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103.
Through the accurate determination of hypocenter location,the measurement of the main focal mechanism solutions and the analyses of time dependent processes for Sichuan Mianzhu earthquake sequence with Ms=5.0 occurred along the middle segment of Longmenshan fault zone on November 30,1999,the distribution of focal depth section,the stress relase and seismicity features are given to reveal the earthquake-geneating structure of the earthquake sequence.The obtained results show the activity features for this sequence as follows:(1) There is no obvious foreshock,the accumulated strain energy releases in nearly pulse way,fluctuation of the seismic activity level is not quite evident during the duration of the sequence,and the statistical relation between the large events and the small events is less compatible with the traditional G-R estimation;(2) The epicenters of the earthquake sequence are not distributed on the main Longmenshan piedmont faults emerging out ground,but near the hidden Longmenshan piedmont faults.The direction of epicenter distribution is not very coincident with the fault strikes.The microscopic epicenters are relatively far from the macroscopic epicenters,The focal depths range from 5km to 16km;(3) The fractures of focal fault plane with the NE strike appear out the strike-slip displacement with a few overthrust components under the major principal compressive stress of NNE direction.From these,we consider it should be paid more attentions to the underground hidden faults near the ground fault zone on a large scale for their generating earthquake risk. 相似文献
104.
大姚地热动态特征分析 总被引:3,自引:1,他引:3
通过大姚高精度水温观测井水地质、井孔条件的分析,震例观测资料、实验观测数据的处理,以及井水水质分析结果,表明大姚水温周期性变化的突出位置是井深75m左右,根本原因是该地层石膏脉稳定释热,含水层热水与井内冷水混合过程中,在通道内形成钙盐类沉淀物(如CaSO4CaCO3),堵塞对流通道,含水层内外压差突破被阻塞通道,热水反复侵入井内,便形成水温周期性变化。地震的孕育、发生和调整过程,由于应力场作用,产生附加地热场,水温基值发生变化,周期畸变或消失,这种附加地热动态是可以恢复的。所以认为大姚地热动态是井区特殊地层地热信息的反映。 相似文献
105.
D. Bocchiola C. Mihalcea G. Diolaiuti B. Mosconi C. Smiraglia R. Rosso 《Advances in water resources》2010
We develop a simple model to evaluate the daily flow discharges in the ablation season for the 11 km2 Pantano basin in the Retiche Italian Alps, based upon the data gathered during a three years field campaign. The Pantano basin embeds the Venerocolo debris covered and the Avio debris free glaciers, covering 2.14 km2 in the Adamello Group, where the widest Italian glacier Adamello is located. First, degree-day models based upon air temperature are tuned to calculate snow and ice melt at daily scale. Glaciers’ meteorological data are collected from an automatic weather station (AWS), operating on the glacier during summer 2007. The melt factors in the debris covered areas of the glacier are estimated against debris thickness, using a data driven parameterization. The flow discharge from the catchment is estimated using semi distributed flow routing for the ablation seasons of four years, from 2006 to 2009. The predicted discharges are compared to those derived from inverse reservoir's routing at the Benedetto lake, catching the basin outflow. The proposed approach is valuable as a tool to investigate the hydrology of poorly gauged glacierized areas, including those with debris covered ice, widely diffused and yet poorly understood. Pending accurate parameterization the approach is usable for water resources evaluation and for long term assessment of the climate change impact on the glacierized areas within the Alps. 相似文献
106.
克拉通边缘岩石圈金属再富集与金-钼-稀土元素成矿作用 总被引:5,自引:6,他引:5
克拉通是大规模成矿的重要构造环境,其边缘产出了众多世界级规模的金、钼、稀土元素矿床。然而,克拉通如何控制巨型矿床的形成与分布尚不十分清楚。文章基于作者和前人的研究成果,探讨了扬子和华北克拉通岩石圈早期金属富集与后期金属活化问题。在全球范围,多数克拉通在其形成之后长期保持稳定,但部分克拉通(如华北、扬子)在克拉通化之后又经历了早期(元古代)增生与晚期(中生代—新生代)改造。在克拉通化及其之后,处于克拉通边缘的大洋岩石圈或克拉通块体间的有限洋盆发生板片俯冲,释放出含金属组分(REE、Cu、Au)的富CO2流体,交代亏损的大陆岩石圈地幔(SCLM),并使之发生交代和金属再富集。俯冲诱发的弧岩浆在大陆下地壳底侵可形成新生下地壳,伴随着少量硫化物的堆积而发生金属(Au、Cu)再富集。由于克拉通相对稳定,新生下地壳在进变质脱水过程中仍能保存部分金属,释放的(含Au)变质流体很可能被封存或固结在地壳的某个部位。在克拉通破坏改造期,软流圈上涌改变克拉通SCLM热结构并诱发其部分熔融,产生富REE的碳酸岩熔体和富水的基性岩浆(如煌斑岩)。前者在浅部地壳侵位并出溶成矿流体,形成碳酸岩型REE矿床;后者在深部地壳脱挥发分(H2O+CO2),诱发新生下地壳重熔和含Au硫化物(和/或含Au流体囊)活化,形成富Au岩浆系统或流体系统。这些深地壳熔/流体沿克拉通边界或岩石圈不连续运移至上部地壳,岩浆系统直接出溶成矿流体,形成以斑岩体为中心的斑岩型Au矿,含Au富CO2流体流沿断裂网络系统活动并沉淀金属,形成石英脉型和蚀变岩型Au矿。伴随克拉通破坏改造,克拉通边界断裂或基底断裂重新活化,并诱发古老下地壳熔融,产生含Mo岩浆系统。这个理论框架不同于已有的造山带成矿理论模式,它解释了克拉通边缘异常富集Au、Mo、REE矿床及其成矿规律,可用于类似克拉通地区的成矿预测。 相似文献
107.
《Chemie der Erde / Geochemistry》2015,75(1):65-72
This study was conducted on recent desert samples—including (1) soils, (2) plants, (3) the shell, and (4) organic matter from modern specimens of the land snail Eremina desertorum—which were collected at several altitudes (316–360 m above sea level) from a site in the New Cairo Petrified Forest. The soils and shellE. desertorum were analyzed for carbonate composition and isotopic composition (δ18O, δ13C). The plants and organic matterE. desertorum were analyzed for organic carbon content and δ13C. The soil carbonate, consisting of calcite plus minor dolomite, has δ18O values from −3.19 to −1.78‰ and δ13C values −1.79 to −0.27‰; covariance between the two values accords with arid climatic conditions. The local plants include C3 and C4 types, with the latter being dominant. Each type has distinctive bulk organic carbon δ13C values: −26.51 to −25.36‰ for C3-type, and −13.74 to −12.43‰ for C4-type plants.The carbonate of the shellE. desertorum is composed of aragonite plus minor calcite, with relatively homogenous isotopic compositions (δ18Omean = −0.28 ± 0.22‰; δ13Cmean = −4.46 ± 0.58‰). Most of the δ18O values (based on a model for oxygen isotope fractionation in an aragonite-water system) are consistent with evaporated water signatures. The organic matterE. desertorum varies only slightly in bulk organic carbon δ13C values (−21.78 ± 1.20‰) and these values suggest that the snail consumed more of C3-type than C4-type plants. The overall offset in δ13C values (−17.32‰) observed between shellE. desertorum carbonate and organic matterE. desertorum exceeds the value expected for vegetation input, and implies that 30% of carbon in the shellE. desertorum carbonate comes from the consumption of limestone material. 相似文献
108.
《Geoforum》2015
This research addresses recent environmental governance in Bolivia through its relations to indigeneity and respatializations. It introduces and develops the concept of “speaking like an indigenous state” to examine the Bolivian state’s recent use of a pair of indigenous linguistic concepts, Living Well and Earth Mother, representing the identities of citizens and their rights to resources and livelihoods. State relations to indigenous social movements highlight the use of Living Well and Earth Mother concepts through accommodation, resistance, and protaganism. Six active issues of environmental governance are examined: (1) climate change and justice movement; (2) agrarian reform, agrobiodiversity, and food justice; (3) water resources; (4) indigenous territories; (5) Protected Areas; and (6) extractive industries (mining, hydrocarbons). The usages of Living Well and Earth Mother show versatility as they have been mobilized in the respatializing of the politics and social-power dynamics of environmental issues at scales of the state, global and international institutions, and community and local levels. Analysis also reveals deployment of Living Well and Earth Mother that is discursively influential and yet conceptually reduced and unevenly applied, thus suggesting a characteristic of verisimilitude. My analysis determines that respatialization at various levels, including territorial transitions of sub-national regional spaces, are associated with the heightened articulation of environmental governance through indigeneity and “speaking like an indigenous state” amid resource nationalism. Linkages and logics operating within this conjuncture differ from the prevailing interpretation of the Bolivian state’s use of Living Well and Earth Mother as solely an unwitting contradiction or instrumentalist camouflage. 相似文献
109.
从生态学和地理学的角度提出“水土流失带”的概念,及其在城市边缘地区的分布,剖析了它的空间结构,物质组成结构,指出其域界范围,宽度、“环状”;分布,垂直结构特征及物质组成结构的多元性。 相似文献
110.
新疆旅游资源的类型、等级及空间分布特征 总被引:2,自引:3,他引:2
在全面掌握新疆旅游资源的实查资料基础上,对全疆旅游资源做系统分类与定量评价,总结其类型、等级和空间分布特征,并从新疆地理环境变迁和多民族、多文化的社会环境两方面分析新疆高品质旅游资源的成因。结果表明:新疆旅游资源类型多样,与全国相比,主类、亚类齐全,基本类型占66.5%;八大类中建筑与设施和地文景观的种类较丰富;建筑与设施类景点最多,水域风光和生物景观次之;新疆旅游资源等级较高,优良级占43.6%,整体为中间大两头小的谷仓型结构;高等级集中于凸峰、观光游憩湖区、林地、草地、野生动物栖息地、废城与聚落地、石窟、边境口岸、特色街巷、传统手工产品与制品、民间演艺等类;空间分布呈现为三带两环状和六点状集聚特征,这与新疆地貌格局和高品质景点的聚群作用有关;新疆自然旅游资源是整个地理环境演变过程的产物;而多民族、多文化的社会环境是人文类的主要成因。 相似文献