scholarly journals IIOROKHAN COMPLEX OF MINOR INTRUSIONS IN THE EASTERN PART OF THE BUREYA MASSIF: GEOLOGY, AGE, GOLD MINERALISATION

2021 ◽  
pp. 45-64
Author(s):  
E.V. Nigai ◽  
◽  
V.A. Guryanov ◽  
S.N. Dobkin ◽  
M.V. Arkhipov ◽  
...  
Keyword(s):  
Continental Margin ◽  
Gold Mineralization ◽  
Far East ◽  
Boundary Structure ◽  
High Alumina ◽  
Low Concentrations ◽  
Tectonic Settings ◽  
Characteristic Features ◽  
Deep Source ◽  
Bureya Massif

In this paper we analyze and summarize some recently acquired data coupled with the findings of previous geological, geochronological and metallogenic studies on igneous rocks of the Iorokhan gold-bearing complex in the eastern part of the Bureya massif. Four phases, whose rocks are of hypabyssal and subvolcanic intrusive facies, are shown to define the structure of the Iorokhan complex of minor intrusions; characteristic features of their composition and structural and tectonic settings of localization are given; geological and geochronological data are reported on their age (103 ± 1.0–97.4 ± 6.5 Ma), i.e. late Albian–early Cenomanian. By the ratio of alumina, calcium and alkalis, most of their compositions correspond to I-type high-alumina magnesia and magnesia-ferruginous varieties (A/CNK < 1.1) with low concentrations of HFSE, including HREE. Melting of an amphibolitic source rock produced a melt that could be a deep source of the Iorokhan diorites. A brief description of the Noni deposit is given and the main factors contributing to the localization of gold mineralization are considered. The ranges of the Iorokhan magmatites in the East Bureya volcano-plutonic zone can be considered as one of the fragments of the boundary structure between the continental margin of the eastern part of the Bureya massif and the accretionary wedges of the Sikhote-Alin orogenic belt. The Iorokhan complex of minor intrusions is assumed to be a small fragment of the wide belt of Late Albian–Early Cenomanian magmatite occurrence in the southern Far East of Russia, which formed in a setting of transform continental margin and zones of compression associated with extension resulting in the development of pull-apart basins typical of such margins.

scholarly journals Gold in Mineralized Volcanic Systems from the Lesser Khingan Range (Russian Far East): Textural Types, Composition and Possible Origins

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 103
Author(s):  
Nikolai Berdnikov ◽  
Victor Nevstruev ◽  
Pavel Kepezhinskas ◽  
Ivan Astapov ◽  
Natalia Konovalova
Keyword(s):  
Iron Oxide ◽  
Subduction Zones ◽  
Gold Mineralization ◽  
Russian Far East ◽  
Far East ◽  
Volcanic Rocks ◽  
Liquid Immiscibility ◽  
Explosive Volcanism ◽  
Deep Roots ◽  
Scientific Debate

While gold partitioning into hydrothermal fluids responsible for the formation of porphyry and epithermal deposits is currently well understood, its behavior during the differentiation of metal-rich silicate melts is still subject of an intense scientific debate. Typically, gold is scavenged into sulfides during crustal fractionation of sulfur-rich mafic to intermediate magmas and development of native forms and alloys of this important precious metal in igneous rocks and associated ores are still poorly documented. We present new data on gold (Cu-Ag-Au, Ni-Cu-Zn-Ag-Au, Ti-Cu-Ag-Au, Ag-Au) alloys from iron oxide deposits in the Lesser Khingan Range (LKR) of the Russian Far East. Gold alloy particles are from 10 to 100 µm in size and irregular to spherical in shape. Gold spherules were formed through silicate-metal liquid immiscibility and then injected into fissures surrounding the ascending melt column, or emplaced through a volcanic eruption. Presence of globular (occasionally with meniscus-like textures) Cu-O micro-inclusions in Cu-Ag-Au spherules confirms their crystallization from a metal melt via extremely fast cooling. Irregularly shaped Cu-Ag-Au particles were formed through hydrothermal alteration of gold-bearing volcanic rocks and ores. Association of primarily liquid Cu-Ag-Au spherules with iron-oxide mineralization in the LKR indicates possible involvement of silicate-metallic immiscibility and explosive volcanism in the formation of the Andean-type iron oxide gold-copper (IOCG) and related copper-gold porphyry deposits in the deeper parts of sub-volcanic epithermal systems. Thus, formation of gold alloys in deep roots of arc volcanoes may serve as a precursor and an exploration guide for high-grade epithermal gold mineralization at shallow structural levels of hydrothermal-volcanic environments in subduction zones.

How submarine channels (re)shape continental margins

2020 ◽  
Vol 90 (11) ◽  
pp. 1581-1600
Author(s):  
Luke A. Pettinga ◽  
Zane R. Jobe
Keyword(s):  
Continental Margin ◽  
Evolution Model ◽  
Sediment Supply ◽  
Tectonic Deformation ◽  
Continental Margins ◽  
Sedimentary Processes ◽  
Submarine Channels ◽  
Active Tectonic ◽  
Tectonic Settings ◽  
Longitudinal Profiles

ABSTRACT Submarine landscapes, like their terrestrial counterparts, are sculpted by autogenic sedimentary processes toward morphologies at equilibrium with their allogenic controls. While submarine channels and nearby, inter-channel continental-margin areas share boundary conditions (e.g., terrestrial sediment supply, tectonic deformation), there are significant differences between the style, recurrence, and magnitude of their respective autogenic sedimentary processes. We predict that these process-based differences affect the rates of geomorphic change and equilibrium (i.e., graded) morphologies of submarine-channel and continental-margin longitudinal profiles. To gain insight into this proposed relationship, we document, classify (using machine learning), and analyze longitudinal profiles from 50 siliciclastic continental margins and associated submarine channels which represent a range of sediment-supply regimes and tectonic settings. These profiles tend to evolve toward smooth, lower-gradient longitudinal profiles, and we created a “smoothness” metric as a proxy for the relative maturity of these profiles toward the idealized equilibrium profile. Generally, higher smoothness values occur in systems with larger sediment supply, and the smoothness of channels typically exceeds that of the associated continental margin. We propose that the high rates of erosion, bypass, and deposition via sediment gravity flows act to smooth and mature channel profiles more rapidly than the surrounding continental margin, which is dominated by less-energetic diffusive sedimentary processes. Additionally, tectonic deformation will act to reduce the smoothness of these longitudinal profiles. Importantly, the relationship between total sediment supply and the difference between smoothness values of associated continental margins and submarine channels (the “smoothness Δ”) follows separate trends in passive and active tectonic settings, which we attribute to the variability in relative rates of smoothness development between channelized and inter-channel environments in the presence or absence of tectonic deformation. We propose two endmember pathways by which continental margins and submarine channels coevolve towards their respective equilibrium profiles with increased sediment supply: 1) Coupled Evolution Model (common in passive tectonic settings), in which the smoothness Δ increases only slightly before remaining static, and 2) Decoupled Evolution Model (common in active tectonic settings), in which the smoothness Δ increases more rapidly and to a greater final value. Our analysis indicates that the interaction of the allogenic factors of sediment supply and tectonic deformation with the autogenic sedimentary processes characteristic of channelized and inter-channel areas of the continental margin may account for much of the variability between coevolution pathways and depositional architectures.

scholarly journals GEODYNAMICS AND MAGMATISM OF THE PACIFIC-TYPE TRANSFORM MARGINS. ASPECTS AND DISCRIMINANT DIAGRAMS

2021 ◽  
pp. 3-24
Author(s):  
A.V. Grebennikov ◽  
◽  
A.I. Khanchuk ◽  
Keyword(s):  
Continental Margin ◽  
Tectonic Setting ◽  
Island Arc ◽  
Igneous Rocks ◽  
High Alumina ◽  
Plate Boundaries ◽  
Spreading Ridge ◽  
Convergent Margins ◽  
Oceanic Plate ◽  
Plate Movement

Transform margins represent lithospheric plate boundaries with horizontal sliding of oceanic plate, which in time and space replaced the subduction related convergent margins. This happened due to: spreading ridge–trench intersection (California; Queen Charlotte–Northern Cordilleran, West of the Antarctic Peninsula, and probably the Late Miocene–Pleistocene Southernmost South America) or ridge death along continental margin (Baja California); change in the direction of oceanic plate movement (Western Aleutian–Komandorsk; Southernmost tip of the Andes); and island arc-continent collision (New Guinea Island). Post-subduction magmatism is related to a slab window that resulted either from the spreading ridge collision (subduction) with a continental margin or slab tear formation, or slab break-off after subduction cessation due to other reasons. Igneous magmatic series formed in consequence of these events show diversity of tholeiitic (sub-alkaline), alkaline or calc-alkaline, high-alumina and adakitic rocks. The comprehensive geochemical dataset (more than 2400 analyses) on igneous rocks of the model transform and convergent geodynamic settings allowed to substantiate the most informative triple diagrams for the petrogenic oxides TiO2 × 10 – Fe2O3Tot – MgO and trace elements Nb – La– Yb. Mostly approved for the rock compositions with SiO2 < 63 wt. %, the new plots are capable of distinguishing igneous rocks formed above zones of subduction at an island arc and continental margin (related to convergent margins), from those formed in the tectonic setting of transform margins along continents or island arcs.

The petrochemistry of the Lower Proterozoic metamorphic rocks from the Dabieshan-Lianyungang area, the southeastern margin of the North China Platform

1991 ◽  
Vol 55 (379) ◽  
pp. 263-276 ◽  
Author(s):  
Sang Longkang
Keyword(s):  
Continental Margin ◽  
North China ◽  
Active Continental Margin ◽  
The South ◽  
North China Platform ◽  
The North ◽  
Lower Proterozoic ◽  
Southeastern Margin ◽  
Tectonic Settings ◽  
North China Plate

AbstractBased on geological studies, 141 rock analyses and 5 trace element analyses of metabasites, the present paper deals with the rock association, chemical features, protolith formation and the original tectonic settings upwards through the Lower Proterozoic metamorphic strata in the Dabieshan-Lianyungang area, in the south-east of the North China Platform. The results of the study indicate that the lower and middle parts of the metamorphic strata comprise terrigenous clastics, phosphoritic and aluminous sedimentary formations which formed under stable continental margin conditions. In the middle-upper part a calc-alkaline volcano-sedimentary formation under the active continental margin was developed. The Lower Proterozoic meta-strata of sedimentary-volcanosedimentary origin from bottom upwards suggest that the tectonic evolution of the south-eastern margin of the North China Platform is a process from stabilization to mobilization. This process suggests a northward subduction of the Yangtze Plate under the North China Plate during the later part of the early Proterozoic.

scholarly journals Characteristic features of soybean varieties of the Khabarovsk selection

2020 ◽  
Author(s):  
О.Л. ШЕПЕЛЬ ◽  
В.О. КОМОЛЫХ ◽  
М.П. ЗВОЛИМБОВСКАЯ
Keyword(s):  
Far East ◽  
Comparative Assessment ◽  
High Tech ◽  
Monsoon Climate ◽  
Technological Parameters ◽  
East Region ◽  
The Far East ◽  
Characteristic Features ◽  
First Time ◽  
Research Institute

Приведена историческая справка по селекции сои в Дальневосточном научно-исследовательском институте сельского хозяйства, начиная с 1938 г. В 2018 г. впервые проведена сравнительная оценка сортов сои хабаровской селекции по биологическим и технологическим параметрам, изучен биохимический состав семян. Представлены сорта различного направления использования – пищевого, кормового, универсального. За годы успешной селекции создана линейка сортов с разным периодом вегетации – от среднескороспелых (Марината, Антон Толпышев) до среднепозднеспелых (Батя, Иван Караманов, Учитель); с высокой устойчивостью к полеганию (0 баллов) и имеющие прикрепление первого боба на высоте от 8,0 см и более. Среди сортов присутствуют как мелкосемянные (МОК, масса 1000 семян 79,5 г), так и крупносемянные (Учитель, масса 1000 семян 253,8 г). Высокое содержание белка отмечено у сортов Хабаровская 117 (42,1 %), Хабаровская 01 (41,3 %), Мария (40,9 %), Хабаровская 4 (40,7 %), ПИМ-95 (40,7 %), МОК (40,7 %), Учитель (40,3 %); среди кормовых сортов – у Черной кормовой (41,2 %) и Л-74-10 (40,7 %). Сорта Иван Караманов и Салтус рекомендуются как масличные. Сорта Локус, МОК, Пим-95, ВАЗ-100 пригодны для получения функциональных продуктов. Предлагаемые современные сорта сои ДВ НИИСХ в условиях муссонного климата обладают высокой продуктивностью, высокотехнологичны в производстве и являются основой для увеличения валового производства сои в Дальневосточном регионе. The historical information on soybean breeding at the Far East Research Institute of Agriculture, from 1938 to the present day, is provided. In 2018, for the first time, a comparative assessment of soybean varieties of the Khabarovsk selection by biological and technological parameters was carried out, the biochemical composition of seeds was studied. Varieties of various directions of use are presented – food, feed, universal. Over the years of successful breeding, a line of varieties with a different growing season has been created – from mid-season (Marinata, Anton Tolpyshev) to mid-late (Batya, Ivan Karamanov, Uchitel); with high resistance to lodging (0 points) and having the attachment of the first bean from 8.0 cm or more. Among the varieties there are both small-seeded (MOK, weight of 1000 seeds 79.5 g), and large-seeded (Uchitel, weight of 1000 seeds 253.8 g). High protein content was observed in the varieties Khabarovskaya 117 (42.1 %), Khabarovskaya 01 (41.3 %), Maria (40.9 %), Khabarovskaya 4 (40.7 %), PIM-95 (40.7 %), MOK (40.7 %), Uchitel (40.3 %); among fodder varieties – Black fodder (41.2 %) and L-74-10 (40.7 %). Varieties Ivan Karamanov and Saltus are recommended as oilseeds. Varieties Locus, MOK, Pim-95, VAZ-100 are suitable for obtaining functional products. The modern soybean varieties offered by the Far East Research Institute of Agriculture in the monsoon climate are highly productive, high-tech in production, and are the basis for increasing gross soybean production in the Far East Region.

scholarly journals Vendian-Cambrian granites of the Ufaley block (Middle Urals): a new isotope data, source composition, potential ore content

2020 ◽  
Vol 1 (2) ◽  
pp. 48-63
Author(s):  
Galina Yur’evna SHARDAKOV ◽  
◽  
Mariya Vladimirovna CHERVYAKOVSKAYA ◽  
Keyword(s):  
Gold Mineralization ◽  
Mobile Belt ◽  
Time Interval ◽  
Middle Urals ◽  
Junction Zone ◽  
East European ◽  
Icp Ms ◽  
Long Time ◽  
Deep Source ◽  
Composition Of Minerals

Relevance. The junction zone between the Uralian mobile belt (UMB) and the East European Platform (EEP) is long, heterogeneous and characterized by asynchrony in the geodynamic settings. For many of its constituent parts, the age, source composition and ore content of magmatic complexes, which are necessary to build a complete picture of geological history, are not completely clear. The aim of this work is to study petrogeochemistry, age, isotopic parameters, and reconstruction of the source composition for granites of the Bitim complex in the eastern part of the Ufaley block (Middle Urals). This structure is considered to be a fragment displaced from the EEP to the east. Research methodology. The analysis of rocks for petrogenic and rare components, microprobe studies of the composition of minerals and isotope studies of U–Pb, Lu–Hf (LA–ICP–MS) were performed. Petrocheochemical comparison was made, author’s data about Ar–Ar, Rb–Sr age and the behavior of Sr and Hf isotopes were analyzed. Results. Granitoids of the Bitim complex formed over a long time interval – 579–520 Ma, corresponding to the Upper Vendian (taking into account errors – to the boundary with the Cambrian). The isotopic labels of the studied granites are as follows: 87Sr/86Sr = 0.703389, εHf (t) is +1.5...+12.5, 176Hf/177Hf = 0.28253–0.282797. Conclusions. The geodynamics of the Vendian stage is the activation of movements along previously existing riftogenic faults. Deep source of magma generation for granites was heterogeneous: the mantle played a significant role, the crustal component was represented by ancient graywacks. U–Pb dating of zircons transformed as a result of the post-Cambrian tectonothermal activity is comparable with the ages of the main geodynamic events in UMM (spreading, subduction, collision). The behavior of F, Cl, S in apatites, which is an indicator of the fluid regime, shows that gold mineralization of the quartz-vein type can be associated with the Bitim granites. Studies are clarified the imagination about the structure of the junction zone between UMM and EEP and can be used in geological and metallogenic mapping.

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