Lost and found

Consulting type specimens is a necessary element of taxonomic research in palaeontology. Every taxonomist from time to time has to examine the types to make sure that the identifications are correct. This can be a difficult proposition when the fossils in question were collected in the early nineteenth century. But just because a historical fossil collection is said to be 'lost', doesn't mean it cannot be found.     

Peculiarities of cover clayey loam disintegration of the Moscow Region and the red clay of China

The comparative characteristic disintegration of cover clayey loam and red clay is described. This revealed a significant effect of humidity on the intensity disintegration of cover clayey loam and red clays. It is necessary to incorporate the disintegration of these subsoils during their construction.     

Reconstruction of the surface of the Late Valdai ice sheet in the area of Khibini and Lovozerskii mountain ranges on the Kola Peninsula

On the basis of location levels of push marginal formations and maximal distribution heights of charted lateral moraine, the surface form of the Late Valdai ice sheet in the region of Khibini and Lovozerskii massifs during cool stadial phases of the Middle and Younger Dryas was reconstructed. It has been established that the glacier surface came to 700 m and 500 m, respectively, and its inclination varied from 30 to 70 m per 10 km, which is well below that in marginal fields of ice sheets of Western Greenland and East Antarctica. The maximal ice thickness in the Middle Dryas came to about 600 m, and in the Younger Dryas, it was about 400 m. The inclination of the glacier surface increased during the cool stadial phase. On the whole, it coincides well with the drift directions of detrital sediments by ice streams, established by the transfer direction of detrital sediments, orientation of drumlins, ice scars, and other factors of ice activity.     

Genesis of melilitolite from Colle Fabbri: inferences from melt inclusions

Melilite and wollastonite from the Colle Fabbri stock contain silicate melt and silicate-carbonate inclusions. The homogenization temperatures of silicate inclusions are within the magmatic temperature range of mantle ultrabasic melts: about 1,320?±?15 °С. Their composition is melilititic and evolves to the composition of leucite tephrite and phonolite. The composition of silicate-carbonate inclusions are high SiO₂, Ca-rich, enriched in alkalies and are similar to that of inclusions of carbonatite melts in the minerals of melilitolites of other intrusive ultramafic complexes. They are also similar to the compositions of metasomatized travertine covering the melilitolite stock. The presence of primary silicate and silicate-carbonate inclusions evidences that the melilitite magma from which melilitolites of Colle Fabbri crystallized was associated with carbonatite liquid. This liquid was highly fluidized, mobile and aggressive. Actively interacting with overlying travertine, the liquid enriched them with alkalies, aluminosilicates and incompatible elements, which resulted in the equalization of their compositions. Heterogeneous compositional dominions were formed at the contact between melilitolite and wall pelites. In the minerals of these contact facies high-Si melt inclusions of varying composition have been observed. Their occurrence is related to the local assimilation by the high-temperature melilitite magma of pelitic country rocks. The content of incompatible elements in melilitite melts and melilitolites is higher than the mantle norm and they have peculiar indicator ratios, spectra, Eu/Eu^* ratio, which suggest a peculiar mantle source.     

A geoelectric model for the Uzon caldera,Kamchatka

The results of magnetotelluric and magnetovariational studies in the Uzon caldera are considered. An analysis of magnetotelluric parameters yielded the required method of interpretation. The MTS curves were interpreted in the framework of a 2D model using the REBOCC program. Geoelectric cross sections of the caldera were constructed along two orthogonal lines. Anomalies of high electrical conductivity were identified in the sediments and in the basement and were found to be confined to the locations of geothermal springs. The higher conductivity of these anomalies is here related to the presence of highly mineralized hydrothermal solutions. Electrical conductivity was used for an approximate estimation of porosity in the sediments and basement. A subvertical zone of higher porosity was identified at depths of 1.5–3.5 km in the caldera with a connection to the channelways of fluids rising into the sediments. It is hypothesized that highly mineralized solutions are diluted with vadose water in that zone and come through fissures onto the ground surface in the form of hot springs. The totality of these data suggested a conceptual model to characterize the main features in the generation of hydrothermal springs in the Uzon caldera.     

Dynamics of the auroral Es layer during weak and strong disturbances in the magnetosphere

The paper is dedicated to studying the dynamics of the auroral ionosphere at the level of the sporadic Es layer during magnetospheric disturbances. A new approach to this problem, proposed in the paper, uses the geomagnetic PC index, which is calculated using the magnetic data in the polar caps of the northern and southern hemispheres and manifests the geoefficiency of the interplanetary electric field. It is shown that variations in the sporadic electron concentration in the auroral Es layer could be related to changes in the PC index with a high degree of statistical reliability. However, the character of precipitations of sporadic particles into the ionosphere under high (PC > 2 mV/m) and low (PC < 2 mV/m) magnetic activity differs substantially. During strong magnetic disturbances and under intensified electric fields in the interplanetary environment, the intensity of particle precipitation from the magnetosphere into the E region of the high-latitude ionosphere is governed by the values of the PC magnetic index. During weak magnetic disturbances, short-time pulses of an increase in the PC values, caused by the variability in electric field in the magnetosphere, are the main factor in the occurrence of sporadic ionization in the Es layer.     

A candidate for the Global Stratotype Section and Point at the base of the Serpukhovian in the South Urals,Russia

The Verkhnyaya Kardailovka section is one of the best candidates for the GSSP (Global Stratotype Section and Point) at the base of the Stage (Mississippian). For boundary definition, the first appearance of the conodont Lochriea ziegleri Nemirovskaya, Perret et Meischner, 1994 in the lineage Lochriea nodosa (Bischoff, 1957)?L. ziegleri is used. L. ziegleri appears in the Venevian Substage somewhat below the base of the Serpukhovian in the Moscow Basin. The position of the FAD of L. ziegleri within the Hypergoniatites?Ferganoceras Genozone is confirmed and lies between 19.53 and 19.63 m above the section’s base. Before 2010, deep-water stylonodular limestone containing the boundary in unnamed formation C at Kardailovka was well exposed but only 3 m of Viséan strata cropped out immediately below. Recent trenching exposed another 10 m of underlying Viséan carbonates in formation C and older Viséan siliciclastics and volcanics in unnamed formation B. The contact between formation B and underlying crinoidal limestones in unnamed formation A representing the middle Viséan Zhukovian (Tulian) regional Substage was excavated. The boundary succession, situated in the Magnitogorsk tectonic zone above the Devonian Magnitogorsk arc and Mississippian magmatic and sedimentary rift succession, was deposited west of the Kazakhstanian continent during closure of the Ural Ocean. In the lower part of the section, Viséan tuffaceous siliciclastics and volcanics of formation B record rapid deepening after deposition of neritic middle Viséan crinoid lime grainstone of formation A and subsequent subaerial exposure. The overlying condensed upper Viséan to Serpukhovian succession in formation C comprises deep-water limestone deposited in a sediment-starved basin recording minor turbidite influx and carbonate-mound development. The δ¹³C_carb plot shows a positive shift of 1‰ V-PDB (from +2 to +3‰) between 17.0 and 17.75 m (3.05 and 1.97 m below FAD L. ziegleri). The δ¹⁸O_apatite graph displays a prominent upward shift from 19.9 to 21.1‰ V-SMOW (at 19.15 to 19.51 m) in the nodosa Zone below FAD of Lochriea ziegleri.     

Mineral composition of sediments from the Eastern Laptev Sea shelf and East Siberian Sea

The mineral composition of the heavy fraction in surface sediments of the Laptev and East Siberian seas has been analyzed. The multivariate statistics methods were used to define the main heavy mineral assemblages with outlining regional differences in their compositions and principal factors responsible for the formation of sediment mineral affinity in the study areas. It is shown that the distribution of the determined heavy mineral assemblages is controlled by the geostructural positions of sedimentation basins.     

Detailed paleoseismological research on the flank of the Lake Imandra depression (Kola region): New approaches and results

We present results of detailed paleoseismological research at the key site on the flank of the Lake Imandra depression (Kola region, northeast of the Fennoscandian Shield). Study of various groups of paleoseismic deformations in the fault zone and application of new methods and approaches made it possible to recognize a segment of a large seismotectonic zone where violent earthquakes occurred repeatedly at the end of the Late Glacial and in the Holocene. The dates of earthquakes and the location of their foci are determined.