Touhuanping Fault, an active wrench fault within fold-and-thrust belt in northwestern Taiwan, documented by spatial analysis of fluvial terraces     

Yoko Ota  Yu-Nung Nina Lin  Yue-Gau Chen  Nobuhisa Matsuta  Takuya Watanuki  Ya-Wen Chen 《Tectonophysics》2009,474(3-4):559-570

This study aims at the recent activity and development of an active wrench fault, the Touhuanping Fault in northwestern Taiwan. Northwestern Taiwan has been proposed in a current situation between the mature to waning collision in terms of tectonic evolution. The main drainage in this area, the Chungkang River, flows close to the trace of the fault mentioned above. We examined various types of deformation of fluvial terraces along the Chungkang River as a key to understanding the nature and rate of the late Quaternary tectonics. The E–W trending Touhuanping Fault has long been mapped as a geological boundary fault, but its recent activity was suspected. Field survey revealed that its late Quaternary activity is recorded in the offset fluvial terraces. Our result shows dextral slip and vertical offset with upthrown side on the south, and activated at least twice since the emergence of terrace 4 (older terrace 3 with OSL date of ca. 80 ka). Total amount of offset recorded in the Touhuanping terrace sequence is 15 m for dextral and 10 m for vertical offset. Estimated recurrence time of earthquake rupture may be a few tens of thousand years. Uplift on the upthrown side of the Touhuanping Fault also resulted in the formation of drowned valleys which were graded to terrace 4. Other deformation features, such as back-tilting, westward warping, and a range-facing straight scarp, were also identified. A second-order anticline roughly parallel to the Touhuanping Fault is suggested to be the origin of the northward tilting on terrace 3; it could have resulted from a flower structure on the Touhuanping Fault at shallow depth. This may demonstrate that the buried segment of the Touhuanping Fault has also been active since 80 ka. In the northern study area, the westward warping at terrace 2 probably represents late Quaternary activity of another NE–SW trending Hsincheng Fault.  相似文献   

地裂缝场地地铁隧道地震动力响应的振动台试验研究   总被引：1，自引：1，他引：0  

黄强兵  高欢  刘妮娜  马玉杰 《地质力学学报》2018,24(6):785-794

以西安轨道交通3号线地铁隧道近距离通过地裂缝场地为工程背景,采用几何比1:30的大型振动台模型试验,研究不同地震波作用下通过地裂缝带上盘场地地铁隧道的地震动力响应。试验结果表明:地裂缝场地上盘加速度响应表现出明显的放大效应;浅埋地铁隧道对地震波在土层中的传播具有一定阻碍作用,而隧道两侧拱腰位置围岩土层加速度放大效应最强;隧道特征部位PGA放大系数拱腰最大,拱底次之,拱顶最小,其中靠近地裂缝侧拱腰的PGA放大系数大于远离一侧;地裂缝附近动土压力增量明显增加,而靠近隧道附近,动土压力增量明显降低;地震作用下隧道通过地裂缝场地上下盘出现差异沉降,地表出现多条与地裂缝近似平行和正交的裂缝;隧道环向受剪切作用在靠近地裂缝一侧的拱肩部位环向应变最大,而隧道轴向受挤压作用在左右拱腰处应变出现最大值。研究结果可为地裂缝场地地铁隧道结构抗震设计与防灾减灾提供重要科学参考与借鉴。   相似文献   

Assessment of hydrogeochemistry and contamination of Varamin deep aquifer,Tehran Province,Iran     

Nina Mahmoudi  Mohammad Nakhaei  Jahangir Porhemmat 《Environmental Earth Sciences》2017,76(10):370

The present study investigates the hydrogeochemistry and contamination of Varamin deep aquifer located in the southeast of Tehran province, Iran. The study also evaluates groundwater suitability for irrigation uses. The hydrogeochemical study was conducted by collecting and analyzing 154 groundwater samples seasonally during 2014. Based on evolutionary sequence of Chebotarev, the aquifer is in the stage of SO₄ + HCO₃ in the north half of the plain and it has evolved into SO₄ + Cl in the south half. The unusual increase in TDS and Cl^? toward the western boundaries of the aquifer indicates some anomalies. These anomalies have originated from discharge of untreated wastewater of Tehran city in these areas. The studied aquifer contains four dominant groundwater types including Na–Ca–SO₄ (55%), Na–Ca–HCO₃ (22%), Na–Cl (13%) and Ca–Cl (10%). The spatial distributions of Na–Cl and Ca–Cl water types coincide with observed anomalies. Ionic relationships of SO₄ ^2? versus Cl^? and Na⁺ versus Cl^? confirm that water–rock interaction and anthropogenic contribution are main sources of these ions in the groundwater. The main processes governing the chemistry of the groundwater are the dissolution of calcite, dolomite and gypsum along the flow path, and direct ion exchange. Reverse ion exchange controls the groundwater chemistry in the areas contaminated with untreated wastewater. Based on Na% and SAR, 10.3 and 27% of water samples are unsuitable for irrigation purposes, respectively. Regarding residual sodium carbonate, there is no treat for crop yields. Only 6% of water samples represent magnesium adsorption ratios more than 50% which are harmful and unsuitable for irrigation.  相似文献   

The effect of decrease in salinity on the dynamics of abundance and the cell size of <Emphasis Type="Italic">Corethron Hystrix</Emphasis> (Bacillariophyta) in laboratory culture     

Nina A. Aizdaicher  Zhanna V. Markina 《Ocean Science Journal》2010,45(1):1-5

Effect of salinity on abundance dynamics and cell size of microalga Corethron hystrix Hensen (Bacillariophyta) were studied. C. hystrix can normally grow within a rather narrow salinity range between 32 and 28‰. The viable cells of this microalga change their morphological characters at a salinity of 24‰. This salinity level probably marks the beginning of cell division restriction, because the general number of cells by the end of the experiment was lower than in the control. The decrease of salinity to 16‰ caused pronounced irreversible morphological changes: cell height increased, chloroplasts compressed, protoplasm became granular, cytoplasm retracted, and spines shortened.  相似文献   

Influence of atmospheric circulation on precipitation in Altai Mountains   总被引：2，自引：0，他引：2  

Natalia Malygina  Tatiana Papina  Nina Kononova  Tatiana Barlyaeva 《山地科学学报》2017,14(1):46-59

We analyzed the changes in precipitation regime in the Altai Mountains for 1959-2014 and estimate the influence of atmospheric circulations on these changes. Our study showed that during last 56 years the changes in the precipitation regime had a positive trend for the warm seasons(April-October),but weakly positive or negative trends for the cold seasons(November-March). It was found that these changes correspond to the decreasing contribution of “Northern meridional and Stationary anticyclone(Nm-Sa)” and “Northern meridional and East zonal(Nm-Ez)” circulation groups and to the increasing contribution of “West zonal and Southern meridional(Wz-Sm)” circulation groups,accordingly to the Dzerdzeevskii classification. In addition,it was found that the variation of precipitation has a step change point in 1980. For the warm seasons,the precipitation change at this point is associated with the reduced influence of “West zonal(Wz)”,“Northern meridional and Stationary anticyclone(Nm-Sa)” and “Northern meridional and Southern meridional(Nm-Sm)” circulation groups. For the cold seasons,a substantialincrease of “Wz-Sm” and a decrease of “Nm-Sa”,“Nm-Ez” circulation groups are responsible for the precipitation change in the two time periods(1959-1980 and 1981-2014).  相似文献   

Three New Stoneflies (Insecta: Plecoptera) from the Yixian Formation of Liaoning, China   总被引：1，自引：1，他引：0  

LIU Yushuang  REN Dong  Nina D. SINITSHENKOVA  SHIH Chungkun 《《地质学报》英文版》2008,82(2):249-256

Three new genera and species Archaeoperla rarissimus gen. et sp. nov. （Perlidae）, Liaotaenionema tenuitibia gen. et sp. nov. （Taeniopterygidae） and Parvinemoura parvus gen. et sp. nov. （？Nemouridae） are described and illustrated. All of them were collected from Yixian Formation of the western Liaoning, China. Hitherto, A. rarissimus is the oldest species possessing typical characters of Perlidae; the finding of L. tenuitibia indicates taeniopterygids once lived in the northeastern China in the late Mesozoic, but frequent volcanic activities, climate changes, or other environmental changes might have resulted in the disappearance of Taeniopterygidae in northern China after Mesozoic. Ancestral groups of Nemouridae have been abundant from Middle Jurassic, and male genitalia of P. parvus gen. et sp. nov. has been developed and similar to extant Nemouridae in the late Mesozoic. The stonefly fossils found from Yixian Formation are not divers at the species level, but rich at the family level. The diversity of stonefly implies different microclimate existed in the northeastern China at that time. A large old lacustrine basin existed in the western Liaoning, surrounded by hygrophilous plants on swampland and lake shore, warm and humid; tall arbor and boscage on the hillside nearby, mild and dry; mountains in the distance, rivulets running among the mountains, cool and wet. Many insects, prefer cool climate （e.g. stonefly, raphidiopterans, et ai.）, lived in the mountains with rivulets.  相似文献   

Boron metasomatism and behaviour of rare earth elements during formation of tourmaline rocks in the eastern Arunta Inlier,central Australia     

Raith  Johann G.  Riemer  née Schöner  Nina  Meisel  Thomas 《Contributions to Mineralogy and Petrology》2004,147(1):91-109

Tourmaline rocks of previously unclear genesis and spatially associated with W- (Cu)-bearing calc-silicate rocks occur in Palaeoproterozoic supracrustal and felsic intrusive rocks in the Bonya Hills in the eastern Arunta Inlier, central Australia. Tourmalinisation of metapelitic host rocks postdates the peak of regional low-pressure metamorphism (M₁/D₁, ~500 °C, ~0.2 GPa), and occurred synkinematically between the two main deformation events D₁ and D₂, coeval with emplacement of Late Strangways (~1.73 Ga) tourmaline-bearing leucogranites and pegmatites. Tourmaline is classified as schorl to dravite in tourmaline–quartz rocks and surrounding tourmaline-rich alteration zones, and as Fe-rich schorl to foitite in the leucogranites. Boron metasomatism resulted in systematic depletion of K, Li, Rb, Cs, Mn and enrichment of B, and in some samples of Na and Ca, in the tourmaline rocks compared to unaltered metasedimentary host rocks. Whole-rock REE concentrations and patterns of unaltered schist, tourmalinised schist and tourmaline–quartz veins—the latter were the zones of influx of the boron-rich hydrothermal fluid—are comparable to those of post-Archaean shales. Thus, the whole-rock REE patterns of these rocks are mostly controlled by the metapelitic precursor. In contrast, REE concentrations of leucogranitic rocks are low (10 times chondritic), and their flat REE patterns with pronounced negative Eu anomalies are typical for fractionated granitic melts coexisting with a fluid phase. REE patterns for tourmalines separated from metapelite-hosted tourmaline–quartz veins and tourmaline-bearing granites are very different from one another but each tourmaline pattern mirrors the REE distribution of its immediate host rock. Tourmalines occurring in tourmaline–quartz veins within tourmalinised metasediments have LREE-enriched (La_N/Yb_N=6.3–55), shale-like patterns with higher REE (54–108 ppm). In contrast, those formed in evolved leucogranites exhibit flat REE patterns (La_N/Yb_N=1.0–5.6) with pronounced negative Eu anomalies and are lower in REE (5.6–30 ppm). We therefore conclude that REE concentrations and patterns of tourmaline from the different tourmaline rocks studied are controlled by the host rock and not by the hydrothermal fluid causing boron metasomatism. From the similarity of the REE pattern of separated tourmaline with the host rock, we further conclude that incorporation of REEs in tourmaline is not intrinsically controlled (i.e. by crystal chemical factors). Tourmaline does not preferentially fractionate specific REEs or groups of REEs during crystallisation from evolved boron- and fluid-rich granitic melts or during alteration of clastic metasediments by boron-rich magmatic-hydrothermal fluids.Editorial responsibility: J. Hoefs  相似文献   

A hybrid coordinate ocean model for shelf sea simulation   总被引：1，自引：0，他引：1  

Nina Gjerde Winther  Geir Evensen   《Ocean Modelling》2006,13(3-4):221-237

The general circulation in the North Sea and Skagerrak is simulated using the hybrid coordinate ocean model (HYCOM). Although HYCOM was originally developed for simulations of the open ocean, it has a design which should make it applicable also for coastal and shallow shelf seas. Thus, the objective of this study has been to examine the skills of the present version of HYCOM in a coastal shelf application, and to identify the areas where HYCOM needs to be further developed. To demonstrate the capability of the vertical coordinate in HYCOM, three experiments with different configurations of the vertical coordinate were carried out. In general, the results from these experiments compares quite well with in situ and satellite data, and the water masses and the general circulation in the North Sea and Skagerrak is reproduced in the simulations. Differences between the three experiments are small compared to other errors, which are related to a combined effect of model setup and properties of the vertical mixing scheme. Hence, it is difficult to quantify which vertical coordinate configuration works best for the coastal region. It is concluded that HYCOM can be used for simulations of coastal and shelf seas, and further suggestions for improving the model results are given. Since HYCOM also works well in open ocean and basin scale simulations, it may allow for a realistic modelling of the transition region between the open ocean and coastal shelf seas.  相似文献   

The Nature of Decision Making in the Practice of Dwelling: A Practice Theoretical Approach to Understanding Maintenance and Retrofitting of Homes in the Context of Climate Change     

Håkon Fyhn  Nina Baron 《社会与自然资源》2017,30(5):555-568

In order to make existing private housing more energy efficient, various policies aim at influencing decisions made by homeowners regarding renovation and retrofitting in Scandinavia. Presenting two case studies from Denmark and Norway, we take one step back and observe the whole process of keeping a home habitable. Inspired by theories of Tim Ingold and Elizabeth Shove, we suggest calling this process “the practice of dwelling.” Rather than focusing on decisions and acts pertaining to retrofitting alone, we observe how maintenance and retrofitting are parts of an ongoing practice of dwelling. The cases demonstrate how decisions can be understood as embedded in the practice of dwelling, and how a readiness for decisions regarding retrofitting is created, or not, in this practice. We suggest shifting focus from the outcome of decisions, to attention toward the process that leads to readiness for making the decision in the first place.  相似文献   

Inhomogeneities in the circumstellar envelope of the A0E herbig star AB aur     

Nina Beskrovnaya  Mikhail Pogodin  Ivan Najdenov  Iosiff Romanyuk 《Astrophysics and Space Science》1995,224(1-2):429-430

Simultaneous high-resolution spectroscopy in H andUBVRI polarimetric observations are proposed as an effective method for the search for circumstellar inhomogeneities in A0-type Herbig stars. The new results for AB Aur are presented as a successful example of the use of this method. The analysis of about 100 CCD H profiles (R = 30 000) and more than 150 polarimetric measurements obtained in January, 1994 allowed to discover a long-lived stream-like inhomogeneity in the circumstellar gaseous envelope.  相似文献