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201.
从旅游产品生命周期理论出发,对我国著名风景名胜区云台山进行实证研究。通过研究云台山景区的主要指标的演变过程,分析探讨了云台山生命周期的发展轨迹。研究结果表明,云台山风景区已经历了旅游产品生命周期的导入期和成长期,目前已步入旅游产品生命周期的成熟阶段,为使其生命周期控制在理想阶段,此时,云台山应在充分发挥自身优势的同时,根据旅游市场变化趋势,通过优化现有产品、整合现有资源、区域合作、开发新产品、开拓新市场、大力发展旅游相关服务等措施提高市场竞争力,延长成熟期。  相似文献   
202.
利用遥感技术对澳大利亚芒特艾萨地区铜多金属矿的遥感地质特征进行研究。根据ETM遥感影像数据,对芒特艾萨地区的遥感地质矿产解译,总结和分析该区区域地层、构造和岩浆岩的影像特征。在解剖芒特艾萨铜矿等3处典型铜多金属矿床的基础上,分析各控矿要素的遥感影像特征,初步建立了该类型铜多金属矿的遥感地质找矿模型。根据找矿模型圈定1处遥感地质特征相符的找矿远景区。通过遥感影像数据研究,划分和进一步缩少找矿靶区,对减少境外矿产投资的盲目性具有一定的指导意义。  相似文献   
203.
A field investigation on Quaternary glacial landforms in Laoshan Mountain has discovered many glacial potholes, scouring grooves on top of granite ridges, and large boulders. These erosional landforms were formed by the meltwater from the overlying ice cap, suggesting that there was at least an ice cap covering Laoshan Mountain and the surrounding areas or even a continental ice sheet over the vast area of Shandong Province in the Late Pleistocene. The ice sheet was obstructed by the Laoshan Mountain, Dazhu Mountain and Xiaozhu Mountain in the coastal areas as it moved toward the Yellow Sea. The ice flows eroded the bedrock and carved the weak intersection of the fault systems in the NE and NW directions into a deep channel, which gradually formed a fjord in the area of the Jiaozhou Bay basin by 20.00 ka BP. The seawater gradually invaded the fjord from the beginning of the Holocene (11.00 ka BP) and Jiaozhou Bay was eventually formed. Similar fjords are easily found along the east of China and they share a similar origin because of the Quaternary glaciation in the region.  相似文献   
204.
Impacts of Yulong Mountain Glacier on Tourism in Lijiang   总被引:3,自引:1,他引:2  
Introduction The mountain tourism has been repeatedly identified as potentially vulnerable to global climate change and has received greater research attention. Implications of climate change can be seen, for example, in less snow, receding glaciers, melt…  相似文献   
205.
Glaciovolcanic deposits are critical for documenting the presence and thickness of terrestrial ice-sheets, and for testing hypotheses about inferred terrestrial ice volumes based on the marine record. Deposits formed by the coincidence of volcanism and ice at the Mount Edziza volcanic complex (MEVC) in northern British Columbia, Canada, preserve an important record for documenting local and possibly regional ice dynamics. Pillow Ridge, located at the northwestern end of the MEVC, formed by ice-confined, fissure-fed eruptions. It comprises predominantly pillow lavas and volcanic breccias of alkaline basalt composition, with subordinate finer-grained volcaniclastic deposits and dykes. The ridge is presently  4 km long,  1000 m in maximum width, and  600 m high. Fifteen syn- and post-eruptive lithofacies are recognized in excellent exposures along the glacially dissected western side of the ridge. We recognize five lithofacies associations: (1) poorly sorted tuff breccia and dykes, (2) proximal pillow lava, dykes and tuff breccia, (3) distal pillow lava, poorly sorted conglomerate and well-sorted volcanic sandstone, (4) interbedded tuff, lapilli tuff, and tuff breccia units, and (5) heterolithic volcanogenic conglomerate and sandstone. Given the abundance of pillow lavas and the lack of surrounding topographic barriers capable of impounding water, we agree with Souther [Souther, J.G., 1992. The late Cenozoic Mount Edziza volcanic complex. Geol. Soc. Can. Mem., vol. 420. 320 pp] that the bulk of the edifice formed while confined by ice, but have found evidence for a more complex and variable eruption history than that which he proposed. Preliminary estimates of water-ice depths derived from FTIR analyses of H2O give ranges of 300 to 680 m assuming 0 ppm CO2, and 857 to 1297 m assuming 25 ppm CO2. Variations in depth estimates among samples may indicate that water/ice depths changed during the evolution of the ridge, which is consistent with our interpretations for the origins of different lithofacies associations. Given that the age of the units are likely to be ca. 0.9 Ma [Souther, J.G., 1992. The late Cenozoic Mount Edziza volcanic complex. Geol. Soc. Can. Mem., vol. 420. 320 pp], Pillow Ridge may be the best documentation of a regional high stand of the Cordilleran Ice Sheet (CIS) in the middle Pleistocene, and an excellent example of the lithofacies and stratigraphic complexities produced by variations in water levels during a prolonged glaciovolcanic eruption.  相似文献   
206.
The ca. 8800 14C yrs BP Sulphur Creek lava flowed eastward 12 km from the Schriebers Meadow cinder cone into the Baker River valley, on the southeast flank of Mount Baker volcano. The compositionally-zoned basaltic to basaltic andesite lava entered, crossed and partially filled the 2-km-wide and > 100-m-deep early Holocene remnant of Glacial Lake Baker. The valley is now submerged beneath a reservoir, but seasonal drawdown permits study of the distal entrant lava. As a lava volume that may have been as much as 180 × 106 m3 entered the lake, the flow invaded the lacustrine sequence and extended to the opposite (east) side of the drowned Baker River valley. The volume and mobility of the lava can be attributed to a high flux rate, a prolonged eruption, or both. Basalt exposed below the former level of the remnant glacial lake is glassy or microcrystalline and sparsely vesicular, with pervasive hackly or blocky fractures. Together with pseudopillow fractures, these features reflect fracturing normal to penetrative thermal fronts and quenching by water. A fine-grained hyaloclastite facies was probably formed during quench fragmentation or isolated magma-water explosions. Although the structures closely resemble those developed in lava-ice contact environments, establishing the depositional environment for lava exhibiting similar intense fracturing should be confirmed by geologic evidence rather than by internal structure alone. The lava also invaded the lacustrine sequence, forming varieties of peperite, including sills that are conformable within the invaded strata and resemble volcaniclastic breccias. The peperite is generally fragmental and clast- or matrix-supported; fine-grained and rounded fluidal margins occur locally. The lava formed a thickened subaqueous plug that, as the lake drained in the mid-Holocene, was exposed to erosion. The Baker River then cut a 52-m-deep gorge through the shattered, highly erodible basalt.  相似文献   
207.
Glaciers are of crucial importance for the livelihood of the local populations, which depend on their meltwater for water and energy supplies. For this reason, seasonal variations of oxygen‐18 of glacial stream water and their sources within a small glacial catchment in south western China were investigated during the wet season. The results showed significant difference of oxygen‐18 existed among meltwater, rainwater, ground water and stream water, and significantly seasonal variation of precipitation occurred during the observed period. The streamflow of Baishui catchment was separated into components of ice‐snowmelt and precipitation using oxygen‐18. As shown by the result of the two‐component mixing model, on average, 53.4% of the runoff came from ice‐snowmelt during the wet season, whereas the remaining 46.6% were contributed by precipitation in the catchment. According to monthly hydrograph, the contribution of snow and glacier meltwater varied from 40.7% to 62.2%, and that of precipitation varied from 37.8% to 59.3% in wet season. Uncertainties for this separation were mainly caused by the variation of tracer concentrations. The roles of glacier and snow meltwater should be noticed in water resource management in those glacial regions in south western China. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
208.
云南省玉龙雪山表土花粉垂直散布与植被关系研究   总被引:4,自引:4,他引:0       下载免费PDF全文
对云南省玉龙雪山地区8个垂直植被带下采集的49个表土样品进行表土孢粉的垂直散布研究,同时选择43个受人类活动干扰较少的样品和20个主要木本花粉类型进行了降维对应分析(DCA)。结果表明,玉龙雪山地区不同垂直植被带的孢粉组合具有不同的代表性成分与变化特征,能够较好地反映相应的植被带类型。在植物稀疏、花粉产量低的高山杜鹃灌丛植被带中,孢粉组合以外来的松属、冷杉属、落叶松属、云杉属和铁杉属等为主;   冷杉林、落叶松林、云杉林和铁杉林等植被带孢粉组合的指示性成分分别是冷杉属、落叶松属、云杉属和铁杉属花粉,它们对应的峰值分别为13.6%,4.7%,39.4%和11.5%;   针阔混交林、中山湿性常绿阔叶林的孢粉组合分别以高含量的常绿栎类、栲/石栎属为特征,并都含有多种落叶阔叶乔木和灌木的花粉,但后者比前者所包含的阔叶乔木与灌木成分更多,且蕨类孢子的峰值也出现在中山湿性常绿阔叶林中;   云南松林的孢粉组合中除松属外很少有木本花粉出现。DCA排序结果较好地反映了现代植被与环境之间的相互关系,认为温度是决定不同植被带样点分布的最重要因素,这与垂直植被带随着海拔升高、温度逐渐降低而发生更替的规律是一致的。  相似文献   
209.
Strontium, Nd, Pb, Hf, Os, and O isotope compositions for 30 Quaternary lava flows from the Mount Adams stratovolcano and its basaltic periphery in the Cascade arc, southern Washington, USA indicate a major component from intraplate mantle sources, a relatively small subduction component, and interaction with young mafic crust at depth. Major- and trace-element patterns for Mount Adams lavas are distinct from the rear-arc Simcoe volcanic field and other nearby volcanic centers in the Cascade arc such as Mount St. Helens. Radiogenic isotope (Sr, Nd, Pb, and Hf) compositions do not correlate with geochemical indicators of slab-fluids such as (Sr/P) n and Ba/Nb. Mass-balance modeling calculations, coupled with trace-element and isotopic data, indicate that although the mantle source for the calc-alkaline Adams basalts has been modified with a fluid derived from subducted sediment, the extent of modification is significantly less than what is documented in the southern Cascades. The isotopic and trace-element compositions of most Mount Adams lavas require the presence of enriched and depleted mantle sources, and based on volume-weighted chemical and isotopic compositions for Mount Adams lavas through time, an intraplate mantle source contributed the major magmatic mass of the system. Generation of basaltic andesites to dacites at Mount Adams occurred by assimilation and fractional crystallization in the lower crust, but wholesale crustal melting did not occur. Most lavas have Tb/Yb ratios that are significantly higher than those of MORB, which is consistent with partial melting of the mantle in the presence of residual garnet. δ 18O values for olivine phenocrysts in Mount Adams lavas are within the range of typical upper mantle peridotites, precluding involvement of upper crustal sedimentary material or accreted terrane during magma ascent. The restricted Nd and Hf isotope compositions of Mount Adams lavas indicate that these isotope systems are insensitive to crustal interaction in this juvenile arc, in stark contrast to Os isotopes, which are highly sensitive to interaction with young, mafic material in the lower crust.  相似文献   
210.
Although major crustal lineaments may play an important role in mineralisation, the relationship between lineaments and mineral deposits can be quite cryptic, and structural controls may vary as a function of scale along lineaments. Major lineaments alone may be of limited use for detailed target generation. The Cloncurry Lineament in the Eastern part of the Mount Isa Inlier is a crustal scale structure defined by potential field-derived ‘worms’. Weights-of-evidence quantifies the association between mineral occurrences and this lineament. Autocorrelation is used to recognise structural controls on mineralisation at different scales, by progressively limiting the lengths of the vectors between mineral occurrence points in the autocorrelation plot. The weights-of-evidence analysis shows that Au, Au–Cu, Cu–Au and Cu deposits have a positive spatial correlation to the Cloncurry Lineament, which suggests it that acted as a primary crustal scale control on the localisation of Cu and Au through focussing mineralisation systems on a broad scale. However, autocorrelation defines a variety of local structural controls, which can be interpreted as shear zones, variably oriented fault sets, en echelon fault arrays, and potentially the orientation of bedding and/or iron formations which localise fluid flow and mineral deposition at finer scales. The results suggest that major lineaments defined by geophysical contrasts can be used in conjunction with techniques of spatial analysis for targeting structurally controlled mineralisation in areas under thin cover adjacent to mineralised terrains such as the Mt Isa Inlier.  相似文献   
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