Genesis of Diamond in Metal–Carbon and Metal–Sulfur–Carbon Melts: Evidence from Experimental Data

Doklady Earth Sciences - The experimental data on diamond growth in the Fe–Ni–S–C and Fe–S–C systems with a sulfur content of 5–14 wt % at 5.5 GPa and...     

Biostratigraphy and Sedimentary Settings of the Middle Devonian Succession of the Yuryung-Tumus Peninsula,Khatanga Gulf of the Laptev Sea

The age of the Paleozoic sedimentary successions of the Yuryung-Tumus Peninsula in the Khatanga Gulf is determined as Middle Devonian, late Eifelian, and the beginning of the early Givetian on the basis of the study of brachiopods, ammonoids, nautiloids, bactritoids, gastropods, and conodonts, and in the terminology of the standard conodont succession, these deposits are not older than the late Eifelian Tortodus kockelianus Zone, but include the terminal Eifelian Polygnathus ensensis Zone and the first Givetian Polygnathus hemiansatus Zone and are no younger than the beginning of the early Givetian Polygnathus varcus Zone. The Middle Devonian sedimentary successions of the Yuryung-Tumus Peninsula show the level of the global sedimentary Ka?ak Event. The areas of distribution of the Devonian sedimentary deposits in the Yuryung-Tumus Peninsula in the Khatanga Gulf should be considered as one of the fragments of the regional geological structures of a remote (isolated?) region of the Taymyr Fold System rather than a component of the structures of the northern Siberian Platform.     

Some Causes of Inaccuracies of Short-Term Earthquake Prediction Taking into Account Laboratory Modeling

Doklady Earth Sciences - A series of experiments are carried out with a stick–slip earthquake model consisting of two granite blocks under biaxial compression loading. The mechanical...     

Database of molecular masers and variable stars

We present the database of maser sources in H2 O, OH and Si O lines that can be used to identify and study variable stars at evolved stages. Detecting the maser emission in H2 O, OH and Si O molecules toward infrared-excess objects is one of the methods for identifing long-period variables(LPVs, including miras and semiregulars), because these stars exhibit maser activity in their circumstellar shells. Our sample contains 1803 known LPV objects. Forty-six percent of these stars(832 objects) manifest maser emission in the line of at least one molecule: H2 O, OH or Si O. We use the database of circumstellar masers in order to search for LPVs which are not included in the General Catalogue of Variable Stars(GCVS). Our database contains 4806 objects(3866 objects without associations in GCVS) with maser detection in at least one molecule. Therefore it is possible to use the database in order to locate and study the large sample of LPV stars. The database can be accessed at http://maserdb.net.     

Analysis of Design Characteristics of Snake-Type Atmospheric Probes (Vetrolets) for Studying the Atmosphere of Venus

In Russia, work aimed at designing a spacecraft for the long-term exploration of Venus is currently underway as part of the VENUS-D project. The R&D work proposes the concept of a snake-type atmospheric probe intended for exploring the atmosphere of Venus. This article describes the principles of flight, considers the main design features and engineering characteristics of the probes, and provides recommendations for engineering solutions.     

Latitudinal and temporal shifts in the radial growth-climate response of Siberian larch in the Polar Urals

This paper presents a dendroclimatic analysis of Siberian larch trees sampled along a latitudinal 260-km transect located in the Polar Urals,Russia. Three standardised chronologies were built over a length of 230–293 years using 79 individual tree-ring chronologies collected in the southern,middle and northern parts of the Polar Urals.Bootstrapped correlation functions showed that the annual growth of the larches was mainly influenced by the air temperatures in June and July. The relative role of the temperatures increased from south to north. Daily air temperature data analysis revealed that the duration of the growing season in the northern part of the Polar Urals is 24 days less than that in the southern part. At the present time, air temperatures exceeded threshold of 8~℃, 5 days earlier than it did in the beginning of the 20 th century In response to the increase in the duration of the growing season and the changing winter conditions in the Polar Urals over the last 130 years, radial growth–temperature relationships in larches have weakened;this effect was strongly pronounced in the southern part of the Polar Urals.     

Fast-changing processes in a medium subject to loading as detected by resistivity measurements

Making measurements of electric resistivity at 16 s intervals, the authors noticed fast changes of this parameter prior to the occurrence of the main fracture. The changes are superposed on bay pulsations of increasing amplitude and decreasing period. This finding opens prospects for a wider use of an electric resistivity method and proves the high quality of automatic instruments, in particular their high resolution. It also gives evidence for the occurrence of short-period precursors in the fracture zone while the main fracture is being formed.     

Archaeoseismological investigation of the ancient Ayla site in the city of Aqaba,Jordan

Many tens of severe earthquake damage patterns were revealed at the ancient city of Ayla. The seismic deformation patterns are of various types, including systematic tilting of walls, systematic shifting and rotation of wall fragments and individual stones, arch deformations and joints crossing two or more stones. Features of later repair, supporting walls and secondary use of building stones suggest that the damage patterns can be explained by two historical devastating earthquakes: (I) revealed in the constructions built during the late Rashidun period (644–656 A.D.); (II) revealed in the structures restored and/or built during the Fatimid period (1050–1116 A.D.). The maximum observed intensity of both earthquakes at the studied site was not less than IX (EMS98 scale). The sources of the seismic events were probably the Dead Sea Transform and Wadi Araba Faults that cross the site obliquely. The last 1995 Nuweiba earthquake with maximum observed intensity VIII has also left its clear traces in the excavated ancient Ayla buildings. The severity of the destruction was significantly increased because of site effects.     

High-pressure partial melting of gabbro and its role in the Hawaiian magma source

We have conducted high-pressure experiments on a natural oceanic gabbro composition (Gb108). Our aim was to test recent proposals that Sr-enrichment in rare primitive melt inclusions from Mauna Loa, Hawaii, may have resulted from melting of garnet pyroxenite formed in the magma source regions by reaction of peridotite with siliceous, Sr-enriched partial melts of eclogite of gabbroic composition. Gb108 is a natural, Sr-enriched olivine gabbro, which has a strong positive Sr anomaly superimposed on an overall depleted incompatible trace element pattern, reflecting its origin as a plagioclase-rich cumulate. At high pressures it crystallises as a coesite eclogite assemblage, with the solidus between 1,300 and 1,350°C at 3.5 GPa and 1,450 and 1,500°C at 4.5 GPa. Clinopyroxenes contain 4–9% Ca-eskolaite component, which varies systematically with pressure and temperature. Garnets are almandine and grossular-rich. Low degree partial melts are highly siliceous in composition, resembling dacites. Coesite is eliminated between 50 and 100°C above the solidus. The whole-rock Sr-enrichment is primarily hosted by clinopyroxene. This phase dominates the mode (>75 wt%) at all investigated PT conditions, and is the major contributor to partial melts of this eclogite composition. Hence the partial melts have trace element patterns sub-parallel to those of clinopyroxene with ≈10× greater overall abundances and with strong positive Sr anomalies. Recent studies of primitive Hawaiian volcanics have suggested the incorporation into their source regions of eclogite, formerly gabbroic material recycled through the mantle at subduction zones. The models suggest that formerly gabbroic material, present as eclogite in the Hawaiian plume, partially melted earlier than surrounding peridotite (i.e. at higher pressure) because of the lower solidus temperature of eclogite compared with peridotite. This produced highly siliceous melts which reacted with surrounding peridotite producing hybrid pyroxene + garnet lithologies. The Sr-enriched nature of the formerly plagioclase-rich gabbro was present in the siliceous partial melts, as demonstrated by these experiments, and was transferred to the reactive pyroxenite. These in turn partially melted, producing Sr-enriched picritic liquids which mixed with normal picritic partial melts of peridotite before eruption. On rare occasions these mixed, relatively Sr-rich melts were trapped as melt inclusions in primitive olivine phenocrysts. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.