Quantification of geodiversity and its loss   总被引：1，自引：0，他引：1  

Dmitry A. Ruban 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(3):326-333

Geodiversity, i.e., a diversity of geological heritage sites, can be quantified with an account of geosite types, type counterparts, and their ranks. Higher numbers of geosite types represented within a given territory and their higher ranks indicate a higher geodiversity. Two additional characteristics, namely geoabundance and georichness, allow measure of the quantity of geosites and the diversity-quantity relationship respectively. Geodiversity loss can be evaluated with an accounting of decreases in geosite type ranks linked to the damage of geosites. A calculation of relative and multi-dimensional geodiversity helps in quantitative assessment of the regional geological heritage.  相似文献   

Metasomatic alterations of olivine inclusions in the Budulan mesosiderite     

C. A. Lorenz  M. A. Nazarov  F. Brandstaetter  Th. Ntaflos 《Petrology》2010,18(5):461-470

Mesosiderites are thermal metamorphic breccias consisting of fragments of pyroxene-plagioclase rocks and FeNi metal. The silicate constituent of mesosiderites has a chemical and oxygen isotopic composition analogous to those of meteorites of the HED group: howardites, eucrites, and diogenites. The hypothesis currently most widely accepted for the genesis of mesosiderites is the impact mixing of the material of a differentiated asteroid and an iron meteorite. In contrast to many other classes of meteorites, mesosiderites exhibit no traces of metasomatic processes. The Budulan mesosiderite is the first meteorite of this type in which traces of metasomatism under the effect of an anhydrous fluid were detected. The metasomatic alterations are manifested as chemical zoning of olivine, aggregates of secondary minerals, and the mobilization and redeposition of iron and nickel in the form of metals and sulfides. These alterations were most probably caused by a reaction of olivine with S- and/or CO-bearing gases of endogenic or supergenic provenance. Traces of such metasomatic alterations were previously found in some meteorites and lunar rocks, and these processes could likely play a certain role in the differentiation of chondritic bodies.  相似文献   

Basaltic micrometeorites from the Novaya Zemlya glacier     

Dmitry D. BADJUKOV  Franz BRANDSTÄTTER  Jouko RAITALA  Gero KURAT 《Meteoritics & planetary science》2010,45(9):1502-1512

Abstract– A large number of micrometeorites (MMs) was recovered from glacier deposits located at the north‐eastern passive margin of the Novaya Zemlya glacier sheet. Melted, scoriaceous, and unmelted micrometeorites (UMMs) are present. Unmelted micrometeorites are dominated mostly by chondritic matter, but also a few achondritic MMs are present. Here we report the discovery of four UMMs that, according to their texture, mineralogy, and chemistry, are identified as basaltic breccias. Mineral chemistry and Fe/Mn ratios of two basaltic micrometeorites indicate a possible relationship with eucrites and/or mesosiderites, whereas two others seem to have parents, which appear not to be present in our meteorite collections. The basaltic breccia UMMs constitute 0.5% of the total population of the Novaya Zemlya MM suite. This content should be lowered to 0.25% because the Novaya Zemlya MM collection appears to be biased with carbonaceous UMMs being underrepresented.  相似文献   

WSO-UV progress and expectations     

Boris Shustov  Ana I. Gómez de Castro  Mikhail Sachkov  Alexander Moisheev  Evgeny Kanev  Javier López-Santiago  Oleg Malkov  Dmitry Nasonov  G. Belén Perea  Néstor Sánchez  Igor Savanov  Andrey Shugarov  Sergey Sichevskiy  Oleg Vlasenko  Javier Yañez 《Astrophysics and Space Science》2014,354(1):155-161

The World Space Observatory Ultraviolet (WSO-UV) is the space mission that will grant access to the ultraviolet (UV) range in the post Hubble epoch. WSO-UV is equipped with instrumentation for imaging and spectroscopy and it is fully devoted to UV astronomy. In this article, we outline the WSO-UV mission model and present the current status of the project.  相似文献   

Cosmological evolution of statistical system of scalar charged particles     

Yurii Ignat’ev  Alexander Agathonov  Mikhail Mikhailov  Dmitry Ignatyev 《Astrophysics and Space Science》2015,357(1):1-21

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Multi-frequency studies of the non-stationary radiation of the blazar 3C 454.3     

A. E. Vol’vach  L. N. Vol’vach  A. M. Kut’kin  M. G. Larionov  M. Villata  K. M. Panteri  A. Lahteenmaki  M. Tornikoski  P. Savolainen  G. Tammi  A. F. Aller  H. D. Aller  S. G. Sergeev  V. T. Doroshenko  Yu. S. Efimov  S. A. Klimanov  S. V. Nazarov  G. V. Borman  A. B. Pushkarev  V. I. Zhdanov  E. V. Fedorova  I. B. Vavilova  N. G. Chesnok 《Astronomy Reports》2011,55(7):608-615

Long-term monitoring data at five radio frequencies from 4.8 to 37 GHz obtained at the Crimean Astrophysical Observatory, Metsahovi Radio Observatory of Aalto University, and the University of Michigan Radio Astronomy Observatory are used to analyze variations of the flux of the Active Galactic Nucleus (AGN) 3C 454.3. The dynamical characteristics of the three latest powerful flares from 2004 to 2010 are analyzed in detail. Observations in the gamma-ray (0.1–300 GeV), X-ray (2–10 kev, 15–50 keV), and optical are also used. Delays in the development of flares at different frequencies are derived. An empirical frequency dependence for the delays of flares from the gamma-ray to the radio is determined, which can be fit using a logarithmic low and remains the same from flare to flare. The physical characteristics of the central region of the AGN 3C 454.3 are used to estimate the size of its Strömgren sphere, taking into account the relevant mechanisms for heating and cooling the medium, as well as the adopted laws for the variation of the density and temperature with distance from the source of ionization. A model for the location of the radiation regions in the jet at various frequency ranges during the development of flares is proposed.  相似文献   

Lochkovian (earliest Devonian) transgressions and regressions along the “Tethyan” margin of Gondwana: A review of lithostratigraphical data     

Dmitry A. Ruban 《Gondwana Research》2011,20(4):739-744

Global sea-level rise and consequent regional transgressions are hypothesized at the beginning of the Devonian. A brief review of lithostratigraphical data available from three regions of the “Tethyan” margin of Gondwana, namely Northern Africa, Arabia, and the Tethys Himalaya, suggests that all of them were characterized by a regressive setting in the Lochkovian. In contrast, data from some terranes of the Greater Galatian Superterrane provide evidence of early Lochkovian transgression. The regressive setting documented on the 'Tethyan' margin of Gondwana differs from the transgressive–regressive cycles of Euramerica and the norm of global sea-level rise followed by a highstand. Only regional tectonic processes including those linked with dynamic topography could explain these differences. These processes may have been associated with syn-rift uplift preceding the opening of the Palaeo-Tethys Ocean, mantle uplift at the supercontinent margin, or the Eo-Variscan orogenic phase.  相似文献   

Mode enslavement in a two-layer stellar dynamo     

David Moss  Dmitry Sokoloff 《Monthly notices of the Royal Astronomical Society》2007,377(4):1597-1604

We consider a conventional stellar  α²ω  -dynamo with dynamo generators localized in two spherical shells separated by a passive layer. The signs of the α-effect as well as rotational shear in the dynamo active layers can be chosen to give dynamo waves that propagate in opposite directions (poleward and equatorward) if the layers are considered separately in the framework of the Parker migratory dynamo. In a sequence of numerical experiments we show that the variety of dynamo-generated magnetic configurations in the system under discussion is quite rich. We identify the possibility of almost independent dynamo waves existing in the two layers as well as enslavement of one layer by the other, and of activity waves generated by a joint action of the two layers. We suggest some qualitative explanations of the behaviour and discuss also the limited nature of these explanations. This variety of phenomena suggests previously underexploited freedoms to understand how predictions of dynamo theory may accommodate the observed solar and stellar activity phenomenology.  相似文献   

Solar Activity Record from Archeomagnetic Data     

Dmitry Volobuev 《Solar physics》2004,224(1-2):387-392

Each of the available solar activity (SA) proxy data (historical notes, radio nuclides ¹⁴C and ¹⁰Be production) are contaminated by their specific noise factors. So, any additional proxy with its independent noise factors will essentially increase the accuracy of composite SA restorations. It is proposed here that archaeomagnetic measurements 95% confidence interval (α₉₅) may serve as new proxy for the SA estimation in the past. This proxy is compared with other available proxies during the years 1500–2000.  相似文献   

KREEPy lunar meteorite Dhofar 287A: A new lunar mare basalt     

Mahesh Anand  Lawrence A. Taylor  Kula C. Misra  Svetlana I. Demidova  Mikhail A. Nazarov 《Meteoritics & planetary science》2003,38(4):485-499

Abstract— Dhofar 287 (Dho 287) is a new lunar meteorite, found in Oman on January 14, 2001. The main portion of this meteorite (Dho 287A) consists of a mare basalt, while a smaller portion of breccia (Dho 287B) is attached on the side. Dho 287A is only the fourth crystalline mare basalt meteorite found on Earth to date and is the subject of the present study. The basalt consists mainly of phenocrysts of olivine and pyroxene set in a finer‐grained matrix, which is composed of elongated pyroxene and plagioclase crystals radiating from a common nucleii. The majority of olivine and pyroxene grains are zoned, from core to rim, in terms of Fe and Mg. Accessory minerals include ilmenite, chromite, ulvöspinel, troilite, and FeNi metal. Chromite is invariably mantled by ulvöspinel. This rock is unusually rich in late‐stage mesostasis, composed largely of fayalite, Si‐K‐Ba‐rich glass, fluorapatite, and whitlockite. In texture and mineralogy, Dho 287A is a low‐Ti mare basalt, with similarities to Apollo 12 (A‐12) and Apollo 15 (A‐15) basalts. However, all plagioclase is now present as maskelynite, and its composition is atypical for known low‐Ti mare basalts. The Fe to Mn ratios of olivine and pyroxene, the presence of FeNi metal, and the bulk‐rock oxygen isotopic ratios, along with several other petrological features, are evidence for the lunar origin for this meteorite. Whole‐rock composition further confirms the similarity of Dho 287A with A‐12 and A‐15 samples but requires possible KREEP assimilation to account for its rare‐earth‐element (REE) contents. Cooling‐rate estimates, based on Fo zonation in olivine, yield values of 0.2–0.8°C/hr for the lava, typical for the center of a 10–20 m thick flow. The recalculated major‐element concentrations, after removing 10–15% modal olivine, are comparable to typical A‐15 mare basalts. Crystallization modeling of the recalculated Dho 287A bulk‐composition yields a reasonable fit between predicted and observed mineral abundances and compositions.  相似文献