南大洋二氧化碳源汇分布及其海-气通量研究   总被引：3，自引：0，他引：3       下载免费PDF全文

高众勇  陈立奇  王伟强 《极地研究》2001,(3)

在 1 999年 1 2月 - 2 0 0 0年 2月“雪龙”号科学考察船往返于中山站和长城站期间 ,进行了大气及海表层 CO2 分压的连续测量。研究结果表明 ,在 80°W- 0°- 80°E之间 ,南大洋基本上是大气 CO2 的汇 ,尤其在 45°W- 3 0°W及 1 0°W- 1 0°E之间 ,是 CO2 的强汇区 ,往返的两次观测结果十分相似。观测发现 ,南大洋 1月份吸收大气 CO2 的能力近两倍于 1 2月份 ,这是由于该海域1月的生产力比 1 2月份高 ,因而反映了初级生产对大气 CO2 吸收的显著影响。利用最新的 K值计算方法表明 ,1月份二氧化碳的入海通量为 3 .98mol/(m2 · a) ,1 2月份的为2 .1 3 mol/(m2 · a) ,综合两个月的值平均 ,南大洋夏季 CO2 的平均通量为 3 .0 6 mol/(m2 · a) ,是南半球夏季一个重要的汇区  相似文献   

Thermoluminescence Dating of Alluvial Sequences in Coastal Valleys of Southern New South Wales: Problems and potential     

R. A. L. Wray  D. M. Price  R. W. Young 《The Australian geographer》2001,32(2):201-220

Because of its potential for establishing chronologies far beyond the range of C¹⁴ thermoluminescence (TL) dating has made a significant contribution to the study of the Quaternary history of many Australian landscapes. But, as the reliability of the technique requires the removal by sunlight of any residual TL from quartz grains during transport, inadequate bleaching may yield ages for depositional events that are too old. Inadequate bleaching often can be detected by the shape of curves showing the ratio of natural TL vs laboratory-induced TL with increasing temperature. We use this technique here, together with C 14 dating and pedogenic evidence, to assess the reliability of TL determinations for alluvium in the valleys of the Clyde River and Termeil Creek. The Pleistocene TL ages from these valleys seem reliable, but Holocene dates do not. However, we demonstrate that, even where inadequate bleaching is demonstrable, TL analysis can still yield important insight to depositional processes.  相似文献   

DECADAL VARIABILITY OF THE ANTARCTIC OSCILLATION     

龚道溢  王绍武 《Acta Meteorologica Sinica》2001,(2)

This paper summarizes the long term and decadal time scale fluctuations of atmosphericcirculation in the Southern(Hemisphere)middle and high latitudes.The long time series ofAntarctic Oscillation Indices(AOIs)were established for January.April.July and October basedon the historical sea level pressure maps and NCEP/NCAR reanalysis surface pressure data set.Itwas found that the AOI of January had upward trend at a rate of 1.17 hPa/100 a.and July haddownward trend at a rate of—1.49 hPa/100 a since 1871.The method of wavelet analysis wasapplied to detect the low frequency characteristics of AOIs,and it is clear that there are decadalvariations in the time scale of about 20—30 years in all 4 indices.Since the averaged value of 4months could explain most variance of annual AOI.thus it is reasonable using the mean AOI ofJanuary,April,July and October to represent the annual AOI.The value of annual AOI was muchlower in periods of about 1894—1901.1910—1935,and was much higher in periods of about 1880—1893,1936—1945.The positive anomalies were remarkable since 1980s.Power spectra ofmodeled AOIs from Hadley Center Control Integration(HCCI)were compared with theobservations,it is found that the interannual time scale frequencies were more significant thandecadal frequencies.But.there also had the possibility for generating weak deeadal fluctuations insome special months and years by Hasselmann mechanism.  相似文献   

皖南上震旦统蓝田组中银铅锌等多金属矿床成因探讨   总被引：1，自引：0，他引：1       下载免费PDF全文

李双应 《地质论评》2001,47(2):129-138

皖南地区上震旦统蓝田组，是银铅锌等多金属矿床的重要赋矿层位，区域地质，矿床地质和地球化学特征研究表明，银铅锌等多金属矿床是由于热水沉积作用而形成，热水沉积作用受断裂控制明显，主要呈带状沿着祁门－三阳坑一万家桥深断裂NE方向展布，热水学沉积形成了银铅锌等多金属矿床，铁锰矿床以及蓝田组底部数千平方千米含锰碳酸盐岩，这一认识不仅为皖南地区矿床的成因给予了新的解释，也为今后该区矿产资源的勘察工作提供了新的思路。  相似文献   

厄尔尼诺与拉尼娜     

魏东岩 《化工矿产地质》2001,23(3):165-168

厄尔尼诺与拉尼娜现象是当前预报全球气候系统异常的最强信号 ,前者对全球气候不利影响要比后者大得多。史前记录表明 ,厄尔尼诺与拉尼娜现象不是近几十年才出现的 ,而是至少在15 0 0 0aB .P前就已存在了。从厄尔尼诺与拉尼娜现象演变来看 ,其出现的频率趋于愈加频繁之势  相似文献   

论成矿台阶   总被引：1，自引：0，他引：1  

董和金 《湖南地质》2001,20(3):161-167

成矿台阶系指同一成矿区，同一成矿系列的同一类型矿床的主要矿体赋存在相应的标高范围内，湘南－粤北地区，铌钽矿床的成矿台阶为640－980m;石英脉－黑钨矿床600－1400m，石英脉一白钨矿床100－400m，矽卡岩型白钨矿床100－860m;浅源重熔岩浆系列铅锌矿床600－1100m，深源同熔岩浆系列铅锌矿床－200－100m，最深可达－700m;石英脉型锡石矿床650－1400m，锡石－硫化物，蚀变花岗岩型，云英岩型锡矿床450－650m，香花岭，界牌岭锡多金属矿床－200－270m，利用成矿台阶新理念，指导上述矿床的勘查，可以收到事半功倍的探矿效果。  相似文献   

冈底斯晚第三纪斑岩的岩石学、地球化学及其地球动力学意义   总被引：20，自引：17，他引：20  

高永丰侯增谦  魏瑞华 《岩石学报》2003,19(3):418-428

西藏高原冈底斯中新世(21～12Ma)侵位于冈底斯花岗岩岩基内。斑岩呈东西向断续带状展布(350km)，南北向串珠排布(宽约50km)，明显受NS裂谷和正断层控制。斑岩的主要岩石类型为花岗闪长斑岩、二长花岗斑岩、石英二长斑岩。斑岩高SiO2、Al2O3、K2O和低Y和HREE(Yb)含量；富集轻稀土元素(LREE)和大离子亲石元素(ULE)，尤其富集Sr和K；缺乏Eu异常和／或具弱正异常；普遍具有较高的Sr／Y、(La／Yb)。比值及较低的Y／Yh比值。斑岩显示出明显的adakite地球化学特征，明显不同于冈底斯花岗岩基。对冈底斯岩带的构造-岩浆-热事件序列的综合分析揭示，斑岩是滞留在地幔的洋壳残片在花岗岩基大幅快速隆升后部分熔融的产物，熔融残余相为石榴石 角闪石 单斜辉石 含钛矿物组合，熔体在上升过程中与上覆交代地幔楔发生作用，使岩浆的K含量和Mg^#明显增高。高密度的熔融残留体榴辉岩或角闪榴辉岩沉入下伏地幔或软流圈，这可能导致了冈底斯岩带在20～14Ma期间的隆升。冈底斯中新世斑岩的时空分布厘定了西藏高原冈底斯带EW向伸展的初始时间大约在20Ma左右。高永丰等：冈底斯晚第三纪斑岩的岩石学、地球化学及其地球动力学意义  相似文献   

DECADAL VARIABILITY OF THE ANTARCTIC OSCILLATION^*          下载免费PDF全文

GONG Daoyi  WANG Shaowu 《Acta Meteorologica Sinica》2001,15(2):178-190

This paper summarizes the long term and decadal time scale fluctuations of atmospheric circulation in the Southern(Hemisphere) middle and high latitudes.The long time series of Antarctic Oscillation Indices(AOIs) were established for January.April.July and October based on the historical sea level pressure maps and NCEP/NCAR reanalysis surface pressure data set.It was found that the AOI of January had upward trend at a rate of 1.17 hPa/100 a.and July haddownward trend at a rate of -1.49 hPa/100 a since 1871.The method of wavelet analysis wasapplied to detect the low frequency characteristics of AOIs,and it is clear that there are decadalvariations in the time scale of about 20-30 years in all 4 indices.Since the averaged value of 4months could explain most variance of annual AOI.thus it is reasonable using the mean AOI of January,April,July and October to represent the annual AOI.The value of annual AOI was much lower in periods of about 1894-1901.1910-1935,and was much higher in periods of about 1880-1893,1936-1945.The positive anomalies were remarkable since 1980s.Power spectra of modeled AOIs from Hadley Center Control Integration(HCCI) were compared with the observations,it is found that the interannual time scale frequencies were more significant than decadal frequencies.But.there also had the possibility for generating weak deeadal fluctuations in some special months and years by Hasselmann mechanism.  相似文献   

南天山东西二段地震活动的关联性及其在地震预报中的意义   总被引：1，自引：0，他引：1       下载免费PDF全文

苏乃秦 《地震工程学报》2001,23(3):305-307

采用可定量描述地震活动强弱程度的“地震活动度”方法，研究了新疆南天山东西二段的地震活动特征。发现地震活动自西向东迁移，强度逐渐衰减，东段的地震活动比西段滞后1年左右。进一步分析认为，由于 印度洋板块向北挤压，使帕米尔地区成为应力高度集中区，这是南天山地震活动的动力来源。  相似文献   

Studies in selected fragilarioid diatoms of potential indicator value from Florida (USA) with notes on the genus Opephora Petit (Bacillariophyceae)     

Eduardo A. Morales   《Limnologica》2002,32(2):102

Four araphid diatom taxa were collected from Florida streams and studied with both light microscopy (LM) and scanning electron microscopy (SEM). Three taxa, formerly in the genus Fragilaria Lyngbye, are here placed in the genus Pseudostaurosira Williams et Round. On the basis of ultrastructure observed by SEM, the remaining taxon is placed in a new genus, Sarcophagodes. At least two of the species referred to Pseudostaurosira may have been confused with species of the genus Opephora Petit, which may have led to misinterpretation of the ecological characteristics of the latter genus.All the taxa treated here belong to the Family Fragilariaceae Greville as delimited in current classification schemes. Two new combinations Pseudostaurosiropsis geocollegarum (=Fragilaria geocollegarum Witkowski et Lange-Bertalot), Pseudostaurosira neoelliptica (=Fragilaria neoelliptica Witkowski) and the new species Pseudostaurosira clavatum are presented herein. Additionally, a new genus, Sarcophagodes, is erected to accommodate the new species S. delicatula. LM and SEM details, as well as criteria delimiting these taxa are discussed. More collections and further analyses are needed to assess the distribution of both Opephora and Sarcophagodes.  相似文献