A Preliminary Study on Dust Grains in the Stratosphere     

黄伯钧  欧阳自远 《中国地球化学学报》1990,9(2):105-114

Collected by means of a high-altitude scientific balloon and a self-made automatic sample collector,a total of 276 dust grains were selected for the study of shape,grain size and optical property.Some of the grains were examined by X-ray diffraction and electrom microprobe techniques,The stratospheric dust grains can be classified as 6 types:cosmic dusts,cosmic dusts(?),microtektite,natural pollutants,artificial pollutants and the unknown substances.The different types of dust grains have different characters and distinguishing symbols.Widespread in the space of the solar system,cosmic dusts are the initial substances of the solar system and ,to some degree,have recorded a great wealth of information on the early history of the solar system.So they have become one of the important objects in the field of cosmochemistry at present time,Since the 1960‘s,scholars of many countries have collected cosmic dusts both in the space near the earth(using rock ets,space probes and space shuttles)and in the stratosphere (using high-altitude balloons or U-2air planes).According to the shape(the scanning electron microimage),element composition(the energy-dispersive X-ray spectrum)and optical properties of dust grains,the substances in the stratosphere can be classified as 5 types:cosmic dusts,alumina spheroids,terrestrial artificial pollutants,terrestrial natural pollutants and unknown substances(CDPET,1982).  相似文献   

山西省高凡银金矿床的成因          下载免费PDF全文

毛德宝  沈保丰 《地质找矿论丛》1991,6(3):13-24

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新疆西准噶尔地区两类蛇绿岩中橄榄岩的矿物学研究     

郝梓国  王希斌  鲍佩声  彭根永  金远新 《吉林大学学报(地球科学版)》1991,(1)

两类蛇绿岩中变质橄榄岩的矿物表现出的共同特征是:从二辉橄榄岩→斜辉橄榄岩→斜辉辉橄岩→纯橄岩→铬铁矿石,其橄榄石、斜方辉石和单斜辉石的Mg/(Mg+Fe)(矿物牌号)依次升高,表现出富Mg贫Fe的演化趋势;铬尖晶石的Cr/(Cr+Al)亦同时升高,表现为富Cr贫Al的演化特征。 变质橄榄岩中的矿物均是原始上地幔岩部分熔融的残余物。在部分熔融过程中,橄榄石与铬尖晶石是生成相矿物,而斜方与单斜辉石则是消失相矿物,正是通过两种辉石的不断消失,岩石才从二辉橄榄岩依次转化为纯橄岩,并造成纯橄岩与铬铁矿的紧密伴生。在此过程中,矿物成分时刻都在变化,造岩矿物向富Mg贫Fe,金属矿物向富Cr贫Al方向调整,这与实际测定结果是一致的。  相似文献   

Effect of ocean thermal diffusivity on global warming induced by increasing atmospheric CO2     

Bao Ning  Zhang Xuehong 《大气科学进展》1991,8(4):421-430

A global mean ocean model including atmospheric heating, heat capacity of the mixed layer ocean, and vertical thermal diffusivity in the lower ocean, proposed by Cess and Goldenberg (1981), is used in this paper to study the sen-sitivity of global warming to the vertical diffusivity. The results suggest that the behaviour of upper ocean tempera-ture is mainly determined by the magnitude of upper layer diffusivity and an ocean with a larger diffusivity leads to a less increase of sea surface temperature and a longer time delay for the global warming induced by increasing CO2 than that with smaller one. The global warming relative to four scenarios of CO2 emission assumed by Intergovernmental Panel of Climate Change (IPCC) is also estimated by using the model with two kinds of thermal diffusivities. The result shows that for various combinations of the CO2 emission scenarios and the diffusivities, the oceanic time delay to the global warming varies from 15 years to 70 years.  相似文献   

热液成矿作用的一般动力学方程   总被引：3，自引：1，他引：3       下载免费PDF全文

鲍征宇  唐促华 《地球科学》1994,19(3):313-319

分析了热液成矿作用的基本特点和研究现状，推导出热液成矿作用动力学体系的一般方程，并着重讨论了方程中表征热液与围岩之间化学反应的速率项，除目前一般采用动力学实验实测反应速率常数外，作者根据局域平衡原理，认为成矿作用可视为体系内各点随着温度和压力的变化不断重建平衡的过程，可用温度和压力变化时成矿反应的平衡常数的变化速度表征成矿反应的动力学行为，成矿化学反应的速率还可用主要成矿物质的溶解的变化率来表征。  相似文献   

河北坝上沙漠化土地综合整治优化模式   总被引：1，自引：1，他引：1  

李进  宝音 《中国沙漠》1994,14(4):72-85

本文通过对河北丰宁坝上大滩村农业系统的环境条件、发展历史、结构现状及功能等的分析，针对存在的问题，提出了综合调整系统结构、提高系统功能的原则、对策及整治途径，建立了系统的优化模式并进行了效益分析。  相似文献   

A STUDY ON THE RELATIONSHIP BETWEEN THE ROTATION OF BINARY TYPHOONS AND STEERING CURRENT   总被引：1，自引：0，他引：1  

Bao Chenglan  Ruan Junshi  Zhu Yaojian 《大气科学进展》1986,3(1):115-124

Many studies show that, within a certain distance (ca. 700－800 n mi), two typhoons forming a binary typhoon (BT) system would rotate as a whole and attract each other, which is known as “Fuji-whara Effect” (FE). This paper indicates that only 30.3% of BTs has experienced remarkable cyclonic rotation with a 12-hr angle ≥+10° when two components are less than 20° lat apart, and that the probability is much higher with the eastern, component in the NE than in the SE quadrant for the western one, implying the steering effect of the environmental flow field (EFF) on them.47 observations from 13 BTs are separately used for calculating the angular velocity due to FE and EFF and the results are compared. The conclusion can be stated as follows: FE is dominant with the centers of two elements below 7° lat apart; the EFF steering current plays a major role when they are in the range of 7－15° and for a distance above 15° the principle of FE holds no longer.  相似文献   

Factors affecting zircon metamictization in granites   总被引：2，自引：0，他引：2  

Zhenmin Gao  Jingming Pan 《中国地球化学学报》1986,5(2):180-188

Characteristics of metamict zircon and its relationship to granites are reviewed. The degree of metamictization of zircon increases with increasing acidity and alkali contents of the granites. It is evident that zircon metamictization is caused mainly by radioactive radiation from radioactive elements contained in it rather than by hydrolysis.  相似文献   

The Chemical Composition of Global Subducting Sediments and Its Geological Significance     

Renjie Zhao  Quanshu Yan  Haitao Zhang  Yili Guan  Zhenmin Ge  Long Yuan  Shishuai Yan 《地球科学进展》1986,35(8):789-803

Subducted sediments play an important role in crust-mantle interaction and deep mantle processes, especially for subduction zone magmatism and mantle geochemistry. The current rate of Global Subducting Sediments (GLOSS) is 0.5~0.7 km³/a. The GLOSS are composed of terrigenous material(76 wt.%), calcium carbonate(7 wt.%), opal(10 wt.%) and mineral-bound H₂O⁺(7 wt.%). The chemical compositions of GLOSS are similar to those of upper continental crust which is mainly controlled by the terrigenous materials, and yet the materials formed by marine processes will dilute the terrigenous materials. The components of subducted sediments are different among trenches. In the accretionary margin, the components of subducted sediments are similar to those of the upper crust, while in the non-accretionary margin the components are terrigenous materials plus those produced by marine processes. During subduction, subducted sediments will released fluids, melt or supercritical fluid to affect island arc/back-arc basin magmatism by means of aqueous fluid or sediment melt. In addition, a part of subducted sediments, together with underlying altered oceanic crust/lithosphere, recycle into the mantle and contribute to the mantle heterogeneity. Geochemical tracers indicate that subducted sediments play variable contributions to the magmatic processes in different tectonic setting. Thus, subducted sediments play an important role in two relatively independent dynamics systems (plate tectonics and mantle plume), as well as related mantle evolution models. As a result, by accurately calculating the compositions of subduction sediments and using various geochemical indicators, we can further limit the input and output fluxes of various elements or isotopes, and then obtain more accurately residual subducted components, which can provide us some important clues for geodynamic process.  相似文献   

Mineralogical study of spinel-lherzolite inclusions from basalts in southern and eastern China     

Wankang Huang  Jianguo Xu  Zhenmin Gao  Junya Nan 《中国地球化学学报》1983,2(4):361-376

Ten spinel-lherzolite inclusions and one olivine-websterite inclusion, which were collected from Fujian, Jiangsu, Hebei and Yunnan Provinces, consist of olivine (FΦ_87.7–91.2), enstatite (En_87.3–89.7), Cr-diopside and spinel. According to the Mg/(Mg+Fe²⁺) ratios in the rocks and their mineralogies, they are designated to the Cr-diopside type. The websterite is composed of bronzite (En_71.9) and augite, while the gabbro-norite consists of hypersthene (En_68.9) and augite, belonging to the Al-augite type. The geothermos of spinel-lherzolites were calculated with four geothermometric methods, giving a temperature range of 925°–1,072°C. However, according to P. R. A. Wells' method, temperatures range from 845δ to 1,014°C, and by D. H. Lindsly's approach, from 716°–974°C. Pressures range from 15.1 to 19.8 kb. Genetically, Spinel-lherzolites and olivine-websterite are thought to have been derived from residual mantle material by partial melting at approximately 1,000°C and at a depth of about 50–70 km. Websterite and gabbro-norite may be products of the crystallization-differentiation of alkali basaltic magma.  相似文献