Phosphides in Volcanic Seamount Basalts in the Sea of Japan

Electron microprobe data on phosphide grains detected for the first time in basalts from volcanic edifices in the Sea of Japan are presented. The find of phosphides can testify to the endogenic source of phosphorus and, consequently, volcanogenic hydrothermal origin of phosphorites in the Sea of Japan.     

A Kinematic Model of the Formation of the Sim Trough of the Uralian Foredeep

The structural features and mechanism of the formation of the Sim trough within the Uralian Foredeep, as well as the development of the entire Karatau–Suleiman block, are considered. This wedge-shaped block was subject to lateral extrusion to the north along conjugated strike-slip fault zones under a general latitudinal compression. This factor determined the local meridional compression and latitudinal extension of the block. In the central part of the block, the latitudinal extension was compensated by gradual subsidence, which resulted in the formation of the Sim trough.     

The Composition and Reservoir Properties of the Deposits of the Bazhenov Formation in the Central Part of the Tundrin Depression

The section structure was characterized according to the lithological and petrophysical studies of the core from the Bazhenov Formation that has been uncovered in the central part of the Tundrin Depression. The productive oil intervals where the reservoirs of the pore and fissure-pore types occur were identified.     

Garnet-Pyroxenite-Derived End-Member Magma Type in Kamchatka: Evidence from Composition of Olivine and Olivine-Hosted Melt Inclusions in Holocene Rocks of Kekuknaisky Volcano

Late Quaternary volcanoes of Sredinny Range (Kamchatka) attract geoscientists’ attention by their unusual geochemical features and geodynamic setting. They produced volcanic rocks that are enriched relative to N-MORB in most of incompatible trace elements (except HREE), including strong enrichment in large-ion lithophile elements, and show a negative Nb–Ta anomaly, which is typical for rocks formed in supra-subduction settings. However, modern subduction of the Pacific Plate does not reach the most part of Sredinny Range, as inferred by mapping of Wadati–Benioff zone or seismic tomography. We constrain the source of parental magmas for Sredinny Range volcanic rocks by combining major and trace element geochemical data for olivine and naturally quenched olivine-hosed melt inclusions for Holocene tephra layers of the Kekuknaisky field. Composition of the most magnesian olivine (Ni > 2000 ppm, Fe/Mn ≈ 75 at Mg# ~ 84–85 mol %) and geochemical characteristics of the most primitive melts (FC3MS = 0.61 ± 0.04 (2s)) are consistent with their derivation from a pyroxenite source, while elevated LREE/HREE ratios in lavas indicate that it contained garnet. This garnet-bearing pyroxenite likely originated from the lower crust or lithospheric mantle. Its melting could have occurred due to delamination and sinking into the hotter mantle.     

Palynostratigraphy of the Upper Cretaceous and Paleogene Deposits in the South of Western Siberia by Example of Russkaya Polyana Boreholes,Omsk Trough

The detailed study of Boreholes 8, 10, and 2 in the Russkaya Polyana district (Omsk Trough) made it possible to reveal the complex structure of the Upper Cretaceous sediments formed in unstable conditions of the marginal part of the Western Siberian basin. The Pokur, Kuznetsovo, Ipatovo, Slavgorod, and Gan’kino formations were subjected to palynological analysis and substantiation of their Late Cretaceous age. Eight biostratigraphic units with dinocysts and five units with spores and pollen from the Albian to the Maastrichtian were identified. The joint application of biostratigraphic and magnetostratigraphic methods made it possible to reveal the stratigraphic breaks in the studied sedimentary stratum and to estimate their scope. The age of the Lower Lyulinvor Subformation was specified in the marginal part of the Omsk Trough. The ingression traces of the Western Siberian basin in the Albian were found for the first time in the considered region.     

Magmatic Evolution of Changbaishan Tianchi Volcano,China–North Korea: Evidence from Mineral-Hosted Melt and Fluid Inclusions

Data on mineral-hosted melt, fluid, and crystalline inclusions were used to study the composition and evolution of melts that produced rocks of Changbaishan Tianchi volcano, China–North Korea, and estimate their crystallization parameters. The melts crystallized within broad ranges of temperature (1220–700°C) and pressure (3100–1000 bar), at a drastic change in the redox potential: Δ log \(f_{O_2}\) from NNO + 0.92 to +1.42 for the basalt melts, NNO –1.61 to –2.09 for the trachybasaltic andesite melts, NNO –2.63 to –1.89 for the comendite melts, and NNO –1.55 to –3.15 for the pantellerite melts. The paper reports estimates of the compositions of melts that produced the continuous rock series from trachybasalt to comendite and pantellerite. In terms of trace-element concentrations, all of the mafic melts are comparable with OIB magmas. The silicic melts are strongly enriched in trace elements and REE. The most strongly enriched melts contain concentrations of certain elements almost as high as in ores of these elements. The paper reports data on H2O concentrations in melts of different composition. It is demonstrated that the variations in the H₂O concentrations were controlled by magma degassing. Data are reported on the Sr and Nd composition of the rocks. The deviations in the Sr isotopic composition are proportional to the ⁸⁷Sr/⁸⁶Sr ratio and could be produced in a melt with a high enough ⁸⁷Sr/⁸⁶Sr ratio during a geologically fairly brief time period. The evolution of melts that produced rocks of the volcano was controlled by crystallization differentiation of the parental basalt magmas at insignificant involvement of melt mixing and liquid immiscibility of silicate and sulfide melts. The alkaline salic rocks were generated in shallow-sitting (13–3.5 km) magmatic chambers in which the melts underwent profound differentiation that gave rise to pantellerites and comendites strongly enriched in trace elements (Th, Nb, Ta, Zr, and REE). Data on the composition of the magmas and parameters of their derivation are used to develop a generalized petrologic–geodynamic model for the origin of Changbaishan Tianchi volcano.     

Ultramafic–Mafic Assemblage of Plutonic Rocks and Hornblende Schists of Shirshov Rise,Bering Sea,and Stalemate Ridge,Northwest Pacific: Geodynamic Interpretations of Geochemical Data

The paper presents data on plutonic and metamorphic rocks dredged during Cruise 249 of the German R/V Sonne to the Stalemate Ridge, Northwest Pacific Ocean and the Shirshov Rise, western Bering Sea. Dredges in the northwestern sector of the Stalemate Ridge and central portion of the Shirshov Rise show that the plutonic and metamorphic rocks obtained here are amazingly similar. Our petrologic and geochemical data led us to view the rocks as members of a mafic–ultramafic assemblage typical of cumulate portions of ophiolite complexes and backarc spreading centers. The plutonic complexes of the Shirshov Rise and Stalemate Ridge show similarities not only in the petrography and mineralogy of their protoliths but also in the character of their metamorphic transformations. Plutonic rocks from both areas display mineralogical evidence of metamorphism within a broad temperature range: from the high-temperature amphibolite facies to the greenschist facies. Relations between the index mineral assemblages indicate that the metamorphic history of plutonic complexes in the Stalemate Ridge and Shirshov Rise proceeded along a retrograde path. Hornblende schists accompanying the plutonic rocks of the Stalemate Ridge and Shirshov Rise are petrographically close to foliated amphibolites in subophiolitic metamorphic aureoles. Within the framework of geodynamic interpretations of our results, it is realistic to suggest that the examined plutonic complexes were exhumed from subduction zones of various age.     

Ziminaite,Fe3+VO4, a new howardevansite-group mineral from the Bezymyannyi volcano,Kamchatka, Russia

Mineralogy and Petrology - The new mineral ziminaite, ideally Fe3+VO4, was found in fumarole sublimates at the Bezymyannyi volcano, Kamchatka, Russia. Ziminaite occurs as lamellar, tabular or...     

Rice crop phenology mapping at high spatial and temporal resolution using downscaled MODIS time-series

Satellite data holds considerable potential as a source of information on rice crop growth which can be used to inform agronomy. However, given the typical field sizes in many rice-growing countries such as China, data from coarse spatial resolution satellite systems such as the Moderate Resolution Imaging Spectroradiometer (MODIS) are inadequate for resolving crop growth variability at the field scale. Nevertheless, systems such as MODIS do provide images with sufficient frequency to be able to capture the detail of rice crop growth trajectories throughout a growing season. In order to generate high spatial and temporal resolution data suitable for mapping rice crop phenology, this study fused MODIS data with lower frequency, higher spatial resolution Landsat data. An overall workflow was developed which began with image preprocessing, calculation of multi-temporal normalized difference vegetation index (NDVI) images, and spatiotemporal fusion of data from the two sensors. The Spatial and Temporal Adaptive Reflectance Fusion Model was used to effectively downscale the MODIS data to deliver a time-series of 30 m spatial resolution NDVI data at 8-day intervals throughout the rice-growing season. Zonal statistical analysis was used to extract NDVI time-series for individual fields and signal filtering was applied to the time-series to generate rice phenology curves. The downscaled MODIS NDVI products were able to characterize the development of paddy rice at fine spatial and temporal resolutions, across wide spatial extents over multiple growing seasons. These data permitted the extraction of key crop seasonality parameters that quantified inter-annual growth variability for a whole agricultural region and enabled mapping of the variability in crop performance between and within fields. Hence, this approach can provide rice crop growth data that is suitable for informing agronomic policy and practice across a wide range of scales.     

‘Filament’ marker beds in the Karababa-A Member (Turonian) of the Arabian platform,SE Turkey: Palaeo-environmental significance,stratigraphy and correlation potential

A ‘filament’ event bed/level corresponds to the occurrence of thin elongate calcitic, shells, or plates of pelagic, bivalve or crinoidal, origin, within pelagic, laminated and organic-matter rich limestones. These organic-rich limestones had been generally deposited under hypoxic/anoxic conditions in an outer-ramp environment. These thin elongate, bivalve shells, or crinoidal plates, are found broken in small pieces, disintegrated, or simply preserved parallel to bedding as almost complete specimens. Such ‘filament’ beds were spotted in SE Turkey in deposits, namely the Karababa-A Member, around the Cenomanian-Turonian boundary (C/TB) and above. On a global scale, these filament event beds illustrate sea-level rise related to eustacy and/or climatic change. The abundance of filaments close to the C/TB is a biological marker of high organic productivity resulting from a climatic change to warmer conditions. The prevailing higher sea-level conditions were then favourable to the accumulation and preservation of organic-rich facies, characteristic of the Oceanic Anoxic Event 2 (OAE2). Using both biostratigraphic and carbon isotopic data, those deposits were dated from the latest Cenomanian-Turonian age. ‘Filament’ event beds were recorded in the same order, except for some small differences. A good number of these bio-events are global. Consequently, on a global scale, they are susceptible to constrain the C/TB, especially the base of the Turonian stage, with a significant degree of confidence.