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海南省抱板群研究的新进展 总被引:1,自引:0,他引:1
根据对抱板群的最新研究,自下而上建立两个岩石地层单位,即戈枕村组、峨文岭组。戈枕村组由片麻岩类变粒岩组成,厚度大于2381m,具混合岩化。该组测得锆石一致曲线上交点年龄(1824±77)Ma,混合岩脉体RbSr等时线年龄(1637±31)Ma,推测形成于1600~1800Ma之间,相当于长城纪早期。峨文岭组以各类片岩为主,其次是石英岩和变粒岩,无混合岩化作用。侵入该组的变质花岗岩体,测定3个锆石UPb一致曲线年龄分别为(1456±66)、1441、(1364±25.67)Ma;另一件锆石蒸发法207Pb/206Pb峰值年龄为(1407±20)Ma。以上数据表明其形成年龄为1600~1400Ma,相当于长城纪晚期 相似文献
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浙西南早元古代花岗质岩石的年代 总被引:34,自引:1,他引:34
用单颗粒锆石U-Pb稀释法获得的浙西南前寒武纪变质基底中花岗质岩石的年龄为:下际二长花岗岩1975±80Ma,里庄二长花岗岩1870±36Ma,田后花岗闪长岩1832±80Ma,三枝树混合岩1963±44Ma。这些年龄数据证实本区基底岩石在1875±100Ma时期经历了一次广泛强烈的岩浆热事件,表明八都群(麻源群)岩石的形成应早于2.0Ga。三枝树地区“鹤溪群”中混合岩年龄为1863±44Ma,斜长角闪岩全岩矿物Sm-Nd等时线年龄为2071±48Ma,表明景宁三枝树地区变质岩的时代应为早元古代,并非原来所属“鹤溪群”划归的晚古生代,这套变质岩可能是浙闽变质基底的一部分。 相似文献
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闽北浦城地区元古代侵入岩时代及其构造环境讨论 总被引:2,自引:0,他引:2
在闽北建宁发现年龄为1714±20Ma最早一期的上坪岩体以后,近年又相继在浦城地区发现元古代的侵入岩。它是岩脉、岩瘤侵入于老变质岩中,其中超基性岩测得Sm-Nd等时线年龄为1566.9Ma,片麻状钾长花岗岩中获得单锆石Pb-Pb年龄865Ma,将其时代分别确定为中元古代和晚元古代。根据钐钕稳定同位素特征,超基性岩反映大陆壳岩石的演化特点或者有陆无物质严重混染,稀土分配模式与高铝玄武岩相似,表明它们形成于大陆边缘。片麻状钾长花岗岩据石英氧同位素δ18O11.67‰,为改造型花岗岩,lgτ-lgσ图解表明形成于造山带构造环境。这一最新成果对进一步研究我省前寒武纪构造及岩浆演化具有重要意义。 相似文献
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玲珑花岗岩中锆石的离子质谱U—Pb年龄及其岩石学意义 总被引:44,自引:14,他引:30
胶东招掖玲珑花岗岩锆石SHRIMPU-Pb年龄结果表明,玲珑花岗岩形成于中生代燕山期(岩浆锆石年龄为150~160Ma之间),岩体中产有大量的中生代印支期继承锆石(200~250Ma)及少数前寒武纪继承锆石。大量印支期锆石的存在说明玲珑花岗岩是壳源成因的,其源岩主要是中酸性岩石,推测可能是印支期华北华南两地块碰撞形成的造山花岗岩,这否定了长期以来人们普遍接受的玲珑花岗岩主是胶东群变质岩重熔或交代-重熔的认识。 相似文献
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广西北部新元古代花岗石锆石U—Pb年代学及其构造意义 总被引:14,自引:4,他引:10
广西北部(扬子块体南缘)3个代表性的新元古代花岗岩体(本洞,三防和元宝山岩体)的矿物组合,岩石化学,元素和同位素地球化学特征表明,它们均为铝质S型花岗岩。高精度的SHRIMP和颗粒级锆石U-Pb定年结果表明,本洞,三防和元宝山岩体的形成时代为(820±7)Ma,(825±6)Ma和(824±4)Ma,在误差范围内基本相同,排除了本区存在中元古代末/新 元古代初形成的花岗岩。结合野外地质关系和扬子块 相似文献
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赣中变质基底的组成演化及其基本结构格局 总被引:4,自引:1,他引:4
赣中变质基底具双层结构特点,深层次基底包括中元古代中深变质岩系和由其重熔而成的混合岩及花岗岩,其中深变质岩系原岩的形成年龄为1113±49Ma,黑云斜长花岗岩具岩浆成因特征,结晶年龄为403.1~477Ma。赣中变质基底形成之后,经历了自晋宁期以来的长期而复杂的变质变形演化历史,于加里东期形成的变质核杂岩或穹隆构造,奠定了赣中隆起区的基本结构格局。 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