Aqueous alteration in the matrix of the Vigarano (CV3) carbonaceous chondrite     

Martin R. LEE  Robert HUTCHISON  Andrew L. GRAHAM 《Meteoritics & planetary science》1996,31(4):477-483

Abstract The matrix of Vigarano, a meteorite which belongs to the reduced subgroup of the CV3 chondrites, contains small amounts (<10%) of ferrihydrite and smectite. These hydrous minerals occur together as fine fibrous intergrowths between anhydrous silicate and oxide grains. Coarser crystals of ferrihydrite fill fractures that cut matrix minerals, and smectite also lines narrow channels within olivine grains. These channels may have formed by preferential alteration of olivines along (100)-parallel defects. Formation of ferrihydrite and smectite in the matrix of Vigarano was the result of mild aqueous alteration in a low-temperature (<150 °C), oxidising parent body environment. Partial equilibration of matrix olivines indicates that alteration was followed by thermal metamorphism with a peak temperature of 400–500 °C. Mineralogically similar alteration products, which also were formed by parent body processes, have previously been described from the matrices of four CV meteorites: Bali, Grosnaja, Kaba and Mokoia, all of which belong to the oxidised subgroup. This discovery of the products of oxidative aqueous alteration in Vigarano has important consequences for understanding the chemical and thermal history of the CV class of meteorites.  相似文献   

The Petrology and Geochemistry of Volcanic Rocks on Jeju Island: Plume Magmatism along the Asian Continental Margin   总被引：2，自引：0，他引：2  

TATSUMI  YOSHIYUKI; SHUKUNO  HIROSHI; YOSHIKAWA  MASAKO; CHANG  QING; SATO  KEIKO; LEE  MOON WON 《Journal of Petrology》2005,46(3):523-553

The incompatible element signatures of volcanic rocks formingJeju Island, located at the eastern margin of the Asian continent,are identical to those of typical intraplate magmas. The sourceof these volcanic rocks may be a mantle plume, located immediatelybehind the SW Japan arc. Jeju plume magmas can be divided intothree series, based on major and trace element abundances: high-aluminaalkalic, low-alumina alkalic, and sub-alkalic. Mass-balancecalculations indicate that the compositional variations withineach magma series are largely governed by fractional crystallizationof three chemically distinct parental magmas. The compositionsof primary magmas for these series, using inferred residualmantle olivine compositions, suggest that the low-alumina alkalicand sub-alkalic magmas are generated at the deepest and shallowestdepths by lowest and highest degrees of melting, respectively.These estimates, together with systematic differences in traceelement and isotopic compositions, indicate that the upper mantlebeneath Jeju Island is characterized by an increased degreeof metasomatism and a change in major metasomatic hydrous mineralsfrom amphibole to phlogopite with decreasing depth. The originalplume material, having rather depleted geochemical characteristics,entrained shallower metasomatized uppermost mantle material,and segregated least-enriched low-alumina alkalic, moderatelyenriched high-alumina alkalic, and highly enriched sub-alkalicmagmas, with decreasing depth. KEY WORDS: Jeju Island; magma genesis; mantle plume; subcontinental mantle  相似文献   

四层模式热成风适应   总被引：1，自引：1，他引：1  

陈秋士  励名德 《气象学报》1964,34(3):253-270

本文用四层模式分析了热成风适应。在适应过程中将发生四种波速不同的惯性波来调节流场和温度场的关系。它们的前阵面的速度分别为306米/秒,114米/秒,36.2米/秒,19.2米/秒。层次愈高,快速惯性波的作用愈大;惯性外波在750毫巴以下才有它的重要性。 计算指出:大气中辐合辐散以及垂直运动在垂直方向上互相迭置的现象,是一定条件下热成风适应的结果。本文计算了各种情况的初始条件下温度场和气压场的相互调整。例如375毫巴上单纯非地转风的流场的反气旋涡旋,适应后可建立起对流层暖性、平流层是冷性的高压系统。将初始非热成风的暖温度中心,放在对流层下层和放在对流层中层适应后的结果将不一样。前者只能在对流层下层形成一浅薄的热低压,而后者可在对流层上层建立起一个强大的反气旋,甚至一直影响到平流层。最后,结合气旋发展时所产生的非热成风的特点,讨论了它们的适应。  相似文献   

DIRECT INTERPRETATION OF RESISTIVITY DATA OVER TWO-DIMENSIONAL STRUCTURES*     

T. LEE 《Geophysical Prospecting》1981,29(3):462-469

A direct interpretation scheme is developed which is capable of determining most of the geological features of a ground which can be assumed to be two dimensional in structure. This scheme extends the earlier work of Pekeris (1940) and Koefoed (1968) to the case where the basal layer of a ground is undulating. It also has a limited use for finding the parameters of a dipping dyke in the lower medium. Though the top and dip of the dyke can be determined, this is not true for the thickness.  相似文献   

Constraining anthropogenic CH4 emissions in Nanjing and the Yangtze River Delta,China, using atmospheric CO2 and CH4 mixing ratios     

SHEN Shuanghe  YANG Dong  XIAO Wei  LIU Shoudong  Xuhui LEE 《大气科学进展》2014,31(6):1343-1352

Methane （CH4） emissions estimated with the Intergovernmental Panel on Climate Change （IPCC） inventory method at the city and regional scale are subject to large uncertainties.In this study,we determined the CH4：CO2 emissions ratio for both Nanjing and the Yangtze River Delta （YRD）,using the atmospheric CH4 and CO2 concentrations measured at a suburban site in Nanjing in the winter.The atmospheric estimate of the CH4：CO2 emissions ratio was in reasonable agreement with that calculated using the IPCC method for the YRD （within 20％）,but was 200％ greater for the municipality of Nanjing.The most likely reason for the discrepancy is that emissions from unmanaged landfills are omitted from the official statistics on garbage production.  相似文献   

Horizontal distribution of Changjiang Diluted Water in summer inferred from total suspended sediment in the Yellow Sea and East China Sea     

LEE Dong-Kyu  KWON Jae-Il  SON SeungHyun 《海洋学报(英文版)》2015,34(12):44-50

During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment (TSS) can be used as an excellent tracer for Changjiang Diluted Water (CDW). To analyze the spatial and temporal variations of the CDW distribution, the monthly mean TSS from Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color data are constructed and are converted to salinity using the relationship between salinity observed from AQUARIUS and TSS. The process produces the detailed horizontal distribution of salinity with very high resolution (1 km). From monthly mean salinity map from 2002 to 2012 in July and August, the expansion patterns of CDW are analyzed. The southerly wind in July and southeasterly wind in August transport the CDW eastward and northeastward, respectively. It is found that the yearly variation of the expansion of CDW toward the southern sea area of Korea is mostly due to the variation of southerly wind and the fluctuations of fresh water discharge into the Changjiang estuary show relatively little impact on the eastward extend of CDW. When 11-year mean (from 2002 to 2012) salinity map in August is compared with World Ocean Atlas 2013, it is revealed that wind in August strengthened six times from 1994 and it causes the expansion of CDW extended 150 km further eastward.  相似文献   

Synergy between Virtual Local Air Pollutants and Greenhouse Gases Emissions Embodied in China’s International Trade     

CHEN Yiying  LEE Harry. F.  WANG Ke  PEI Qing  ZOU Ji 《资源与生态学报(英文版)》2017,8(6):571-583

Increasing pressure from the international community to reduce carbon emissions, coupled with the need to reduce domestic air pollutants, is forcing China to deal with both sources of emissions. Air pollutants and greenhouse gases are closely linked via their common source, fossil fuels. As a result of globalization, large portions of these emissions are associated with trade. This study uses data from the World Input-Output Database (WIOD), including 27 EU countries and 13 major countries, covering the period from 2000 to 2009, and applies MRIO (Multiregional input-output) to estimate emissions embodied in China’s international trade. We focus on the synergy between LAPs (local air pollutants) and GHG consumption-based emissions, and the relationship between virtual LAPs and virtual GHGs associated with China’s international trade from 2000 to 2009. The results indicate that a strong synergistic relationship exists and that air pollutant control can serve as an endogenous mechanism to mitigating greenhouse gases. Thanks to domestic actions to control air pollutants, every ton reduction of LAP emissions related to export can save 27.1 tons of GHG emissions in 2005 over emissions efficiency levels, and can save 32.4 tons of GHG emissions in 2009 over 2005. Mitigation actions taken to reduce air pollutants could also reduce GHG emissions.  相似文献   

多导体柱微波成像的连续编码遗传算法          下载免费PDF全文

卿安永  李敬  任朗  李政光  钟顺时 《地球物理学报》1999,42(6):841-848

提出一种能同时重建多个二维良导体目标外形轮廓的新方法——连续编码遗传算法．将目标的横截面轮廓近似表达为三角级数形式,由边界条件得到一积分方程组,在此基础上将成像问题转化为约束优化问题,级数的各项系数为待优化量．积分方程组为约束条件,目标函数定义为实际测量的散射场与反演过程中得到的散射场之间的相对误差函数．采用连续编码遗传算法求解,优化过程通过选择、交叉、变异等遗传操作的选代而实现,待优化目标函数进行线性变换并采用模拟退火原理确定目标后表达为适应度函数,采用联赛选择与比例选择相结合的选择机制和单点交叉方式,变异操作通过对基因施加微小随机扰动实现．上一代中适应度最高的个体直接保留．数值模拟反演实验验证了方法的有效性．与其他反演方法相比,本法具有简单、通用、鲁棒性强等特点．  相似文献   

基于重力剖面的长白山天池火山地壳岩浆囊建模     

管彦武  崔承赞  杨国东  刘嘉麒  李允秀  吴昌桓  金旭  吴燕冈 《岩石学报》2020,36(12):3840-3852

长白山天池火山是中国最具潜在喷发危险的多成因复式火山,在近2000年来,曾经发生过世界上最大规模的喷发。为了进一步研究长白山天池火山的潜在危险,有必要研究火山的岩浆囊位置和分布。为此,在长白山天池火山开展了一条南北方向的重力剖面测量。结合前人工作,如地震勘探P波速度反演和大地电磁测深（MT）电阻率反演,以及地质信息,采用人机交互的形式,建立了一条长约150km的密度模型。从建模结果图中可以发现：（1）长白山天池下方存在地壳岩浆囊;（2）长白山天池北坡地壳存在一个高阻、低密度体,深度在7~15km,距离天池2~10km,可能是富含气体的岩浆囊;（3）在南坡和北坡大约3km深度处普遍存在一个岩浆岩层;（4）在天池下存在一个已经塌陷堵塞的火山颈。  相似文献