西沙岛礁白云岩化特征与成因模式分析   总被引：1，自引：0，他引：1  

曹佳琪  张道军  翟世奎  罗威  修淳  刘新宇  张爱滨  毕东杰 《海洋学报》2016,38(11):125-139

关于碳酸盐岩的白云岩化作用至今仍是一个争论颇大的科学问题。在2012-2013年期间,中海石油（中国）有限公司湛江分公司在西沙石岛钻取了长达1 268.02 m的“西科1井”岩心,在0~1 257.52 m主要由碳酸盐岩组成的岩心中存在有7个白云岩层。本文基于西科1井岩心样品的矿物组成、常量、微量及稀土元素含量等地球化学特征分析,探讨了西沙岛礁特有的白云岩化作用过程。结果表明:西科1井7层白云岩在成因上与埋深和压实成岩作用无关,其分布与海平面下降的地质事件有良好的对应关系,白云岩层元素地球化学特征表明白云岩成岩流体为浓缩的高盐度海水。根据白云岩层的矿物学和地球化学特征,提出了礁滩潟湖环境下高盐卤水渗透回流作用的白云岩化模式:伴随海平面的升降,礁体处于淹没与暴露的交替之中,海平面下降导致了礁滩潟湖的形成,由于西沙海区蒸发量大于降水量而使澙湖中海水盐度增高,最终形成富Mg卤水;澙湖中高盐度富Mg卤水在礁体内下渗和侧向扩散,Mg逐渐替代早期CaCO₃晶格中Ca而形成白云石;海平面的升降变化和礁体淹没与暴露的交替导致了钻井岩心多个白云岩层的形成。海平面升降直接控制了岛礁碳酸盐岩的发育和白云岩化作用,导致海平面升降的古气候变化在岛礁的形成发育中起到主导作用。  相似文献   

INFLUENCES OF LOW-FREQUENCY MOISTURE TRANSPORTATION ON LOW FREQUENCY PRECIPITATION ANOMALIES IN THE ANNUALLY FIRST RAINY SEASON OF SOUTH CHINA IN 2010     

李丽平  许冠宇  倪碧  柳艳菊 《热带气象学报(英文版)》2016,22(S1):46-56

85-station daily precipitation data from 1961—2010 provided by the National Meteorological Information Center and the NCEP/NCAR 2010 daily reanalysis data are used to investigate the low-frequency variability on the precipitation of the first rain season and its relationships with moisture transport in South China, and channels of low-frequency water vapor transport and sources of low-frequency precipitation are revealed. The annually first raining season precipitation in 2010 is mainly controlled by 10–20 d and 30–60 d oscillation. The rainfall is more (interrupted) when the two low-frequency components are in the same peak (valley) phase, and the rainfall is less when they are superposed in the inverse phase. The 10–20 d low-frequency component of the moisture transport is more active than the 30–60 d. The 10–20 d water vapor sources lie in the South India Ocean near 30° S, the area between Sumatra and Kalimantan Island (the southwest source), and the equatorial middle Pacific region (the southeast source), and there are corresponding southwest and southeast moisture transport channels. By using the characteristics of 10–20 d water vapor transport anomalous circulation, the corresponding low-frequency precipitation can be predicted 6 d ahead.  相似文献   

Erratum to: Simulation on Vibration Characteristics of Fractured Rock     

Siqi Li  Tie Yan  Wei Li  Fuqing Bi 《Rock Mechanics and Rock Engineering》2016,49(10):4209-4209

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Regional model simulation of summer rainfall over the Philippines: Effect of choice of driving fields and ocean flux schemes     

R. V. Francisco  J. Argete  F. Giorgi  J. Pal  X. Bi  W. J. Gutowski 《Theoretical and Applied Climatology》2006,86(1-4):215-227

Summary The latest version of the Abdus Salam International Centre for Theoretical Physics (ICTP) regional model RegCM is used to investigate summer monsoon precipitation over the Philippine archipelago and surrounding ocean waters, a region where regional climate models have not been applied before. The sensitivity of simulated precipitation to driving lateral boundary conditions (NCEP and ERA40 reanalyses) and ocean surface flux scheme (BATS and Zeng) is assessed for 5 monsoon seasons. The ability of the RegCM to simulate the spatial patterns and magnitude of monsoon precipitation is demonstrated, both in response to the prominent large scale circulations over the region and to the local forcing by the physiographical features of the Philippine islands. This provides encouraging indications concerning the development of a regional climate modeling system for the Philippine region. On the other hand, the model shows a substantial sensitivity to the analysis fields used for lateral boundary conditions as well as the ocean surface flux schemes. The use of ERA40 lateral boundary fields consistently yields greater precipitation amounts compared to the use of NCEP fields. Similarly, the BATS scheme consistently produces more precipitation compared to the Zeng scheme. As a result, different combinations of lateral boundary fields and surface ocean flux schemes provide a good simulation of precipitation amounts and spatial structure over the region. The response of simulated precipitation to using different forcing analysis fields is of the same order of magnitude as the response to using different surface flux parameterizations in the model. As a result it is difficult to unambiguously establish which of the model configurations is best performing.  相似文献   

同位素地质样品分析的质量监控与质量评估     

张自超  余必胜 《岩矿测试》2000,19(2):137-141

讨论了同位素地质样品分析的质量监控与质量评估问题,提出在同位素地质样品分析中以准确度与精度度并重、标准物质监控与重复样监控相结合的质量监控方法。通过对大量标准样品定值数据与积累的测试数据的统计分析,提出了标准物质测定误差和标准偏差及重复样双份分析的双差允许限的确定方法,并采用准确度分数、精密度分数、空白分数和系统性偏倚分数对测试结果的质量进行定量评估的方法,这些方法适用于实验室内部的质量监控和评估  相似文献   

气象卫星资料在天气预报分析业务中的应用     

毕宝贵  林建  徐晶 《气象》2004,30(11):19-23

对TOVS和云导风非常规反演资料进行了质量控制，并将控制后的反演场与常规观测资料以及T106分析场资料进行变分同化，得到合成分析场。结果表明：在合理的目标函数设计的基础上，合成分析场与仅用常规探空资料相比更接近于实况，弥补了实况资料的不足。运用MICAPS中特有的网格点绘图功能实现了机器自动绘制历史天气图工作。经检验误差较小，线条平滑。该方法为在实时天气图和历史图分析中使用非常规资料提供了一条新的途径，具有一定的实用价值。  相似文献   

新疆克拉玛依中基性岩墙群的地质地球化学和K-Ar年代学   总被引：33，自引：0，他引：33  

李辛子  韩宝福  季建清  李宗怀  刘志强  杨斌 《地球化学》2004,33(6):574-584

新疆克拉玛依中基性岩墙群出现在后碰撞花岗岩(锆石U-Pb年龄约为300～320Ma)及其下石炭统火山岩-硅质岩围岩之中,空间分布受区域构造裂隙控制,总体走向以280°～300°为主,K-Ar表观年龄为241.3～271.5Ma。岩墙群属于亚碱性系列,根据岩性和Mg#的不同,可分为辉绿岩岩墙、高Mg#闪长玢岩岩墙和低Mg#(石英)闪长玢岩岩墙等三组。主元素、稀土元素和其他微量元素等资料表明,形成岩墙群的岩浆起源于亏损地幔,由部分熔融作用形成的原始玄武质岩浆在侵位过程中发生了分离结晶作用,但同时还受到同化混染作用的影响,致使克拉玛依岩墙群具有较典型的AFC过程的成因特征。克拉玛依岩墙群形成于新疆北部后碰撞伸展构造环境,是幔源岩浆活动的产物,因而可以作为地壳垂向生长的标志之一。  相似文献   

河北坝上地区植硅体空间分布特征及其环境意义     

刘林敬  毛欣  姜高磊  赵红梅  李长安  毕志伟  郭娇  朱玉晨 《地质学报》2022,96(6):2184-2194

了解不同区域表土植硅体组合特征及其对气候环境的响应过程，是利用植硅体指标恢复古植被和古气候的基础。本文通过对河北坝上地区103块表土植硅体的分析鉴定，共统计出棒型、尖型、帽型、鞍型、哑铃型、齿型、块状、扁平状、扇型、三棱柱型、锥骨状、导管型、弓型和特殊型14种植硅体类型，其中植硅体类型主要以棒型和尖型为主，而短细胞植硅体的含量较少。通过研究区相对暖湿区、暖干区、冷湿区和冷干区的表土植硅体组合特征对比发现，在相对较冷的区域棒型量含量较高，在相对较暖的区域扇型、扁平状和鞍型含量较高，在相对较湿的区域尖型含量较高，在相对暖湿的区域块状含量较高，在相对冷湿的区域齿型含量较高，这表明研究区表土植硅体组合特征对气候环境响应较为敏感。本研究成果可为重建坝上地区古植被和古气候提供基础资料。  相似文献   

THE TEMPORAL AND SPATIAL PATTERNS OF ENVIRONMENTAL RISK EVENTS IN THE PAST 30 YEARS IN SHENYANG CITY     

Bi Jun  Tang Yijian  Zhang Shen 《地理学报(英文版)》1995,(1)

1.IntroductionEnvironmentalrisk'isamajorenvirotunedlthreattothesustainabilityoftheropon.ItsanalysishasbecomeafOcusofenvironmentalstudyinthepastl0years.0win8torapideconothecdeveloPmentinChina,manykindsOfpotatialriskshavegreatlyhamPeredtheroponalsustainable…  相似文献   

1937年菏泽地震地裂缝追踪研究   总被引：2，自引：0，他引：2       下载免费PDF全文

王瑞田  赵宪超  毕桂香 《地震工程学报》1994,16(4):70-75

本文在前人研究和野外调查工作的基础上，对１９３７年菏泽７．ｏ级和子级地震地裂缝的空间展布特征、性质、成因及其与震中区附近活动断裂的关系进行了深入研究，并以此为依据对两次地震的破裂方式及发震构造进行了讨论，认为菏泽地震的破裂方式为“双震型共扼破裂”，北西向成武—东明隐伏断裂可能为７．Ｏ级地震的主要发震构造。  相似文献