四川理塘地区二叠纪洋岛型岩石组合的识别及其构造意义:来自岩石学、地球化学和年代学证据   总被引：1，自引：0，他引：1  

严松涛  秦蒙  段阳海  文浪 《地质学报》2019,93(2):381-393

甘孜-理塘蛇绿混杂岩带是西南"三江"构造带的重要组成部分,曾经历了古特提斯构造体系的演化,形成了完整的"沟-弧-盆体系"。本文是首次在甘孜-理塘蛇绿混杂岩带内发现有达森隆洼岩组洋岛型岩石组合,通过详细的岩石学、地球化学、年代学研究表明,达森隆洼岩组主要由枕状玄武岩、灰岩、硅质岩组成,玄武岩SiO_2含量为44.18%～48.82%,富TiO_2含量为2.71%～3.02%,∑REE=141.03×10~(-6)～164.94×10~(-6),轻稀土元素较重稀土元素富集,相对富集Rb、Th、U,亏损Ba、K、Sr,无明显的Nb和Ta异常,稀土元素配分曲线和微量元素蛛网图与典型洋岛玄武岩曲线相似。古生物化石显示该套洋岛型岩石组合沉积时代为二叠纪,锆石U-Pb同位素测年获得枕状玄武岩形成年龄为中二叠世。通过本次研究表明,甘孜-理塘洋盆至少在早二叠世时期就已发育有成熟洋盆。  相似文献   

地下高压气体对汶川地震灾害的作用分析   总被引：5，自引：0，他引：5  

赵京轶  汤倩  兰晓雯  巴桑央金  赵永 《震灾防御技术》2009,4(4):406-416

通过对2008年5月28日汶川M8.0级地震后滑坡和堰塞湖的形成和分布特征,以及震后地下喷发物和灾害形成与分布特征的考察,结合龙门山地区侏罗纪前的海洋环境和现今龙门山前川西坳陷存在大量圈闭构造和地下3km的巨厚底层含大量异常高压天然气体这一结构特征分析,发现地下异常高压气体在地震时高速膨胀,在地下裂隙和断层等面状通道快速剪开底层涌出,造成岩体飞移、流动和扩散是产生灾害的重要因素。  相似文献   

西藏自治区谢通门县斯弄多铅锌矿区地球物理特征及找矿方向   总被引：1，自引：0，他引：1  

郎兴海 《地质与勘探》2017,53(3):508-518

浅成低温热液型矿床是一类主要产于陆相火山岩或与陆相火山岩有关的低温热液矿床,矿床埋藏深度浅是其最大的特点,这也使地球物理勘探方法在这类矿床的勘查中具有先天优势。本文通过对西藏斯弄多Pb-Zn-Ag多金属浅成低温热液型矿床的地球物理参数特征研究,采用激发极化法等综合物探技术在矿体外围探获具有巨大前景的Pb-Zn-Au-Ag浅成低温热液型矿体。目前单工程控制有3段矿体:顶部Au-Ag矿体,中部Au矿体,底部Pb-Zn-Ag矿体。矿体最高Au品位可达5.3g/t,Ag最高品位410g/t,Pb+Zn综合平均品位5.9%。研究结果表明,斯弄多地区林子宗群火山岩物性参数稳定,对矿体异常干扰较小,产于该套火山岩中极强硅化体中的浅成低温热液型Au矿多具有中高极化率和中低阻特征。  相似文献   

阿拉善沙漠植物钙质根管:形态特征、分类及其环境指示意义   总被引：1，自引：0，他引：1  

高有红  李卓仑  韩朗  李若兰 《沉积学报》2017,35(1):75-84

在系统总结前人对植物钙质根管定义及形成机制的基础上,采用形态学方法对阿拉善沙漠26组不同形态的植物钙质根管进行了分类,初步统一了我国植物钙质根管的定义及其分类;通过统计阿拉善沙漠不同类型植物钙质根管在全新世的数量分布,探讨了其分布特征可能蕴含的古环境意义。结果表明,植物钙质根管是陆生植物形成的次生碳酸盐结壳,包括钙质根套、绕根结核、根模具、根导管和根状结核五种类型。其中钙质根套和绕根结核的形成受到植物生长及其根围微生物活动的影响,而根模具、根导管和根状结核的形成则不受上述作用的影响。据此将阿拉善沙漠植物钙质根管分为钙质根套和绕根结核两种类型。这两类植物钙质根管在不同时期的相对数量百分比能够指示植物钙质根管形成时期有效湿度的高低,绕根结核数量百分比较高能够指示较高的有效湿度,而钙质根套数量百分比较高则指示了较低的有效湿度。因此,从植物钙质根管中能够提取丰富的古环境信号,并将其运用于沙漠地区的古环境研究中。  相似文献   

Progress in application of quality management system for the airborne ice-sounding raw data          下载免费PDF全文

Zhang Wenbo  Lang Shinan  Cui Xiangbin  Zhao Yukai  Bao Zhenshan 《极地研究》1988,31(4):421

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Resik: A Bent Crystal X-ray Spectrometer for Studies of Solar Coronal Plasma Composition     

J. Sylwester  I. Gaicki  Z. Kordylewski  M. Kowaliński  S. Nowak  S. Płocieniak  M. Siarkowski  B. Sylwester  W. Trzebiński  J. Bakała  J. L. Culhane  M. Whyndham  R. D. Bentley  P. R. Guttridge  K. J. H. Phillips  J. Lang  C. M. Brown  G. A. Doschek  V. D. Kuznetsov  V. N. Oraevsky  A. I. Stepanov  D. V. Lisin 《Solar physics》2005,226(1):45-72

We describe the RESIK (REntgenovsky Spektrometr s Izognutymi Kristalami) instrument, consisting of two double-channel X-ray spectrometers, designed to observe solar active region and flare plasmas. RESIK is one of the instruments making up the scientific payload of the Russian CORONAS-F solar mission. The uncollimated spectrometer uses two silicon and two quartz bent crystals observing flare, active region and coronal spectra in four wavelength bands with a resolving power (/ ) of 1000. The wavelength coverage, 3.3–6.1 Å, includes emission lines of Si, S, Cl, Ar, and K and in the third diffraction order, the wavelength range includes He-like Fe lines (1.85 Å) and Ni lines (1.55 Å) with dielectronic satellites, emitted during intense, hot flares. The instrument is believed to be the best calibrated space-borne crystal spectrometer flown to date. The spectrometer dynamically adjusts the data gathering intervals from 1 s to 5 minutes, depending on the level of solar X-ray emission at the time of observation. The principal aims of RESIK are the measurements of relative and absolute element abundances in the emitting plasma and the temperature distribution of plasma (differential emission measure) over the temperature interval 3 and 50 MK. This paper summarizes the scientific objectives of RESIK and describes the design, characteristics, and performance of the instrument.  相似文献   

Temperature structure of active regions deduced from the helium-like sulphur lines     

Tetsuya Watanabe  Hirohisa Haka  Toshifumi Shimizu  Eijiro Hiei  Robert D. Bentley  James Lang  Kenneth J. H. Phillips  C. David Pike  Andrzej Fludra  Barbara J. I. Bromage  John T. Mariska 《Solar physics》1995,157(1-2):169-184

Solar active-region temperatures have been determined from the full-Sun spectra of helium-like sulphur (Sxv) observed by the Bragg Crystal Spectrometer on board theYohkoh satellite. The average temperature deduced from Sxv is demonstrated to vary with the solar activity level: A temperature of 2.5 × 10⁶ K is derived from the spectra taken during low solar activity, similar to the general corona, while 4 × 10⁶ K is obtained during a higher activity phase. For the latter, the high-temperature tail of the differential emission measure of active regions is found most likely due to the superposition of numerous flare-like events (micro/nano-flares).  相似文献   

Interactions of marine plankton with transuranic elements. II. Influence of dissolved organic compounds on americium and plutonium accumulation in a diatom     

Nicholas S Fisher  Poul Bjerregaard  Lang Huynh-Ngoc  George R Harvey 《Marine Chemistry》1983,13(1):45-56

To assess the significance of naturally occurring dissolved organic matter (DOM) on complexation of transuranic elements in seawater, a series of bioassay experiments was conducted in which the effect of DOM on the accumulation of ²⁴¹ Am, ²³⁷Pu (III–IV), and ²³⁷Pu (V–VI) by the marine diatom Thalassiosira pseudonana was measured. EDTA at 0.3μM complexed both metals substantially, resulting in reduced radio-isotope uptake by the diatom; the greatest effect was on Pu (III–IV). In contrast, there was no apparent complexation of either element by equimolar concentrations of marine fulvic (MFA) or humic acids (MHA), naturally occurring photooxidizable DOM (uncharacterized), or diatom exudates, as none of these materials reduced isotope uptake; on the contrary, there were indications that some of this DOM enhanced transuranic bioaccumulation in the diatom slightly. Subsequent experiments showed this enhancement was probably due to complexation of transition metals by the DOM, leading to fewer ambient ions ‘competing’ for binding sites on the cells; ²⁴¹ Am uptake rates were negatively correlated (r =? 0.846, P < .01) with Σ ASV-labile Cu + Zn + Cd + Pb. These experiments suggest that naturally occurring DOM may not appreciably complex Am or Pu or greatly affect their bioavailability in the sea.  相似文献   

Sun,earth and sky     

Kenneth R. Lang 《Earth, Moon, and Planets》1995,70(1-3):1-20

The Sun is enveloped by a hot, tenuous million-degree corona that expands to create a continuous solar wind that sweeps past all the planets and fills the heliosphere. The solar wind is modulated by strong gusts that are initiated by powerful explosions on the Sun, including solar flares and coronal mass ejections. This dynamic, invisible outer atmosphere of the Sun is currently under observation with the soft X-ray telescope aboard the Yohkoh spacecraft, whose results are presented. We also show observations from the Ulysses spacecraft that is now passing over the solar pole, sampling the solar wind in this region for the first time. Two other spacecraft, Voyager 1 and 2, have recently detected the outer edge of the invisible heliosphere, roughly halfway to the nearest star. Magnetic solar activity, the total radiative output from the Sun, and the Earth's mean global surface temperature all vary with the 11-year sunspot cycle in which the total number of sunspots varies from a maximum to a minimum and back to a maximum again in about 11 years. The terrestrial magnetic field hollows out a protective magnetic cavity, called the magnetosphere, within the solar wind. This protection is incomplete, however, so the Sun feeds an unseen world of high-speed particles and magnetic fields that encircle the Earth in space. These particles endanger spacecraft and astronauts, and also produce terrestrial aurorae. An international flotilla of spacecraft is now sampling the weak points in this magnetic defense. Similar spacecraft have also discovered a new radiation belt, in addition to the familiar Van Allen belts, except fed by interstellar ions instead of electrons and protons from the Sun.  相似文献