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1.
江山-绍兴拼合带平水段可能存在新元古代早期板片窗岩浆活动：来自锆石LA-ICP-MS年代学和地球化学的证据 总被引：3，自引：0，他引：3
系统地报道了江山-绍兴拼合带平水地区的高Mg闪长岩、富Nb玄武玢岩、斜长花岗岩的地球化学特征,锆石年代学及部分样品的Hf同位素组成.高Mg闪长岩类似于埃达克型高镁安山岩,以高Mg#（〉60）、富Na、富含轻稀土元素、亏损重稀土高场强元素及具有较高的Nd同位素组成（εNd（t）=7.0～7.7）为特征.富Nb玄武玢岩相对富Na（Na2O/K2O〉6）,同时具有较高的P2O5（～1.00%）和TiO2（～3.08%）,并富集Nb（9.53～10.27μg·g-1）等高场强元素,其Nd同位素组成（εNd（t）=6.8～8.0）基本与高Mg闪长岩一致,表现出典型富Nb玄武岩的特点.斜长花岗岩属准铝质（A/CNK=0.84～0.89）,高度富Na贫K（Na2O/K2O〉10）,但重稀土与高场强元素（Nb,Ta）的亏损,暗示其属于“SSZ”型大洋斜长花岗岩类.锆石LA-ICP-MSU-Pb测年结果显示,高Mg闪长岩、富Nb玄武玢岩、斜长花岗岩的形成年龄分别为（932±7）,（916±6）和（902±5）Ma,都为新元古代早期岩浆活动的产物.锆石Hf同位素研究显示,斜长花岗岩具极高的Hf同位素组成,εHf（t）值介于11.0～16.2之间,能较好地对应其Nd同位素组成（εNd（t）=7.5～8.4）,远超过一般壳源花岗岩的Nd-Hf同位素体系,而与典型蛇绿岩中的斜长花岗岩同位素组成一致,分析表明,其成因更有可能是在活动陆缘环境下,来自俯冲洋壳部分熔融的产物.综上所述并结合区域地质资料,认为很有可能是夹于扬子-华夏两大板块之间的洋壳形成的板片窗环境,生成了新元古代早期江绍拼合带平水段的特殊岛弧岩浆活动,板片窗下部的软流圈上涌则可能提供了重要的热力学条件. 相似文献
2.
对鲁西上峪辉长闪长岩进行了系统的年代学与地球化学研究,以便对其成因以及中生代岩石圈地幔的性质给予制约．研究表明,鲁西上峪岩体是由一套辉长闪长岩类岩石构成．锆石呈自形一半自形晶,且具有较高的Th/U比值（1．23～2．87）,意味着岩浆成因．对两个辉长闪长岩中锆石进行的LA-ICP—MSU-Pb定年结果（加权平均年龄）分别为（129±1）和（134±2）Ma,这表明该岩体的形成时代为早白垩世．除早期堆积体外（QT-19）,该类岩石的SiO2和MgO含量分别介于50．12％～56．37％和3．52％～6．37％之间;且以高Mg^#（0．54～0．63）、富Na（Na20／K20大于1）、高Cr（73×10^-6～217×10^-6）、Ni（34×10^-6-241×10^-6）为特征．该类岩石强烈富集轻稀土元素和大离子亲石元素、明显亏损高场强元素,^87St／^86Sr（t）值和εNd（t）值分别变化于0．70962～0．71081和-16．60— -13．04之间．结合鲁西铁铜沟、金岭高镁闪长岩和方城、费县玄武岩及其中地幔包体的特征,认为上峪辉长闪长岩的原始岩浆起源于受陆壳物质强烈改造的富集型上地幔．鲁西早白垩世高镁闪长岩Sr-Nd—Pb同位素的空间变化——即自南东向北西方向。^87St／^86Sr（t）值降低、εNd（t）值升高、^207Pb/^204Pb和^208Pb/^204Pb初始比值的降低——与扬子克拉通沿北西方向俯冲于华北克拉通之下的构造模式相吻合． 相似文献
3.
甜水海地块古元古代火山岩的发现及其地质意义 总被引：3，自引：0，他引：3
本文报道甜水海地块西段古元古界布伦阔勒岩群中片理化变流纹岩的单颗粒锆石LA-ICP-MS测年为（2481±14）Ma.这套流纹岩与玄武岩、玄武安山岩互层状产出,可能共同组成布伦阔勒岩群中的古元古界组分.其中玄武岩、玄武安山岩主体属于低铝拉斑玄武岩系列,流纹岩属于低铝钙碱性系列;岩石富集大离子亲石元素和轻稀土,亏损亲石元素P及高场强元素Nb,Ta和Ti等,铕异常不明显.εNd（t）值（3.14～4.88之间）及微量元素地球化学特征显示具有亏损地幔源区特征,并受到强烈的地壳混染.基性火山岩多元素原始地幔标准化分配曲线及Zr/Y-Zr图解表明其形成于大陆板内构造环境.综合喀喇昆仑区域地质资料,参考华北克拉通新太古代基性火山岩研究成果,推测布伦阔勒岩群火山岩与地幔岩浆底侵作用有关. 相似文献
4.
何家庄岩体位于勉略带以北的南秦岭构造带北部,主体岩性为花岗闪长岩．LA—ICP-MS锆石u—Pb同位素定年结果揭示这些花岗闪长岩侵位于～248Ma．岩浆锆石的gnf（t）值在-4．8-8．8之间变化,Hf亏损地幔模式年龄（ToM）为537—1061Ma．何家庄岩体花岗闪长岩属于中钾到高钾钙碱性系列,具有与埃达克岩相似的地球化学特征．所有样品均表现为高的Si02（66．6％～70．0％）,A1203（15．04％-16．10％）,Na20（3．74％~4．33％）含量和Mg#（54．2-61．7）值,高的Sr（627-751ppm）,Cr（55-373ppm）和Ni（17．2-182ppm）含量,低的Y（5．42—8．41ppm）和Yb（0．59～0．74ppm）含量,轻重稀土强烈分异（（La／Yb）N：18．9～34．0）,但重稀土相对平坦,明显的正Eu异常（δEu=1．10～2．22）,富集大离子亲石元素,亏损Nb,Ta,P和Ti．岩石成因研究表明这些花岗闪长岩形成于岛弧环境下俯冲洋壳残片和沉积物构成的混合源的部分熔融,其熔体受到了地幔楔物质的污染．何家庄岩体年龄及岩石成因证明勉略洋壳俯冲从-248Ma之前就已经开始,并且南秦岭地区在早三叠世仍处于洋壳俯冲动力学背景． 相似文献
5.
分布于湖南东北部的石蛤蟆岩体侵位于新元古代地层中。由微细粒斑状黑云母花岗闪长岩和细粒斑状黑云母二长花岗岩等两期侵入体组成。通过锆石SHRIM PU--Pb法测得岩体侵位年龄为157土2Ma（2d）,MSWD=0．98,成岩时代为晚侏罗世。SiO2=68．26％～68．53％,K2O／Na2O=1．37～1．59,岩石属镁质、准铝质-微过铝质、高钾钙碱性-钾玄岩系列;岩石明显富集大离子亲石元素,亏损高场强元素,Rb／Sr较低（0．40～0．56）;乏REE较高（171．48～183．81）,Eu为弱负异常（δEu=0．86～0．93）,（La／Yb）N=27．11～45．87;具较高的eNd值（-5．11）和高T2DM（1．63Ga）。综合研究表明,石蛤蟆花岗岩为混合源高钾钙碱性花岗岩类（KCG）,其花岗岩浆有大量幔源物质加入。讨论认为岩体形成于构造体制转换下的地球动力学背景,是造山晚期张弛作用下的产物。 相似文献
6.
通过21件原油样品实验分析表明,原油烃类中高分子量组分C40^＋（％）与原油黏度存在良好的相关性;利用油田开发取心检查井油砂制备得到油藏剩余油样品44件,通过高温色谱检测得到剩余油烃类低C21^-、中C21～C40、高分子化合物C40^＋含量（％）,利用原油黏度与烃类C40^＋（％）的关系式预测了剩余油黏度;结合油田开发取心检查井的岩石渗透率、含油饱和度等资料,对聚合物驱和水驱油藏剩余油的流动性特征、剩余油性质、下步驱油方式等进行研究．实验结果表明,聚合物驱和水驱2种驱油方式油藏剩余油的烃类组成、黏度和流度都呈现非均质性特征,且前者的非均质性更加明显;聚合物驱与水驱油藏相比烃类C21^-（%）和C21～C40（％）较低、C40^＋（％）的较高,聚合物驱可能相对较多的采出原油的低等和中等分子量化合物,使聚合物驱剩余油中烃类C40^＋（％）增加、剩余油黏度变大、流度下降及流动性变差;水驱油藏剩余油以中黏油为主、有一定数量的低黏油,聚合物驱油藏剩余油以中黏油为主、有一定数量的高黏油;根据油藏剩余油黏度测定结果和流度比控制的最佳范围,确定不同油田及油藏剩余油的驱油方式和聚合物溶液黏度及浓度,为下一步油藏剩余油开发及提高采收率提供了新依据和新方法． 相似文献
7.
测试了东太平洋海隆13°N附近36个玄武岩样品的常量和微量元素组成,并对其中不同类型的环带斜长石进行了背散射图像、元素线扫描及常量元素分析．采自很小空间范围内的玄武岩演化程度差异较大（MgO=9．38wt％～6．76wt％）,对富MgO玄武岩通过COMAGMAT程序进行分离结晶计算,结果显示富MgO玄武质岩浆结晶至低MgO（7wt％）时,其Ni含量（～28×10^-6 g／g）普遍低于实际观测的低MgO玄武岩（〉60×10^-6 g／g）,说明低MgO玄武岩可能经历了更多次的岩浆混合作用．模拟了高MgO（9．38wt％）玄武质岩浆自身的“混合-结晶”作用,观测到的低MgO玄武岩中高的Ni含量可以通过新岩浆少量多次地自身混合作用获得．低MgO岩浆经历的多次“混合-结晶”过程与近年来^226Ra/^230Th不平衡对岩浆滞留时间的研究相符合,即低MgO岩浆在更长的滞留时间内经历了更多次的“混合-结晶”过程．岩浆房内的岩浆混合具有局部均匀性,但低MgO岩浆更接近于周期性混合形成的稳定成分,这也是导致东太平洋海隆岩浆多样性重要原因．另外,薄片微区分析将斜长石环带可分为具高An^#核部和无高An^#核部两类,两种类型斜长石均有多个反环带,指示寄主岩浆经历了多次混合作用．低MgO（7．45wt％）玄武岩中斜长石核部与其中部的An^#具明显差异,而与高MgO（9．38wt％）玄武岩中微粒斜长石中心An^#（平衡结晶产物）相当,进一步说明低MgO玄武岩中斜长石的核部可能形成于周期性侵入岩浆房之前的母岩浆． 相似文献
8.
测定了东太平洋海隆13°N附近1个站位（103°54．48′W,12°42．30′N,水深2655m）热液硫化物的矿物、元素和同位素组成．热液硫化物主要由闪锌矿、黄铜矿和黄铁矿等组成,且在ep—s—1层含有次生氧化形成的针铁矿,为富Zn型硫化物,其稀有元素Li（0．15×10^-6～0．30×10^-6）,Be（0．01×10^-6～0．05×10^-6）,Zr（73．8×10^-9～134.4×10^-9）,Nb（8．14×10^-9～64．7×10^-9）,Hf（2．54×10^-9～28．0×10^-9）和Ta（0．203×10^-9～1．21×10^-9）含量远低于洋壳,具有相对高Au含量,低Co,Ni,Sr,Cs,Ba,Bi和U含量的特点．热液硫化物中Zn．Cr,Cd-Ga,Cu-P和P—In之间均存在显著的正相关关系（R^2〉0.8）,而Zn—Fe和Cu—Ba之间均存在显著的负相关关系（R^2〉0．8）．从低温矿物组合到高温矿物组合,热液硫化物中的分散和稀有元素（In,Li,Cs等）含量在空间上的分布也发生了相应的变化,且热液硫化物中锌、铁和铜硫化物分别控制了Cd,Cs和P等元素含量的变化．由于海底风化作用,使得含次生氧化矿物的红褐色硫化物氧化层中V,Mn和REE等元素相对富集,使ep-s-1层具有与海水一致的REE配分模式,并对热液硫化物中元素比值之间的相关性产生明显的影响．同时,从高温矿物组合到低温矿物组合,热液硫化物中Fe含量和矿δ^34S值逐渐增加,Zn含量和铅同位素比值逐渐减小,反映出海水对热液硫化物形成过程中的元素和硫、铅同位素组成的影响逐渐增加． 相似文献
9.
小墨山岩体侵位于中元古代冷家溪群中,由两期侵人体组成,早期为粗中粒-中粒斑状黑云母二长花岗岩;末期为细粒黑（二）云母二长花岗岩。通过锆石SHRIMPU—Pb法测得岩体侵位年龄为122．5±2．1Ma（20）,MSWD=1．9,成岩时代为早白垩世。主元素中,SiO2变化于67．20％～75．16％,K20含量高,且K2O〉Na2O,K2O／Na2O为1．16～1．72;ASI值变化于0．96～1．10之间,平均1．02,属准铝质-微过铝质、高钾钙碱性系列。岩石明显富集大离子亲石元素,亏损高场强元素,Rb／Sr=0．27～15．13;Nb／Ta=15．9～17．1,为锶和铌亏损型。EREE总体较高,重稀土含量相对较高,轻重稀土分馏稍弱,∑Ce／∑Y为0．49～6．18,（La／Yb）。为0．66～15．54。有较高的εNd（t）,为-6．8～-8．7;T2DM相对较小（1．47～1．62Ga）。综合研究表明,小墨山花岗岩石为壳源型富黑云母过铝花岗岩类（CPG）,其成因应为下地壳物质和上地壳物质混合而成,与花岗岩底侵作用或注入地壳中的幔源岩浆有关,形成的构造背景为陆内挤压造山向非造山转换的后造山拉张环境,是在紧随侏罗纪挤压造山运动之后的构造松驰和拉张减薄条件下所形成。 相似文献
10.
采用正交回归的方法,利用中国地震台网和美国地震台网1983——2001年的观测资料, 对中国地震局地球物理研究所（IGCEA）和美国地质调查局国家地震信息中心（NEIC）测定的体波震级进行了比较. 从正交回归得到的结果看,IGCEA测定的体波震级mb与NEIC测定的体波震级mb不存在系统差. 如果以NEIC测定的体波震级为基准, 对于3.5~4.5级之间的地震,IGCEA测定的震级比NEIC测定的震级偏高0.2～0.1级;对于5.0~5.5级之间的地震,IGCEA与NEIC测定的体波震级没有偏差;对于6.0级以上的地震,IGCEA比NEIC偏低小于0.2级. 而IGCEA测定的体波震级与国际数据中心（IDC）测定的体波震级结果基本一致. 相似文献
11.
Instrumental neutron activation analysis was used for the determination of more than 20 trace and minor elements in water and silt samples (suspended load) of the river Aare. The samples were collected at four different locations along the river between its source and the lake of Bienne. The principal results are: 1. The concentrations of all elements investigated are much lower than WHO-limits for drinking water. 2. Human activities are responsible for an increase of some elements along the river. 3. The concentrations of dissolved trace elements are generally anticorrelated with the water flow rate. 4. The concentrations of the trace elements in particulates (in μg/l) are correlated with the flow rate of water. Except for Ca?Sr there are no significant interelement correlations for all four sampling stations. 相似文献
12.
Albrecht Hofmann 《Earth and Planetary Science Letters》1971,10(4):397-402
Methods are given to correct for isotopic fractionation in the determination of the isotopic composition of mixed-isotope spikes. The simplest method, applicable to Sr, utilizes the fact that the fractionated, measured isotope ratios of a critical three-isotope mixture lie exactly on a tie line that connects the true compositions of spike and normal element. Three-isotope elements that do not have critical mixtures require independent determination of the weight ratio of spike to normal element. A new analytic solution together with a straightforward graphical representation is given to the four-isotope problem. 相似文献
13.
论述了适用于遥测地震台网大震速报的一套计算机处理系统,系统设计以《全国遥测台网观测技术规范》和《近震分析》理论为依据,实现了数据输入,震相选择,数据处理,地震定位,震级计算,结果输出及贮存等多项功能,达到了快速确定地震三要素,提高速报速度和精度之目的,是一个较完善的,实用的速报系统。 相似文献
14.
A procedure for three-dimensional (3-D) coupling of finite elements (FEs), boundary elements (BEs) and infinite boundary elements (IBEs) is presented for the numerical modelling of seismic interaction between arch dams and rock canyons. First, a system of coupling 3-D boundary and infinite boundary elements is developed for simulation of infinite and irregular canyons and for determination, in the frequency domain, of impedance functions on the dam-canyon interface. Secondly, the impedance functions for all degrees-of-freedom are transformed approximately into frequency independent discrete parameters by a curve fitting technique. Finally, these discrete parameters are combined with the dam structure which is discretized by finite elements, thus allowing the response of the arch dam-canyon system to be evaluated. The proposed procedure is efficient because it permits the seismic analysis of arch dam-canyon interaction by the substructure technique in the time domain. To demonstrate both the validity and efficiency of the present procedure, the response of an arch dam-canyon system is obtained under unit impulse acting on the dam-canyon interface as the free field input. Very good agreement is noted when comparing the frequency response determined from the time domain with that from the frequency domain under harmonic excitation applied on the interface of the dam-canyon. 相似文献
15.
《水文科学杂志》2013,58(2):314-324
Abstract An approach to the global estimation of water balance elements and their spatial distribution using GIS is presented. It is primarily related to the catchments where measured data are scarce and the spatial differentiation of the hydrological characteristics is not possible without climatological data. Emphasis is placed on estimating the water balance of transboundary karstic aquifers, where problems concerning the hydrometeorological data, catchment boundaries and determination of water balance elements in general are far more complex. The runoff estimation was done using the Turc and Langbein methods, which are the most frequently applied in this region. The years 1961–1990 were used as the reference period. Based on comparison of the results, the applicability of the methods is discussed. The approach proposed is suitable for estimation of water balance in the study area and may also be applied in a wider region. 相似文献
16.
A method is proposed for correcting the magnetic anisotropy of baked magnetic material from archaeological objects and rocks intended for the study of its magnetization and for gaining data on the angular elements of the ancient geomagnetic field. The application of this correction decreases the spread of individual determinations obtained in studying the sample magnetization from an object and increases the determination accuracy of the average value of the ancient geomagnetic field elements. This, in turn, makes it possible to increase the accuracy of its dating. 相似文献
17.
P. Álvarez-Iglesias 《Marine pollution bulletin》2009,58(4):542-259
Mariculture is an important economic activity in shallow marine areas of the Rías Baixas (Galicia, NW Spain). The maintenance of high product quality requires surveillance of environmental quality, including the risk of metal toxicity. In this study the redox status of intertidal sediments in the Bay of San Simón, and the risk of toxicity posed by their As, Cd, Cr, Cu, Mn, Ni, Pb and Zn contents, were evaluated by determination of operationally defined reactive, silicate-bound, organic and pyrite-related fractions of these elements and of Fe. The large silicate-bound fractions of most of these metals indicate their lithogenic origin; the main exception is Pb, which in all respects exhibits singular behaviour associated with its predominantly anthropogenic origin in a ceramics factory. In sediments with larger fine-grained particle contents, which are oxic only in the top few centimetres, greater proportions of the trace elements are present as sulphides or associated with sulphide minerals: the degree of pyritization of Fe (DOP) is 46% overall, and the pyrite fraction of some elements doubtless increases at the expense of the reactive fraction, most overall degrees of trace metal pyritization (DTMPs) lying in the range 10-50%. A decline in pyrite genesis at depths below about 18 cm in these sediments is attributed to the exhaustion of organic matter susceptible to metabolization by sulphide-generating bacteria. In coarse-grained, oxic sediments the oxidation of sulphides makes pyrite-related fractions very small, and reactive and silicate-bound fractions are negatively correlated; reactive fractions associated with Fe-Mn oxyhydroxides are large, and DOP and DTMPs are low (generally much lower than in mud-rich sediments), except for Pb. Most of the elements studied are mainly present in forms that are neither bioavailable nor potentially bioavailable, and so do not constitute a significant environmental threat. However, the high DTMPs of Cu and Pb indicate significant potential bioavailability, which should be taken into account in evaluations of environmental quality and the risk to bivalve cultures. 相似文献
18.
Milan Burša 《Studia Geophysica et Geodaetica》1966,10(4):401-410
Summary Orbital problems of satellite geodesy are based on the assumption that the geocentric orbital elements, giving the geocentric
position of the satellite being observed, are known for the moment of observation. The determination of such elements, however,
is possible only if the observed topocentric quantities were with sufficient accuracy reduced to geocentric ones. The reduction
assumes, however, that the position of the satellite stations with respect to the centre of mass of the Earth is known. This,
however, is not known and the determination of the geocentric positions is substantially the main problem of present-day geodesy.
In the case of natural celestial bodies, relatively far from the basic body, inaccuracies in correcting for the parallax practically
do not influence the solution. But in the case of near artificial Earth satellites these inaccuracies are not negligible.
The present paper analyzes from this aspect the case when the orbital elements are calculated from one position (three coordinates)
and three velocity components. Relations are derived (14, 15, 19, 22, 32, 38) giving the exactly geocentric elements. The
way in which they differ from the well-known relations of classical celestial mechanics (10, 11, 17, 20, 24–26, 36), giving
only certain approximate elements (we call them quasi-geocentric) consists in considering parameters defining the position
of the origin and direction of the axes of the used reference system in the Earth's body. In the derivation we neglected expressions
equal in order to the squares of the coordinates of the centre of the reference ellipsoid with respect to the centre of mass
of the Earth and to the squares of the angles between the axis of rotation of the ellipsoid and the mean rotation axis of
the Earth's inertia as well between the planes of the initial (Greenwich) astronomic and geodetic meridians.
Адрес: Politickych vězňů 12, Praha 1-Nové Město. 相似文献
Адрес: Politickych vězňů 12, Praha 1-Nové Město. 相似文献
19.
Highly sensitive and selective methods for the determination of trace elements in waters and solutions are made possible by the combination of flotation and spectrophotometry (flotation spectrophotometry). The basis for it are multiply charged anion complexes of the analyte, which form sparingly soluble ion association complexes with singly charged basic dye cations in aqueous solution. Intense shaking of the aqueous solution with an organic solvent (having a low dielectric constant) results in the accumulation of these ion association complexes at the interface or on the vessel walls (flotation step). After separating the ion association complexes from the liquid phases, they are dissolved and dissociated in a polar organic solvent and the absorbance of the basic dye ions is measured as a function of the concentration of the analyte. By the example of the trace determination of arsenic in natural water, the possibilities of analytical chemistry by combination of flotation steps and spectrophotometry are demonstrated. According to the arsenic content, its determination can be performed by flotation spectrophotometry with crystal violet (detection limit 50 ng/ml As), by an indirect determination of arsenic via flotation spectrophotometry of molybdenum in the dodecamolybdoarsenic acid (detection limit 1 ng/ml As) or by the combination of collector precipitation of arsenic with zirconium hydroxide followed by froth flotation and flotation spectrophotometry as the determination technique (detection limit 0.05 ng/ml As). The reproducibilities of these variants are indicated and their accuracy is checked by comparison of methods. 相似文献
20.
A. B. Raevskii 《Izvestiya Physics of the Solid Earth》2008,44(7):548-554
An iterative algorithm is proposed for magnetic induction modulus inversion. The iterative process is based on a recurrence relation for the squared induction modulus, which can be represented at each iteration step by a system of linear algebraic equations for components of the magnetization vector. Formulas for the calculation of matrix elements of this system and the determination of the magnetization at the next iteration step are given. Model and practical examples illustrating the reconstruction of magnetization and anomalous field components are presented. 相似文献