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内蒙古集宁新生代玄武岩的地幔源区特征：元素及Sr-Nd-Pb同位素地球化学证据 总被引：7，自引：8，他引：7
内蒙古集宁玄武岩区位于华北克拉通北缘，东邻汉诺坝玄武岩区。由亚碱性的拉斑玄武岩及碱性的橄榄玄武岩、碧玄岩和碱玄岩组成。玄武岩的SiO2与TiO2含量分别为44．10～52．27wt．％和1．57～2．95wt．％，Mg^#（43—63）及Ni含量（27～210ppm）变化范围较大。集宁玄武岩的微量元素原始地幔标准化曲线及REE球粒陨石标准化曲线与OIB相似，Sr、Nd同位素比值显示了较汉诺坝玄武岩富集的特征。研究表明，虽然集宁玄武岩浆经历了一定程度的橄榄石、单斜辉石的分离结晶作用，但微量元素及Sr、Nd、Ph同位素特征排除了幔源岩浆在喷发到地表过程中受到地壳物质显著混染的可能性。^143Nd／^144 Nd ^87Sr／^86Sr vs．^206Ph／^204Pb的线性相关性表明，集宁玄武岩至少来自两个地幔端元组分：EMI和PREMA，且端元组分与汉诺坝玄武岩相似。尖晶石二辉橄榄岩的低程度部分熔融（2～5％）熔体与石榴石二辉橄榄岩更低程度部分熔融（〈2％）熔体的混合，可以解释集宁玄武岩稀土元素的变化特征。推测EMI位于岩石圈地幔之内且源区深度〈70km，PREMA则来自软流圈地幔。集宁碱性玄武岩与亚碱性玄武岩之间的地球化学差异，可能只是来自岩石圈地幔的EMI型熔体和来自软流圈地幔的PREMA型熔体在形成玄武岩浆时参与混合的比例不同，暗示该地区的岩石圈地幔与软流圈地幔之间经历了强烈的相互作用。集宁玄武岩与汉诺坝玄武岩相似的Sr、Nd、Pb同位素比值及相关性，说明它们具有相似的地幔源区，汉诺坝玄武岩的地球化学差异同样可以用EMI与PREMA组分对岩浆贡献程度的不同来解释。 相似文献
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湘东北中生代基性岩脉微量元素地球化学特征及岩石成因 总被引：7，自引：0，他引：7
湘东北中生代基性岩脉可以分为煌斑岩和辉绿岩两类，前者形成于136.61Ma，后者形成于86.18Ma,与华南中生代主要拉张时期相对应。岩石富集LREE，Eu负异常不明显，其形成主要受地幔部分熔融作用制约。早期煌斑岩类微量元素和Sr、Nd同位素总体上具有富集地幔（EMⅡ型）洋岛玄武岩（OIB）特征，富集Nd、P、Cs，而K、Rb、Sr、U、Th等富集程度不明显，Ta、Nb略有富集，具有软流圈地幔上涌地幔热柱玄武岩岩浆源区性质，表现出软流圈地幔上涌部分熔融的成岩特点。晚期辉绿岩类表现出Ta、Nb、Ti亏损，但LILE并不富集，反映地壳混染程度的增强，具有大陆拉张带（裂谷初期）形成的玄武岩岩浆源区性质，为岩石圈地幔部分熔融形成。二者具有不同的岩浆源区性质，从早期到晚期岩浆源区向上迁移并致使部分陆 物质混入，反映由热点式拉张到岩石圈伸展－减薄的作用过程。 相似文献
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湘东北蕉溪岭富钠煌斑岩地球化学特征 总被引：7，自引：2，他引：7
湘东北蕉溪岭富钠煌斑岩是产于陆内拉张环境的一组特殊的岩石类型，包括闪斜煌斑岩、棕闪煌斑岩、闪辉正煌岩等。在岩石化学组成上，SiO2为45．78％－48．42％，K2O＋Na2O为5．05％－6．56％，属于碱性玄武岩系列，岩石以富集Na2O、TiO2、＜FeO＞、MgO，尤其以富钠为特征，K2O/Na2O平均值为0．41，在煌斑岩分类中属于钠质碱性煌斑岩。岩石∑REE较高，富LREE，不出现铕负异常，δEu平均值为1．04。岩石Rb-Sr等时线年龄为136．61Ma。岩石微量元素组成具有洋岛玄武岩（OIB）型特征，HREE明显亏损，不出现Ta、Nb、Ti的亏损以及LILE富集不明显，表明岩浆源区与岛弧环境无关，并且地壳物质混染程度很低。^87Sr/^86Sr初始比值0．705308－0．705366，εNd(t)为＋3．5－＋3．8，^143Nd/^144Nd初始比值0．512639－0．512654，具有较为均一的洋岛玄武岩（OIB）地幔源区性质，并且位于地幔排列线附近。推测区内存在地幔柱构造环境，岩石的形成是在软流圈地幔上涌条件下导致深剖地幔部分熔融产物，富钠碱性煌斑岩应具有其自身岩浆源。 相似文献
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近年来,东北地区地幔热演化过程的相关研究相对较少,而揭示东北地区地幔热演化过程的有效手段就是研究东北地区玄武岩的成分变异特征.系统总结并对比了大兴安岭北段早白垩世玄武质岩石和新生代玄武质岩石的化学成分变异,以便揭示研究区中生代晚期-新生代的地幔热演化过程.大兴安岭北段早白垩世玄武岩在化学上属于拉斑玄武岩系列,以亏损Nb、Ta、Ti等高场强元素为特征,它们的La/Nb和La/Ta比值分别介于1.8~5.6和30~87,暗示岩浆起源于岩石圈地幔;它们的初始87Sr/86Sr值、εNd（t）和εHf（t）值分别介于0.704 5~0.706 9、-1.52~+3.60和+1.74~+7.77,表明岩浆源区属于弱亏损-弱富集的岩石圈地幔;早白垩世玄武质岩石的Sr-Nd-Pb同位素成分指示岩浆源区是由DM和EMⅡ型地幔端元混合而成,并经历了俯冲流体的交代.表明大兴安岭北段早白垩世玄武质岩浆源区为受早期俯冲流体交代的岩石圈地幔.新生代超钾质和钾质玄武岩具有Nb-Ta的弱负异常,87Sr/86Sr值为0.704 7~0.705 7、εNd（t）值为-6.3~-0.8,而地幔捕掳体具有Sr-Nd同位素亏损特征;钠质玄武岩具有Nb-Ta的正异常,较超钾质和钾质玄武岩具有低的87Sr/86Sr（0.703 5~0.704 2）以及高的εNd（t）值（+3.4~+6.6）,类似MORB的同位素组成,这些特征说明大兴安岭北段新生代玄武质岩石起源于软流圈地幔.综上所述,大兴安岭北段早白垩世和新生代玄武质岩石成分的差异不仅指示其岩浆源区从岩石圈地幔转变为软流圈地幔,更为重要的是它揭示了研究区地幔的热演化过程——从早白垩世高的地温梯度到新生代低的地温梯度的转变.这一过程也是岩石圈从中生代晚期到新生代逐渐增厚的过程.结合区域构造演化,可以得出大兴安岭北段早白垩世的玄武质岩浆作用与岩石圈伸展、减薄形成的裂陷作用相关,而新生代玄武质岩浆作用则与陆内裂谷作用相关. 相似文献
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中国东南沿海中—新生代玄武岩微量元素和Nd—Sr—Pb同位素研究 总被引：18，自引：8，他引：18
本文对中国东南沿海不含幔源包体的中生代玄武岩和含幔源包体的新生代玄武岩进行了微量元素和Nd-Sr-Pb同位素对比研究。中生代玄武岩呈Ta,Nb和Hf负异常，低Ce/Pb,Nb/U比值和高La/Nb比值，与岛弧火山岩和陆壳岩石的微量元素特征相类似，说明在岩浆生成和上升过程中，幔源组分受到了陆壳组分的混染。新生代玄武岩呈Ta,Nb正异常和Pb负异常，高Ce/Pb,Nb/U比值和低La/Nb比值，与海岛玄武岩（OIB）相类似，Nd-Sr同位素成分与夏威夷玄武岩类似，因而它们未受明显的陆壳混染。^143Nd/^144Nd与^206Pb/^204Pb之间的负相关关系和^87Sr/^86Sr与^206Pb/^204Pb之间的正相关关系说明本区新生代玄武岩起源于中等亏损程度的软流圈地幔，并与EMII富集地幔组分发生了混合。 相似文献
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冈底斯基性次火山岩地球化学和Sr-Nd-Pb同位素：碰撞后火山作用亏损地幔源区的约束 总被引：15，自引：4，他引：15
青藏高原隆升与伸展构造模式（地幔对流减薄、板片断离和大陆俯冲）认为地幔软流圈上涌为藏南碰撞后火山作用提供了热源,而已有研究成果没有包括碰撞后火山作用软流圈地幔源区的岩石学、地球化学证据,而是集中在富集岩石圈地幔.出露于冈底斯东段达孜-甲马地区的基性次火山岩的^40Ar/^39Ar坪年龄为38.07～42Ma.次火山岩具有高Mg#值和相容微量元素含量（Cr、Ni、V、Sc）,低LILE、和LREE,低LREE/HREE分离.原生样品呈现平坦的稀土配分曲线和LILE亏损的原始地幔标准化曲线,显示出OIB地球化学亲和性.岩石具有低Sr、低Pb和高Nd同位素组成[（^87Sr/^86Sr）i=0.7048～0.7064;（^144Nd/^143Nd） i = 0.5126～0.51286 ;^206Pb/^204Pb = 18.3722～18.5288; ^207Pb/^204Pb = 15.5686～15.6214; ^208 Pb/^204Pb = 38.5203～38.7298],显示出与富集OIB非常相似的Sr-Nd-Pb同位素组成及变化范围.应用我们的分析数据并结合已有研究成果,达孜-甲马基性次火山与adakite、林子宗火山岩、钾质岩-超钾质岩构成了藏南碰撞后火山岩Sr-Nd-Pb同位素组成演化带,基性次火山岩分布于演化带的原生端元,揭示出其岩浆源区与富集岩石圈地幔存在明显的差异.研究结果证明,具有与OIB相似地球化学和Sr-Nd-Pb同位素组成的基性次火山岩的源区是软流圈地幔.由冈底斯带新近纪基性火山作用厘定的软流圈上涌深部过程对洋壳断离模式、基性岩浆底侵作用和西藏高原地壳加厚时限提供了有效的约束. 相似文献
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牙克石地区出露一套早白垩世玄武质火山岩,其SiO2含量为52．81%-53．39％,K2O含量为1．86％-2．87％,岩性为玄武质粗面安山岩。富集大离子亲石元素Rb和Ba,高场强元素Nb和Ta亏损明显,Zr和H阮明显异常,8Eu为0．77-0．82。从同住素的特点看,（^87Sr／^86Sr）,变化于0．704762-0．704941之间,εNd（t）为2．00～2．54;在εNd（t）-（^87Sr／^86Sr）闺解上,样品投影点落入洋岛玄武岩（OIB）和美国盆岭省范围内。^206Pb／^204pb为18．3288-18．4225,^207b／^204Pb为15、4566-15．4893,^208Pb／^204Pb为37．9401-38．0523：在。^207Pb/^24Pb-^206Pb.^204pb和,^208b／^304pb-^306Pb／^204pb图解上．样品投影点都落在亏损洋中脊玄武岩地幔附近。综合考虑本区火山岩的地质、地球化学特点,认为其来源于被俯冲洋壳交代的岩石圈地幔。 相似文献
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大兴安岭北段牙克石地区玄武质火山岩的元素、
同位素地球化学特征及其地质意义 总被引：4，自引：2，他引：2
牙克石地区出露一套早白垩世玄武质火山岩,其SiO2含量为52．81%-53．39％,K2O含量为1．86％-2．87％,岩性为玄武质粗面安山岩。富集大离子亲石元素Rb和Ba,高场强元素Nb和Ta亏损明显,Zr和H阮明显异常,8Eu为0．77-0．82。从同住素的特点看,（^87Sr／^86Sr）,变化于0．704762-0．704941之间,εNd（t）为2．00～2．54;在εNd（t）-（^87Sr／^86Sr）闺解上,样品投影点落入洋岛玄武岩（OIB）和美国盆岭省范围内。^206Pb／^204pb为18．3288-18．4225,^207b／^204Pb为15、4566-15．4893,^208Pb／^204Pb为37．9401-38．0523：在。^207Pb/^24Pb-^206Pb.^204pb和,^208b／^304pb-^306Pb／^204pb图解上．样品投影点都落在亏损洋中脊玄武岩地幔附近。综合考虑本区火山岩的地质、地球化学特点,认为其来源于被俯冲洋壳交代的岩石圈地幔。 相似文献
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从浙东、闽东南的早白垩世“双峰式火山岩”和“复合岩体”中选择了有代表性的玄武岩和角闪辉长岩，分离出钛-磁铁矿，进行Re—Os同位素分析。角闪辉长岩的γos（130Ma）为-83．7～ -47．1，其（^187 Os／^188 Os）。过低，为0．0667和0．0205。这低得不合理的（^187 Os／^188 Os）i表明成岩之后Re-Os体系可能受到扰动，某些地质过程导致外加Re的进入，使岩石的^187 Re／^188 Os比值偏高、（^187 Os／^188 Os）;及γOs（t）值偏低。玄武岩的γOs（130Ma）=21．4—267．8，其（^187 Os／^188 Os）。为0．1531～0．4639。Re—Os、Sm—Nd同位素及微量元素地球化学研究表明，早白垩世玄武岩浆不是来自富集地幔，而是来自亏损的地幔源区，在其演化过程中经受了地壳岩石和熔体的混染。晚中生代时期，东南沿海“大陆弧”下的地幔可能不是富集的岩石圈地幔，具有亏损特性，因而是软流圈地幔。 相似文献
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Snežana S. Nenadović Ljiljana M. Kljajević Maja A. Nešić Marijana Ž. Petković Katarina V. Trivunac Vladimir B. Pavlović 《Environmental Earth Sciences》2017,76(2):79
The paper presents chemical and structural analysis of geopolymer materials which are obtained by alkali-activated calcined clay (metakaolin) originated from Serbia under strictly defined conditions. Characterization of the metakaolin and geopolymers molecular structure has been done using X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The paper presents the possibility of obtaining geopolymer structure and differences in chemical and structural characterization of these materials taking into account the concentration of NaOH as a variable parameter. The results of MALDI analysis of metakaolin and synthesized geopolymer structures using various matrix system: 2,4,6 trihydroxyacetophenone (THAP), α-cyano-4-hydroxycinnamic, 2,6 dihydroxyacetophenone and laser desorption/ionization, have shown that THAP matrix is the most appropriate for analysing these aluminosilicate materials. 相似文献
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Melilite and wollastonite from the Colle Fabbri stock contain silicate melt and silicate-carbonate inclusions. The homogenization temperatures of silicate inclusions are within the magmatic temperature range of mantle ultrabasic melts: about 1,320?±?15 °С. Their composition is melilititic and evolves to the composition of leucite tephrite and phonolite. The composition of silicate-carbonate inclusions are high SiO2, Ca-rich, enriched in alkalies and are similar to that of inclusions of carbonatite melts in the minerals of melilitolites of other intrusive ultramafic complexes. They are also similar to the compositions of metasomatized travertine covering the melilitolite stock. The presence of primary silicate and silicate-carbonate inclusions evidences that the melilitite magma from which melilitolites of Colle Fabbri crystallized was associated with carbonatite liquid. This liquid was highly fluidized, mobile and aggressive. Actively interacting with overlying travertine, the liquid enriched them with alkalies, aluminosilicates and incompatible elements, which resulted in the equalization of their compositions. Heterogeneous compositional dominions were formed at the contact between melilitolite and wall pelites. In the minerals of these contact facies high-Si melt inclusions of varying composition have been observed. Their occurrence is related to the local assimilation by the high-temperature melilitite magma of pelitic country rocks. The content of incompatible elements in melilitite melts and melilitolites is higher than the mantle norm and they have peculiar indicator ratios, spectra, Eu/Eu* ratio, which suggest a peculiar mantle source. 相似文献
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Siamak Hashemi David B. Hughes Barry G. Clarke 《Geotechnical and Geological Engineering》2006,24(4):973-984
Geotechnical investigations have been carried out for many years in order to identify the depth, extent and the properties
of the glacial deposits of Northern England. This valuable source of data exists in various forms because of the differences
in the design of the investigations, the codes of practice relevant at the time of investigations, and contractors practice.
An electronic store of these data would be a valuable asset not only to future development but to help in scientific studies
of glacial till. This paper presents an overview of NETDATA (Northern England Till DATA), a relational database which is designed
to store that data in a consistent format, allowing flexibility for further use. A preliminary analysis of the data has resulted
in a characteristic data set for the tills. 相似文献
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Mineral assemblages and chemical compositions of minerals foundin impure dolomitic marbles embedded in gneisses and migmatitesof the E. Greenland Caledonian fold belt (Scoresby Sund) suggestthat the marbles were metamorphosed near 630 °C at 5 kbpressure. The analysis of complex textural and mineralogicalrelations among minerals such as dolomite, calcite, forsterite,pargasite, chlorite, spinel, diopside and phlogopite led tothe conclusion that the major mineralogical features of therocks were probably caused by sodium metasomatism at constanttemperature and pressure. The effect of the inferred sodiummetasomatism may be summarized by three schematic reactionsall involving modal changes of excess dolomite, calcite, forsterite,chlorite and spinel: (a) nucleation and growth of pargasite,(b) resorption of phlogopite, and (c) growth of pargasite fromphlogopite. 相似文献
17.
B.A. Mndez-Ortiz A. Carrillo-Chvez E. Gonzlez-Partida J. Tritlla G. Levresse F. Gonzlez-Posadas H. Martínez-Kemp 《Journal of Geochemical Exploration》2006,89(1-3):276
Brine chemical data obtained from oil wells in Cretaceous oilfields in the Southeastern Basin of Mexico show a complex evolution, with the following main hydrochemical processes: (1) mixing of highly evaporated brines, past the point of halite precipitation with seawater; (2) water/rock interactions between brines and carbonated rocks (dolostones). 相似文献
18.
X. Zheng Y. Zhang T. Cheng M. Zhao H. Kong Z. Jin 《International Journal of Environmental Science and Technology》2016,13(8):2091-2096
In order to prepare iron phosphate by waste sludge, we report a method for effective utilization of the sludge obtained from the electrocoagulation treatment of source-separated urine. The sludge was dissolved with hydrochloric acid and pretreated with H2O2 and Na3PO4; finally, NaOH was added to precipitate iron phosphate from the solution. Thermal treatment of the precipitate at 750 °C in air yielded crystalline quartz-like anhydrous FePO4. The precipitate was characterized by a number of thermal techniques such as thermogravimetry/differential thermal analysis, scanning electron microscopy, and X-ray powder diffraction. 相似文献
19.
《International Geology Review》2012,54(3):272-280
The Gejiu tin field in southern China consists of six major deposits and many minor ones containing more than 120 million tons (pre-mining resource) at 1% Sn and significant amounts of Cu, Ag, Zn, and Pb. It is one of the largest tin fields of primary deposits in the world. Mineralization is the result of the intrusion of granitic plutons into Permian and Triassic sedimentary rocks, which are dominantly limestone, dolomitic limestone, and dolomite. Five (mostly peraluminous) granitic intrusives (64-115 Ma) are present in the area. The largest orebodies are spatially and temporally related to the Laoka (principally), Beipaotai, and Marsong granites. Tin mineralization is mainly within greisens developed at the outermost zone of a skarn zonal sequence and are mineralogically dominated by fluorite, quartz, and micas. The deposits are the result of volatile-rich ore solutions that evolved late in the plutonic crystallization history. The solutions produced metamorphic skarns as well as ore skarns, both of which later became “greisenized” skarns. Gejiu is the largest example of what has been, up to now, a style of mineralization reported only in minor amounts. 相似文献
20.
R V Krishnamurthy D P Agrawal V N Misra S N Rajaguru 《Journal of Earth System Science》1981,90(2):155-160
Radiocarbon dates on pedogenic CaCO3, accumulated at various depths in a stabilised dune at Budha Pushkar, Rajasthan, show inversion with respect to ‘stratigraphy’. Occurrence of younger carbonates overlain by older ones at various levels, is interpreted in terms of a shift in climatic conditions causing pedogenic carbonates to be leached to greater depths. Based on this model, several wetter regions during the last 6000 years have been identified. The most significant shift from a dry to a wet phase seems to have taken place between 5000 and 4500 years ago. Conclusions drawn from this study is in agreement with that based on pollen data and extends this method as a potential palaeoclimatic indicator. 相似文献