefulness of secondary materials. On the demand side, implementation of new and more efficient processes, development of substitution technologies, material savings, and the invention of entirely new technologies that fulfill the same function without the need of using the scarce and suddenly more expensive material are effective reactions to a price rise. The effectiveness of this self-regulating mechanism can be shown by examples of historical price peaks of metals, such as Mo, Co, and Ta, and the current rare earth elements peak. Concerning supply from secondary resources, a model is developed in order to determine how far the supply from this resource domain can be achieved and how the recycling rate is influenced by growth rate and lifetime. The feedback control cycle of mineral supply is influenced on the demand side by ever shorter life cycles, by products getting more complex with ever more elements involved in their production, and by an increase in element dispersion. All these factors have an immediate effect on the feasibility of sourcing raw materials from the technosphere. The supply side of primary materials is influenced by increasing lead times for new production and by relatively low flexibility in responding to changing demand. Content Type Journal Article Category Invited Paper Pages 1-17 DOI 10.1007/s00126-012-0437-0 Authors Friedrich-W. Wellmer, Neue Sachlichkeit 32, 30655 Hannover, Germany Manfred Dalheimer, Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598

Description:    Mesozoic mineral deposits in South China include world-class deposits of W, Sn and Sb and those that provide the major sources of Ta, Cu, Hg, As, Tl, Pb, Zn, Au and Ag for the entire country. These deposits can be classified into polymetallic hydrothermal systems closely related to felsic intrusive rocks (Sn–W –Mo granites, Cu porphyries, polymetallic and Fe skarns, and polymetallic vein deposits) and low-temperature hydrothermal systems with no direct connection to igneous activities (MVT deposits, epithermal Au and Sb deposits). Recent studies have shown that they formed in the Triassic (Indosinian), Jurassic–Cretaceous (Early Yanshanian), and Cretaceous (Late Yanshanian) stages. Indosinian deposits include major MVT (Pb–Zn–Ag) deposits and granite-related W–Sn deposits. Early Yanshanian deposits are low-temperature Sb–Au and high-temperature W–Sn and Cu porphyry types. Many Late Yanshanian deposits are low-temperature Au–As–Sb–Hg and U deposits, and also include high-temperature W–Sn polymetallic deposits. The formation of these deposits is linked with a specific tectonothermal evolution and igneous activities. This special issue brings together some of the latest information in eight papers that deal with the origins and tectonic environments of mineral deposits formed in these stages. We anticipate that this issue will stimulate more interests in these ore deposits in South China. Content Type Journal Article Category Article Pages 1-10 DOI 10.1007/s00126-012-0431-6 Authors Rui-Zhong Hu, State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China Mei-Fu Zhou, Department of Earth Sciences, The University of Hong Kong, Hong Kong, China Journal Mineralium Deposita Online ISSN 1432-1866 Print ISSN 0026-4598