Suture zones of the Urals as integral prospective ore-bearing tectonic structures

Rift-related (1.2 Ga) and collision (380–240 Ma) suture zones of the Urals are described. The riftrelated suture zones comprise an ultramafic-gabbro complex with titanomagnetite mineralization, an ultramafic complex with chromite mineralization, and a complex of alkali granitoids with rare-metal (including REE) mineralization accompanied by K-feldspathites, albitites, and calcite metasomatic rocks. The collision suture zones are distinguished by early collision granitoids specialized for tungsten (scheelite) and gold, as well as by raremetal granites and such derivatives of them as pegmatite and greisen with rare-metal and colored-stone mineralization. The suture zones are characterized by long-term (up to 80 Ma or more) continuous-discontinuous periods of ore deposition; heterogeneous sources of ore matter and ore-bearing fluids; a polyelemental composition of lithogeochemical halos and an integral mineral composition of altered wall rocks; and the occurrence of mafic, intermediate, and felsic dikes at large gold deposits, as well as wide variations in PT parameters of the ore-forming process: T = 620?150°C and P = 3.2?0.6 kbar. Collision played a dual role in ore formation. On the one hand, collision led to deformation and metamorphism of precollision massive sulfide deposits and, to a lesser degree, Au-bearing Fe and Cu skarn and porphyry copper deposits, and, on the other hand, to the formation of new gold, rare-metal, quartz, colored-stone, talc, muscovite, and noble serpentine deposits. As a rule, this polygenetic mineralization differs in age and is related to collision volcanic and plutonic complexes. This diversity can be a good basis for metallogenic analysis, forecasting, and prospecting of various metallic deposits and industrial minerals. Polygenetic mineralization of various age known in suture zones is accompanied by integral lithogeochemical and metasomatic halos characterized by a continuous-discontinuous history. The complexity of ore mineralization and often nonlinear metallogeny increase the practical value of suture zones.     

Estimates of uncertainty in the prediction of past climatic variables

Fitting a regression line to a set of measurements to investigate the relationship between a proxy estimate of past climate and known climatic parameters is a routine procedure. It is generally accepted that the higher the correlation between parameters, the more reliable the reconstruction. However, there is a lack of published work upon what correlation is the minimum acceptable value. Simulated data was used to demonstrate that the relationship between proxy values and the climatic data are adversely affected by falling correlation, to the point where, in a training set consisting of 100 pairs of temperature and tree-ring proxies, the mean 95% confidence interval width for the reconstructed temperature exceeds the total range of temperatures in the training set at or below r = 0.65. This correlation is typical of that used in many climate-proxy reconstructions, and it suggests that understanding of past climate variability may be somewhat constrained.     

Permafrost features as evidence of climatic change

Permafrost features indicate certain upper limits for annual air and ground temperatures, with the air temperatures being usually the lower because of insulating snow and vegetation. The following features generally imply mean annual air temperatures no higher than those indicated and commonly lower: permafrost itself, large sorted forms of patterned ground, palsas, and rock glaciers, 0°C; ice-wedge polygons and well-developed soil-wedge polygons, ?5°C; open-system pingos, ?2°C; closed system pingos, ?6°C; the implication of cryoplanation terraces remains to be established, with estimates ranging from near 0° to ?12°C.Use of fossil permafrost features as temperature indicators is complicated by problems of correct identification and dating, soil type, and local and regional environmental variables such as precipitation and vegetation. Nevertheless the fact that certain maximum paleotemperatures can be reasonably established in places warrants expanded research in former periglacial areas to evaluate temperature increases to the present. The majority of determinations in Europe, where most of the work has been done to date, indicate minimum air temperature increases of 13°–18° since the maximum of the last glaciation.     

Turbulent transport of atmospheric aerosols and formation of large-scale structures

Turbulent transport of aerosols and droplets in a random velocity field with a finite correlation time is studied. We derived a mean-field equation and an equation for the second moment for a number density of aerosols. The finite correlation time of random velocity field results in the appearance of the high-order spatial derivatives in these equations. The finite correlation time and compressibility of the velocity field can cause a depletion of turbulent diffusion and a modification of an effective mean drift velocity. The coefficient of turbulent diffusion in the vertical direction can be depleted by 25 % due to the finite correlation time of a turbulent velocity field. The latter result is in compliance with the known anisotropy of the coefficient of turbulent diffusion in the atmosphere. The effective mean drift velocity is caused by a compressibility of particles velocity field and results in formation of large-scale inhomogeneities in spatial distribution of aerosols in the vicinity of the atmospheric temperature inversion. Results obtained by Saffman (1960) for the effect of molecular diffusivity in turbulent diffusion are generalized for the case of compressible and anisotropic random velocity field. A mechanism of formation of small-scale inhomogeneities in particles spatial distribution is also discussed. This mechanism is associated with an excitation of a small-scale instability of the second moment of number density of particles. The obtained results are important in the analysis of various atmospheric phenomena, e.g., atmospheric aerosols, droplets and smog formation.     

Tree-ring growth curves as sources of climatic information

Regional growth curves (RGCs) have been recently used to provide a new basis for removing nonclimatic trend from tree-ring data. Here we propose a different use for RGCs and explore their properties along two transects, one meridional and the other elevational. RGCs consisting of mean ring width plotted against cambial age were developed for larch samples from 34 sites along a meridional transect (55-72°N) in central Siberia, and for 24 sites on an elevational gradient (1120 and 2350 m a.s.l.) in Tuva and neighboring Mongolia at approximately 51°N. There are systematic gradients of the parameters of the RGCs, such as I₀-maximum tree-ring width near pith, and I_min, the asymptotic value of tree-ring width in old trees. They are smaller at higher latitude and elevation. Annual mean temperature and mean May-September temperature are highly correlated with latitude here, and hence RGC parameters are correlated with these climatic variables. Correlations with precipitation are more complex, and contradictory between meridional and elevational transects. The presence of a similar gradient in the elevational transect is consistent with temperature being the causal factor for both gradients, rather than, for example, latitude-dependent patterns of seasonal photoperiod change. Taking ring measurements from collections of relict and subfossil wood, the RGC-latitude and RGC-temperature relationships are used to estimate paleo-temperatures on centennial time scales. These estimates are consistent with earlier “traditional” dendroclimatic approaches, and with independent information on the northern extent of forest growth in the early mid-Holocene. It may be possible to use this same approach to make estimates of century-scale paleo-temperatures in other regions where abundant relict wood is present.     

Ptygmatic structures: an analysis and review

Buckling of an isolated elastic-plastic layer embedded in a Newtonian viscous matrix has been studied and the generation of ptygmatic folding leading ultimately to clod and fragmentation at the crests as well as along the limbs has been discussed. The cause of formation of some of the uncommon ptygmatic structures has also been evaluated along with a review of the different postulates.

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Zusammenfassung Im Experiment wird die Aufwölbung einer isolierten, elastisch-plastisch Lage in einer viscosen Newton'schen Matrix simuliert. Es entstehen hierbei ptygmatische Falten, die im Endstadium sowohl in den Scheiteln als auch auf den Flanken zerscheren und zerbrechen. Es kann dabei auch die Entstehung ungewöhnlicher ptygmatischer Strukturen studiert werden.

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Résumé Le gondolement d'une couche de plastique élastique enrobée dans une matrice visqueuse newtonienne montre que la formation de plis ptygmatiques conduit finalement à des loupes et des cassures dans les charnières comme aussi le long des flancs. La cause de la formation de certaines structures ptygmatiques a été également considérée sur la base des différents postulats.

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- Newton'a. , c . .

     

Radiolaria as paleoclimatic indicators: Pleistocene climatic fluctuations in the equatorial Pacific Ocean

Late Pleistocene radiolarian assemblages were examined in two cores (V24-58 and RC11-209) from the eastern equatorial Pacific Ocean, using Nigrini's 1970 method of recurrent group analysis. The radiolarian “climatic index” curves obtained by this analysis were in close agreement with fluctuations in carbonate levels established previously for the same cores. This correspondence suggests that equatorial radiolarian assemblages changed significantly in response to Pleistocene climatic oscillations. The radiolarian “climatic indices” of the two cores showed close agreement with each other. Our data indicate that equatorial radiolarian assemblages may prove useful for regional correlations between cores, and for paleoclimatic interpretations.     

Trace-element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in Central China

We analyzed variations in the Sr/Ca, Ba/Ca, REE/Ca (REE: rare earth element), Zn/Ca, and Pb/Ca ratios preserved in an annually layered stalagmite, XL21, from central China. The stalagmite record spans the 95 year period AD 1914–2008. The Sr/Ca and Ba/Ca ratios have a significant positive correlation with the stalagmite's growth rate, suggesting that they were primarily controlled by growth-rate variations. Variations in REE/Ca ratios are consistent with local temperature changes, suggesting temperature influenced REE concentrations in the stalagmite over decadal to annual timescales. Higher temperature in this humid area can increase vegetation cover, microbial activity, and organic decomposition in the soil, resulting in enhanced pCO₂, organic matter concentration and reduced pH, and consequently increased REE mobilization from the overlying soil layer and host rock. Higher temperatures may also increase the natural Zn mobilization from the overlying soil mediated by organic matter and consequently may have led to increased Zn retention in XL21. An increasing trend is seen in the Pb/Ca ratios from XL21 since 1985, which is consistent with increased lead production in this area, and indicates an increase in mine-derived lead pollution in the local environment over the past 30 years.     

Suspended-load fallout rate as an independent variable in the analysis of current structures

The dynamic interpretation of most current-structure sequences derives directly from experiments on the succession of bedforms produced by flows in flumes. The results of these and related studies have been used to construct stability field diagrams in which the fields of individual bedforms are usually expressed as a function of flow intensity (power, velocity, bed shear stress, etc.) and grain size. The data underlying existing stability-field diagrams were collected largely from the study of flows carrying coarse-grained sediment entrained through particle-by-particle bed erosion. Many flows, however, do not entrain sediment through simple bed erosion. Most turbidity currents originate by the development of turbulence in slumps, slides, and other slope failures. Such flows generally form with highly concentrated suspended loads and their bed-load layers derive sediment from the collapsing suspended-sediment clouds. Because the collapse properties of such clouds may be related as much to suspended particle concentration, size distribution, particle interactions, and other factors as to flow intensity, the stability fields of bedforms developed beneath such flows may differ in flow intensity-grain-size relationships from those beneath flows deriving sediment from bed erosion alone. Useful stability-field diagrams for turbidity currents must include suspended-load fallout rate as a third variable, independent of flow intensity and mean grain size. A preliminary stability-field diagram of this type indicates that Bouma T_abc sequences may theoretically form with essentially no velocity variation of the attendant flow. This type of analysis may have considerable relevance to the interpretation not only of turbidites but also of other deposits formed where bed-load layers are fed from above rather than below. These include shallow-shelf storm units deposited from highly concentrated flows and volcaniclastic layers formed where pyroclastic debris falls directly into moving water.     

Estimates of large magnitude Late Cambrian earthquakes from seismogenic soft‐sediment deformation structures: Central Rocky Mountains

A variety of unusual early post‐depositional deformation structures exist in grainstone and flat‐pebble conglomerate beds of Upper Cambrian strata, western Colorado, including slide scarps, thrusted beds, irregular blocks and internally deformed beds. Thrusted beds up to tens of centimetres thick record thrust movement of a part of a bed onto itself along a moderate to steeply inclined (15° to 40°) ramp, locally producing hanging wall lenses with fault‐bend geometries. Thrust plane orientations are widely distributed, and in some cases nearly oppositely oriented in close proximity, indicating that they did not form as failures acted upon by gravity forces. Irregular bedded to internally deformed blocks are isolated on generally flat upper bedding surfaces. These features represent parts of beds that detached, moved up onto and some distances across, the laterally adjacent undisturbed bed surfaces. Deformation of thin intervals of mud on the ocean floor by moving blocks rules out the possibility of storm‐induced deformation, because the mud was not eroded by high shear stresses that would accompany the extremely large forces required to produce and move the blocks. Finally, internally deformed beds are characterized by large blocks, fitted fabrics of highly irregular fragments and contorted lamination, which represent heterogeneous deformation, such as brecciation and liquefaction. The deformation structures were produced by earthquakes linked to the reactivation of Mesoproterozoic, crustal‐scale shear zones in the central Rockies during the Late Cambrian. Analysis of the deformation structures indicates very large body forces and calculated earthquake‐generated ground motion velocities of ca 1·6 m sec^?1. These correspond to moment magnitudes of ca 7·0 or more and a Mercalli Intensity of X+. These are the only known magnitude estimates of Phanerozoic (other than Quaternary) large‐intensity earthquakes for the Rocky Mountain region, and they are as large as, or larger than, previous estimates of Proterozoic earthquakes along these major shear zones of the central Rockies.     

Impact of climatic change on an arid watershed: Nahal Yael,southern Israel

The Nahal Yael basin is underlain chiefly by schist, amphibolite, and granite. Thin (generally <1 m thick), grussy colluvium which covered the lower portions of granitic hillslopes in the late Pleistocene has now been stripped completely, causing marked contrasts in outcrop morphologies, even where there is no contrast of fracture density or petrologic characteristics. Formerly mantled slopes are now smooth and crumbly, and lack desert varnish. Previously unmantled slopes are rough and craggy, and varnished but little weathered. Such stripping suggests a change from a semiarid to a drier and/or warmer climate. Slopes underlain by amphibolite responded similarly to the climatic change, but the amphibolite was more deeply weathered, and the colluvium was only partially stripped. The least stripping of colluvium occurred on schist hillslopes, partly because schist outcrops require more rain to generate runoff, and partly because angular blocks of schist require larger flows for transport, compared to other slope lithologies. The stream subsystem responded to the climatically induced changes in the discharge of water and sediment from the hillslopes. Increase in sediment yield caused valley alluviation in the early Holocene, and a decrease in sediment yield later in the Holocene caused entrenchment of the valley fill. More granite and amphibolite gravel-size particles are transported now than when the hillslopes were extensively mantled. Dense networks of trails are not common on Holocene geomorphic surfaces, but are present on remnants of Pleistocene surfaces.     

A one-dimensional integral approach to calculating the failure probability of geotechnical engineering structures

This study focuses on the geotechnical engineering structures with implicit or unknown expressions of performance functions. A one-dimensional integral approach (ODIA) consisting of sampling, evaluation of statistical moments for multivariable functions, probability density function fitting, and simple integration of failure probability was developed through system integration. A convergence study of an illustrative example was conducted, and the error analysis revealed that the accuracy of ODIA is equivalent to that of the second-order reliability method. Applications of ODIA to a slope and surrounding rock of an excavation were presented to further confirm the accuracy, efficiency, and practicability of the approach.     

Long-term variations of monthly insolation as related to climatic changes

Qualitative multivariate models which combine past insolations of selected months at selected latitudes explains 55 to 67% of the variance in the 135 millenia long oxygen isotope record of Pleistocene climates.The insolation was computed from a new astronomic solution which includes terms to the second order with respect to the disturbing masses, and the third degree with respect to the planetary eccentricities and inclinations (Berger, 1978 a).Barring human interference, the models predict the next peak of natural cooling between 3 and 6 millenia after present. Following amelioration, another much colder peak is predicted at about 55–60 millenia after present.

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Zusammenfassung Verschiedene multivariate Modelle die zurückgreifend die Sonneneinstrahlung ausausgewählter Monate und Breitengrade kombinieren, erklären 55% bis 67% der gesamten klimatischen Variation der letzten 135 000 Jahre, die durch Sauerstoffisotopen-Daten belegt wurden.Diese monatlichen Sonneneinstrahlungen wurden nach einer neuen astronomischen Lösung für die Elemente der Erdbahn berechnet. Diese Lösung ist aus der zweiten Ordnung der Masse und dem dritten Grad der Exzentrizitäten und der Inklinationen berechnet (Berger, 1978 a). Ohne menschliches Eingreifen ergibt sich aus den Modellen eine Abkühlung, deren Höchstwert zwischen 3000 und 6000 Jahren nach unserer Zeit erreicht sein wird. Nach einer fühlbaren Verbesserung des Klimas ergibt sich eine weitere, strengere Abkühlung in etwa 60 000 Jahren.

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Résumé Différents modèles de régression multivariée, combinant les insolations du passé géologique pour des mois et les latitude pré-sélectionnées, expliquent 55 à 67% de la variation climatique totale des 135 000 dernières années, telle que fournie par les données géologiques.Ces insolations mensuelles furent calculées à partir d'une nouvelle solution astronomique pour les éléments orbitaux de la Terre. Cette solution est précise au second ordre des masses et au 3^d degré des excentricités et des inclinaisons (Berger, 1978 a).A l'exclusion de toute intervention humaine, les modèles prévoient un refroidissement dont le maximum sera atteint entre 3000 et 6000 après notre ère (A. P.). Après une amélioration sensible, un autre refroidissement, nettement plus intense, est prévu vers 60 000 ans A. P.

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, , 55 67 % , , 135 000 . , , (, 1978 ). , 3 6 . 50 60 .

     

Spherical particles as tracers of atmospheric ceramic industry

Castellón province houses the nucleus of ceramics production in Spain (93%). This nucleus, located around in the villages of Castellón, Villarreal, Alcora and Onda, has gone through a special process of industrial expansion. The emissions, most of them of particulate material, can constitute a real environmental problem. A study designed to identify the crystalline and glassy phases in the depositable particulate material has been carried out by SEM/EDX and X-ray diffraction methods. Quartz, calcite, illite, kaolinite, chlorite, and feldspars have been the main crystalline phases identified. The number of spherical morphology particles found in the depositable material is remarkable. The vitreous material found was spherical nodules. Due to the shape, size (1–10 μm), and chemical composition of these particles, they can be excellent tracers of the ceramics industry emissions.The presence of Zn, Ba, or Fe are due to the massive use of these substances as opacifying and pigmentation agents in many ceramics frits and glaze compositions. This fact gives a valuable information that will facilitate the studies guided to obtain important aims such as: toxicology, average size of a particle, formation mechanisms, etc.     

Carbonate precipitation in artificial soils as a sink for atmospheric carbon dioxide

Turnover of C in soils is the dominant flux in the global C cycle and is responsible for transporting 20 times the quantity of anthropogenic emissions each year. This paper investigates the potential for soils to be modified with Ca-rich materials (e.g. demolition waste or basic slag) to capture some of the transferred C as geologically stable CaCO₃. To test this principal, artificial soil known to contain Ca-rich minerals (Ca silicates and portlandite) was analysed from two sites across NE England, UK. The results demonstrate an average C content of 30 ± 15.3 Kg C m⁻² stored as CaCO₃, which is three times the expected organic C content and that it has accumulated at a rate of 25 ± 12.8 t C ha⁻¹ a⁻¹ since 1996. Isotopic analysis of the carbonates gave values between −6.4‰ and −27.5‰ for δ¹³C and −3.92‰ and −20.89‰ for δ¹⁸O, respectively (against V-PDB), which suggests that a combination of carbonate formation mechanisms are operating including the hydroxylation of gaseous CO₂ in solution, and the sequestration of degraded organic C with minor remobilisation/precipitation of lithogenic carbonates. This study implies that construction/development sites may be designed with a C capture function to sequester atmospheric C into the soil matrix with a maximum global potential of 290 Mt C a⁻¹.