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91.
刘鹏  陈立人  李顺大 《山地学报》2000,18(2):177-179
根据浙江省芳香植物的组成 ,及该区的地理条件和芳香植物分布规律 ,将其划分为 5个区 ,分别进行探讨并列出部分芳香植物作为各地开发利用时参考。  相似文献   
92.
鄂东南地区印支期以来构造变形特征及油气意义   总被引:8,自引:5,他引:8  
利用区域地震大剖面及MT资料,结合地面地质调查成果,对鄂东南地区的深部地质结构及典型构造样式进行了分析,认为该区发育以基底岩系顶面和志留系顶面为主滑脱面的大型逆冲推覆构造,并识别出双重逆冲构造、叠瓦状构造、台阶式结构、对冲构造及反冲断层等典型构造样式;同时对上下地质结构的变异进行了探讨,提出志留系滑脱层之下的“原地体”具有变形相对较弱、褶皱宽缓开阔的特点,在后期拉张改造中受到上盘“异地体”的保护,应是有利的油气勘探领域,双重逆冲构造内部发育的断层相关褶皱(如随阳构造)是重点勘探目标。  相似文献   
93.
 The carbonation reaction CaMg(CO3)2 (dolomite)+2SiO2 (coesite)=CaMgSi2O6 (diopside)+2 CO2 (vapor) has been determined experimentally between 3.5 and 6 GPa in a multiple-anvil, solid-media apparatus. This reaction, a candidate for carbonation of eclogites (garnet+clinopyroxene) in the Earth’s mantle, lies at higher pressure for a given temperature than do the carbonation reactions for peridotites (olivine+orthopyroxene±clinopyroxene). A depth interval may exist within the Earth’s mantle under either ‘normal’ or ‘subduction’ thermal regimes where carbonated peridotite could coexist with carbonate-free, CO2-bearing eclogite. Received: 25 May 1994/Accepted: 13 June 1995  相似文献   
94.
Sensitive spectral observations made in two frequency bands near 6.0 and 17.6 GHz are described for Orion and W51. Using frequency switching we were able to achieve a dynamic range in excess of 10,000 without fitting sinusoidal or polynomial baselines. This enabled us to detect lines as weak as T A ∼1 mK in these strong continuum sources. Hydrogen recombination lines with Δn as high as 25 have been detected in Orion. In the Orion data, where the lines are stronger, we have also detected a systematic shift in the line center frequencies proportional to linewidth that cannot be explained by normal optical depth effects.  相似文献   
95.
96.
本文主要讨论了1974年5月11日云南省永善一大关地震的主震及其强余震的发震构造。指出主震至少由两次破裂组成,且与走向N34°W、倾向NE的断层有关,破裂方向自东南而西北。6月15日的最强余震其发震构造走向N40°E、倾向SE。最强余震发生前,释放应变的速率增快;同时,震中沿一定方向排列。  相似文献   
97.
P. MARSH  J. W. POMEROY 《水文研究》1996,10(10):1383-1400
Models of surface energy balance and snow metamorphism are utilized to predict the energy and meltwater fluxes at an Arctic site in the forest–tundra transition zone of north-western Canada. The surface energy balance during the melt period is modelled using an hourly bulk aerodynamic approach. Once a snowcover becomes patchy, advection from the bare patches to the snow-covered areas results in a large spatial variation in basin snowmelt. In order to illustrate the importance of small-scale, horizontal advection, a simple parameterization scheme using sensible heat fluxes from snow free areas was tested. This scheme estimates the maximum horizontal advection of sensible heat from the bare patches to the snow-covered areas. Calculated melt was routed through the measured snowcover in each landscape type using a variable flow path, meltwater percolation model. This allowed the determination of the spatial variability in the timing and magnitude of meltwater release for runoff. Model results indicate that the initial release of meltwater first occurred on the shallow upland tundra sites, but meltwater release did not occur until nearly two weeks later on the deep drift snowcovers. During these early periods of melt, not all meltwater is available for runoff. Instead, there is a period when some snowpacks are only partially contributing to runoff, and the spatial variation of runoff contribution corresponds to landscape type. Comparisons of melt with and without advection suggests that advection is an important process controlling the timing of basin snowmelt.  相似文献   
98.
认识青藏高原东部现代表土的色度特征及其空间分布,理解其与现代气候因子之间的联系,对于高原地区黄土-古环境重建和揭示第四纪环境变化历史具有重要意义。通过对研究区表层土壤色度的详细分析,对比现代气候资料,探讨了青藏高原东部表层土壤色度的空间变化特征及其环境意义。结果表明:① 高原东部表土色度参数空间变化特征差异显著,表现为随纬度升高,土壤亮度呈先减小后增大的趋势,而红度和黄度则逐步减小;随经度的升高,黄度先增大后减小,而红度值逐步减小;红度和黄度整体随着海拔上升而呈先减小后升高的特征。这些变化特征和差异是表土色度对高原东部复杂地理环境和水热条件变化响应的结果。② 在高原的干旱-半湿润区,土壤亮度对降水的响应敏感;红度和黄度对大尺度的温度变化响应较敏感,而较冷的环境下,红度对温度响应复杂,但与降水存在一定的联系。红度/黄度比值主要指示了气候控制下的赤铁矿和针铁矿的变化和竞争,对干旱-半湿润区域的降水变化响应较为敏感。青藏高原东部现代表土色度与气候密切相关,其空间变化特征一定程度上反映了该地区现代气候因子的空间变化;另一方面由于该区地形和气候复杂多变,部分色度指标与气候关系复杂,在重建青藏高原东部黄土古环境变化历史时需要谨慎。  相似文献   
99.
Dacites form a relatively small proportion of lavas in the Taupo Volcanic Zone, New Zealand (5km3), and occur mainly on the eastern side. In this paper their origin is considered in terms of three processes: (a) partial melting of crustal rocks; (b) fractional crystallisation of basalt and andesite; and (c) sub-surface mixing of basic and acid magma. Modelling techniques are used to calculate the most acceptable degree of fractional crystallisation and magma mixing to fit major-element data, and these values are used to compare calculated and observed trace-element values. The success or failure of the model is determined by the closeness of the two sets of values. For partial-melt models, trace-element values alone are calculated by the batch-melting equation.Results indicate that White Island dacite can best be modelled by fractional crystallisation; Manawahe by fractional crystallisation plus limited crustal contamination; Maungaongaonga by partial melting of Western Basement greywacke, and Tauhara by partial melting of this greywacke together with minor mixing with a more basic magma. Results from Parekauau and Horohoro indicate that these lavas are unlikely to have formed by any of the processes examined.  相似文献   
100.
We investigate the distinctive distribution and pattern of subkilometer-sized cones in Isidis Planitia, and their relationship to the material that fills the basin. We observe that: (1) the cones show uniform size, spacing, and morphology across the entire basin; (2) they have large central depressions (relative to cone basal diameters) that are generally filled in and commonly show layering; (3) cone chains form highly organized spatial patterns; cones are also found in isolation and in dense fields; (4) many adjacent chains are parallel, and evenly spaced, creating a pattern that mimics lava flows that have experienced compressional folding; (5) no flows are associated with the cones, even where summit crater rims are breached; (6) the cones are at least temporally related to basin fill; (7) the basin fill material is largely fine-grained, but with locally indurated layers at shallow depth; blocks ejected by small craters from these locally indurated layers are commonly dark in color; and (8) relationships between cones along a chain show no systematic temporal formation sequence along the chain. We conclude that the basin was likely inundated by one or more hot, partially welded pyroclastic flows; devolatilization of these flows remobilized volcaniclastic material to form the cones without associated lava flows. The volume of gas required to account for the observed number of cones is low and does not require the presence of ground water or ice.  相似文献   
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