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1.
大兴安岭地区晚侏罗世—早白垩世流纹岩类广泛分布.根据岩石学和微量元素地球化学特征将其划分为两类, 分别称其为Ⅰ型流纹岩和Ⅱ型流纹岩.稀土和微量元素分析结果显示: (1) Ⅰ型流纹岩呈右倾的稀土分布曲线, 不相容元素以强烈富集Rb, Ba, Th, K和亏损Sr, Ti, P, Nb为特征, 其形成与钙碱性系列玄武岩浆的结晶分异作用有关; (2) Ⅱ型流纹岩具有与大陆裂谷流纹岩一致的稀土和不相容元素分布模式, 以Ba, Sr的强烈亏损与I型流纹岩相区别, 与碱性系列玄武岩类构成双峰式火山岩组合, 其成因与地壳岩石的非理想熔融作用相联系.两类流纹岩的形成与地幔柱上涌导致上覆岩石圈伸展作用有关. 相似文献
2.
西天山乌孙山地区大哈拉军山组火山岩LA-ICP-MS锆石U-Pb年龄及其构造环境 总被引：5，自引：0，他引：5
西天山乌孙山地区大哈拉军山组由玄武岩、安山岩、英安岩、流纹岩及相应的火山碎屑岩组成,安山岩和流纹岩分布最广。LA-ICP-MS锆石U-Pb定年结果表明,火山活动喷发的安山岩与安山质晶屑凝灰熔岩分别形成于353.9Ma±6.5Ma和356.3Ma±4.4Ma,属于早石炭世早期。通过区域对比,西天山大哈拉军山组的火山岩浆作用显示从伊犁中天山板块南北缘向伊犁盆地内部逐渐变年轻的特点,且火山岩喷发时代差别不大(约40Ma)。岩石地球化学研究表明,火山岩属钙碱性系列,富集轻稀土元素,相对亏损重稀土元素。中性火山岩富集大离子亲石元素(如Cs、Rb、Th、U),而相对亏损高场强元素,具有明显的Nb、Ta、Ti负异常,显示出岛弧火山岩的特征;酸性火山岩相对富集Rb、Th、U、Ta等元素,具有明显的Ba、Sr、P、Eu、Ti等元素的负异常。综合伊犁-中天山板块南缘的构造演化特征,认为大哈拉军山组形成于活动大陆边缘环境,产在板块俯冲-碰撞的最后阶段。 相似文献
3.
《四川地质学报》2021,(3)
新疆东天山滑石山一带贝义西组主要为一套海相火山岩,有基性和中酸性两类,以酸性火山岩为主,火山岩相划分为爆发相和溢流相,以溢流相为主,具双峰式喷发特征。基性玄武岩为钠质碱性岩石,轻稀土富集,铈亏损,大离子亲石元素K、Rb相对富集,Sr亏损明显,高场强元素(HFSE)无明显亏损。酸性火山岩主要为高钾钙碱性岩石,轻稀土富集,铈、铕亏损,大离子亲石元素K、Rb相对富集,Sr亏损明显,高场强元素(HFSE)无明显亏损。酸性火山岩通过LA-ICP-MS锆石U-Pb获得年龄为799～808Ma。结合地质背景认为贝义西组火山岩形成于大陆裂谷环境,是Rodinia超大陆在塔里木克拉通北缘裂解产物。 相似文献
4.
《四川地质学报》2022,(3)
新疆东天山滑石山一带贝义西组主要为一套海相火山岩,有基性和中酸性两类,以酸性火山岩为主,火山岩相划分为爆发相和溢流相,以溢流相为主,具双峰式喷发特征。基性玄武岩为钠质碱性岩石,轻稀土富集,铈亏损,大离子亲石元素K、Rb相对富集,Sr亏损明显,高场强元素(HFSE)无明显亏损。酸性火山岩主要为高钾钙碱性岩石,轻稀土富集,铈、铕亏损,大离子亲石元素K、Rb相对富集,Sr亏损明显,高场强元素(HFSE)无明显亏损。酸性火山岩通过LA-ICP-MS锆石U-Pb获得年龄为799～808Ma。结合地质背景认为贝义西组火山岩形成于大陆裂谷环境,是Rodinia超大陆在塔里木克拉通北缘裂解产物。 相似文献
5.
大兴安岭中生代玄武岩的地球化学特征：壳幔相互作用的证据 总被引：67，自引：26，他引：41
大兴安岭中生代玄武岩类由北区碱性系列岩石和南区亚碱性系列岩石组成, 主要活动时期为晚侏罗世至早白垩世, 在时间、空间上显示大体呈北北东向展布的环状 “热向斜构造”。北区碱性系列岩石高度富集轻稀土元素和大离子亲石元素, 其丰度类似于板内碱性玄武岩, 但明显亏损高场强元素这一特点又类似于火山弧钙碱性玄武岩。南区亚碱性系列岩石强烈亏损高场强元素的特征类似于火山弧钙碱性玄武岩, 但轻稀土元素和大离子亲石元素富集程度又类似于洋中脊拉斑玄武岩和岛弧拉斑玄武岩。显然, 大兴安岭中生代玄武岩系列显示地球化学双重性, 也就是既有板内特征又有火山弧特征, 既有富集特征又有亏损特征。这种地球化学双重性表明, 大兴安岭地区存在若干不同性质的地幔源： 富集性的、亏损性的、过渡性的地幔源。解释一个地区存在多元地幔源区模式的最佳方案是地幔柱。这种包含富集成分和亏损成分的地幔柱源区的形成是与古生代地质时期古亚洲域闭合过程中俯冲洋壳与亏损地幔相互作用的动力学、地球化学过程有关。 相似文献
6.
渤海湾黄骅盆地晚中生代—新生代火山岩地球化学：岩石成因及构造体制转换 总被引：1，自引：0，他引：1
本文研究了渤海湾黄骅盆地早白垩世基性-中性-酸性火山岩和第三纪基性火山岩的元素和Sr-Nd同位素地球化学特征。早白垩世火山岩以碱性系列为主,不同基性程度的岩石具有一致的富集Sr、Ba、K、Rb等大离子亲石元素,强烈亏损Nb、Ta、Zr等高场强元素,轻重稀土强烈分异,Sr-Nd同位素组成与EM I相似,Sr同位素初始比高于方城玄武岩和汉诺坝基性麻粒岩。主量和微量元素分析表明,酸性火山岩主要来自于地壳重熔,基性火山岩具有板片流体/熔体交代富集的特征,二者的岩浆混合作用可能是中性火山岩的成因,它们共同构成了东北亚晚中生代活动大陆边缘岛弧火山岩的一部分。第三纪基性火山岩以碱性系列为主,弱富集大离子亲石元素和Ti,不亏损Nb、Ta等高场强元素,Zr呈弱亏损,Sr-Nd同位素组成显示呈亏损型,亏损程度低于碱锅玄武岩和汉诺坝玄武岩,但总体与OIB相似,表明岩浆源区为软流圈地幔,并且高热上涌的软流圈对上部带有俯冲带印记的岩石圈地幔的萃取可能是导致弱富集的原因。从早白垩世的岛弧环境到第三纪陆内裂谷盆地,其控制因素可能归咎于东北亚东侧大洋板块的俯冲和相互转换。法拉隆板块于晚中生代向东北亚俯冲,但晚白垩世时被伊佐奈崎与北新几内亚板块取代,后两者之间的洋脊俯冲引起的“板片窗”效应,导致了渤海湾地区裂谷盆地的发育和同期软流圈地幔来源的玄武质火山活动。 相似文献
7.
南秦岭元古宙板内火山作用特征及构造意义 总被引：18，自引：2，他引：18
南秦岭元古宙火山岩主要由两大类岩石构成，一类为SiO245%-57%的基性火山岩系，另一类为SiO267%-78%的酸性火山岩系，主要岩石类型为细碧岩、玄武岩和石英角班岩、流纹岩。基性火山岩整体上属拉斑玄武岩系列，酸性火山岩属钙碱系列。火山岩强烈富集稀土元素，尤其是轻稀土元素，酸性火山岩和基性火山岩有相似的稀土元素特征，显示了源区特征的不同。基性火山岩富集强不相容元素，相对亏损Nb和Ti, 成于大陆裂谷环境，具有大陆拉斑玄武岩的特征。同位素特征表明基性火山作用与地幔柱活动密切相关。南秦岭的中、晚元古代大陆拉张及由古地幔柱活动所引发的陆裂火山岩浆活动是古秦岭洋打开的先兆。 相似文献
8.
9.
周翔 《吉林大学学报(地球科学版)》2019,49(4):1001-1014
松辽盆地北部早白垩世营城组发育一套以流纹岩为主的中酸性火山岩，其具有高硅、铝，富碱和低镁、铁的特征，不同类型火山岩均具有轻稀土富集、重稀土亏损、轻重分异严重的特征。其中：酸性流纹岩表现为富集Pb、U、Th、Ta、Hf和Zr等元素，亏损Sr、Ba、Eu等元素；中性安山岩、粗安岩和基性玄武岩则亏损不明显；中酸性英安岩介于两者之间。地化特征分析表明，营城组岩浆来源于亏损地幔，是地幔底侵导致地壳部分熔融，并受到地幔物质的混染，酸性岩喷出前经历了较强的岩浆分异作用。构造判别图解指示营城组火山岩形成于板内伸展环境，具有与板块俯冲作用有关的、发育于活动陆缘或岛弧的火山岩类似的演化特征。结合中国东部构造环境演化特征，认为松辽盆地北部早白垩世火山活动可能是古太平洋板块北北西方向高速俯冲导致地壳岩石圈减薄、地幔物质上涌的产物。 相似文献
10.
通过对新疆卡拉麦里姜巴斯套组火山岩野外地质特征、岩石学和高精度同位素年代学的研究,发现姜巴斯套组火山岩具典型双峰式组合,岩石类型包括玄武岩-酸性火山碎屑岩-玄武粗面安山岩;得到玄武粗面安山岩LA-ICP-MS锆石U-Pb年龄为（319.8±2）Ma（加权均方偏差值为3）,表明姜巴斯套组火山岩形成于早石炭世谢尔普霍夫阶。对火山岩地球化学特征的研究表明,姜巴斯套组火山岩钙碱性系列、高钾钙碱性系列和钾玄岩系列岩石兼而有之,岩石的稀土元素配分曲线均为轻稀土元素富集型,无明显Eu异常,玄武岩和玄武粗面安山岩具有K正异常和Sr负异常,酸性火山碎屑岩表现出Nb、Ta和Ti显著亏损。总体来说,姜巴斯套组火山岩富集大离子亲石元素,相对亏损高场强元素。玄武岩和玄武粗面安山岩表现出大陆裂谷（大陆板内拉张区域）岩石特征;酸性火山碎屑岩表现出岛弧或者活动大陆边缘岩石属性。总之,姜巴斯套组火山岩形成于卡拉麦里洋盆闭合碰撞造山后的拉张伸展环境,卡拉麦里地区在早石炭世末期就进入了碰撞后的陆内伸展拉伸阶段。 相似文献
11.
A.K. Ferguson 《Lithos》1978,11(3):189-194
Data are presented on the Ca-content of olivines in a range of volcanic rocks from a variety of suites. These include olivine basalts through to trachytes from Gough, St. Helena and Tristan da Cunha Islands; trachytes from central Victoria, Australia, and a leucitite and phonclitic-tephrite series from Bufumbira, Uganda. In olivine crystals from basaltic lavas the Ca- and Mn-contents are low and Fe shows the most significant zoning from core to rim. In Fe-rich olivines from trachytic differentiates Ca and Mn frequently show more significant variation than Fe. While the Mn-content is proportional to the Fe-content of these olivines, Ca-zoning, in many cases, is unrelated to Fe-content. The marked Ca-enrichment in olivines occurs with the absence of plagioclase in the host lavas. The Ca(Al Na K) ratio is shown to be related not only to the Ca-content of the olivines in the lava, but may be used to predict olivine stability in evolved compositions. 相似文献
12.
Volcanic rocks in Ertix,Xinjiang,occurring in the collision zone between the Siberia Plate and the Junggar Plate,are distributed along the Eritix River Valley in northern Xinjiang.The volcanic rocks were dated at Late Paleozoic and can be divided into the spilite-keratophyre series and the basalt-andesite series.The spilite-keratophyre series volcanic rocks occur in the Altay orogenic belt at the southwest margin of the Siberia Plate.In addition to sodic volcanic rocks.There are also associated potassic-sodic volcanic rocks and potassic volcanic rocks.The potassic-sodic volcanic rocks occur at the bottom of the eruption cycle and control the distribution of Pb and Zn deposits.The potassic volcanic rocks occur at the top of the eruption cycle and are associated with Au and Cu mineralizations.The sodic volcanic rocks occur in the middle stage of eruption cycle and control the occurrence of Cu(Zn) deposits.The basalt-andesite series volcanic rocks distributed in the North Junggar orogenic belt at the north margin of the Junggar-Kazakstan Plate belong to the potassic sodic volcain rocks.The volcanic rocks distributed along the Ulungur fault are relatively rich in sodium and poor in potassium and are predominated by Cu mineralization and associated with Au mineralization.Those volcanic rocks distributed along the Ertix fault are relatively rich in K and poor in Na,with Au mineralization being dominant. 相似文献
13.
Volcanic rocks of the Rhyolite and Andesite Formations from the Central Andes (Chile, Argentina, Bolivia) have been analyzed for tin. Mean values of tin in rhyolitic rocks from Chile and Argentina are about 2 ppm, from the Bolivian Altiplano 3 ppm, and from the Bolivian Eastern Cordillera 4, 5 ppm. This means that an elemental increase of regional scale towards the Bolivian tin province exists. 相似文献
14.
A radiochemical N.A.A. method was used to obtain new values on W distribution in some 125 volcanic rocks, mainly basalts and andesites, from different petrotectonic environments.These W data are below previously reported abundances. New median values in various types of rocks are suggested (ppm W). Basalts: ocean floor, 0.15; ocean islands subalkaline, 0.28; ocean islands alkaline, 0.60; island arc, 0.19: continental margin, 0.40; continental subalkaline, 0.30: continental alkaline, 1.35. Andesites: island arc, 0.23; continental margin, 1.05.Median values for all 91 basalts and all 20 andesites are 0.36 and 0.29 ppm respectively. 相似文献
15.
碧口群火山岩岩石成因研究 总被引：12，自引：1，他引：12
新元古代(846~776Ma)碧口群火山岩喷发于大陆板内裂谷环境。该火山岩系以基性火山岩为主,酸性火山岩次之,中性火山岩少见。根据岩石地球化学数据,碧口群裂谷基性熔岩总体上属于低Ti/Y(<500)岩浆类型。元素和同位素数据表明,碧口群基性熔岩的化学变化不是由一个共同的母岩浆的结晶分异作用所产生。它们极有可能是源于地幔柱源(εNd(t)≈+3,87Sr/86Sr(t)≈0.704,La/Nb≈0.7)。地壳混染作用对于碧口群裂谷基性熔岩的形成有重要贡献。我们的研究揭示,碧口群火山岩存在空间上的岩石地球化学变化。东部红岩沟和辛田坝—黑木林地区的碧口群基性熔岩以拉斑玄武岩为主,产生于幔源石榴子石稳定区的高度部分熔融。相反,西部白杨—碧口地区的碧口群基性熔岩的母岩浆则是形成于幔源的尖晶石-石榴子石过渡带:碱性熔岩是产生于部分熔融程度较低的条件下,拉斑玄武质熔岩则是产生于部分熔融条件较高的条件下。它们经受了浅层位辉长岩质(cpx+plag±ol)分离作用,化学变异较大。 相似文献
16.
Violetta Gottini Grasso 《International Journal of Earth Sciences》1968,57(3):930-935
The authoress calculates the frequency of the TiO2-content in the lavas of the active volcanoes and shows by the aid of a quotient =Al2O3 – Na2O/TiO2 the pronounced bimodality of the frequency curve from which she concludes that the great variety of the magmas cannot be explained by a magmatic differentiation but only by a double origin of the magmas from the upper mantle and from the sialic crust of the earth.
Dedicated to Professor Dr. A.Rittmann on the occasion of his 75. birthday
This study is a part of the researches, carried out with the funds of the National Research Council of Italy under the direction of Prof. A.Rittmann. 相似文献
Zusammenfassung Die Verfasserin berechnet die Häufigkeit des TiO2-Gehalts in den Laven der tätigen Vulkane und zeigt vermittelst eines Quotienten =Al2O3 – Na2O/TiO2 die ausgesprochene Bimodalität der Häufigkeitskurve, woraus sie den Schluß zieht, daß die große Verschiedenheit der Magmen nicht durch eine magmatische Differentiation erklärt werden kann, sondern daß man eine zwiefache Herkunft der Magmen annehmen muß: aus dem oberen Mantel und aus der sialischen Kruste der Erde.
Résumé L'auteur calcule la fréquence du pourcentage de TiO2 dans les laves des volcans la bimodalité cans actifs et montre, à 1 aide d un quotient =Al2O3 – Na2O/TiO2 la bimodalité prononcée des courbes de fréquence, et en tire la conclusion que la grande variété des magmas ne peut pas être expliquée par une différenciation magmatique, mais par l'origine double des magmas: du manteau supérieur et de la crôute sialique de la terre.
Riassunto L'autrice calcola la frequenza del contenuto in TiO2 nelle lave dei vulcani attivi e dimostra mediante un quoziente =Al2O3 – Na2O/TiO2 la pronunziata bimodalità delle curve di frequenza e ne trae la conclusione che la grande varietà dei magmi non è dovuta a differenziazione magmatica ma ad una duplice provenienza: dal mantello superiore e dalla crosta sialica della terra.
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Dedicated to Professor Dr. A.Rittmann on the occasion of his 75. birthday
This study is a part of the researches, carried out with the funds of the National Research Council of Italy under the direction of Prof. A.Rittmann. 相似文献
17.
V. Rama Murthy 《Geochimica et cosmochimica acta》1974,38(4):611-627
K, Rb, Sr, Ba and rare earth elements of some Archean volcanic rocks from the Vermilion greenstone belt, northeast Minnesota, were determined by the isotopic dilution method. The characteristics of trace element abundances, supported by the field occurrences and major element chemistry, suggest that these volcanic rocks were formed in an ancient island arc system. A felsic rock is suggested to be derived by partial melting of a basaltic source, presumably in an ancient subduction zone.It is well known that the distribution coefficients (liquid/source) for the above trace elements are almost invariably greater than one. Continuous extraction of volcanic liquids from the upper mantle through geologic time would result in depletion of these elements in the upper mantle. However, all trace element abundances in many Archean volcanic rocks are almost identical to their modern equivalents. This gross constancy of trace element concentration in rocks of different geologic age raises some important questions as to the evolution of the upper mantle. It is proposed that the trace elements have been repeatedly and fully recycled in a restrictive and closed system of crust and upper mantle during the last three billion years (recycled mantle), or the trace elements have been replenished from the lower part of the mantle by some undefined process (replenished mantle). It is believed that interplay of both recycling and replenishment have been responsible for crust-mantle evolution in geological history. 相似文献
18.
Compositions of immiscible liquids in volcanic rocks 总被引：8，自引：5，他引：8
A. R. Philpotts 《Contributions to Mineralogy and Petrology》1982,80(3):201-218
Immiscible liquids, preserved as chemically distinct, glassy globules, (Si-rich and Fe-rich) occur in many tholeiitic basalts and some alkaline and calcalkaline lavas. The glasses typically form part of a dark mesostasis containing skeletal magnetite crystals. In thick flows, the Si-rich liquid may crystallize to granophyric patches, and the Ferich one to aggregates of hedenbergite, magnetite, and accessory phases. The mesostases containing these immiscible phases constitute from 20% of a primitive olivine tholeiite (MgO=7.5%) to 50% of a highly fractionated quartz tholeiite (MgO=2.8%), but may be less if the rock is oxidized. Abundant ferric iron promotes early crystallization of magnetite and prevents the iron enrichment necessary to reach the immiscibility field; thus, aa flows rarely exhibit immiscibility, whereas the more reduced pahoehoe ones do.Alumina and alkalis are concentrated in the Si-rich liquid, whereas the remainder of the major elements are concentrated in the Fe-rich melt; but the partitioning of Fe, Mg, Ca, and P is less pronounced in alkaline rocks than in tholeiites. Conjugate liquids have compositions of granite and Fe-rich pyroxenite, though the Si-rich melt in alkaline rocks is more syenitic and the Fe-rich one contains considerable normative alkali feldspar. The liquids coexist with plagioclase and augite of, respectively, An50 and Ca34Mg19Fe47 compositions in tholeiites, and An40 and Ca42Mg29Fe29 in alkaline rocks. Immiscibility is not restricted to K-rich residual liquids, but the miscibility gap is narrower for Na-rich compositions. In tholeiitic basalts with 52% SiO2, the Na2O/K2O ratios in conjugate liquids are equal, but at lower silica contents the Si-rich liquid is relatively more sodic, whereas at higher silica contents it is relatively more potassic. This may explain the association of sodic granites with mid ocean ridge basalts.Immiscible liquids are present in sufficient amounts in so many volcanic rocks that magma unmixing should be considered a viable means of differentiation during the late stages of fractionation of common magmas, at least at low pressures. 相似文献
19.
山东中生代火山岩年代学研究 总被引：11，自引：3，他引：8
山东中生代火山岩年代学研究与中国东部许多重大地质问题有直接联系.本次在胶莱盆地标准剖面系统采集了青山群各组的火山岩样品,在安丘大盛群标准剖面采集田家楼组火山岩样品,同时还采集了淄博、蒙阴、莒县等地火山岩样品,进行K-Ar法年龄测定,获得青山群火山岩年龄大致在118-93Ma之间,对应于白垩纪中上部.其中,后夼组始于约117Ma,属于阿普特阶;八亩地组109～103Ma,属于阿尔布阶;石前庄组103.7～93.3Ma,位于阿尔布阶上部至赛诺曼阶,其底部与八亩地组顶部相当,可能两个组之间没有明显的间断;方戈庄组始于93.3Ma,属于上白垩统的土仑阶.鲁东莱阳盆地的八亩地组和鲁西蒙阴八亩地组火山岩年龄基本一致,说明鲁东和鲁西尽管有岩性差异,但同层位火山岩的喷发时间大致相同.大盛群田家楼组下部火山岩年龄95Ma,与石前庄组上部层位相当,说明大盛群与青山群为交叉对应关系.淄博群坊子组中的火山岩年龄120.1Ma和105.7Ma,山东可能不存在侏罗纪火山岩. 相似文献
20.
广东“马山火山岩”是指分布于广东省开平市东山镇东南马山一带、出露面积不到30km^2的一套中酸性火山岩(图1)，其与周边寒武系、奥陶系和泥盆系的接触关系不明。1：20万区域地质调查根据在马山邻近地区泥盆纪地层中发现有与马山流纹岩相似矿物组成和结构构造的火山质砾石，而将马山 相似文献