Food production — Problems and prospects

This paper reviews the different problems associated with food production in relation to population growth. A number of solutions are put forward to improve the situation.     

The chemically distinct nucleus and structure of the S0 galaxy NGC 80

The giant lenticular galaxy NGC 80, which is the brightest member of a rich group, possesses a central evolutionarily-distinct region: the stars in the nucleus and in a circumnuclear ring of radius 5″t–7″ have a mean age of only 7 Gyr, whereas the stellar population of the bulge is older than 10 Gyr. The nucleus of NGC 80 is also chemically distinct: it is a factor of 2–2.5 richer in metals than its immediate neighborhood and is characterized by a high magnesium-to-iron abundance ratio [Mg/Fe]≈+0.3. The global stellar disk of NGC 80 has a two-tiered structure: its outer part has an exponential scale length of 11 kpc and normal surface density, while the inner disk, which is also exponential and axisymmetric, is more compact and brighter. Although the two-tiered structure and the chemically distinct nucleus obviously have a common origin and owe their existence to some catastrophic restructuring of the protogalactic gaseous disk, the origin of this remains unclear, since the galaxy lacks any manifestations of perturbed morphology or triaxiality.     

The Timescales of Magma Mixing in the Plumbing System of Bezymianny Volcano (Kamchatka): Insights from Diffusion Chronometry

Intrusion of magma of contrasting composition into a magma chamber often triggers eruptions of arc volcanoes. Application of the diffusion chronometry method allowed us to determine the time when fresh magma was supplied to the shallow chamber of Bezymianny volcano in the case of six eruptions in 2006–2012 and to compare them to the recorded seismic activity of this volcano. Two types of eruptions of Bezymianny volcano were distinguished, with a contrasting orthopyroxene rim being formed in the respective magmas (a) up to 3 years and (b) up to 2 months before the beginning of an eruption. It was shown that these differences are caused by two different paths of magma supply to the shallow chamber of Bezymianny volcano.     

Holocene record of productivity in the NW Iberian continental shelf

A multiproxy approach (textural characteristics, heavy metal concentrations and benthic foraminifera data) was adopted to study the OMEX core KSGX 40, collected at the Galicia Mud Deposit (NW Iberian outer continental shelf) and recording the last ca. 4.8 ka cal BP. Geochemical profiles of Fe, Mn, Zn, Co, Cr, Cu, Ni, Pb, Al and Ca show significant temporal variations. Benthic foraminifera productivity proxy suggests that the recorded muddy events were contemporaneous of a higher C_org flux to the marine benthic environment. The higher flux of organic matter, following a long-term intensification of the upwelling and coinciding with a finer sedimentation, led to depressed levels of oxygen beneath the water-sediments interface and to early diagenetic processes of several redox-sensitive elements.     

Paleoproterozoic accretion in the Northeast Siberian craton: Isotopic dating of the Anabar collision system

Geochronological database considered in the work and characterizing the Anabar collision system in the Northeast Siberian craton includes coordinated results of Sm-Nd and Rb-Sr dating of samples from crustal xenoliths in kimberlites, deep drill holes, and bedrock outcrops. As is inferred, collision developed in three stages dated at 2200–2100, 1940–1760, and 1710–1630 Ma. The age of 2000–1960 Ma is established for substratum of mafic rocks, which probably originated during the lower crust interaction with asthenosphere due to the local collapse of the collision prism. Comparison of Sm-Nd and Rb-Sr isochron dates shows that the system cooling from ≈700 to ≈300°C lasted approximately 300 m.y. with a substantial lag relative to collision metamorphism and granite formation. It is assumed that accretion of the Siberian craton resulted in formation of a giant collision mountainous structure of the Himalayan type that was eroded by 1.65 Ga ago, when accumulation of gently dipping Meso-to Neoproterozoic (Riphean) platform cover commenced.     

Mechanical Behaviour of the Interface Between Cemented Tailings Backfill and Retaining Structures Under Shear Loads

Understanding the shear behaviour of the interface between cemented tailings backfill and retaining wall structures (barricades, bulkheads) is important for the optimal design of barricades or bulkheads, and for mine operators to balance strength and safety against cost. However, our understanding of the shear behaviour of the aforementioned interface is limited. This paper is aimed at investigating the interfacial behaviour and properties of cemented tailings backfill-retaining wall structures, including stress–strain behaviour, cohesion, friction angle and shear stiffness through direct shear tests. Two different types of barricade or bulkhead materials (brick and concrete) are used in this study. Interface shear tests are performed at various curing times of the cemented backfill. Valuable results are obtained with regards to the interface shear behaviour of backfill-retaining structures. Based on these results, interfacial properties between cemented tailings backfill and barricades or bulkheads show a significant time-dependent variation.     

The Most Ancient Diamond Crystals of the Siberian Platform

Doklady Earth Sciences - Based on a study of diamond grains from placers of the northeastern Siberian Platform, it is shown that certain types of diamonds (rounded dodecahedroids, diamonds of the...     

Early Pleistocene magmatism in the central part of the Greater Caucasus

An isotope-geochronological study of young magmatism in the central part of the Greater Caucasus (Kazbek neovolcanic area) on the territory of Russia and Georgia has been carried out. It was proved for the first time that, in the Early Pleistocene, there was a separate impulse of magmatic activity in this area. The area of endogenic activity for the period identified was contoured on the basis of the integrated isotope-geochronological, petrological-geochemical, and geological data. It has been shown that the Early Pleistocene volcanism inherits the area of Neogene volcanism in the Kazbek region and, therefore, presents the final impulse of the second (Pliocene) stage of the Late Cenozoic magmatism. Thus, Early Pleistocene volcanism was not a precursor of Late Quaternary magmatism as the latter has other spatial patterns of the location of volcanic centers.