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Secondary alteration of minerals in basalts of the Evevpenta gold occurrence(North Kamchatka， Russia) as indicators of ore forming processes

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地学前缘 2023年

作者： Anastasiya Sergeeva Pavel Zhegunov Elena Skilskaia Mariya Nazarova Elena Kartasheva Anna Kuzmina Svetlana Moskaleva Olesya Zobenko Sharapat Kudaeva Ekaterina Plutakhina Kseniya Shishkanova institute of volcanology and seismology， Far Eastern Branch， Russian Academy of Sciences

This paper describes in detail the mineralogy of the propylitic alteration of basalt host rocks in the Evevpenta gold occurrence in North Kamchatka. The vein system of the Evevpenta consists of quartz， adularia-quartz， quartz-carbonate veins， and， hydrothermal breccias hosted in dacite. Vein minerals are native gold， tellurides， sulfides， selenides， Au-Ag chlorides. The propylitic alteration occurs at a distance from the epithermal veins; however， it contains characteristic mineral assemblages useful for the reconstruction of an ore-formation environment. Four distinct hydrothermal alteration assemblages were recognized within the propylitic zone in this study: (1) Fluorapatite-fluorine-aluminous titanite， (2) Quartz-calcite-clinochlore， (3) Quartz-calcite-stilbite-montmorillonite， and 4. Calcite-mordenite. The earliest mineral assemblage was formed from an acid F-enriched hydrothermal fluid. The concentration of fluoride in fluid was 0.2–1.2 g/L， and temperature of about 550 ℃. The long-term interaction between the acid hydrothermal fluid and olivine basalt host rocks resulted in increasing pH to near neutral that caused chloritization process. The chloritization stage hydrothermal fluid was enriched in Fe and Mg with temperatures of about 175–210℃， chlorite I， and 120–140℃， chlorite II. The final stage of alteration consists of zeolite group minerals， which were precipitated from the hydrothermal fluid of pH ～ 9 and temperature >135℃. The high pH of the hydrothermal fluid could be explained by the presence of bicarbonates and carbonates and removal of the iron salt from the solution. Based on the alteration mineral assemblages of the propylitic zone， the physical and chemical conditions of the Evevpenta vein system are discussed. The transport of ore elements took place due to the formation of precious metal Cl–and OH–complexes at the stage of hydrothermal system formation with circulation of alkaline sodium chloride solutions. Chalcogens were also transferred by

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GPS time-series and its response to M_S=8.1 Kunlunshan earthquake

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Acta Seismologica Sinica(English Edition) 2005年第4期18卷 419-426,499页

作者：敬少群吴云乔学军周硕愚施顺英 institute of seismology China Earthquake Administration

In this paper, observation data in 25 GPS reference stations of China have been analyzed by calculating GPS position coordinate time-series with GIPSY. Result shows there is an obvious trend variation in such time-series. The trend variations of time series along the longitude and latitude coordinate reflect the motion of each position in the global-plate, in which the trend variation in the vertical direction reveals some large-scale construction information or reflects the local movement around the positions. The analysis also shows that such time-series have a variation cycle of nearly 1.02 a, but the reason still remains to be further studied. At the end of this paper, response of the time-series to MS=8.1 Kunlunshan earthquake was analyzed, and the seismogenic process of MS=8.1 Kunlunshan earthquake, according to the time proceeding and the feature of anomaly, was divided into 3 phases-changes in blocks with forces, strain accumulation, quick accumulation and slow release of energy. At the initial stage of seismogenic process of MS=8.1 earthquake and at the imminent earthquake, coseismic process as well as during the post earthquake recovery, anomaly in vertical direction is always in a majority. The anomalous movement in vertical direction at the initial stage resulted in a blocking between faults, while at the middle stage of seismogenic process, the differential movement between blocks are in a majority, which is the major reason causing energy accumulating at the blocking stage of faults.

关键词： GPS time-series trend variation periodic variation seismogenic process blocking between faults energy accumulation

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Analysis of Some Characteristics of the Fault Activities in Eastern China by Satellite Images

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Acta Geologica Sinica(English Edition) 1991年第4期65卷 357-369,457-458页

作者： Xie Guanglin institute of seismology,State Seismological Bureau institute of seismology State Seismological Bureau

Active faults have special electromagnetic effect and remote sensing characteristics, and exhibit unique im-agery marks in satellite images. A comprehensive comparison of images of active faults in eastern China and ananalysis of geologic and geomorphic data can tell us some characteristics of fault activity in the area during theneotectonic period: 1) The fault activities of the north-south tectonic zone, North China and Taiwan werestronger than those of southeastern and northeastern China; 2) the faulting in the north-south tectonic zone,North China and Taiwan has continued up to now, and most of the fault activites in southeastern andnorth-eastern China have become weaker since the Middle Pleistocene; 3) the activity is unsteady in time, mostbeing intermittent, or episodic, i.e. alternately strong and weak; 4) most active faults of a definite size can be di-vided into several segments which somewhat differ from each other in the characteristics of the activity.

关键词： Analysis of Some Characteristics of the Fault Activities in Eastern China by Satellite Images

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Seismic evaluation of rocking structures through performance assessment and fragility analysis

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Earthquake Engineering and Engineering Vibration 2016年第1期15卷 115-127页

作者： Mohammad G. Vetr Abolfazl Riahi Nouri Afshin Kalantari International institute of Earthquake Engineering and seismology (IIEES) Tehran Iran

Numerical studies have been conducted for low- and medium-rise rocking structures to investigate their efficiency as earthquake-resisting systems in comparison with conventional structures. Several non-linear time-history analyses have been performed to evaluate seismic performance of selected cases at desired ground shaking levels, based on key parameters such as total and flexural story drifts and residual deformations. The Far-field record set is selected as input ground motions and median peak values of key parameters are taken as best estimates of system response. In addition, in order to evaluate the probability of exceeding relevant damage states, analytical fragility curves have been developed based on the results of the incremental dynamic analysis procedure. Small exceedance probabilities and acceptable margins against collapse, together with minor associated damages in main structural members, can be considered as superior seismic performance for medium-rise rocking systems. Low-rise rocking systems could provide significant performance improvement over their conventional counterparts notwithstanding certain weaknesses in their seismic response.

关键词： rocking structures conventional structures seismic performance fragility curves

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3-D velocity structure in the central-eastern part of Qilianshan

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Acta Seismologica Sinica(English Edition) 2004年第3期17卷 272-281页

作者： ZHANG Yuan-sheng(张元生) ZHOU Min-du(周民都) RONG Dai-lu(荣代潞) ZHANG Li-guang(张立光) XU Zhong-qiu(许中秋) Lanzhou institute of seismology China Earthquake Administration Lanzhou 730000 China Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China Earthquake Administration of Lanzhou City Lanzhou 730000 China

The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the digital seismic network set up for a Sino-French cooperation program since 1996. The inversed velocity structure does primarily reflect some important features of the deep structure in the region and provide the scientific background for the further study of active tectonic structure and the calculation of earthquake parameters.

关键词： central-eastern Qilianshan micro-earthquake observation 3-D velocity structure focal pa-rameters joint inversion

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Application of perfectly matched layer to soil-foundation interaction analysis

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 753-768页

作者： Mohammad Davoodi Abbas Pourdeilami Hosein Jahankhah Mohammad Kazem Jafari International institute of Earthquake Engineering and seismology TehranIran

Despite of the limitation in modeling infinite space, the finite element method(FEM) is one of the most used tools to numerically study the geotechnical problems regarding the capacity of simulating different geometries, conditions and material behaviors. A kind of absorbing layer named perfectly matched layer(PML) has been applied to modeling the radiation damping using FEM, which makes the dynamic analysis of soil-structure interaction more accurate. The PML is capable of absorbing incident waves under any angle and frequency, ensuring them to pass through the model boundaries without *** this context, a new FEM program has been written and the PML formula has been implemented by rewriting the dynamic equation of motion and deriving new properties for the quadrilateral *** analysis of soil-foundation interaction by applying the PML is validated by the evaluation of impedance/compliance functions for different ground conditions. The results obtained from the PML model match the extended mesh results, even though the domain is small enough that other types of absorbing boundaries can reflect waves back to the foundation. The mechanism of the wave propagation in the region shows that the forced vibrations can be fully absorbed and damped by the boundaries surrounded by PMLs which is the role of radiation damping in FEM modeling.

关键词： Perfectly matched layer (PML) Finite element method (FEM) Wave propagation Impedance/compliance

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Identification of expected seismic activity areas by forecasting complex seismic-mode parameters in Uzbekistan

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Geodesy and Geodynamics 2018年第2期9卷 121-130页

作者： T.U.Artikov R.S.Ibragimov T.L.Ibragimova M.A.Mirzaev institute of seismology

In this paper, the author proposed a methodology to reveal expected seismic activation places for coming years by a complex of forecasting parameters of a seismic mode. Areas in Uzbekistan where currently observed anomalies in various parameters of a seismic mode has been revealed. By number of displayed abnormal signs the areas has been ranked based on probability of occurrence of strong earthquakes there. It has prepared schemes of the synoptic forecast of expected seismic activation places in case of occurrence of strong earthquakes in the Central-Asian region.

关键词： Long-term forecast of earthquakes Parameters of seismic mode Seismic activity Seismic gap

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Pattern recognition of seismogenic nodes using Kohonen selforganizing map: example in west and south west of Alborz region in Iran

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Earthquake Science 2017年第3期30卷 145-155页

作者： Mostafa Allamehzadeh Soma Durudi Leila Mahshadnia seismology Department International Institute of Earthquake Engineering and SeismologyIIEES

Pattern recognition of seismic and mor- phostructural nodes plays an important role in seismic hazard assessment. This is a known fact in seismology that tectonic nodes are prone areas to large earthquake and have this potential. They are identified by morphostructural analysis. In this study, the Alborz region has considered as studied case and locations of future events are forecast based on Kohonen Self-Organized Neural Network. It has been shown how it can predict the location of earthquake, and identifies seismogenic nodes which are prone to earthquake of M5.5＋ at the West of Alborz in Iran by using International institute Earthquake Engineering and seismology earthquake catalogs data. First, the main faults and tectonic lineaments have been identified based on MZ （land zoning method） method. After that, by using pattern recognition, we generalized past recorded events to future in order to show the region of probable future earthquakes. In other word, hazardous nodes have determined among all nodes by new catalog generated Self-organizing feature maps （SOFM）. Our input data are extracted from catalog, consists longitude and latitude of past event between 1980-2015 with magnitude larger or equal to 4.5. It has concluded node D1 is candidate for big earthquakes in comparison with other nodes and other nodes are in lower levels of this potential.

关键词： Clustering - Earthquake prediction ~ Self-organizing feature maps (SOFM)

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Revealing the seismicity increase in interrelationships in various seismic zones in Uzbekistan as a case study

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Geodesy and Geodynamics 2015年第5期6卷 351-360页

作者： Artifeou T.U. Ibragimov R.S. Ibragimova T.L. Mirzaev M.A. Artikov M.T. institute of seismology

A new research method was developed to investigate the influence of an increase in seismicity from one zone on the increase in other zones nearby. By applying the developed method to each main seismic zone in Uzbekistan, we specify the external seismic zone activation, which has the greatest impact on activation within the research zone. We also identify each external seismic zone characterized by high seismic activity and large seismic potential that has the greatest impact on each seismic zone in Uzbekistan.

关键词： External seismic zoneInternal seismic zoneSeismicitySeismic energyEarthquakeInterrelationship

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Effects of basement structural and stratigraphic heritages on volcano behaviour and implications for human activities （the IGCP project 455）

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Episodes 2005年第3期28卷 158-170页

作者： Alessandro Tibaldi Alfredo Mahar F. A. Lagmaye Vera V. Ponomareva Università degli Studi di Milano-Bicocca Dipartimento di Scienze Geologiche e Geotecnologie Milan Italy National institute of Geological Sciences Quezon City Philippines institute of volcanology and seismology Petropavlovsk-Kamchatsky Russia

The IGCP project 455 （2001-2005） is intended to con- tribute to the comprehension of volcano behaviour in different geodynamic settings from a poorly known perspective： the reciprocal influence exerted by volcanoes on their substrate and by the basement on the volcanoes. The main task is to assess the role of this influence in determining natural geological hazards such as eruptions, landslides and earthquakes. The geologic-tectonic control of the substrate on the volcanoes has been usually considered questionable or less important than the conditions of the deep magma source, whereas the control of volcanoes on their basement has even received very little attention. This project improves the comprehension of these phenomena by a strong interdisciplinary approach that ties data on the various geological conditions and heritages of the basement with the deformation processes and geological evolution of different volcanic edifices. We compiled stratigraphic, structural, geomorphological, geophysical, geotechnical, petrographic, geochemical and geochronological data. These data have been transferred to the laboratory-working groups, thus providing realistic numerical and physical simulation even of complex geological structures. Here we present a selection of the main results obtained for some of the studied key volcanoes. Alicudi （Italy） located in a low-tectonic rate setting, Stromboli （Italy） in extensional tectonic setting, Reventador （Ecuador） in compressional setting, and the Northern Volcanic Group of Kamchatka （Russia）, Galeras （Colombia） and Mayon （Philippines） in a transtensional setting.

关键词：火山地层地质条件人类活动

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