东秦岭造山带花岗岩类长石铅同位素组成及其构造学意义   总被引：10，自引：2，他引：10       下载免费PDF全文

张宏飞  张本仁 《地质学报》1997,71(2):142-149

本文对东秦岭造山带内２７个花岗岩类央体４８件长石样品进行了铅同位素成分的测定，结果表明，本区的南秦岭不同时代花岗岩类以贫铀铅和钍铅为特征，具有明显的铅同位素块体效应，反映它们属地同一个铅同位素构造－地球化学省；而本区的北秦岭区岗岩类从晚元古代到早古生长，长石铅同位素组成以富铀铅和钍铅的为特征，但从晚古生长开始，花岗岩类长石铅同位素组成明显发生变化，以贫铀铅和钍铅为特征，反映晚古生长及其后形成花岗质  相似文献   

原油族组分成气的化学动力学模型及其标定   总被引：27，自引：2，他引：27       下载免费PDF全文

卢双舫  付晓泰 《地质学报》1997,71(4):367-373

利用等温密封热解实验技术及恒速升温热解实验与PY—GC分析技术的结合,本文分别建立并标定了原油中各族组分,即饱和烃、芳烃、非烃和沥青质成气的化学动力学模型。结果表明,原油中不同族组分成气的过程均可用平行一级反应描述,但不同组分在平均活化能及活化能分布上有明显的差异。各族组分在地史过程中成气的过程可由各自的化学动力学模型来描述。这将使原油成气过程的定量、动态描述成为可能。  相似文献   

EXPERIMENTAL STUDY ON EFFECTS OF HUMIDITY AND CHEMICAL COMPOSITION UPON IMAGINARY PART OF REFRACTIVE INDEX OF AEROSOL PARTICLES^*          下载免费PDF全文

LI Zihu  DONG Zhen  YANG Jun  HUANG Shihong 《Acta Meteorologica Sinica》2004,18(4):517-526

Experimental study is made of the relationship between the imaginary part of refractive index (IRI) of atmospheric aerosol particles and relative humidity,and between IRI and chemical element through the assay of chemical constituents of the particles.Evidence suggests that atmospheric humidity and aerosols' chemical ingredients have great effects on the IRI's and they should thus be considered in the research of the radiation properties of the particles in the atmosphere.  相似文献   

GRADIENT DISTRIBUTION OF ACID RAIN IN THE SCENIC RESORT OF THE BAIYUN MOUNTAIN IN GUANGZHOU     

黄健  李福娇  江奕光  李琼 《热带气象学报(英文版)》2004,10(1):95-105

1 INTRODUCTION Sitting in the central part of the Pearl River Delta, Guangzhou is one of the cities in China that are most polluted by acid rain. Broad attention has been brought to the problem. Since the early 1980s, a series of observation and studies h…  相似文献   

Type-specific and indicator taxa of phytoplankton as a quality criterion for assessing the ecological status of Finnish boreal lakes   总被引：6，自引：0，他引：6  

Liisa Lepist  Anna-Liisa Holopainen  Heidi Vuoristo 《Limnologica》2004,34(3):236-248

Key issues in the implementation of the Water Framework Directive are classification of lakes using biological quality parameters and type-specific reference conditions. This work is one of three studies considering different metrics of phytoplankton in the classification of ecological status. Phytoplankton was studied in a total of 55 Finnish boreal lakes, including 32 reference lakes. We tested the suitability of taxonomic composition and abundance of phytoplankton groups for biological classification. We also preliminarily determined the type-specific taxa for the studied lakes. The type-specific taxa for reference conditions are coincidently the indicator species/taxa for high ecological status. Interestingly, some taxa type-specific for impacted oligo-humic lakes proved to be the type-specific taxa for humic reference lakes. The pressure of human impact was observed not only as increase of biomass but also as changes in the species composition. The phytoplankton composition indicated the ecological status of impacted lakes moderately well. There was some variation in the indications given by different algal groups, probably due to the preliminary class boundaries used. However, the preliminary combination of indicative parameters to estimate the ecological status of the studied impacted lakes was in general in accordance with earlier classification of water quality in Finnish lakes.  相似文献   

赣中周潭群石榴石、斜长石和黑云母微区化学成分特征及其地球动力学意义   总被引：5，自引：0，他引：5  

胡恭任刘丛强  章邦桐唐红峰 于瑞莲 《岩石矿物学杂志》2004,23(4):337-345

周潭群变质岩中石榴石、斜长石和黑云母微区化学成分变化明显，石榴石变斑晶具典型的生长环带，由晶体中心向两侧边缘XMg、XFe值以光滑曲线递增，XCu、XMn值以光滑曲线递减，反映其增温过程；晶体最边缘的化学成分反映变质峰期的温度条件。通过石榴石变斑晶生长环带剖面分析，应用Grt-Bi温度计和GASP压力计，确定本区变质作用PT轨迹为顺时针形式，发生于大陆碰撞造山带环境。  相似文献   

影响C₄草本植物C/N比值变化的因素与土壤有机C积累的关系   总被引：6，自引：1，他引：6       下载免费PDF全文

朴河春  朱建明  余登利  冉景丞 《第四纪研究》2004,24(6):621-629

文章对采自贵州从低海拔的东部到高海拔的西部且大致平行的石灰岩和砂岩两地带均生长的3种C₄草本植物,即巴茅(Miscanthusfloridulus)、白茅(Imperatacylindrica)和类芦(Neyraudiareynaudiana),以及相对应的土壤表层样品,进行了营养元素和C同位素组成分析;研究营养元素含量随着海拔的不同而出现的变化趋势,以及这些元素之间的相互协变作用,尤其是Ca和N之间的相互协变作用对植物的N含量、C/N比值和^δ13C值的影响,以了解植物的C/N比值(指示植物残留物质量的一种标志)与土壤有机C积累的关系。研究结果表明,植物的N含量和^δ13C值具有随海拔的上升而显著增大趋势,而植物的C/N比值在砂岩地区虽有减小的趋势,在石灰岩地带则没有。对所研究的C4草本植物来说,在土壤pH值为5.8的中性条件下显示出Ca的最大吸收,因此,Ca与其他营养元素之间的协变模式在两种土壤类型中表现出相反的倾向,并存在土壤交换性Ca的边界浓度:当土壤可交换性Ca的含量为2.24mg/g,相应土壤的pH值在5.8以下时,随着土壤可交换性Ca浓度的增大,植物的N含量上升,而植物的C/N比值会显著降低;当Ca在边界浓度以上时,随着土壤可交换性Ca浓度的增大,植物的N含量下降,而植物的C/N比值有增加的趋势。由此可见,植物残留物的N含量和C/N比值受Ca元素含量的相  相似文献   

The Shape and Volume of the Skaergaard Intrusion, Greenland: Implications for Mass Balance and Bulk Composition   总被引：6，自引：0，他引：6  

NIELSEN  TROELS F. D. 《Journal of Petrology》2004,45(3):507-530

Re-examination of the Skaergaard intrusion in the context ofits regional setting, combined with new data from explorationdrilling, has resulted in a revised structural model for theintrusion. It is modelled as an irregular box, c. 11 km fromnorth to south, up to 8 km from east to west, and 3·4–4km from the lower to the upper contact. The walls of the intrusionare inferred to follow pre-existing and penecontemporaneoussteep faults, and the floor and roof seem largely controlledby bedding planes in the host sediments and lavas, similar toregional sills. The suggested shape and volume are in agreementwith published gravimetric modelling. Crystallization alongall margins of the intrusion concentrated the evolving meltin the upper, central part of the intrusion, best visualizedas an ‘onion-skin’ structure inside the box. Thetotal volume is estimated to c. 280 ± 23 km³, of which13·7% are referred to the Upper Border Series (UBS),16·4% to the Marginal Border Series (MBS) and 69·9%to the Layered Series (LS). In the LS, the Lower Zone (LZ) isestimated to constitute 66·8%, the Middle Zone (MZ) 13·5%and the Upper Zone (UZ) 19·7%. The new volume relationshipsprovide a mass balance estimate of the major and trace elementbulk composition of the intrusion. The parental magma to theSkaergaard intrusion is similar to high-Ti East Greenland tholeiiticplateau basalts with Mg number c. 0.45. The intrusion representsthe solidification of contemporary plateau basalt magma trappedand crystallized under closed-system conditions in a crustalreservoir at the developing East Greenland continental margin. KEY WORDS: bulk composition; emplacement; mass proportions; Skaergaard intrusion; structure  相似文献   

Precise/ Small Sample Size Determinations of Lithium Isotopic Compositions of Geological Reference Materials and Modern Seawater by MC-ICP-MS   总被引：6，自引：1，他引：6  

Alistair B. Jeffcoate  Tim Elliott  Alex Thomas  Claudia Bouman 《Geostandards and Geoanalytical Research》2004,28(1):161-172

The Li isotope ratios of four international rock reference materials, USGS BHVO-2, GSJ JB-2, JG-2, JA-1 and modern seawater (Mediterranean, Pacific and North Atlantic) were determined using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). These reference materials of natural samples were chosen to span a considerable range in Li isotope ratios and cover several different matrices in order to provide a useful benchmark for future studies. Our new analytical technique achieves significantly higher precision and reproducibility (< ± O.3%o 2s) than previous methods, with the additional advantage of requiring very low sample masses of ca . 2 ng of Li.  相似文献   

HJ-1复合型钻井液的研究及应用          下载免费PDF全文

王政敏  牛振中  颜志华 《探矿工程》2004,31(5):48-50

分析和探讨了HJ-1复合型钻井液对复杂地层护壁的作用机理及护壁性能试验情况，介绍了其在寨上矿区复杂地层钻探中的成功应用。  相似文献