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1.
汉诺坝玄武岩中辉石岩类包体Nd,Sr,Pb同位素及其成因信息   总被引:2,自引:1,他引:2  
对汉诺坝地区的12个辉石岩和1个麻粒岩包体进行了Nd、Sr、Pb同位素测定,发现辉石岩组成有很大变化,^143Nd/^144Nd比值为0.51160-0.51314,^87Sr/^6Sr比值为0.7029-0.7086,^206Pb/^204Pb比值为15.942-18.683,^207Pb/^204Pb比值为15.24-15.569,^208Pb/^204Pb比值为36.213-38.744,显  相似文献   

2.
张成立  金海龙 《岩石学报》1999,15(3):430-437
武当地块基性岩墙群与耀岭河群基性火山岩的Sr、Nd、Pb同位素特征反映它们具相同的混合地幔源区。前者的(^87Sr/^86Sr)i=0.6905 ̄0.7061,εNd(t)=-1.9 ̄5.0,Δ^208Pb/^204Pb=35.49 ̄190.26,Δ^207Pb/^204Pb=4 ̄85,Th/Ta低,La/Yb变化大;后者的(^87Sr/^86Sr)i=0.6487 ̄0.7075,εNd(t)=0  相似文献   

3.
托云盆地晚白垩世--早第三纪碱性橄榄玄武岩Sr、Nd、Pb同位素组成表明,本区玄武岩以低Sr、Pb和相对高的Nd同位素值(^87Sr/^86Sr为0.703554 ̄0.703884;^143Nd/^144Nd为0.512838 ̄0.512904;^206Pb/^204Pb为18.0063 ̄18.4720;^207Pb/^204Pb为15.4411 ̄15.5060;^208Pb/^204Pb为37.  相似文献   

4.
以区域地球化学研究成果为基础,通过Pb、Sr、Nd同位素特征分析,揭示出东江口岩体群的Pb同位素特征与南泰岭东段基底具有耦合关系,而与其它构造单元则存在明显的差异,^204Pb-^207Pb/^206Pb,^204Pb-^208Pb/^206Pb图解研究表明,该岩体群为下地壳源花岗岩类,Nd同位素特征(tDN和εNd(t)表明,耀岭河群最适合于作为岩体群的主要物源。该岩体群和耀岭河群的Sr同位素存  相似文献   

5.
邢光福  陶奎元 《岩石学报》1997,13(4):473-487
对乔治王岛11个火山岩和2个侵入岩样品做了Sr-Nd-Pb同位素分析,其中(87Sr/86Sr)i=0.70326~0.70392,εNd=3.02~6.72,206Pb/204Pb=17.776~18.515,207Pb/204Pb=15..506~15.571,208Pb/204Pb=37.868~38.308。根据以上同位素组成及其相互关系并结合岩石学和微量元素特征及火山岩中熔融包裹体成分,得出以下结论:(1)研究的乔治王岛岩浆岩起源于亏损地幔(DMM)和地幔流体交代成因的富集地幔EMI混合形成的源区;(2)该源区具有广义Dupal异常,它正是由于EMI组份加入即通过流体交代作用而产生的;(3)流体主要是俯冲深海沉积物脱碳酸盐作用而释放出的富CO2流体。  相似文献   

6.
扬子岩浆岩带东段基性岩地球化学   总被引:20,自引:7,他引:13  
邢凤鸣 《地球化学》1998,27(3):258-268
长江中下游中生代岩浆岩带称为扬子岩浆岩带。该带岩浆岩属高钾钙碱性岩系和橄榄安粗岩系,共基性端员玄武岩和辉长岩高钾富碱,硅弱不饱和,富集Rb、Ba、Th、K、LREE等强不相容元素,强烈亏损Cr、Ni等强相容元素;REE球粒陨石标准化曲线为右倾型,在La/Sm-La图上排列成一斜线,是地幔不同程度部分熔融为主的产物。基性岩εNd较高,Isr较低,在εNd-ISr图上沿地幔排列及其延长线分布,略向右漂  相似文献   

7.
冀西北水泉沟正长岩杂岩体的成因   总被引:11,自引:5,他引:11  
包志伟  赵振华 《岩石学报》1996,12(4):562-572
水泉沟碱性正长岩杂岩体侵入于太古宇桑干群变质岩中,岩体主要由碱性长石正长岩、角闪碱长正长岩、正长岩、石英碱长正长岩等组成,属碱性岩系列,在岩石的石英颗粒中见有熔融包体的存在。岩石的稀土元素分布模式呈平滑的右倾模式,无明显的铕异常。岩石的Pb同位素组成为206Pb/204Pb=16.457~18.286、207Pb/204Pb=15.270~15.472、208Pb/204Pb=36.539~37.393,石英的δ18O值为8.0‰~8.5‰,(87Sr/86Sr)i≈0.705,岩石的tDM为1.6~1.9Ga,εNd(t)为-7.45~-13.1,明显大于区域基底的εNd(t)值(-20±)。以上结果表明,岩体为上地幔和下地壳物质部分熔融的产物。岩体角闪石39Ar-40Ar年龄327Ma,为海西期岩浆作用的产物  相似文献   

8.
汉诺坝玄武岩中辉石岩类包体Nd、Sr、Pb同位素及其成因信息   总被引:13,自引:1,他引:13  
对汉诺坝地区的12个辉石岩和1个麻粒岩包体进行了Nd、Sr、Pb同位素测定,发现辉石岩组成有很大变化,143Nd/144Nd比值为0.51160—0.51314,87Sr/86Sr比值为0.7029—0.7086,206Pb/204Pb比值为15.942—18.683,207Pb/204Pb比值为15.264—15.569,208Pb/204Pb比值为36.213—38.744,显示了其复杂成因q推测具有高Sr、低Nd和低Pb同位素组成的辉石岩是地幔早期富集的产物,与麻粒岩、辉长岩包体有类似成因;具有弱至中等亏损的Nd、Sr同位素和高放射成因Pb的辉石岩是亏损地幔近期富集或交代的产物  相似文献   

9.
根据中生代火山岩和侵入岩的岩石类型与组合及其岩石化学特征等,将中国东南中生代大陆边缘分成陆缘火山(岩浆)弧(Cva)、陆缘弧后(间)火山盆地带(Abv)和裂陷火山(岩浆)带(Rv),并深入研究了它们的Sr、O、Pb和Sm、Nd同位素组成特征。Cva具较低的ISr和δ18O值及变化较大的Pb同位素组成与较高的εNd值;Abv具较高的ISr和δ18O值及较稳定的Pb同位素组成与较低的εNd值;Rv则具较低(较稳定)的ISr值和Pb同位素组成及变化较大的δ18O值与εNd值。由此推断,Cva和Abv的岩浆均为陆缘亏损地幔与上地壳成分混合形成(前者地幔成分居多,后者以地壳成分为主),Rv的岩浆则具陆内交代-亏损地幔与较多的下地壳物质混合源的成因特征。  相似文献   

10.
藏北鱼鳞山超钾质火山岩为一中等规模的熔岩被, 可分为三期。前两期主要为霞石黝方白榴石响岩、霞石白榴斑岩等, 后期主要为方钠石霓石粗面岩、霓霞粗面岩等。时代为18~30 Ma。本区超钾质岩浆 Si O2 强烈不饱和、强碱性、高度富集 L R E E及 L I L E、放射成因 Sr、 Pb 及非放射成因 Nd 同位素 (86 Sr/87 Sr= 0708766~0709162, 206 Pb/204 Pb= 18882888~ 19104751, 207 Pb/204 Pb= 15642037 ~ 15828458, 208 Pb/204 Pb= 39138921 ~ 39686835 及143 Nd/144 Nd= 0512116 ~0512342),其上述特征指示岩浆源区为受到地壳物质强烈交代的富集 E M I I型地幔。藏北拉嘎拉钠质碱性橄榄玄武岩为高原面上的剥蚀残丘, 时代为60 Ma。其岩石学、 R E E、微量元素及 Sr Nd Pb 同位素指示了岩浆源区为受到洋壳俯冲物质交代的轻度富集地幔。本研究结果指示, 羌塘高原南部富集地幔的形成可能是受到印度板块俯冲的影响。  相似文献   

11.
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.  相似文献   

12.
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.  相似文献   

13.
Robert L. Linnen   《Lithos》2005,80(1-4):267-280
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.  相似文献   

14.
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).  相似文献   

15.
Well investigated platforms have been selected in each continent, and the history of Cretaceous transgressions and regressions there is concisely reviewed from the available evidence. The factual records have been summarized into a diagram and the timing of the events correlated between distant as well as adjoining areas.On a global scale, major transgressions were stepwise enlarged in space and time from the Neocomian, via Aptian-Albian, to the Late Cretaceous, and the post-Cretaceous regression was very remarkable. Minor cycles of transgression-regression were not always synchronous between different areas. Some of them were, however, nearly synchronous between the areas facing the same ocean.Tectono-eustasy may have been the main cause of the phenomena of transgression-regression, but certain kinds of other tectonic movements which affected even the so-called stable platforms were also responsible for the phenomena. The combined effects of various causes may have been unusual in the Cretaceous, since it was a period of global tectonic activity. The slowing down of this activity followed by readjustments may have been the cause of the global regression at the end of the Cretaceous.  相似文献   

16.
China, as many other parts of the world, has a serious shortage of water resources. In China, there is a total amount of 2.8×10^12 m3 of freshwater, but that is only 2000 m3 per capita, which is about one quarter of the world average. Thereforc, seawater desalination engineering is of great significance to the nation.  相似文献   

17.
正Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the  相似文献   

18.
正The Wulashan-Hademengou gold ore district in Baotou city,Inner Mongolia,is a further newly discovered super-large gold metallogenic belt in northern China.The accumulated proven gold metal amount is 84.46 t,with an average grade of3.53 g/t and a gold metal amount of 63.16 t,with an average grade of 3.30 g/t.The potential reserves are over 100 t.  相似文献   

19.
正Since the first discovery of the excellent performance of nickel-bearing iron alloys in 1889,scientists have developed3000 more kinds of nickel alloys,which still have an enormous market demand at present.However,the scarcity of global nickel ore resources has restricted economic development.In recent years,experts from the Institute of Multipurpose Utilization of Mineral Resources have studied the comprehensive utilization technique of low-grade nickel ores from  相似文献   

20.
正Professor Shu received his undergraduate training in Paleontology at Peking(Beijing)University in1964–1969,obtaining his Master's degree at Northwest University(Xi’an)and Ph.D.in China University of Geosciences(Beijing);he was Visiting Scholar at the Smithsonian Institution,Washington,D.C.,USA in 1988,Humboldt Research Fellow at University of Bonn in 1988–1989,at University of Wuerzburg,Germany in 1994–1995,and Visiting Scholar at Cambridge University,UK  相似文献   

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