The Thermal History of the Huangmeijian Granite Intrusion in Anhui and Its Relation to Mineralization: Isotopic Evidence   总被引：3，自引：0，他引：3  

Zheng Yongfei  Fu Bin  Gong Bing Department of Earth  Space Sciences  University of Science  Technology of Chin  Hefei Liu Xinzhu 《《地质学报》英文版》1996,70(2)

Whole-rock Rb-Sr, zircon U-Pb and hornblende, biotite and K-feldspar K-Ar ages areused to reconstruct the cooling history of the Huangmeijian intrusion in the Anqing-Lujiangquartz-syenite belt in Anhui. Oxygen isotope geothermometry of mineral pairs demonstrates thatdiffusion is a dominant factor controlling the closure of isotopic systems. Assuming the coolingof the intrusion is synchronous with a dicrease in local geothermal gradients, an emplacementdepth of about 8 km and the magma crystallization temperature of 800±50℃ are estimated. TheHuangmeijian intrusion experienced a rapid cooling process and uplifted after its emplacementand crystallization at 133 Ma B.P. with a cooling rate of 34.5℃/Ma and an uplifting rate of 0.35mm/a. The intrusion was rising until it rested at a depth of 3km at a temperature of 300±50℃about 14 Ma later. Then the intrusion was in slow cooling and uplifting with a cooling rate of4.4℃/Ma and an uplifting rate of 0.04 mm/a. U-Pb dating of pitchblende is done for the hydrothermal uranium deposit formed in thecontact zone of the Huangmeijian intrusion. The result shows that the mineralization age is closeto the closing time of the K-Ar system in biotite. The fluid inclusion thermometry indicates thatthe mineralization temperature is in agreement with the closure temperature of the biotite K-Arsystem. This suggests a close relationship between the slow cooling of the intrusion and thehydrothermal uranium mineralization process.  相似文献   

不同温度下铝牺牲阳极合金元素对工作电位影响的灰箱分析     

刘学庆  张经磊  郭公玉  王佳  李相波  刘玉珊 《海洋科学集刊》2003,(45):118-123

目前，城市用水中约80%是工业用水，而工业用水中约80%是工业冷却水。为节约淡水，人们试图利用海水代替淡水做工业冷却水。但在海水冷却系统中，换热器的出口及其后续部分的钢铁设施由于海水温度较高(一般在50℃左右，有的还大于55℃)，腐蚀现象相当严重，解决该部位的腐蚀防护问题是直接利用海水代替淡水做工业冷却水中不可缺少的一个环节。牺牲阳极是防止海水中钢铁设备腐蚀的一种行之有效的方法，但常用的几种牺牲阳极在该温度下不能适用。因此，找出牺牲阳极性能在不同温度下的变化规律，对研制能在高温下使用的牺牲阳极有着重要的理论和实际意义。 工作电位是牺牲阳极一项重要的性能指标。牺牲阳极只有具备了足够负的工作电位，才能在实际应用中保持足够的驱动电压(朱相荣等，1999；火时中，1988)，达到长期使用的目的。有关文献报道了牺牲阳极添加元素对工作电位的影响(朱承德等，1997；Gurrappa1997；张信义等，1996)，但哪些元素对阳极工作电位的影响更大些，元素对工作电位的影响是否有一定的规律，却均无报道。本文作者根据以上文献选择元素，自制了28种铝基牺牲阳极，并按国标GB4948-85的方法进行实验，用灰箱分析的数学方法对得到的数据进行分析，所得结果对研制高温海水中如何应用牺牲阳极有一定的指导作用。  相似文献   

上地幔橄榄石电导率影响因素及高压相变初探     

代立东  李和平  王多君 《地球物理学进展》2003,18(2):256-260

人们对上地幔标志性矿物橄榄石的认识，基本上是经历一个从直流到交流，又从交流到阻抗谱的认识过程．本文主要通过对橄榄石电导率的影响因素出发，包括温度、压力、铁镁比值、氧逸度等因素的影响和制约．用目前国际高温高压学术界公认的阻抗谱技术探讨了橄榄石在高压下的相变，并在此基础上，进一步研究地球物理学家非常关心的热点问题-冷地幔的实验室的模拟，并作了充分的论证．  相似文献   

Early Cooling History of Eciogites from the Dabie-Sulu Orogen： Constraints from Diffusion Kinetics of Garnet     

CHEN Daogong  CHENG Hao 《《地质学报》英文版》2004,78(3):848-853

Abstract For the first time, we apply different geospeedometric models to garnet zoning patterns that were obtained in this study from detailed EMP analyses for garnets from eclogites and granulite in the Dabie‐Sulu orogen. Various zonings of cation diffusion were preserved in the garnets, enabling the acquirement of average cooling rates for the high‐to ultrahigh‐pressure rocks without using geochronological approaches. The coesite‐bearing hot eclogites yield fast cooling rates of about 20 to 30°C/Ma subsequent to peak metamorphic temperatures, whereas the cold eclogite gives a relatively slow cooling rate of 8°C/Ma at its initial exhumation. A very slow cooling rate of <0.3°C/Ma is obtained for the granulite at Huangtuling, suggesting that the granulite may not be involved in the continental deep subduction.  相似文献   

A theoretical spongy spray icing model with surficial structure   总被引：1，自引：0，他引：1  

R. Z. Blackmore  E. P. Lozowski 《Atmospheric Research》1998,49(4):267-288

In an attempt to improve the predictive capability of atmospheric icing models, we have developed a theoretical model of spongy ice formation, including the surficial morphology under a falling supercooled liquid film. A steady-state model of freshwater spongy spray icing for a stationary vertical cylinder is presented. A falling film submodel accounts for the flow of excess liquid on the icing surface. Traditional heat and mass balance equations at the outer surface of the falling film are formulated, along with heat and mass balances for the falling film and for the dendritic freezing zone. The rate of advance of the icing interface is calculated by analogy with the rate of advance of freely-growing ice crystals in bulk supercooled liquid. This allows, for the first time, the prediction of ice accretion flux and accretion sponginess, for a specific icing configuration and environmental conditions. An analysis of the model's sensitivity to spray temperature reveals that spray supercooling enhances both the rate of accretion and its sponginess. A comparison of the model's performance with experiments shows rather good agreement, and suggests that further research into the nature of the icing surface and its effect on the accreted ice is warranted.  相似文献   

东乌珠穆沁中铁陨石的金属相冷却速率及其演化历史     

王道德  毛艳华  陶克捷 《地球化学》1998,(2)

采用剖面中间浓度与镍纹石带宽度关系测定了东乌珠穆沁中铁陨石的金相冷却速率,其冷却速率介于0．05℃／Ma与0.02℃／Ma之间,采用铁纹石颗粒或铁纹石带中心镍含量与到最靠近铁纹石颗粒边界或镍纹石带高镍边的关系所获得的冷却速率介于0．1℃／Ma与0．01℃／Ma之间,并与根据镍纹石层纹的测定结果一致。两种方法的测定结果都表明,东乌珠穆沁中铁陨石比任何其他类型陨石更缓慢冷却（＜05℃／Ma）。根据东乌珠穆沁中铁陨石结构和岩石学特征及宇宙射线暴露年龄,该陨石经受了吸积熔融和分异作用-壳的重熔-局部冲击熔融-破裂和重新组合或重新吸积-开挖和喷射等复杂的演化历史。  相似文献   

Cooling rates in the shock veins of chondrites: constraints on the (Mg, Fe)2SiO4 polymorph transformations     

Ming Chen  Xiande Xie  A. El Goresy  B. Wopenka  T. G. Sharp 《中国科学D辑(英文版)》1998,41(5):522-528

The occurrence of γ-phase, a high-pressure polymorph of olivine (α-phase), in the shock veins of Sixiangkou chondrite was due to a greater cooling rate (> 10 000°C·s^-1) in the veins. Because γ-phase partially reverted to β-phase and no back-transformation from β-phase to α-phase took place, the shock veins of Peace River chondrite with a cooling rate of 1 000–2 000δC·s^-1 contain a great amount of β-phase. In the shock veins of Mbale chondrite with a cooling rate of <500°C·s^-1, the majority of γ-phase reverted to α-phase. The heat dissipation in shock veins took place after a stage of shock compression of chondrite parent body, and the parent body was broken into fragmental pieces. Cooling rate in the shock veins constrained the back-transformations of (Mg, Fe)₂SiO₄ high-pressure polymorphs. Project of Chen and Xie supported by the National Natural Science Foundation of China (Grant No. 496720981, Natural Science Foundation of Guangdong Province (Grant No. 960500), and the Science Foundation of Academia Sinica for the returned scholars.  相似文献   

2001年北半球大气环流特征及其对中国气候异常的影响   总被引：3，自引：0，他引：3  

艾 《气象》2002,28(4):21-24

2001年受前期赤道东太平洋海温长期冷水位相的影响，北半球大气环流的主要特征表现为：500hPa西太平洋副热带高压冬春季偏强，夏季秋偏弱；欧亚地区夏季500hPa位势高度距平场上中高纬从西到东呈现为“－＋－”分布形式，贝加尔湖地区为正距平中心；东亚冬、夏季风偏弱；7月赤道辐合带异常偏强、偏北等。在上述大气环流的影响下，我国的天气气候发生了异常。  相似文献   

地形及冷热源扰动不同分布对南沙海域西南大风形成过程影响的数值试验          下载免费PDF全文

张翔  周学群 《应用气象学报》1995,6(2):163-170

利用一个p-σ混合坐标五层原始方程模式，进行了地形及冷热源扰动的不同分布对南沙海域西南大风过程形成作用的数值试验。结果表明，亚洲南部特殊的地形及海陆分布是形成南沙海域西南大风过程的基本条件，但它造成的最大风速只能达8m/s，比观测值要小。试验中发现，在有地形作用的前提下，澳大利亚冷空气的向北爆发及菲律宾附近热源扰动的作用均可各自在南沙海域形成12m/s以上的大风过程，而孟加拉湾附近的热源扰动则对南沙海域西南大风过程的形成无明显作用。  相似文献   

THE COOLING OF SICHUAN PROVINCE IN RECENT 40 YEARS AND ITS PROBABLE MECHANISMS   总被引：46，自引：1，他引：46       下载免费PDF全文

Li Xiaowen  Zhou Xiuji  Li Weiliang  Chen Longxun 《Acta Meteorologica Sinica》1995,9(1):57-68

The analysis of temperature variation trends at 160 meteorological stations in China from 1951 to 1992 showed thata relatively large area of China became warm in recent years,but there still existed an obvious cooling center in Sichuanbasin.We also analyzed the variation trends of some meteorological factors which could probably cause this cooling,and the results indicated that the global solar radiation,the insolation duration and the visual range decreased sharply inrecent years,but the cloud amount changed slightly in Sichuan basin.We also found that the decrease of surface solarradiation caused by the increase of the anthropogenic aerosols' backscattering in the lower troposphere was a notablereason for the cooling of Sichuan basin in recent years.We also confirmed this conclusion by using of a one-dimensionalclimate model.  相似文献