Synchronous deposition of massive sulphide deposits in the Iberian Pyrite Belt: New data from Las Herrerías and La Torerera ore-bodies

Two small to medium sized massive sulphide deposits, Las Herrerías and La Torerera, located in the Iberian Pyrite Belt (IPB) are examined from a geological and palynostratigraphic perspective. The palynological assemblages are assignable to the Retispora lepidophyta–Verrucosisporites nitidus (LN) miospore Biozone (Latest Devonian: Latest Famennian/Strunian) of Western Europe. This age permits correlation with some of the main massive sulphide deposits dated so far in the region (viz., Tharsis, Aznalcóllar, Sotiel-Coronada or Neves-Corvo), and validates once again the hypothesis that a single mineralizing event was responsible for the genesis of most of the IPB’s massive sulphide deposits. The present study confirms that palynostratigraphy is an invaluable high-resolution biostratigraphic tool in the IPB, applicable to dating, correlation and ore-exploration.     

现代海底烟囱中流体包裹体的研究

大洋中脊的海底块状硫化物矿床是当前地球科学的一个热点。因为他不仅具有经济效益,而且可以直接观测到这些矿床的形成过程。这些矿床均有许多黑烟囱和白烟囱。在这些烟囱中成矿流体不断地流过,并同时沉淀出Cu,Pb,Zn硫化物和脉石矿物。本研究的样品是取自北纬21°N的太平洋洋脊中现代大洋海底的Zn(Cu)型硫化物烟囱。对这些烟囱的矿物共生组合进行研究发现其矿物组合相当简单,分硫化物和脉石矿物两种。硫化物中以其含量多少排列为闪锌矿,黄铁矿,黄铜矿和磁黄铁矿。脉石矿物以硬石膏为主,见少量重晶石。在烟囱中这些硫化物和脉石矿物的分布是有分带性的。从外到内为硬石膏带,黄铁矿带,闪锌矿带。闪锌矿带向里可见到少量黄铜矿和磁黄铜矿,及硬石膏,但它们尚未构成一个带。烟囱的中心常常是空的,因为是原来的热液通道。 发现两类流体包裹体:一类为水溶液相包裹体。另一类为CH_4的包裹体。其均一温度是从180～265℃。最外面的硬石膏带,均一温度从180～245℃(平均212℃)。黄铁矿带均一温度从185～260℃(平均218℃)。闪锌矿带均一温度从190～265℃(平均229℃)。从平均的均一温度看似乎从边上到中心从212—218—229℃向上升,说明一个趋势,中间的温度较高,边上的较低。成矿溶液的盐度与海水相差不大,但略大於海水     

Retrieval of Brown Carbon based on the aerosol complex refractive indices in the winter of Wuhan

Abstract

The impact of Brown Carbon (BrC) to aerosol light absorption has been paid more attention recently and there are a large number of studies showing that the influence of BrC on radiative forcing should not be ignored. BrC also acts as an important component of haze pollution which is occurring frequently in Wuhan, China. Therefore, it is essential to estimate their optical properties, composition, and mass concentration. Considering most haze pollution happens during the coldest time, we retrieved BrC columnar content during winter in Wuhan for the first time. Our method bases on the fact that BrC showed the strong spectral dependence on UV-light absorption. Using this method, we found that BrC makes up the small proportions of total aerosol volume (less than 10%). In the winter of 2011, we retrieved the daily-averaged columnar-integrated mass concentration of BrC on clear day is 4.353 mg/m² while that of haze day is 12.750 mg/m². According to the sensitivity study, we found that the results highly relied on the assumed aerosol refractive index. To reduce the uncertainty of this approach, we need to gain a better understanding of the temporal variability of the radiation absorbing components of these aerosols in the future.     

Coral Diseases in the Indo-Pacific: A First Record

Abstract. . The so-called "band" diseases of reef corals, the White Band Disease (WBD) and the Black Band Disease (BBD), were observed in the Red Sea and in the Philippines. Since they were previously known only from the western Atlantic, this is the first record for the Indo-Pacific region. WBD is neither infectious nor contagious and the pathogen is unknown. BBD is highly infectious and contagious and is caused by the cyanophyte Phormidium corallyticum. Susceptibility to WBD occurs throughout the order Scleractinia, but the effects of the disease are most severe among Acroporidae. Susceptibility to BBD seems to be restricted to Faviidae, with Platygyra and Goniastrea species the most heavily afflicted. WBD cannot be influenced by any parameter tested so far. BBD can be enhanced by light and by water eutrophication, and its advance can be stopped by antibiotics. An active WBD seems to be a precondition for the origin of BBD.     

Transport and fate of Danube Delta terrestrial organic matter in the Northwest Black Sea mixing zone

Within the framework of the European project EROS 21, a biogeochemical study of particles transported from the Danube Delta to the Northwestern Black Sea whose carbon cycle is dominated by riverine inputs was carried out in spring off the Sulina branch of the Danube Delta. The distribution of particulate organic carbon (POC), chlorophyll a (Chl a), C/N, and δ¹³C evidenced an omnipresent contribution of terrestrial organic matter throughout the study area together with a dilution of these inputs by freshwater and marine organisms. Four lipid series, n-alkanoic acids, n-alkanes, n-alkanols, and sterols were analyzed by gas chromatography and gas chromatography/mass spectrometry. Several signature compounds were selected to delineate dispersion of terrestrial organic carbon: (1) long-chain n-alkanoic acids in the range C₂₄–C₃₄, long-chain n-alkanes in the range C₂₅–C₃₅, long-chain n-alkanols in the range C₂₂–C₃₀, 24-ethylcholesta-5,22-dien-3β-ol (29Δ^5,22) and 24-ethylcholesterol (29Δ⁵) for vascular plant-derived material and (2) coprostanol (27Δ^0,5β) for faecal contamination associated with sewage effluents. A marked decrease was observed between the concentrations of different vascular plant markers characterizing the two end members: riverine at salinity 0.3 and marine at salinity 15.5. The decrease observed for marine/riverine end members (expressed as a function of organic carbon) varied in a large range, from 4% for n-alkanes to 18.6%, 20.4% and 24% for n-fatty acids, n-alkanols and sterols, respectively. These values reflect a combination of various processes: size-selective particle sedimentation, resuspension of different particle pools of different sizes and ages, and/or selective biological utilization. The multi-marker approach also suggested the liberation in the mixing zone of terrestrial moieties, tightly trapped in macromolecular structures of the riverine material. The greatest decrease for marine/riverine end members was observed for coprostanol (0.9%), underlining the efficiency of the mixing zone as a sink for sewage-derived carbon.     

Meiobenthos from an active methane seepage area in the NW Black Sea

Meiobenthos densities and higher taxon composition were studied in an active gas seepage area at depths from 182 to 252 m in the submarine Dnieper Canyon located in the northwestern part of the Black Sea. The meiobenthos was represented by Ciliata, Foraminifera, Nematoda, Polychaeta, Bivalvia, Gastropoda, Amphipoda, and Acarina. Also present in the sediment samples were juvenile stages of Copepoda and Cladocera which may be of planktonic origin. Nematoda and Foraminifera were the dominant groups. The abundance of the meiobenthos varied between 2397 and 52,593 ind.·m⁻². Maximum densities of Nematoda and Foraminifera were recorded in the upper sediment layer of a permanent H₂S zone at depths from 220 to 250 m. This dense concentration of meiobenthos was found in an area where intense methane seeps were covered by methane‐oxidizing microbial mats. Results suggest that methane and its microbial oxidation products are the factors responsible for the presence of a highly sulfidic and biologically productive zone characterized by specially adapted benthic groups. At the same time, an inverse correlation was found between meiofauna densities and methane concentrations in the uppermost sediment layers. The hypothesis is that the concentration of Nematoda and Foraminifera within the areas enriched with methane is an ecological compromise between the food requirements of these organisms and their adaptations to the toxic H₂S.     

A new Carboniferous coal/shale driven gas play in the Western Black Sea Region (Turkey)

The sedimentary sequence in the Western Black Sea region of Turkey both onshore and offshore offers many possibilities for different hydrocarbon plays. This study presents a new play, which considers Carboniferous coals and shales as source beds, Cretaceous sandstones as reservoirs and Cretaceous shales and marls as seal rocks. The evaluation of this play is performed using the petroleum system approach. Results suggest that the coals and shales have a good to very good source rock potential for gas, that the Cretaceous synrift sandstones are good reservoirs. On the other hand, the sealing efficiency of respective Cretaceous units is assumed to be sufficient based on their lithological (shales and carbonaceous marls) characteristics. Stratigraphic traps, which formed by transgression and by onlap on paleohighs, were sealed and potentially available at 97 million years (ma) before present. Structural traps related to Early Cretaceous extension were also sealed around 97 ma. On the contrary, traps formed by folding and thrusting during the Alpine orogeny only formed during the last 50 ma. The timing of gas generation and migration was determined by one and two-dimensional basin modeling in one well and along a cross-section. The modeling results indicated that during the period between 90 and 42 ma, large volumes of gas were generated from the Carboniferous source rocks. Comparison with the age of stratigraphic and structural traps showed that stratigraphic and normal fault traps were potentially available for the entire volume of generated gas and that the other structural traps associated with Alpine orogeny were available only for gas generated and/or re-migrated during the last 50 ma. The evaluation of this new play results in the conclusion, that the Western Black Sea region is worthy of further exploration for conventional accumulations of thermogenic gas.     

Chemical speciation of copper and zinc in surface waters of the western Black Sea

The chemical speciation of Cu and Zn was investigated by voltammetric titration methods in the surface waters (10 m) of the western Black Sea during an Istanbul–Sevastopol cruise conducted in November 1998. Supporting parameters (temperature (T), salinity (S), pH, alkalinity (Alk), suspended particulate matter (SPM) and dissolved and particulate ²³⁴Th) were obtained in order to distinguish hydrographic features against involvement of the metals in biogeochemical processes. In the Turkish continental slope region, the cruise track intersected a narrow vein of colder water originating on the western shelf. The core of this cold water vein was characterised by a relatively low salinity, higher specific alkalinity and higher metal (especially Cu) and metal-binding ligand concentrations.A very large portion of Cu (93–99.8%) and Zn (82–97%) was organically complexed. The degree of complexation was highest in shelf waters and lowest in the central gyre. Titration data for Cu were modelled by two classes of organic binding ligands characterised by (C_L1=3–12 nM, log K₁′=13.1–13.9) and (C_L2=20–70 nM, log K₂′=9.4–11.2). These ligands occurred mainly in the ‘dissolved’ phase, as defined by 0.4-μm filtration. The stronger Cu-binding ligand seemed to be produced in situ in response to Cu concentration, whereas the weaker Cu-binding ligand appeared to be derived from terrestrial sources and/or reducing shelf sediments. Titration results for Zn were generally represented by one class of ligands (C_L1=8–23 nM, log K₁′=9.4–10.2), which were almost uniformly distributed between the ‘dissolved’ (78±8%) and the particulate phase (22±8%). The concentration of these strong Zn-binding ligands showed a very good correlation with SPM (r²=0.64), which improved when the dissolved ligands alone were considered (r²=0.78). It is hypothesised that these ligands were produced in situ by the bacterial breakdown of particulate organic matter.     

Discovery of anomalous gallium enriched in stone coal: Significance,provenance and recommendations

Gallium (Ga) is a critical mineral that plays an irreplaceable role in consumer electronics, clean energy technologies and the aerospace industry. Nowadays competition for gallium resources at the national strategic level has begun to emerge, but gallium resources are unevenly distributed globally, and their presence is not guaranteed. New discoveries revealed an average gallium concentration of thirty-one samples from M₁, M₂, M₃ and M₄ stone coal-bearing seams of the Cambrian strata on South Qinling Orogenic Belt in central China is 157 mg/kg (9.98–747 mg/kg), which is 27.6-fold higher than the global hard coal average, as well as the existing association of Mo–V–U–Cd–Zn–Ba–Se–Mg–Ni–Cu enrichment. Ga average of these coal seams are 344 mg/kg (M₃, 44.5–747 mg/kg, n = 11), 270 mg/kg (M₄, 14.3–270 mg/kg, n = 5), 53.8 mg/kg (M₂, 22.6–75.4 mg/kg, n = 8) and 19.8 mg/kg (M₁, 9.98–34.9 mg/kg, n = 7) respectively, as well as the thickness of approximately 6, 12, 8, and 20 m, which be close to or exceed to the boundary grade standard (30 mg/kg) and minimum recoverable thickness (0.7 m) of gallium resources exploration. These findings indicate that the Cambrian stone coal deposits, especially in the middle and late Cambrian period, should be considered as promising alternative sources of gallium. The anomalous gallium-enriched sediments originated from a complex combination of hydrothermal fluids, original biomass and terrigenous materials. For the M₁ stone coal-bearing seams, gallium most likely occurred in the mode of GaAs, Ga_xIn_1-xAs and GaO(OH), while modes of gallium in the M₂ to M₄ seams is interrelated with the organic affinity and clay minerals. The crude reserve estimate of gallium resources in central China is approximately 10.06 × 10⁴ tons, corresponding to a super-large coal-hosted gallium ore deposit. The unique paleogeographic location and geological structure in central China resulted that this newly discovered deposit is a unique type of gallium-enriched deposit that has been discovered worldwide. These discoveries will provide the critical parameters when developing distinctive beneficiation processes and appropriate extraction procedures, as well as guidance and effective for future prospecting regions of gallium resources around the globe, involving a combination consider the distribution of regional deep–large fault zones and the middle to late Cambrian black rock series deposits.