Structural,lithological, and geochemical constraints on the dynamic magma plumbing system of the Jinchuan Ni–Cu sulfide deposit,NW China     

Xie-Yan?SongEmail author  Leonid?V.?Danyushevsky  Reid?R.?Keays  Lie-Meng?Chen  Yu-Shan?Wang  Yu-Long?Tian  Jia-Fei?Xiao 《Mineralium Deposita》2012,47(3):277-297

Eastern and western portions of the Jinchuan ultramafic intrusion have previously been interpreted as dismembered segments of a single elongate intrusion by late faults. However, the different stratigraphic sequences of the two portions indicate that they are originally two separate intrusions, referred to as Eastern and Western intrusions in this study. The Eastern intrusion is characterized by a concentric distribution of rock types with a core of sulfide dunite enveloped by lherzolite, whereas the Western intrusion is composed of the Upper and Lower units, interpreted as magmatic mega cycles with regular variations in lithology and chemistry. In the Western intrusion, the Upper unit consists of fine-grained dunite, lherzolite, and pyroxenite from its base to its top. The MgO contents decrease upward from the dunites (42–45 wt.%) to the lherzolites (36–41 wt.%), while Al₂O₃ and incompatible elements increase upward. In contrast, the Lower unit consists of coarse-grained dunites and lherzolites containing 37–40 and 28–35 wt.% MgO, respectively. Sharp contacts between the Upper and Lower units and fine-grained dunite xenoliths at the top of the Lower unit indicate that the Lower unit intruded along the base of the Upper unit. Disseminated and net-textured sulfides primarily occur in the Lower unit and comprise the no. 24 ore body. Very low S contents (<100 ppm) of the wall rocks at Jinchuan indicate that they were not the source of S causing sulfide immiscibility. Sulfide segregation more likely occurred in deep-seated magma chambers, and sulfides were deposited in the Western intrusion when sulfide-bearing magmas passed through the intrusion. In contrast, the Eastern intrusion was formed by injections of sulfide-free and sulfide-bearing olivine-crystal mushes, respectively, from another deep-seated staging magma chamber. The Eastern and Western intrusions and the deep-seated magma chambers comprise a complicated magma plumbing system at Jinchuan. Normal faults played a significant role in the formation of the magma plumbing system and provided pathways for the magmas.  相似文献   

The surface of Mercury from ground-based astronomical observations     

L. V. Ksanfomality 《Solar System Research》2008,42(6):451-472

Recent ground-based astronomical short-exposure observations of Mercury have yielded more than 50000 electronic pictures of the planet at different phases and different positions relative to the Earth. The work was fulfilled in several observatories. The use of available and newly developed processing methods applied to large volumes of electronic frames allowed the images of a considerable portion of Mercury’s surface to be synthesized. We present the images of the 90°–180°W, 215°–280°W, and 50°–90°W sectors containing, among others, the longitudes not covered by spacecraft imaging. Along with the listed images, we present the results of recent observations of Mercury carried out on November 20–24, 2006 during the morning elongation at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) (Nizhnii Arkhyz, Karachai-Circassia, the Caucasus). The 265°–350°W longitude sector of Mercury was observed. The observations were made under good weather conditions. Among the main tasks of the new observations was obtaining a complete view of the S Basin. Previously, this basin had been investigated in fragments only by the actual solar illumination conditions. During the period of November 20–24, 2006, the S Basin was on the sunlit side of the planet. The complete image of the basin was obtained from the processing of a large number of electronic frames. The appearance of the S Basin is compared with the data on its relief acquired with radar methods. In this longitude sector, a number of other unusual surface features were found; among them, are a huge “Medallion” crater and other formations. The results considered in the present and earlier published studies are compared with the Mariner 10 data (1974–1975) and with the data received from the Messenger spacecraft during its first flyby of the planet (January 2008).  相似文献   

A waveguide-based flexible CO2-laser heating system for diamond-anvil cell applications     

Alexander Kurnosov  Hauke Marquardt  Leonid Dubrovinsky  Vasily Potapkin 《Comptes Rendus Geoscience》2019,351(2-3):280-285

Fiber-based laser heating systems offer high flexibility and are increasingly used in high-pressure/high-temperature research. Previous fiber-based laser heating systems were based on lasers delivering radiation with 1-μm wavelength that show unfavorable heating characteristics for many sample materials. We report on the development and first experiments of a waveguide (fiber)-based CO₂-laser heating system that can be used in a flexible manner for high-temperature research and for high-pressure/temperature experiments when combined with diamond-anvil cells. The waveguide-based CO₂-laser heating system allows convenient heating of optically transparent samples without the need for adding an additional laser absorber. In a pilot experiment, the flexible heating system has been installed on a Brillouin scattering system to measure high-temperature sound-wave velocities in single-crystal MgO. The waveguide-based CO₂-laser heating system offers perspectives for a variety of scientific applications, most importantly those that require the use of synchrotron facilities where space is limited and flexible solutions are required.  相似文献   

Trace and minor elements in sphalerite: A LA-ICPMS study   总被引：18，自引：0，他引：18  

Nigel J. Cook  Cristiana L. Ciobanu  Allan Pring  William Skinner  Leonid Danyushevsky  Frank Melcher 《Geochimica et cosmochimica acta》2009,73(16):4761-4791

Sphalerite is an important host mineral for a wide range of minor and trace elements. We have used laser-ablation inductively coupled mass spectroscopy (LA-ICPMS) techniques to investigate the distribution of Ag, As, Bi, Cd, Co, Cu, Fe, Ga, Ge, In, Mn, Mo, Ni, Pb, Sb, Se, Sn and Tl in samples from 26 ore deposits, including specimens with wt.% levels of Mn, Cd, In, Sn and Hg. This technique provides accurate trace element data, confirming that Cd, Co, Ga, Ge, In, Mn, Sn, As and Tl are present in solid solution. The concentrations of most elements vary over several orders of magnitude between deposits and in some cases between single samples from a given deposit. Sphalerite is characterized by a specific range of Cd (typically 0.2-1.0 wt.%) in each deposit. Higher Cd concentrations are rare; spot analyses on samples from skarn at Baisoara (Romania) show up to 13.2 wt.% (Cd²⁺ ↔ Zn²⁺ substitution). The LA-ICPMS technique also allows for identification of other elements, notably Pb, Sb and Bi, mostly as micro-inclusions of minerals carrying those elements, and not as solid solution. Silver may occur both as solid solution and as micro-inclusions. Sphalerite can also incorporate minor amounts of As and Se, and possibly Au (e.g., Magura epithermal Au, Romania). Manganese enrichment (up to ∼4 wt.%) does not appear to enhance incorporation of other elements. Sphalerite from Toyoha (Japan) features superimposed zoning. Indium-sphalerite (up to 6.7 wt.% In) coexists with Sn-sphalerite (up to 2.3 wt.%). Indium concentration correlates with Cu, corroborating coupled (Cu⁺In³⁺) ↔ 2Zn²⁺ substitution. Tin, however, correlates with Ag, suggesting (2Ag⁺Sn⁴⁺) ↔ 3Zn²⁺ coupled substitution. Germanium-bearing sphalerite from Tres Marias (Mexico) contains several hundred ppm Ge, correlating with Fe. We see no evidence of coupled substitution for incorporation of Ge. Accordingly, we postulate that Ge may be present as Ge²⁺ rather than Ge⁴⁺. Trace element concentrations in different deposit types vary because fractionation of a given element into sphalerite is influenced by crystallization temperature, metal source and the amount of sphalerite in the ore. Epithermal and some skarn deposits have higher concentrations of most elements in solid solution. The presence of discrete minerals containing In, Ga, Ge, etc. also contribute to the observed variance in measured concentrations within sphalerite.  相似文献   

Early Ordovician brachiopods from south-west Wales     

L. Robin M. Cocks  Leonid E. Popov 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(6):677-690

The Early Ordovician brachiopods of south-west Wales (Pembrokeshire and Carmarthenshire) are identified, in most cases for the first time. That period is termed the local Arenig Stage in Britain, but it is now correlated with the Floian, Dapingian, and earlier half of the Darriwilian, which are more recently established international stages in the system of stratigraphical nomenclature. The rocks in south-west Wales were laid down as turbidites in a backarc basin which formed part of the margin of the relatively small independent microcontinent of Avalonia at that time. However, since the Rheic Ocean between Avalonia and the immense Gondwana continent was relatively narrow in the Arenig, the brachiopods reviewed here can be established to be part of the Mediterranean Province, which was also extensive in the higher-latitude sectors in and around Gondwana in the Early Ordovician. The 17 brachiopod species identified within the Arenig brachiopod faunas of south-west Wales are described, including the new species Aporthophyla prisca, Tritoechia bolohaulensis, Skenidoides pontyfennensis and Paurorthis? llangynogensis.  相似文献   

Some properties of the companions of KIC 8462852 (based on KEPLER data)     

L. V. Ksanfomality 《Astronomy Reports》2017,61(4):347-360

The properties of the object KIC 8462852 or its exoplanets, discovered in the KEPLERmission, remain unexplained. The hypotheses that the object is a swarm of cometary bodies, wreckage from a catastrophic collision of asteroids, or an exoplanet KIC 8462852b encounter serious difficulties, and even contradictions with Kepler’s laws, if the eclipsing object is taken to be a physical body revolving around the central star. The hypothetical orbit of KIC 8462852b does not correspond to the expectations for a Dyson sphere in terms of energetic and other requirements. The mass characteristics of the eclipsing object remain unknown. Material from Boyajian et al. (2015) and subsequent publications on this topic are used.  相似文献   

Water Flows and Pools on Mars     

Ksanfomality  L. V. 《Solar System Research》2003,37(5):397-413

There is increasing evidence that the nature of extended dark features on slopes of Martian craters and uplands is related to existing sources of liquid water located on these slopes and to confined water flows rather than to the movement of large masses of dry sand (dust) or rock falls. Images acquired by the Mars Global Surveyor Mars Orbiter Camera at spatial resolutions of a few meters per pixel make it possible to distinguish such objects. The availability of big reserves of ground ice on Mars and conditions for the local conversion of ice to the liquid phase is now universally accepted. Although the presence of liquid water on the Martian surface is usually thought to be impossible because of low pressures and low mean temperatures, there is a sufficient number of lowlands on Mars where pressure exceeds the critical value required for the existence of liquid water. The extended narrow gullies on slopes with tributaries were formed, as it is supposed, by water streams. The structure of gullies has an unusual appearance, reverse of that of mountain rivers on Earth: gullies are broad in the upper part of a slope, narrow downslope, end with a thin stream, and disappear at the valley or crater floor. Both tributaries and the major channel seem to be directed uphill. This paper provides a simple explanation of this apparent paradox. Under low-temperature conditions, the conversion of liquid water to the ice phase should be considered in dynamics: the water released by the source comes in contact with a cold ground, partly soaks in ground, and freezes, forming an ice bed along which the stream moves further and continues to interact with ground. The distance from the source at which water completely disappears depends on the initial temperature of the source, its abundance, and the ground temperature. The apparent paradox is explained by the interaction of a cooling stream with a very cold ground. As regards the side structures, they are not tributaries but branches, which rapidly freeze. This paper also shows that a high source debit and/or sufficiently high ambient temperature promote the formation on the valley floor of a small pond that accumulates water flows. The walls of this pond consist of frozen ground and ice. Objects that might be small water reservoirs are detected in some new images of Mars. High concentration of sources of groundwater in two equatorial regions of Mars may serve as a useful indication to the location of places promising for searching traces of life on this planet.  相似文献   

Evaluation of the Possibilities of the STV CCD Detector for the Observations of Planets     

Ksanfomality  L. V.  Dzhapiashvili  V. P.  Kakhiani  V. O.  Kvaratskhelia  O. I.  Korol'  A. N.  Mayer  A. K.  Petashvili  P. P. 《Solar System Research》2002,36(4):341-347

The results of planetary observations performed with a new CCD detector are presented. The available firmware for collecting a great number of electronic images and the high quantum efficiency of the employed CCD make it possible to observe objects the visibility of which is limited by the short duration of astronomical phenomena. Among such tasks are, for instance, the taking of a large number of images of Mercury by the short exposure method. With a high quantum efficiency of the light detector, short exposure makes it possible to appreciably reduce the blurring of astronomical images caused by the atmospheric instability. This study was performed at the Abastumani Astrophysical Observatory of the Republic of Georgia early in November 2001.  相似文献   

Venera 9 and 10: Thermal radiometry     

L.V. Ksanfomality 《Icarus》1980,41(1):36-64

New data about the top clouds of Venus were obtained during the radiometric experiment on-board the Venera 9 and Venera 10 orbiters. A diurnal component of the ir thermal radiation was determined for the latitude range ?40, +50°. The brightness temperature of radiation referred to the normal was measured; it was 244°K at night and 239°K at the subsolar point for the 7- to 13-, 17- to 30-μm bands. Minimum temperatures correspond to the meridian of local time 16.00^h and are 232°K. There is also a zone of lower temperatures in the region of local time 7.5^h. Absolute temperatures were measured with an accuracy of _?1.9°^+1.2°. Thermal radiation has no distinct latitudinal dependence but has a day-night asymmetry, with the night radiation flux exceeding that on the day side by 17%. The limb-darkening law for thermal radiation is rather complicated, depending on the time of day. There are at least two states of the radiating cloud cover: day and night. The extinction coefficient is close to 0.24 km^?1. The analysis shows that the source function of the medium is close to Planck's function. During the day the flux of thermal radiation is assumed to be weakened by an aerosol medium forming by photochemical processes. Comparison of experimental and calculated data yields a particle concentration in the radiating cloud cover of about 95 cm^?3. Experimental data and the results of ground-based measurements were used to determine the radiometric albedo of Venus, 0.79_?0.01^+0.02.  相似文献   

Resolved images of an unknown sector on the surface of Mercury     

L. V. Ksanfomality 《Astronomy Letters》2005,31(11):767-785

We took electronic photographs of Mercury on the side of the planet that was not photographed from the Mariner-10 spacecraft in 1973–1975 by the millisecond-exposure method in ground-based observations. Based on these photographs, we synthesized resolved images of the surface of unknown regions of the planet. The capabilities of the method are limited by the small angular size of the planetary disk (only 7.3 arcsec at average quadrature), specific difficulties of Mercury’s ground-based observations, their very limited duration, and the laboriousness of the subsequent computer-aided observational data processing. The millisecond-exposure method is complex, but a sufficient number of primary electronic photographs can be taken under good seeing conditions for the subsequent synthesis of Mercurian images with a resolution of no worse than the diffraction limit. A giant basin about 2000 km in diameter and other large structures are distinguished in the synthesized images of the planet. In the regions where radar data are available, these structures can be identified with previously found ones. In some measure, the synthesized images allow the relief of the longitude sector 210°–290° W to be reconstructed on Mercury. It can be asserted with caution that the large relief features are distributed asymmetrically over the surface of Mercury, much as observed on other terrestrial planets, the Moon, and many satellites of giant planets.  相似文献