Bladed Texture and Exploration Implications. A Case Study from the Kuklitsa Deposit,Krumovgrad Goldfield,SE Bulgaria     

Marinova  Irina 《Geology of Ore Deposits》2019,61(2):185-197

This study demonstrates that the bladed texture, which is common in epithermal, low-sulfidation (adularia-sericite) precious metal deposits, can serves as exploration vector towards precious metal mineralization. The paper presents two styles of bladed texture in the Kuklitsa gold deposit (Krumovgrad goldfield, SE Bulgaria) observed at both different altitude and lateral position in respect to regional low-angle detachment fault. The first style has formed as a crackle breccia just above the detachment fault where bladed texture consists of 10–20 vol % pseudorhombic adularia, 90-80 vol % quartz, scarce pyrite, and electrum, which is often observed under optical microscope. The second style is present in steep veins which fill listric faults of sharp tectonic contacts. It is developed at a higher level relative to the detachment fault. Bladed texture there consists of 1–2 vol % pseudorhombic adularia, 99-98 vol % quartz, and scarce both electrum and pyrite. Electrum of the two styles of bladed texture comprises only gold and silver but in different proportions with a higher gold content for the first style: fineness of 765, on average, for the first style vs. fineness of 692 for the second one. In this way, it is found that the adularia abundance correlates positively with the electrum one and negatively with the quartz abundance. The author uses the proportions of adularia, quartz and electrum, the fineness of electrum, and the relative distance to the detachment fault to conclude that the first style of bladed texture has been formed at higher temperature relative to the second style. The author infers that the first style is promising for mineralization of higher grade. Methods used comprise field observations and sampling, optical and electron microscopy, powder X-ray diffraction and electron microprobe analysis.

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A New Interlaboratory Characterisation of Silicon,Rare Earth Elements and Twenty‐Two Other Trace Element Concentrations in the Natural River Water Certified Reference Material SLRS‐6 (NRC‐CNRC)     

Delphine Yeghicheyan  Dominique Aubert  Martine Bouhnik‐Le Coz  Jrme Chmeleff  Sophie Delpoux  Irina Djouraev  Guy Granier  Franois Lacan  Jean‐Luc Piro  Tristan Rousseau  Christophe Cloquet  Aurlie Marquet  Christophe Menniti  Catherine Pradoux  Rmi Freydier  Emmanoel Vieira da Silva‐Filho  Krzysztof Suchorski 《Geostandards and Geoanalytical Research》2019,43(3):475-496

The natural river water reference material SLRS‐6 (NRC‐CNRC) is the newest batch of a quality control material routinely used in many international environmental laboratories. This work presents a nine‐laboratory compilation of measurements of major and trace element concentrations and their related uncertainties, unavailable in the NRC‐CNRC certificate (B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Y, Zr and REEs). Measurements were mostly made using inductively coupled plasma‐mass spectrometry. The results are compared with equivalent data for the last batch of the material, SLRS‐5, measured simultaneously with SLRS‐6 in this study. In general, very low concentrations, close to the quantification limits, were found in the new batch. The Sr isotopic ratio is also reported.  相似文献   

Groundwater of the crystalline basement in the eastern part of the East-European Platform     

Rafael L. Ibragimov  Irina N. Plotnikova 《Journal of Geochemical Exploration》2009

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Mid-Miocene thermal impact on the lithosphere by sub-lithospheric convective mantle material: Transition from high- to moderate-Mg magmatism beneath Vitim Plateau,Siberia     

Irina Chuvashova  Sergei Rasskazov  Tatyana Yasnygina 《地学前缘(英文版)》2017,8(4):753-774

High-Mg lavas are characteristic of the mid-Miocene volcanism in Inner Asia.In the Vitim Plateau,small volume high-Mg volcanics erupted at 16-14 Ma.and were followed with voluminous moderate-Mg lavas at 14-13 Ma.In the former unit,we have recorded a sequence of(1) initial basaltic melts,contaminated by crustal material,(2) uncontaminated high-Mg basanites and basalts of transitional(K-Na-K) compositions,and(3) picrobasalts and basalts of K series;in the latter unit a sequence of(1) initial basalts and basaltic andesites of transitional(Na-K-Na) compositions and(2) basalts and trachybasalts of K-Na series.From pressure estimation,we infer that the high-Mg melts were derived from the sublithospheric mantle as deep as 150 km,unlike the moderate-Mg melts that were produced at the shallow mantle.The 14-13 Ma rock sequence shows that initial melts equilibrated in a garnet-free mantle source with subsequently reduced degree of melting garnet-bearing material.No melting of relatively depleted lithospheric material,evidenced by mantle xenoliths,was involved in melting,however.We suggest that the studied transition from high-to moderate-Mg magmatism was due to the mid-Miocene thermal impact on the lithosphere by hot sub-lithospheric mantle material from the Transbaikalian low-velocity(melting) domain that had a potential temperature as high as 1510℃.This thermal impact triggered rifting in the lithosphere of the Baikal Rift Zone.  相似文献   

Biological reduction of chlorinated solvents: Batch-scale geochemical modeling     

Irina Kouznetsova  Xiaomin Mao  Clare Robinson  D.A. Barry  Jason I. Gerhard  Perry L. McCarty 《Advances in water resources》2010

Simulation of biodegradation of chlorinated solvents in dense non-aqueous phase liquid (DNAPL) source zones requires a model that accounts for the complexity of processes involved and that is consistent with available laboratory studies. This paper describes such a comprehensive modeling framework that includes microbially mediated degradation processes, microbial population growth and decay, geochemical reactions, as well as interphase mass transfer processes such as DNAPL dissolution, gas formation and mineral precipitation/dissolution. All these processes can be in equilibrium or kinetically controlled. A batch modeling example was presented where the degradation of trichloroethene (TCE) and its byproducts and concomitant reactions (e.g., electron donor fermentation, sulfate reduction, pH buffering by calcite dissolution) were simulated. Local and global sensitivity analysis techniques were applied to delineate the dominant model parameters and processes. Sensitivity analysis indicated that accurate values for parameters related to dichloroethene (DCE) and vinyl chloride (VC) degradation (i.e., DCE and VC maximum utilization rates, yield due to DCE utilization, decay rate for DCE/VC dechlorinators) are important for prediction of the overall dechlorination time. These parameters influence the maximum growth rate of the DCE and VC dechlorinating microorganisms and, thus, the time required for a small initial population to reach a sufficient concentration to significantly affect the overall rate of dechlorination. Self-inhibition of chlorinated ethenes at high concentrations and natural buffering provided by the sediment were also shown to significantly influence the dechlorination time. Furthermore, the analysis indicated that the rates of the competing, nonchlorinated electron-accepting processes relative to the dechlorination kinetics also affect the overall dechlorination time. Results demonstrated that the model developed is a flexible research tool that is able to provide valuable insight into the fundamental processes and their complex interactions during bioremediation of chlorinated ethenes in DNAPL source zones.  相似文献   

Great Silk Road on the Territory of Kazakhstan: From Past to Future     

Akhmetkal MEDEU  Maulken ASKAROVA  Roman PLOKHIKH  Irina SKORINTSEVA  Aruzhan BEKKULIYEVA 《资源与生态学报(英文版)》2015,6(2):114-118

The Great Silk Road is a trade route linking the East and West which gave impetus to the development of ancient society, and Kazakhstan is the heart of the trade route. At the initial stage, intensive transaction of goods took place between the West and East through The Great Silk Road. This paper reviewed the history of development of the Silk Road and suggested that today to construct the "New Silk Road", Kazakhstan should face many issues, and take many steps to become a Eurasian hub through taking full of advantages. Above all, developing mechanisms of integration and sustainable development is our urgent need.  相似文献   

Strontium stable isotopes fractionate in the soil environments?   总被引：1，自引：0，他引：1  

Ludwik Halicz  Irina Segal  Noa Fruchter  Mordechai Stein  Boaz Lazar   《Earth and Planetary Science Letters》2008,272(1-2):406-411

This study shows that the stable isotopic composition of strontium (the ⁸⁸Sr/⁸⁶Sr ratio expressed as δ^88/86Sr value relative to the NBS987 standard) varies significantly in sedimentary terrestrial environments. The abundances of ⁸⁶Sr, ⁸⁸Sr isotopes were analyzed by MC-ICP-MS “Nu Plasma”. All studied rocks and waters show δ^88/86Sr values that are distinctly different from the measured NBS987 standard (yielding 0.01 ± 0.05‰, all errors are reported as 2σ). Modern corals from the northern Gulf of Aqaba, Red Sea yielded significantly different value than seawater (δ^88/86Sr = 0.22 ± 0.07‰, compared to 0.35 ± 0.06‰, respectively), in an excellent correlation with the δ^88/86Sr analyses reported by Fietzke and Eisenhauer [Fietzke, J., Eisenhauer, A., 2006. Determination of temperature-dependent stable strontium isotopes (⁸⁸Sr/⁸⁶Sr) fractionation via bracketing standard MC-ICP-MS. Geochm. Geophys. Geosyst. 7 (no. 8)] on other coral samples. All carbonate samples that originated in the marine environment: corals (porites and acropora from the northern Gulf of Aqaba); Cretaceous limestone and runoff from the Judea Mountains as well as lacustrine evaporitic aragonite (Dead Sea); and Red Sea and Atlantic seawater yield an average δ^88/86Sr value of 0.26 ± 0.1‰. On the other hand, secondary materials (products of chemical weathering) from the terrestrial environment of the Judea Mountain such as terra rossa soil and speleothem calcite (that derives its Sr from the above-lying soil) yielded significantly lower δ^88/86Sr value of − 0.17 ± 0.06‰. This indicates that strontium isotopes fractionate in the soil environment calling for a possible development of strontium isotopes as a tracer for processes of chemical weathering and pedogenesis.  相似文献   

Quantifying sediment storage on the floodplains outside levees along the lower Yellow River during the years 1580–1849     

Yunzhen Chen  Irina Overeem  Albert J. Kettner  Shu Gao  James P. M. Syvitski  Yuanjian Wang 《地球表面变化过程与地形》2019,44(2):581-594

The lower Yellow River channel was maintained by artificial levees between 1580 and 1849. During this period, 280 levee breaches occurred. To estimate sediment storage on the floodplains outside the levees, a regression model with a decadal time step was developed to calculate the outflow ratio for the years when levee breaching occurred. Uncertainty analysis was used to identify the likely outflow ratio. Key variables of the model include annual water discharge, a proxy for levee conditions, and potential bankfull discharge of the channel before flood season. Uncertainty analysis reveals an outflow ratio of 0.35–0.56. We estimate that during this period, 18.8–30.1% of the total ~312 Gt of sediment load was deposited on the floodplains outside the levees. Human-accelerated erosion in the Loess Plateau caused a 4-fold increase in sediment delivery to the lower Yellow River, which could not be accommodated by channel morphodynamic changes. As a result, 21.2–27.5% of the total sediment load was deposited within the levees, creating a super-elevated channel bed that facilitated an uncommonly high breach outflow ratio. Hence, the factor of a large super-elevation relative to the mean main channel depth should be considered when designing diversions to restore floodplains. © 2018 John Wiley & Sons, Ltd.  相似文献   

Comparison of Dispersive and Nondispersive Models for Wave Run-Up on a Beach     

Abdalazeez  A.  Didenkulova  I. I.  Dutykh  D.  Denissenko  P. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(5):494-501

Izvestiya, Atmospheric and Oceanic Physics - The applicability of dispersive and nondispersive wave models for describing long-wave propagation and run-up on a beach in the case of composite bottom...  相似文献   

Winter distribution of euphausiids (Euphausiacea) in the Barents Sea (2000–2005)     

Natalia G. Zhukova  Valentina N. Nesterova  Irina P. Prokopchuk  Galina B. Rudneva 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):1959

The purpose of the study is to analyze the state of the Barents Sea euphausiids populations in the warm period (2000–2005) based on the study of their structure dynamics and distribution under the influence of abiotic and biotic factors. For estimation of their aggregations in the bottom layer, the traditional method was used with the help of the modified egg net (0.2 m² opening area, 564 μm mesh size). The net is used for collecting euphausiids in the autumn–winter period when their activity is reduced, which results in high-catch efficiency. The findings confirmed the major formation patterns of the euphausiids species composition associated with climate change in the Arctic basin. As before, in the warm years, one can see a clear-cut differentiation of space distribution of the dominant euphausiids Thysanoessa genus with localization of the more thermophilic Thysanoessa inermis in the north-west Barents Sea and Thysanoessa raschii in the east. The major euphausiids aggregations are formed of these species. In 2004, the first data of euphausiids distribution in the northern Barents Sea (77–79°N) were obtained, and demonstrated extremely high concentrations of T. inermis in this area, with the biomass as high as 1.7–2.4 g m⁻² in terms of dry weight. These data have improved our knowledge of the distribution and euphausiids abundance during periods of elevated sea-water temperatures in the Barents Sea. The oceanic Atlantic species were found to increase in abundance due to elevated advection to the Barents Sea during the study period. Thus, after nearly a 30-year-long absence of the moderate subtropical Nematoscelis megalops in the Barents Sea, they were found again in 2003–2005. However in comparison with 1960, the north-east border of its distribution considerably shifted to 73°50′N 50°22′E. The portion of Meganyctiphanes norvegica also varied considerably—from 10% to 20% of the total euphausiids population in the warm 1950s–1960s almost to complete disappearing in 1970–1990s. The peak of this species’ occurrence (18–26%) took place in the beginning of warm period (1999–2000) after a succession of cold years. The subsequent reduction of the relative abundance of M. norvegica to 7% might have been mostly caused by fish predation during a period of low population densities of capelin. This high predation pressure may therefore have been mediated both by other pelagic fishes (i.e. herring, blue whiting, polar cod) but also by demersal fishes such as cod and haddock. Similar sharp fluctuations in the capelin stock (the major consumer of euphausiids) created marked perturbations in the food web in the Barents Sea in the middle 1980s and the early 1990s.  相似文献