A 450-ka long record of glaciation in Northern Mongolia based on studies at Lake Khubsugul: high-resolution reflection seismic data and grain-size variations in cored sediments     

Andrey Petrovich Fedotov  Michael A. Phedorin  Mark De Batist  Galina A. Ziborova  Alexsey Yu Kazansky  Michael Yu Semenov  Galina G. Matasova  Andrey V. Khabuev  Sergey A. Kugakolov  Sergey V. Rodyakin  Svetlana M. Krapivina  Tom Pouls 《Journal of Paleolimnology》2008,39(3):335-348

We use high-resolution reflection seismic data and detailed grain-size analysis of a drill core (KDP-01) from Lake Khubsugul (northern Mongolia) to provide an improved reconstruction of the glacial history of the area for the last 450 ka. Grain-size analysis of suspended sediment load in modern rivers draining into the lake and of moraine material from the northern part of the catchment shows that the silt fraction is transported to the central part of the lake mainly by river suspension, whereas the clay fraction is mainly transported by glacial meltwater during deglaciation. The changes in of the clay/silt ratio in Lake Khubsugul sediments correlates well with the standard global paleoclimate records: low clay/silt ratios indicate warm climates, while a high clay/silt ratio reflects glacial erosion and cold climates. Pulses of clay input into the lake occur at the final stages of glacial periods (i.e., glacial maxima and subsequent onsets of deglaciation). The periodicity in glacial clay input in Lake Khubsugul is in tune with global periods of deglaciation, but there are differences in the intensity of the deglacial events for MIS-12 and MIS-2. These differences are attributed to specific conditions in regional distribution of moisture during glaciation, glacial ice volumes, and solar insolation intensity at the onset of deglaciation. Deglaciation of the Khubsugul glaciers occurred in response to an increase in summer solar insolation above a threshold value of 490 W/m². Two types of deglaciation can be distinguished: (1) slow melting during several tens of 1,000 years during weak increases in summer insolation, and (2) short and fast melting during several thousands of years in response to strong increases in summer insolation. The maximum ice volume in the area of Lake Khubsugul during the past 450 ka occurred during the period of 373–350 ka BP (MIS 11a-10) and was caused by high levels of moisture in the region, whereas the MIS-2 and MIS-12 glacial periods were characterized by minima in ice volume, due to the strong aridity in the region.  相似文献   

Gold fineness and Au/Ag ratios of pyrite-containing ores as additional indicators of physico-chemical conditions of hydrothermal ore formation     

Galina Palyanova 《Journal of Geochemical Exploration》2009

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Middle to late Pleistocene record of explosive volcanic eruptions in marine sediments offshore Kamchatka (Meiji Rise,NW Pacific)     

Alexander N. Derkachev  Sergey A. Gorbarenko  Vera V. Ponomareva  Maxim V. Portnyagin  Galina I. Malakhova  Yanguang Liu 《第四纪科学杂志》2020,35(1-2):362-379

This paper presents the first detailed study of a late Pleistocene marine tephra sequence from the NW Pacific, downwind from the Kamchatka volcanic arc. Sediment core SO201-2-40, located on the Meiji Rise ~400 km offshore the peninsula, includes 25 tephras deposited within the last 215 ka. Volcanic glass from the tephras was characterized using single-shard electron microprobe analysis and laser ablation inductively coupled mass spectrometry. The age of tephras was derived from a new age model based on paleomagnetic and paleoclimate studies. Geochemical correlation of distal tephras to Kamchatkan pyroclastic deposits allowed the identification of tephras from the Karymsky, Gorely, Opala and Shiveluch eruptive centers. Three of these tephras were also correlated to other marine and terrestrial sites and hence are identified as the best markers for the north-west Pacific region. These are an early Holocene tephra from the Karymsky caldera (~8.7 ka) and two tephras falling into the Marine Isotope Stage (MIS) 6 glacial time: an MIS 6.4 tephra from Shiveluch (~141 ka) and the MIS 6.5 Rauchua tephra (~175 ka) from Karymsky. The data presented in this study can be used in paleovolcanological and paleoceanographic reconstructions.  相似文献   

Air recirculation and ventilation in the coastal regions of the Black Sea     

Galina Surkova 《Central European Journal of Geosciences》2013,5(2):196-207

An initial investigation of recirculation is carried out for the coast of the Black Sea. The local mesoscale circulations (land-sea breezes, mountain and valley winds) in coastal areas are shown to be an additional risk factor in creating favorable conditions for air stagnation and accumulation of air pollutants in the surface atmosphere layer. Two types of annual recirculation patterns are revealed for northern and north-eastern coast of the Black Sea. Long-term changes in recirculation are investigated. It is shown that the recirculation parameter values remained quasistable until the mid-1970s. Since 1976–1977, steady intensification of recirculation in both winter and summer is identified.  相似文献   

New seismic array solution for earthquake observations and hydropower plant health monitoring     

Galina N. Antonovskaya  Natalya K. Kapustian  Alexander I. Moshkunov  Alexey V. Danilov  Konstantin A. Moshkunov 《Journal of Seismology》2017,21(5):1039-1053

We present the novel fusion of seismic safety monitoring data of the hydropower plant in Chirkey (Caucasus Mountains, Russia). This includes new hardware solutions and observation methods, along with technical limitations for three types of applications: (a) seismic monitoring of the Chirkey reservoir area, (b) structure monitoring of the dam, and (c) monitoring of turbine vibrations. Previous observations and data processing for health monitoring do not include complex data analysis, while the new system is more rational and less expensive. The key new feature of the new system is remote monitoring of turbine vibration. A comparison of the data obtained at the test facilities and by hydropower plant inspection with remote sensors enables early detection of hazardous hydrodynamic phenomena.  相似文献   

Landslides triggered by the 1949 Khait earthquake, Tajikistan, and associated loss of life   总被引：3，自引：0，他引：3  

Stephen G. Evans  Nicholas J. Roberts  Anatoli Ischuk  Keith B. Delaney  Galina S. Morozova  Olga Tutubalina 《Engineering Geology》2009,109(3-4):195-212

Earthquake-triggered landslides are a major geological hazard in Central Asia. In July 1949, the M7.4 Khait earthquake triggered many hundreds of landslides in a mountainous region near the southern limit of the Tien Shan Mountains, central Tajikistan. These landslides involved widespread rock-slope failure as well as large numbers of flowslides in loess that mantles the steep slopes of the region. In the Yasman valley hundreds of loess landslides coalesced to form a massive loess flow (est. vol. 245 Mm³) that travelled up to 20 km on a slope of only 2°. In an adjacent valley, the Khait landslide involved transformation of an earthquake-triggered rockslide into a very rapid flow by the entrainment of saturated loess into its movement. It travelled 7.41 km over a vertical distance of 1421 m with an estimated average velocity of ~30 m/s. We estimate its volume as 75 Mm³, an order of magnitude less that previously published estimates. The Khait landslide was simulated using DAN. The number of casualties due to earthquake-triggered landslides in the epicentral region was considerable. Approximately 4000 people were killed in the Yasman valley loess flow as 20 villages (kishlaks) were overwhelmed. In the Khait landslide alone we estimate ca. 800 people lost their lives when the villages of Khait and Khisorak were overrun by rapidly moving debris. Our data indicates that a total of approximately 7200 people were killed by earthquake-triggered landslides in the epicentral region of the Khait earthquake and that, in terms of loss of life, the 1949 Yasman valley loess flow was one of the most destructive landslides in recent history.  相似文献   

Mineral inclusions in sublithospheric diamonds from Collier 4 kimberlite pipe, Juina, Brazil: subducted protoliths, carbonated melts and primary kimberlite magmatism   总被引：5，自引：3，他引：2  

Galina P. Bulanova  Michael J. Walter  Chris B. Smith  Simon C. Kohn  Lora S. Armstrong  Jon Blundy  Luiz Gobbo 《Contributions to Mineralogy and Petrology》2010,160(4):489-510

We report on a suite of diamonds from the Cretaceous Collier 4 kimberlite pipe, Juina, Brazil, that are predominantly nitrogen-free type II crystals showing complex internal growth structures. Syngenetic mineral inclusions comprise calcium- and titanium-rich phases with perovskite stoichiometry, Ca-rich majoritic-garnet, clinopyroxene, olivine, TAPP phase, minerals with stoichiometries of CAS and K-hollandite phases, SiO₂, FeO, native iron, low-Ni sulfides, and Ca–Mg-carbonate. We divide the diamonds into three groups on the basis of the carbon isotope compositions (δ¹³C) of diamond core zones. Group 1 diamonds have heavy, mantle-like δ¹³C (−5 to −10‰) with mineral inclusions indicating a transition zone origin from mafic protoliths. Group 2 diamonds have intermediate δ¹³C (−12 to −15‰), with inclusion compositions indicating crystallization from near-primary and differentiated carbonated melts derived from oceanic crust in the deep upper mantle or transition zone. A ²⁰⁶Pb/²³⁸U age of 101 ± 7 Ma on a CaTiSi-perovskite inclusion (Group 2) is close to the kimberlite emplacement time (93.1 ± 1.5 Ma). Group 3 diamonds have extremely light δ¹³C (−25‰), and host inclusions have compositions akin to high-pressure–temperature phases expected to be stable in pelagic sediments subducted to transition zone depths. Collectively, the Collier 4 diamonds and their inclusions indicate multi-stage, polybaric growth histories in dynamically changing chemical environments. The young inclusion age, the ubiquitous chemical and isotopic characteristics indicative of subducted materials, and the regional tectonic history, suggest a model in which generation of sublithospheric diamonds and their inclusions, and the proto-kimberlite magmas, are related genetically, temporally and geographically to the interaction of subducted lithosphere and a Cretaceous plume.  相似文献   

Mobility and retention of heavy metals, arsenic and sulphur in podzols at eight locations in northern Finland and Norway and the western half of the Russian Kola Peninsula     

Marja Liisa Räisänen  Galina Kashulina  Igor Bogatyrev 《Journal of Geochemical Exploration》1997,59(3):175-195

The mobility and retention of heavy metals, arsenic and sulphur in podzols from eight areas located north of the Arctic Circle in Finland, Norway and Russia were determined by analyzing the < 2.0 mm fraction, using an ammonium acetate (pH 4.5) extraction in addition to a concentrated nitric acid digestion for the humus samples, and a hot aqua regia digestion for the mineral soil samples. Total C, H and N concentrations were determined in humus and mineral soil samples with a CHN analyser.Ni, Cu, Co and As were strongly enriched in the humus layer in the contaminated sites (Monchegorsk, Kurka, Zapoljarnij) when compared to their concentrations in the parent tills and in podzols from the background sites. In most study sites the illuvial layer showed a low capacity to retain the metals and As, the exception included a strongly eroded profile at Monchegorsk, where Ni was tightly fixed in the illuvial layer while Cu was mobile. In contrast to metals, airborne S was not accumulated in the humus layer, but was accumulated in the illuvial layer, more markedly at eroded sites than in places where the humus was covered as at Monchegorsk.  相似文献   

Estimation and evaluation of real-time precipitable water vapor from GLONASS and GPS   总被引：1，自引：0，他引：1  

Cuixian Lu  Xingxing Li  Maorong Ge  Robert Heinkelmann  Tobias Nilsson  Benedikt Soja  Galina Dick  Harald Schuh 《GPS Solutions》2016,20(4):703-713

The revitalized Russian GLONASS system provides new potential for real-time retrieval of zenith tropospheric delays (ZTD) and precipitable water vapor (PWV) in order to support time-critical meteorological applications such as nowcasting or severe weather event monitoring. In this study, we develop a method of real-time ZTD/PWV retrieval based on GLONASS and/or GPS observations. The performance of ZTD and PWV derived from GLONASS data using real-time precise point positioning (PPP) technique is carefully investigated and evaluated. The potential of combining GLONASS and GPS data for ZTD/PWV retrieving is assessed as well. The GLONASS and GPS observations of about half a year for 80 globally distributed stations from the IGS (International GNSS Service) network are processed. The results show that the real-time GLONASS ZTD series agree quite well with the GPS ZTD series in general: the RMS of ZTD differences is about 8 mm (about 1.2 mm in PWV). Furthermore, for an inter-technique validation, the real-time ZTD estimated from GLONASS-only, GPS-only, and the GPS/GLONASS combined solutions are compared with those derived from very long baseline interferometry (VLBI) at colocated GNSS/VLBI stations. The comparison shows that GLONASS can contribute to real-time meteorological applications, with almost the same accuracy as GPS. More accurate and reliable water vapor values, about 1.5–2.3 mm in PWV, can be achieved when GLONASS observations are combined with the GPS ones in the real-time PPP data processing. The comparison with radiosonde data further confirms the performance of GLONASS-derived real-time PWV and the benefit of adding GLONASS to stand-alone GPS processing.  相似文献   

Interim IAGOD Conference on “Metallogeny of the Pacific Northwest： Tectonics, Magmatism, and Metallogeny of Active Continental Margins”     

Dr.Galina A. Gonevchuk Dr. Reimar Seltmann 《《幕》》2005,28(3):215-217

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