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Martirosyan  A.  Balassanian  S.  Simonian  R.  Asatryan  L. 《Natural Hazards》1999,20(1):1-20
As a result of work carried out during the first two stages of the Global Seismic Hazard Assessment Program (GSHAP) for the Test Area Caucasus, a uniform earthquake catalogue was compiled and a Seismic Source Zones Model was designed. At the final stage of the program, the computation of seismic hazard was done by different methods.The results of a computation done using the Probabilistic Seismic Hazard Assessment methodology, as well as primary intermediate steps and preparatory work are given in the present paper. Peak horizontal ground acceleration is chosen as the parameter representing seismic hazard. Final computer calculations were done with the SEISRISK III program. The two final Seismic Hazard maps for different return periods are presented. The work was carried out at the National Survey for Seismic Protection of the Republic of Armenia.  相似文献   

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The profile of geoconservation is now higher than ever before with a significant number of people employed worldwide within geoconservation or having an element of it included within their role. Sixty years ago, employment within geoconservation, and even geoconservation itself, were largely unheard of. In 1950, an experienced geologist in his late 50s, William Archibald Macfadyen, ‘Macfadyen’ or ‘Mac’ to his colleagues, became the first full-time professional geoconservationist. After serving in two World Wars and enjoying a long career working as a geologist and hydrogeologist in the Middle East and Africa, he was employed by the newly created government conservation agency in Great Britain, the Nature Conservancy. His role was to help implement new national nature conservation legislation that included the conservation of geological and geomorphological features. Between 1950 and 1960, Macfadyen pioneered geoconservation, working to interpret and implement the new legislation to protect a series of geological and geomorphological sites across Great Britain. Working largely alone he visited, and scheduled for protection, a series of well over 600 sites, developed records to support their conservation, addressed practical conservation issues relating to site damage and enhancement, established a geological advisory committee to support his work, published an account of some of the sites protected and successfully applied his geological expertise to wider issues relating to wildlife conservation. He undoubtedly built the foundations of geoconservation in Great Britain, and in doing so influenced its development worldwide. It is argued here that Macfadyen is worthy of recognition as the ‘father of geoconservation’.  相似文献   

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Post-Wealden dinosaur remains are rare in the UK, so any material from late Early or Late Cretaceous deposits is potentially of palaeoecological and palaeobiogeographical significance. Four dinosaur specimens collected from the Woburn Sands Formation (Aptian) of Upware, Cambridgeshire were described briefly by Walter Keeping in 1883, but have not been reappraised since. These specimens are identified herein as a ?turiasaurian sauropod tooth and indeterminate iguanodontian ornithopod remains (a tooth, middle caudal vertebra, pollex ungual). Although collected from the Woburn Sands Formation, it is likely that all of these fossils were reworked from older (now absent) sediments and they have usually been regarded as either ‘Wealden’ or Neocomian in age, presumably due to previous identifications of some of these specimens as Iguanodon. However, consideration of UK dinosaur faunas and regional geology indicates that these fossils could potentially be older. Further work is needed on the derived terrestrial fossils of the Lower Greensand Group in order to constrain their ages more precisely so that they can be incorporated into broader studies of regional diversity and palaeoecology.  相似文献   

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Pentanogmius Taverne (Actinopterygii: Tselfatiiformes) is a Late Cretaceous bony fish. Here, the diagnosis for the genus is emended and a new species, P. fritschi sp. nov., described. The new species is based on a nearly complete skeleton from the Britton Formation (upper Cenomanian–lower Turonian) of the Eagle Ford Shale in Dallas County, Texas, USA. The skeleton measures about 1.7 m in total length and represents the sole Cenomanian–Turonian example of Pentanogmius in North America. The most peculiar aspect of this new species is the morphology of the dorsal fin in which its anterior one-third is elongate to form a ‘hook-shaped sail.’ Pentanogmius fritschi sp. nov. was likely an active swimmer in open ocean environments that possibly fed opportunistically on a variety of relatively small pelagic fishes and invertebrates. The present stratigraphic record and anatomical evidence indicate the following phylogenetic hypothesis among the three North American Pentanogmius species: [P. fritschi sp. nov. [P. evolutus + P. crieleyi]].  相似文献   

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Comprehensive studies of cores from 7 boreholes drilled in the Pal’yanovo area provided insight into the Bazhenovo Horizon in southwestern Siberia represented by the lower subformation of the Tutleim Formation. The work presents a typification of organic-rich biogenic-terrigenous rocks. The Bazhenovo Horizon is divided into 11 lithotypes grouped into 5 large members. Members I?IV correspond to the lower subformation of the Tutleim Formation; member V, to the upper subformation. The identified members are traced explicitly over the Pal’yanovo area, making it possible to examine the whole vertical succession of the Tutleim Formation and reconstruct its evolution based on the proposed sedimentation model.  相似文献   

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<正>The Tengchong geothermal area,an active tectonic region with frequent earthquakes,is located in Yunnan Province of southwestern China.This area contains abundant active hot springs, which often display high metal concentrations and obvious mineralization phenomena.At 19:19 on 9 July 2009,an earthquake occurred in Yao'an,Chuxiong,Yunnan Province,which is 300 km to the northeast of the Tengchong geothermal area.We sampled water in the hot springs in the Tengchong area from 4 July to 9 July 2009 and from 10 July to 15 July 2009 to study the changes of elemental concentrations before and after the earthquake and discuss the influence of the earthquake on the mineralization of the hot springs.The concentrations of most trace elements increased slightly,but the concentration of REE(rare earth elements) decreased by 50%after the earthquake in the hot springs around a NS-trending fault.The elemental concentrations remained unchanged in Longtan and Suanshuigou,which are related to an inactive crater.The elemental concentrations in other springs controlled by superficial and small-scale faults decreased after the earthquake.The earthquake can stimulate the activity of deep faults and magma chambers,as is responsible for the increase of metal concentrations in the hot springs along the NS-trending deep fault;whereas it can decrease the porosity of permeable rocks,resulting in the decline of the flux of ore-bearing fluids and the corresponding mineralization in the hot springs related to superficial faults.  相似文献   

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In the year of 2011, a super-large molybdenum deposit was discovered in the Shapinggou area, Jinzhai county, Anhui Province by the Bureau of Geology and Mineral Exploration of Anhui Province, with its reserve more than 2.2 million ton, just next to the Klimax molybdenum deposit (>3.3 million ton) in Colorado. It has ranged the world’s second largest molybdenum deposit, with potential economic value up to 100 billion dollars. Geological surveys suggest orebodies from the Shapinggou porphyry molybdenum deposit extend 1000 m long by up to 900 m wide. A drillhole intersects one orebody as thick as 945 m, with 0.2 wt% Mo. This entire deposit suggests 332+333 ore reserve as 1.275 billion ton and Mo metal reserve as 2 million ton; this does not include the reserves of the east-west ends. Based on the current exploration work, a total Mo metal reserve of 2.2 million ton can be accomplished. The Shapinggou molybdenum deposit is characterized by its large scale, high grade, concentrated orebodies and high economic value. The Shapinggou porphyry molybdenum deposit is the largest metal deposits during the 50 years’ prospecting history in Anhui Province. Its discovery rewrites China’s history of “no large-scale deposit in the eastern Dabie Mountains”, and validates that the Qinling-Dabie orogenic belt is the most significant Au-Mo metallogenic belt.  相似文献   

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In the Southwestern Tianshan, the geologic ages of many strata and their depositional environments are still poorly constrained because of complex structures. The Mada’er area is located in the Kuokesaleling belt, Southwestern Tianshan. The cherts from the former Wupata’erkan Group contain abundant radiolarian fossils, including 10 species which are identified as late Devonian to early Carboniferous in age. Eleven chert samples have SiO2 contents ranging from 88.80 wt% to 93.28 wt%, and 2.02 wt% to 3.72 wt% for Al2O3. The SiO2/Al2O3 ratios of all samples vary from 23.84 to 46.11, much lower than those of the pure cherts (80–1400). These values suggest that the cherts contain high ratios of terrigenous materials. The Al2O3/(Al2O3+Fe2O3) ratios vary between 0.64 and 0.77, whereas V and Cu concentrations range from 10.92 ppm to 26.7 ppm and from 2.15 ppm to 34.1 ppm respectively. The Ti/V ratios vary from 25.53 to 44.93. The total REE concentrations of the cherts are between 30.78 ppm and 59.26 ppm, averaging 45.46 ppm. The (La/Ce)N ratios range from 0.81 to 1.12, and 0.88–1.33 for (La/Yb)N, averaging 1.09, which suggests a continental margin environment. Consequently, it is inferred that the cherts formed in a residual sea environment during the late Devonian to early Carboniferous time, which suggests that the collision between the Karakum-Tarim and Kazakhstan-Junggar plates did not occur at the time. In addition, the regional geological information indicates that the study area experienced a post-collision stage during the early Permian, and thus it is likely that the collision between the two plates took place in the late Carboniferous.  相似文献   

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In the southwestern Tianshan,the geologic ages of many strata and their depositional environments are still poorly constrained because of complex structures.The Mada'er area is located in the Kuokesaleling belt,Southwestern Tianshan.The cherts from the former Wupata'erkan Group contain abundant radiolarian fossils,including 10 species which are identified as late Devonian to early Carboniferous in age.Eleven chert samples have SiO_2 contents ranging from 88.80 wt%to 93.28 wt%, and 2.02 wt%to 3.72 wt%for ...  相似文献   

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The revival of ethnic identities and the search for historical roots have been significant factors in re-shaping the map of the world in the late twentieth century. Multi-ethnic states have come under increasing strain throughout the century and undermining the concept of the nation-state. However, the successor states to the colonial empires in Africa exhibit the same strains as the often highly fragile successors to the European continental empires earlier in the century. The survival of these quasi-states has been dependent upon the support of the international community for over thirty years as a reaction to the era of colonialism. Anti-colonialism offers little practical support for states in a post-colonial, post-Cold War era. In some cases the result has been disintegration and the emergence of the collapsed state. The revived political movements aimed at democratisation and self-determination have unleashed forces which may be incompatible with the survival of the current state system.  相似文献   

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An analysis of drill cores and well logs shows that the main micro-facies of the third member sand bodies of the Qingshankou Formation in Qian’an are subaqueous distributary channel facies, sheet sand facies and subaqueous fan facies (olistostrome). Maps showing the distribution of these micro-facies together with inter-channel bay and prodelta mocro-facies are presented for different time-slices (lower, middle and upper parts of the Qingshankou Formation). These maps reveal the instability and change of sediment transport in the Baokang sedimentary system during the depositional period. Sediment transport was from the west in the early stage, from the south in the middle stage and from the northwest in the late stage. Values of thickness, porosity and permeability of the sand bodies in the third member of the Qingshankou Formation show that they have low to medium porosity and low permeability, and are characterized by serious reservoir heterogeneity. The joints between micro-facies and subaqueous fan micro-facies are characterized by the highest heterogeneity, the sheet sand and distal sand bar subfacies come next, and the heterogeneity of the subaqueous distributary channel sand bodies is relatively weak.  相似文献   

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Based on the CCD images,IIM data and DEM data of China's lunar exploration project (Chang'E-Ⅰ) and related processed and analytic results,an integrated study of regional geology of Sinus Iridum and its adjacent area was conducted,and a series of relevant researches and analyses were carried out,including analysis of impact craters and their extrusive and accumulative materials,division of stratigraphic and tectonic units and classification of rock types,integrated analysis of chronology and lunar evolution history.In consideration of crater's shape features,quantity and preserving status of filling materials,the lunar impact craters can be divided into 7 types and 11 subtypes,and the accumulative materials of craters are divided into 6 types and 9 accumulative groups.According to the content and distribution of TiO2 and image characteristics,the basalts are divided into high-TiO2,medium-TiO2 and low-TiO2 basalts.Discussion was made on division of tectonic units and evolution features in the study area.The geological map of the Sinus Iridum Quadrangle (LQ-4) at a scale of 1∶2.5 M was preliminarily compiled with the ArcGIS system,and the spatial database of the map was established.Related technical specification,procedure and method for lunar geological mapping have been worked out,so as to lay a foundation for the forthcoming geological mapping of the global Moon in China by using the data of Chang'E-Ⅱ and also for comprehensive study and geological mapping of other celestial bodies in the future.  相似文献   

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The basement of the central Qilian fold belt exposed along the Minhe-Ledu highway consists of psammitic schists, metabasitic rocks, and crystalline limestone. Migmatitic rocks occur sporadically among psammitic schist and metabasitic rocks. The mineral assemblage of psammitic schist is muscovite + biotite + feldspar + quartz ± tourmaline ± titanite ± sillimanite and that of metabasitic rocks is amphibole + plagioclase + biotite ± apatite ± magnetite ± pyroxene ± garnet ± quartz. The migmatitic rock consists of leucosome and restite of various volume proportions; the former consists of muscovite + alkaline feldspar + quartz ± garnet ± plagioclase while the latter is either fragments of psammitic schist or those of metabasitic rock. The crystalline limestone consists of calcite that has been partly replaced by olivine. The olivine was subsequently altered to serpentine. Weak deformations as indicated by cleavages and fractures were imposed prominently on the psammitic schists, occasionally on me  相似文献   

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