共查询到20条相似文献，搜索用时 93 毫秒
1.
大兴安岭西坡中生代火山岩形成机制 总被引：3，自引：0，他引：3
依据火山喷发特点、火山岩岩石组合及火山岵的同位素年代学证据,大兴安岭西坡地区发育的大量中生代火山岩可分为三个旋回,自早而晚依次为：晚侏罗世的塔木兰沟旋回、上库力旋回和早白垩世的伊列克得旋回。不同旋回火山岩具有不同的地质、地球化学特征。在岩浆起源、源区性质和演化过程等方面,不同旋回火山岩既有相似之处,也存在明显差别。火山岩为深部作用和过程的产物,对其形成机制的研究,有助于理解本区中生代发生的剧烈的火 相似文献
2.
湘黔桂雪峰期地层单元岩石地球化学特征 总被引：6，自引：0，他引：6
扬子地块江南构造域的湘黔桂地区，雪峰期地层单元中的变质中基性至基性火山岩显示大陆玄武岩至玄武岩类的地球化学特征，变中酸性至酸性火山岩类主要显示Ｓ型，其次为Ｓ与Ｉ过渡型的花岗质岩浆的地球化学特征；变砂岩类和变泥岩类显示大陆边缘砂岩类和泥岩类的地球化学特征。根据其岩石地球化学特征，具双峰式火山岩组合及沉积相特征，推测其属于内硅铝裂隙盆地陆缘环境中的产物。 相似文献
3.
东天山觉罗塔格地区晚石炭世岛弧火山岩 总被引：3，自引：0，他引：3
东天山觉罗塔格地区土古土布拉克组火山岩是晚石炭世火山活动的产物,火山岩与一套陆相碎屑岩互层产出,岩石组合为岛弧拉斑玄武岩、钙碱性(高铝)玄武岩、高铝玄武安山岩、英安岩和流纹岩,火山活动总体上具有由早期中基性火山岩向晚期中酸性火山岩演化的规律.岩石化学和地球化学特征表明,火山岩的w(SiO2)基本上连续变化于47.68%～75.19%之间,无明显的成分间断,安山岩所占的比重最大,并不具有双峰式火山岩的特点.其中w(SiO2)小于57.48%的中基性火山岩具有高w(Al2O3)(16.34%～20.22%),较富钾,富集大离子亲石元素,具明显的Nb、Ta负异常;w(SiO2)介于62.11%～75.19%之间的安山岩、英安岩和流纹岩岩石化学特征与准铝质的Ⅰ型花岗质岩石相似,其地球化学特征也反映出岛弧花岗岩的特点,表明东天山觉罗塔格地区路白山一带在晚石炭世仍处于古亚洲洋向南俯冲的岛弧环境. 相似文献
4.
选取塔里木东北部的笔架山二叠纪火山岩带为研究对象,通过年代学、岩石学和地球化学等研究,论证火山岩的亲缘关系以及火山岩与侵入岩的关系,探讨岩浆演化过程与源区性质。笔架山一带二叠纪火山岩分布于笔架山镁铁质-超镁铁质岩带北侧。火山岩的岩石类型主要有玄武岩、玄武质安山岩、安山岩、英安岩和流纹岩。流纹岩的LA-ICP-MS锆石U-Pb年龄为(285.0±2.9)Ma,属二叠纪乌拉尔世。该火山岩多属拉斑玄武岩系列。玄武岩、玄武质安山岩、安山岩的岩石学及地球化学特征表明,它们都是由拉斑玄武质岩浆通过分离结晶作用演化而成,玄武岩岩浆在上升过程中经历了一定程度的同化混染作用。玄武岩的w(TiO2)(2.35%~3.81%)、w(TFeO)(10.59%~13.87%)、w(P2O5)(0.35%~0.50%)高,属于高钛玄武岩系列,富集轻稀土元素和大离子亲石元素,Nd-Sr同位素组成具有OIB亲和性,地球化学特征显示出玄武岩的岩浆源区属尖晶石稳定域。笔架山二叠纪侵入岩和火山岩的时空关系、岩石地球化学特征和岩浆演化程度的研究表明:二者是同源岩浆分异的产物,岩浆进入现存岩浆房后,大量的堆晶相形成了镁铁-超镁铁质侵入岩,而演化的岩浆沿岩浆房顶部或旁侧的断层带溢出而形成基性-中性火山岩;酸性火山岩是由幔源岩浆的热量引起地壳重熔形成的。 相似文献
5.
华北板块南缘熊耳群火山岩岩石学及其形成环境讨论 总被引：1，自引：0，他引：1
熊耳群火山岩系以熔岩为主,其岩石学、岩石化学及地球化学特征表明为双模式火山岩套:下、上熊耳群的主要岩石类型为钾细碧岩及细碧岩、钾角斑岩及角斑岩,属碱性玄武岩浆系列,其源岩浆来自地幔,在上升过程中曾在中间岩浆房停顿并与壳层物质混染。中熊耳群的主要岩石类型为钾石英角斑岩,属拉斑玄武岩浆系列,岩浆来源于下地壳的熔融。火山岩系的岩石地球化学特征及区域分布特征表明熊耳群火山岩系产于活动大陆边缘裂谷带,豫西—陕西这一裂谷带从下熊耳群至上熊耳群火山活动从北向南移动,从东向西扩展,上熊耳群形成时裂谷深度最大,东西范围也最广。中熊耳群形成时期裂谷带为相对闭合阶段,壳层熔融物质上升喷发。 相似文献
6.
熊耳群火山岩系以熔岩为主,其岩石学、岩石化学及地球化学特征表明为双模式火山岩套:下、上熊耳群的主要岩石类型为钾细碧岩及细碧岩、钾角斑岩及角斑岩,属碱性玄武岩浆系列,其源岩浆来自地幔,在上升过程中曾在中间岩浆房停顿并与壳层物质混染。中熊耳群的主要岩石类型为钾石英角斑岩,属拉斑玄武岩浆系列,岩浆来源于下地壳的熔融。火山岩系的岩石地球化学特征及区域分布特征表明熊耳群火山岩系产于活动大陆边缘裂谷带,豫西-陕西这一裂谷带从下熊耳群至上熊耳群火山活动从北向南移动,从东向西扩展,上熊耳群形成时裂谷深度最大,东西范围也最广。中熊耳群形成时期裂谷带为相对闭合阶段,壳层熔融物质上升喷发。 相似文献
7.
溧水盆地位于长江中下游成矿带东部,与庐枞、宁芜等火山岩盆地相似,发育中生代火山岩。为了探讨溧水盆地不同旋回火山岩形成时代、岩浆源区及岩浆活动的大地构造背景及其与铁铜成矿关系等问题,本次研究选取溧水盆地广泛出露且与成矿关系密切的中生代龙王山旋回和大王山旋回火山岩进行了锆石精确定年和Hf同位素分析以及全岩主微量元素分析。研究表明溧水盆地岩浆活动起始时间为~135 Ma,峰期时间为135~124 Ma。龙王山、大王山旋回火山岩Hf同位素特征相似,εHf(t)值范围大多在-6~-11之间,暗示其源区可能相似。岩石地球化学特征显示龙王山—大王山旋回岩浆由中基性向中酸性过渡,并向高钾富碱方向演化,空间上从北西-南东方向演变,与盆地内铁铜金锶矿的形成有关。龙王山旋回火山岩明显Sr正异常,推测龙王山旋回可能是Sr矿的矿源层。结合岩石地球化学和同位素特征,认为岩浆源区为可能为富集地幔,在喷发早期受到了少量陆壳物质的混染。溧水盆地与长江中下游其它火山岩盆地形成时代相似,可能受同一构造背景控制。结合前人研究成果分析认为在~135 Ma为太平洋板块俯冲的转折点,即俯冲作用减弱,俯冲板块发生后撤,形成区域性拉张环境,从而形成的一系列火山岩盆地。 相似文献
8.
唐古拉山东段莫云地区二叠纪玄武岩地球化学特征及源区性质 总被引：3，自引：0，他引：3
在青藏高原腹地,二叠纪火山岩分布于唐古拉山东段,古地理上位于北羌塘盆地东缘。对唐古拉山东段莫云地区中二叠世栖霞期尕笛考组火山岩的主量元素、微量元素和Sr-Nd同位素进行了分析。岩相学和地球化学指标显示二叠纪火山岩为玄武岩,该套岩石低SiO2、MgO、K2O和Mg#值(0.39～0.48),富Na2O、TFeO、TiO2、P2O5含量,富集LREE和高场强元素(Nb、Ta、Zr、Hf、P、Ti),(La/Yb)N=14.89～23.23,(Gd/Yb)N=2.30～3.58,Eu异常不明显(δEu=0.76～0.99),具有明显的Th正异常和K、Sr负异常,显示与板内碱性玄武岩相似的地球化学特征;同位素组成以低(87Sr/86Sr)i(0.7033～0.7039)、高εNd(t)(+4.2,t=271Ma)为特点,反映岩浆源区既有亏损地幔源(DMM)又有富集地幔源(EMⅠ)的双重属性。岩浆起源可能与地幔柱诱导的软流圈上涌导致含石榴子石橄榄岩的岩石圈地幔部分熔融有关。莫云玄武岩形成于板内伸展环境(初始裂谷),具有主动裂谷作用性质。 相似文献
9.
长白山区图们江流域新生代火山岩的岩石化学研究 总被引：5，自引：3，他引：5
图们江流域新生代火山岩以溢流式喷发为特征，其主要岩石类型以拉斑玄武岩为主，含少量玄武质粗安岩、碱性玄武岩、玄武质安山岩和粗面玄武岩。根据图们江流域火山岩的Mg#（Mg#=100Mg^2＋／（Mg^2＋＋Fe^2＋））值多数≤60，Ni含量〈100μg／g和主、微量元素地球化学特征综合表明，形成火山岩的岩浆不是原始岩浆，它们是原始岩浆在上地幔经历了橄榄石、辉石分离结晶作用后形成的以拉斑玄武岩为主，包括碱性玄武岩和粗面玄武岩等演化岩浆，结晶分异作用是岩浆演化过程的主要控制因素。拉斑玄武质岩浆在上升过程中发生了不同程度的壳源物质同化混染作用，发生在上地壳遭受较大程度混染的岩浆K2O含量明显偏高（〉2．6％），形成玄武质粗安岩。 相似文献
10.
11.
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
12.
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
13.
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
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of 相似文献