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151.
P. J. Tarabbia 《Australian Journal of Earth Sciences》2013,60(6):617-620
Strontianite (SrCO3), witherite (BaCO3) and alstonite (CaBa[CO3]2) were among the range of epigenetic coal cleat/fracture carbonates identified within the Wittingham Coal Measures, Jerrys Plains Subgroup in the Hunter Valley. Three stages of diagenetic cement development, all related to basin evolution, are postulated. Material for the development of the various carbonates was derived from: basinal pore fluids, surrounding rock and organic matrix as a result of diagenetic exchange, active mass transport or devolatilization of basement rocks during metamorphism, including plutonic intrusion. 相似文献
152.
153.
概述了硬梁包水电站左岸磨子沟泥石流的基本特征、泥石流危险性、泥石流发展趋势,泥石流对工程区的影响进行了分析和评价,为解决该泥石流沟治理设计提供了依据。 相似文献
154.
研究湖陆风特征不仅能够为提高天气气候的预测能力奠定基础,而且对风能资源的开发利用等具有重要的实用意义。利用大理国家气候观象台近地面通量观测系统的2007年3月-2008年5月资料,采用涡动相关法等分析了大理近地层中湖陆风、峡谷风特征及形成原因和影响因素。结果表明:大理地区白天以东风和东南风为主,夜间以西风和西南风为主。进一步对湍流和湍流通量特征分析发现,大理地区白天不稳定层结多于夜间;湍流强度白天强于夜间,并且随着风速的增大而减小;湍流通量具有明显的日变化特征,热量交换形式以潜热为主。 相似文献
155.
地球物理学中关于电磁波勘探研究通常采用的是地球半空间模型.然而,对于几十公里的有限长电缆源(长偶极源),远距离电磁波场探测必须要考虑电离层的影响,它是一个全空间问题.关于包含电离层、空气层和地球介质(我们称“地-电离层”模式)的电磁波场特征的研究在国外较少,国内几乎是空白.本文采用全空间积分方程法首先对小尺度的可控源电磁波场特征进行了研究,由于此时电离层的影响可忽略,它应该和半空间成熟的CSAMT模拟结果一致,对比结果表明,二者是一致的,验证了全空间模拟方法的可靠性和有效性.随后进行了50 km长电缆电离层和空气层高度都为100 km的“地-电离层”模式大尺度电磁波场模拟,以探讨大尺度可控源电磁波场的特征.给定频率的“地-电离层”模式电磁场的衰减曲线表明长电缆远距离电磁波场由于受电离层的作用存在衰减逐渐变小的过渡场和衰减变小的波导场.为了探讨复杂介质“地-电离层”模式电磁波特征,对“地-电离层”模式的典型地盾和地台多层介质模型进行了数值模拟,得到了偶极源长度50 km、电流200A、收发距离远达1600 km和2500 km的合理的电磁场结果.最后,对一简单含油储层结构模型进行了长偶极、大功率、远距离电磁波场响应计算.储层横向不均匀复杂结构模拟的结果表明,考虑电离层和大气层的“地-电离层”模式大尺度深层复杂介质模拟时,电磁场对深部目标体仍有很好的异常响应. 相似文献
156.
利用三维(3D)全空间积分方程准线性解作为数值模拟手段,对包含电离层、大气层和地球介质层的“地-电离层”典型异常目标体多层介质模型进行了数值模拟,得到了偶极源长度100 km、电流200 A、收发距离远达1600 km的合理的异常电性目标体的电阻率-频率响应结果.通过对不同埋深异常目标体的电阻率-频率特征的讨论,认为当考虑电离层和大气层的“地-电离层”大尺度深层横向不均匀复杂介质模拟时,电磁场对深部目标体仍有很好的异常响应,但当异常体电阻率及同一电阻率的岩石埋深不同时,其电阻率-频率的响应特征有很大不同,这正反映了不同岩石物性参数的电阻率-频率响应特征.文中结果表明从长偶极大功率源(WEM)激励的电磁场观测资料区分岩石的电阻率参数是可能的,这为利用WEM观测资料建立电性参数和岩石/地层参数经验关系奠定了基础. 相似文献
157.
Numerical simulation for the coupling effect of local atmospheric circulations over the area of Beijing,Tianjin and Hebei Province 总被引:8,自引:0,他引:8
ShuHua Liu ZhenXin Liu Ju Li YinChun Wang YanJun Ma Li Sheng HePing Liu FuMing Liang GuoJun Xin JianHua Wang 《中国科学D辑(英文版)》2009,52(3):382-392
Using the model system MM5.V3 and multi-layer grid nesting technique, we have done a multi-scale numerical simulation over
the area of Beijing, Tianjin and Hebei Province to analyze the temperature and wind field there and study its local circulations.
The results show a coupling effect of Urban Heat Island Circulation (UHIC), Mountain Valley Breeze (MVB) and Sea Land Breeze
(SLB) occurs in this area when the synoptic system is weak. The SLB can penetrate deep into the mainland for about 200 km
when it is blooming. MVB can extend to south and cover almost the whole plain area in Beijing. Both MVB and SLB are diurnal
periodical; meanwhile the phase of MVB drops behind that of SLB for about six hours. As a local circulation, the UHIC weakens
the two circulations above, and it also has a diurnal period. As a result, the coupling effect of circulations reveals not
only different features in spring-summer period and autumn-winter period in a year but also the difference between early morning
to noonday and afternoon to night in a day. We noted the diffusion of contamination over the area around Beijing, and found
the steady presence of a transport routine of contamination over North-China throughout the year caused by the Coupling Effect
mentioned above. This find is important for studying the environment pollution in this area.
Supported by Central Public Welfare Special Fund Program for the Institute and Higher Education (Grant No. IUMKY200701), Public
Welfare Special Fund Program (Meteorology) of China Scientific and Technological Ministry (Grant Nos. CYHY20080620, CYHY200706004),
Spread New Technology Program of China Meteorological Administration (Grant No. CMATG2007M15) and Urban Meteorology Scientific
Research Fund Program of the Institute of Beijing Urban Meteorology, China Meteorological Administration (Grant No. UMRF200702) 相似文献
158.
Widespread till and moraines record excursions of middle-Pleistocene ice that flowed up-slope into several watersheds of the Valley and Ridge Province along the West Branch of the Susquehanna River. A unique landform assemblage was created by ice-damming and jökulhlaups emanating from high gradient mountain watersheds. This combination of topography formed by multiple eastward-plunging anticlinal ridges, and the upvalley advance of glaciers resulted in an ideal geomorphic condition for the formation of temporary ice-dammed lakes. Extensive low gradient (1°–2° slope) gravel surfaces dominate the mountain front geomorphology in this region and defy simple explanation. The geomorphic circumstances that occurred in tributaries to the West Branch Susquehanna River during middle Pleistocene glaciation are extremely rare and may be unique in the world. Failure of ice dams released sediment-rich water from lakes, entraining cobbles and boulders, and depositing them in elongated debris fans extending up to 9 km downstream from their mountain-front breakout points. Poorly developed imbrication is rare, but occasionally present in matrix-supported sediments resembling debris flow deposits. Clast weathering and soils are consistent with a middle Pleistocene age for the most recent flows, circa the 880-ka paleomagnetic date for glacial lake sediments north of the region on the West Branch Susquehanna River. Post-glacial stream incision has focused along the margins of fan surfaces, resulting in topographic inversion, leaving bouldery jökulhlaup surfaces up to 15 m above Holocene channels. Because of their coarse nature and high water tables, jökulhlaup surfaces are generally forested in contrast to agricultural land use in the valleys and, thus, are readily apparent from orbital imagery. 相似文献
159.
HARVEY K. FLAD 《Geographical review》2009,99(3):356-376
ABSTRACT. Thirty years ago D. W. Meinig argued that certain landscapes “are part of the iconography of nationhood.” From the earliest European settlement, the North American “wilderness” forged the crucible that shaped U.S. culture. By the early nineteenth century romantic aesthetic theories and nationalistic patriotism influenced American perspectives on the emerging cultural landscape. Artists, writers, and travelers sought out places for their healthful and scenic qualities as well as for moral instruction from nature. The locus of this confluence of politics, philosophy, and art was the Hudson River Valley of New York State. Guesthouses and hotels, especially in and around the Catskill Mountains, accommodated these travelers. This article examines the cultural basis of the mountain resort in its appropriation and marketing of a regional landscape and its incorporation as a national icon, with a specific history of the development of Mohonk Mountain House by the Smiley family from 1869 to 2008. 相似文献
160.