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变质锆石拉曼光谱研究--以大别造山带为例 总被引：5，自引：0，他引：5
对大别山的道士冲辉石岩、双河榴辉岩和碧溪岭石榴橄缆岩的锆石进行了激光拉曼探针，阴极发光（CL）观察和U、Th等微量元素的微区分析及U－Pb同位素测定，发现锆石拉曼光谱波数和半高宽都能指示其蜕晶化程度，但对于高度蜕晶化锆石，波数已经不再完全适用，而只能通过其特征谱峰半高宽来确定。碧溪岭石榴橄榄岩锆石微区微量元素和拉曼探针分析发现，半高宽和Th/U比正相关，这是由岩浆锆石在变质过程中不同程度的固态重结晶作用造成的，其可能曾经遭受过约220Ma的热事件扰动。双河榴辉岩锆石则可能遭受了流体参与下的变质重结晶作用的影响。锆石重结晶作用是变质岩中锆石年龄和化学组成变化的主要原因。 相似文献
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大别山高压-超高压片麻岩锆石的拉曼光谱学研究 总被引：1，自引：0，他引：1
对大别山高压-超高压片麻岩的锆石进行了激光拉曼探针、阴极发光(CL)、U-Pb年龄和U、Th等微量元素的测定分析.研究结果表明:锆石拉曼光谱1008cm-1峰的半高宽普遍小于20cm-1,指示锆石结晶程度较好到中等程度的蜕晶化;早期继承锆石在三叠纪高压-超高压变质作用中经历了退火和重结晶作用,所受的放射性通量是从200Ma的早侏罗纪开始积累的,表明高压-超高压岩石在这一时间已出露地表;北大别白垩纪岩浆热事件对高压-超高压岩石的影响很小;大多数锆石数据都落在天然锆石的放射性破坏趋势(RDT)中,表明锆石在高压、超高压过程中基本发生了完全的重结晶. 相似文献
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北大别漫水河混合岩化片麻岩中锆石微区微量元素特征及其地质意义 总被引：1，自引：1，他引：1
本文通过对北大别漫水河片麻岩的锆石进行阴极发光(CL)显微图像观察及激光剥蚀等离子体质谱(LA-ICP-MS)微区微量元素分析，试图对重结晶和深熔成因变质锆石的微量元素特征进行制约。CL图像显示该片麻岩锆石存在复杂的内部结构，有原岩岩浆锆石、重结晶变质锆石和深熔锆石。不同锆石区域的Hf、P、Ti、Nb、Ta和Ce等元素含量及Nb/Ta比值相似。但重结晶和深熔锆石的Th/U比值明显低于原岩锆石(分别为0.33～1.12、0.03～0.60和0.92～1.99).重结晶锆石区域低Th/U比值是由于重结晶过程中Th比U更易排出锆石晶格，而深熔锆石区域低Th/U比值是其结晶的熔体中低Th和高U含量的原因。不同锆石区域的稀土元素含量也不相同。原岩锆石稀土总量高(621.9～1331.6ppm)，变化较大，而深熔锆石和重结晶锆石稀土总量低(分别为236.8～642.5ppm；98.5～435，6ppm)。不同锆石区域的稀土元素配分模式相似。但重结晶锆石的稀土元素含量比原岩锆石低3～4倍，可能是重结晶过程中稀土元素被逐出锆石晶格所致。深熔锆石的稀土元素含量受深熔熔体与残留体之间平衡与否的制约，如果熔体与残留体之间达到了平衡，则深熔锆石与原岩锆石有相似的稀土元素含量；反之，深熔锆石的稀土元素含量就会低于原岩锆石。漫水河片麻岩深熔锆石的稀土含量比原岩锆石低1～4倍，反映了深熔熔体与残留体之间没有达到平衡。结合已有的花岗岩与混合岩化岩石的年龄和同位素特征，说明北大别混合岩化片麻岩可能与同时代花岗岩的形成有成因关系。 相似文献
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大别山双河超高压榴辉岩中变质锆石；离子探针和微区结构研究 总被引：19，自引：6，他引：19
对南大别双河超高压岩板榴辉岩中锆石进行了阴极发光、喇曼光谱、U- Pb和氧同位素离子探针微区分析。发现大部分锆石具有核边结构 ,其核和边有明显不同的 U ,Th,Pb含量、Th/ U比、2 0 6 Pb/ 2 38U年龄和δ1 8O值。锆石边部具有变质锆石的结构和化学特征 ,核部具有岩浆锆石向变质锆石变化的过渡特征。 17个点 U - Pb同位素分析中大多数为不一致年龄 ,由 14个正向不一致点所构成的不一致线与一致曲线的上、下交点年龄分别为 2 4 89± 2 5和 2 4 8± 16 Ma,它们代表了榴辉岩原岩形成时间和前进变质至峰期变质过程中原岩岩浆锆石重结晶和变质增生作用的时间 ,大别山变质锆石的成因是复杂的 ,它既可以是变质新生锆石 ,呈独立的颗粒或原岩岩浆锆石的增生边 ,也可以是由原岩锆石在固相或流体存在下的重结晶作用形成。不同程度的重结晶作用是超高压条件下双河榴辉岩原岩岩浆锆石发生的主要的物理化学变化 ,它导致锆石中 U、Th、Pb和Th/ U比的降低和岩浆振荡环带的消退 相似文献
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大别-苏鲁造山带高级变质岩中锆石微区U，Th和Pb化学组成特征统计 总被引：4，自引：2，他引：4
对大别-苏鲁造山带27个高级变质岩(以榴辉岩和片麻岩为主)中锆石进行了337次微区离子探针U.Th和Pb测定和U-Pb年龄研究。根据测定点年龄的不同，可以把变质岩中锆石分成三种不同成因区域，一是变质岩原岩(继承)锆石区域，它遭受了不同程度的变质重结晶作用，其^206Pb/^238U年龄值大于277Ma；二是三叠纪高压.超高压变质阶段形成的变质锆石区域，其年龄限定为273-184Ma；三是碰撞造山变质作用后形成的锆石区域，其年龄小于148Ma。对三种类型锆石中U，Th和Pb特征分析发现：片麻岩锆石中U的含量是榴辉岩类锆石中U的丰度的两倍，片麻岩类和榴辉岩类锆石中Th的丰度大致相近。各类岩石变质阶段形成的变质锆石和原岩锆石区域相比，U含量有升有降，而Th含量则大幅下降，下降幅度一般在2-10倍，高者可达20-30倍以上。除石榴石橄榄岩外，各类岩石变质锆石中区域的Th/U比都小于0.1，这是判断高压-超高压变质成因锆石的极重要化学指标。大别山超高压变质阶段后形成的锆石的Th/U比多数类似于其原岩锆石，少数接近变质锆石，说明白垩纪后期热扰动对变质岩中已存在的锆石的影响如同岩浆结晶过程。各类岩石中锆石Pb的含量变化比较复杂，Pb-U正相关性表明锆石中普通铅含量很低，绝大部分为放射成因铅。 相似文献
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本文对北大别西部的湖北英山万家老屋、罗田七道河尹家店和安徽金寨丁埠乡李集3个片麻岩样品中锆石进行了BSE显微结构分析，并在此基础上对锆石进行了离子探针U－Pb年龄测定。结果表明北大别存在两种类型的片麻岩，它们的原岩分别形成于晋宁期和燕山期，其中英山万家老屋片麻岩的形成年龄为794Ma，后期地质事件对其锆石U－Pb年龄造成的影响较小；七道河尹家店片麻岩的形成年龄为730Ma，并可能受到燕山期岩浆事件的影响，得到了140Ma左右的变质年龄；丁埠乡李集片麻岩的形成年龄为140Ma。结合已有的年代学结果，北大别地体广泛存在晋宁期的岩浆事件，表明其可能为扬子板块的北缘。 相似文献
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不同成因锆石阴极发光及微量元素特征:以新疆阿尔泰地区花岗岩和伟晶岩为例 总被引：2，自引：0，他引：2
新疆阿勒泰可可托海地区出露大量花岗岩和伟晶岩脉,利用阴极发光显微照相(CL)、电子探针背散射(BSE)和激光剥蚀电感耦合等离子质谱技术(LA-ICP-MS),观察和分析岩石中锆石的内部结构、稀土元素及Th,U含量后结果表明:该区花岗岩锆石具振荡环带和强烈的阴极发光特征,Th/U比值较高(Th/U=0.16～0.99),轻稀土亏损、重稀土富集,具较大的Ce正异常,为典型岩浆成因锆石。伟晶岩(KP-08-11)锆石为热液锆石,不具振荡环带和阴极发光,具低的Th/U比值(0.01～0.13),强烈富集稀土元素,尤其是轻稀土元素较花岗岩锆石高一个数量级,Ce的正异常相对较低。伟晶岩(KP3-08-1)锆石为变质重结晶锆石,Th/U比值分布范围较广(0.01～0.78),强烈亏损稀土元素,稀土元素配分模式存在显著的"REE四分组效应"。微量元素特征表明,伟晶岩(KP-08-11)锆石可能结晶自富U贫Th的残余岩浆流体,而伟晶岩(KP3-08-1)的锆石经历了蜕晶质化和变质重结晶作用,但依然保持了共存伟晶岩熔体的微量元素特征。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
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
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
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
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
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
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Emmanuel Skourtsos Daniel Vachard Alexandra Zambetakis-Lekkas Rossana Martini Louisette Zaninetti 《Comptes Rendus Geoscience》2002,334(12):925-931
Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931. 相似文献
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正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.) 相似文献
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正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.) 相似文献
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正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.) 相似文献
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正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus., 相似文献
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正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an 相似文献