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中国东部新生代玄武岩的地球化学：Ⅰ.主元素和微量元素组成：岩石成因… 总被引：17，自引：8，他引：17
所研究的玄武岩包括拉斑玄武岩、碱性玄武岩、苦橄粗玄岩和钾质玄武岩。主元素和微量元素的组成变化表明，中国东部玄武岩既是不同深度地幔部分熔融的产物，又经历了岩浆结晶分层作用。强不相容元素比值的变化特征显然与岩石圈地幔交代作用有关。软流圈地幔的上涌并导致上覆不均一的岩石圈地幔的部分熔融是形成中国东部新生代玄武岩的主要机制。 相似文献
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峨眉山大火成岩省西部苦橄岩及其共生玄武岩的地球化学：地幔柱头部熔融的证据 总被引：12，自引：12，他引：12
丽江地区的苦橄岩位于峨眉山大火成岩省的西部，其与辉斑玄武岩、无斑玄武岩和玄武质火山碎屑岩共生。苦橄岩中的斑晶主要为富镁橄榄石，其F0含量最高达91．6％，CaO含量最高达0．42％，其内含有少量玻璃包裹体，指示了橄榄石是在熔体中结晶形成的。苦橄岩中的铬尖晶石具有高的Cr#值（73-75）。计算的初始岩浆的MgO含量大约为22wt％，初始熔融的温度为1630-1680℃。研究结果表明，玄武质岩石是苦橄质岩浆通过橄榄石和单斜辉石分离结晶形成的。苦橄岩和玄武岩的Nd-Sr-Pb同位素比值差别不大，只落在一个很小的范围内（如εNd（t）=-1．3 to＋4．0）。高的εNd（t）值以及抗蚀变不相容元素的原始地幔标准化图解与洋岛玄武岩相似，并且其重稀土元素特征指示了源区有石榴子石的残余，而且是低部分熔融的产物。同位素比值与抗蚀变不相容元素比值（如Nb／La）的相关性表明，岩浆形成过程中有少量的大陆地壳物质或者相对低εNd（t）组分的大陆岩石圈地幔的混染。因此，总体上，苦橄岩的地球化学特征的研究结果支持了峨眉山大火成岩省是地幔柱头部熔融的成因模型。 相似文献
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前人对峨眉山玄武岩的研究已经取得大量的研究成果,但对于一些关键科学问题如岩浆源区组成、源区温压条件等还存在分歧,或有待进一步探讨。本文报道了四川木里地区二叠纪苦橄岩和相关玄武岩的岩石学、地球化学和Sr-Nd同位素特征,并进一步探讨了苦橄岩和相关玄武岩的岩浆源区性质、岩浆形成条件。研究表明:四川木里地区二叠纪火成岩主要岩石类型为苦橄岩、高钛玄武岩和低钛玄武岩;苦橄质岩浆来源于地幔柱头部中心的高温区域(地幔柱轴部),岩浆主要起源于石榴石稳定域;高钛和低钛玄武质岩浆来源于地幔柱尾部,高钛玄武质岩浆主要起源于石榴石稳定域,而低钛玄武质岩浆起源于石榴石稳定域和尖晶石稳定域的过渡带;苦橄质和玄武质岩浆在上升过程中都不同程度混染了大陆岩石圈地幔物质,其中低钛玄武质岩浆可能有少量地壳物质的混染。 相似文献
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塔里木板块东北部坡一镁铁质-超镁铁质层状侵入体岩石成因 总被引：7，自引：4，他引：3
坡一侵入体位于塔里木板块东北部坡北岩体内,是该岩体第三阶段岩浆活动形成的十几个小侵入体中的一个,锆石U-Pb年龄为278±2Ma。该侵入体属于以超镁铁质岩石为主的层状岩系,堆晶结构与韵律性堆晶层理非常发育。岩浆分异充分,形成了从纯橄岩到石英闪长岩的多种岩石类型。在超镁铁质岩石中,所有的橄榄石和大部分斜方辉石是堆晶相,少量斜方辉石是填隙相,大部分单斜辉石、褐色普通角闪石和黑云母是填隙相。在镁铁质岩石中,橄榄石和斜方辉石全部是堆晶相,单斜辉石与斜长石既可以是堆晶相,也可以是填隙相;褐色普通角闪石、黑云母和石英均为填隙相。超镁铁质岩石属拉斑玄武岩系列,镁铁质岩石属钙碱性系列。侵入体中大量存在的捕掳体、微量元素地球化学、Nd-Sr同位素组成的EMⅡ型演化趋势,充分证明了同化混染作用伴随岩浆演化过程而逐渐增强,并不断促进了岩浆的分异,而且导致了岩石化学系列的转化。PGE和亲硫元素地球化学以及硫同位素组成证明,硫主要来自于岩浆,硫化物形成于岩浆阶段,岩浆未经历过早期硫化物熔离作用,硫化物熔离起始于橄榄岩相结晶的晚期阶段,并伴随着此后的岩浆演化过程而继续熔离。硫化物熔离是岩浆自身演化和同化混染共同作用的结果。橄榄石Fo分子含量和全岩FeO含量显示,原生岩浆是苦橄质岩浆;源区物质应该是石榴石辉石岩;岩浆生成于地幔柱轴部。在塔里木板块东北部还存在分别来自于软流圈和亏损型大陆岩石圈地幔的二叠纪岩浆岩,它们都应该是塔里木大火成岩省的组成部分。 相似文献
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云南宾川-永胜-丽江地区低钛玄武岩和苦橄岩的岩石成因与源区性质 总被引：3，自引：2，他引：3
云南宾川-永胜-丽江地区是峨眉山玄武岩厚度最大、喷发最早的地区,最主要的岩石类型是低钛和高钛玄武岩,并有少量摘要云南宾川—永胜—丽江地区是峨眉山玄武岩厚度最大、喷发最早的地区,最主要的岩石类型是低钛和高钛玄武岩,并有少量的苦橄质玄武岩、苦橄岩和麦美奇岩。大部分火山岩的岩石化学组成属于拉斑玄武岩系列,少数低钛玄武岩属碱性玄武岩系列。它们不同程度地富集大离子亲石元素和轻稀土元素,相对亏损重稀土元素,稀土元素分馏明显,显著亏损相容元素(Co,V,Cr,Ni)。陆壳物质对低钛玄武岩浆的混染程度明显大于对苦橄质岩浆的影响程度。而且混染作用对于Sr同位素和大离子亲石元素的影响程度明显大于对Nd同位素和稀土元素的影响程度。Nd和Sr同位素证明,混染物主要是下地壳变质岩,也有少量上部陆壳物质。未受混染的样品具有适度亏损的Nd、Sr同位素组成。低钛玄武岩和苦橄岩类岩石是不同原生岩浆分异演化的产物。低钛玄武岩的原生岩浆是高镁拉斑玄武岩浆,原生苦橄质岩浆以EM-55为代表(MgO= 16.56%)。此外,还有一种比EM-55更富镁的原生岩浆。高镁拉斑玄武岩浆分异过程中的主要分离结晶相/堆晶相是单斜辉石,并有少量斜长石。苦橄岩浆分异过程中的主要分离结晶相/堆晶相是橄榄石,并有少量单斜辉石。参考相关的实验岩石学成果,可以证明,地幔柱源区由两种岩石组成:一种是50%榴辉岩和50%橄榄岩反应形成的石榴石辉石岩,另一种是橄榄岩。在地幔柱绝热上升过程中,位于其轴部的石榴石辉石岩的熔融作用始于≈165km,主要的熔融作用发生于165～128km,持续到66km,熔融产物为苦橄岩浆。橄榄岩的部分熔融始于≈150km,持续到66km,熔融产物是比EM-55更富镁的岩浆。地幔柱头部的熔融作用始于≈100km,终止于66km,主要的熔融作用发生于尖晶石稳定域,熔融产物为低钛玄武岩浆。 相似文献
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羌塘南部地区大面积出露基性—超基性火成岩。基性岩墙和玄武岩沿龙木错-双湖板块缝合带的南侧呈近东西向分布,大地构造位置位于冈瓦纳大陆北缘,分布范围西起国境线,东到双湖地区,总长约800km,形成时代集中在晚石炭世—早二叠世(284~318Ma),反映出岩浆的快速侵位-喷溢的过程。基性岩墙和玄武岩主要为碱性系列岩石,少数为亚碱性系列,Ti和Fe的含量均比较高,Mg#比较低,表明它们都是原始岩浆经不同程度分异结晶后的残余熔体。基性岩墙和玄武岩的稀土元素、微量元素、形成环境等均与板内玄武岩或典型的地幔柱成因玄武岩具有相似的特点。另外,苦橄质岩石多与基性岩墙和玄武岩一起产出,主要为单斜辉石橄榄岩和二辉橄榄岩,矿物成分贫挥发性组分,主量、稀土和微量元素的特点反映出其很可能代表了地幔柱原始岩浆结晶的产物而非岩浆捕获体,而且其源区很可能为石榴子石二辉橄榄岩。由此,初步认为羌塘南部基性岩墙和玄武岩为地幔柱的头部减压熔融的产物,而苦橄质岩石为地幔柱尾柱通道熔融的产物。 相似文献
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羌塘南部地区大面积出露基性—超基性火成岩。基性岩墙和玄武岩沿龙木错-双湖板块缝合带的南侧呈近东西向分布,大地构造位置位于冈瓦纳大陆北缘,分布范围西起国境线,东到双湖地区,总长约800km,形成时代集中在晚石炭世—早二叠世（284～318Ma）,反映出岩浆的快速侵位-喷溢的过程。基性岩墙和玄武岩主要为碱性系列岩石,少数为亚碱性系列,Ti和Fe的含量均比较高,Mg#比较低,表明它们都是原始岩浆经不同程度分异结晶后的残余熔体。基性岩墙和玄武岩的稀土元素、微量元素、形成环境等均与板内玄武岩或典型的地幔柱成因玄武岩具有相似的特点。另外,苦橄质岩石多与基性岩墙和玄武岩一起产出,主要为单斜辉石橄榄岩和二辉橄榄岩,矿物成分贫挥发性组分,主量、稀土和微量元素的特点反映出其很可能代表了地幔柱原始岩浆结晶的产物而非岩浆捕获体,而且其源区很可能为石榴子石二辉橄榄岩。由此,初步认为羌塘南部基性岩墙和玄武岩为地幔柱的头部减压熔融的产物,而苦橄质岩石为地幔柱尾柱通道熔融的产物。 相似文献
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广东三水盆地火山岩:地球化学特征及成因——兼论火山岩性质的时空演化和南海形成的深部过程 总被引：12，自引：1，他引：12
位于中国东南部的三水盆地、珠江口盆地、雷琼半岛和北部湾地区广泛分布新生代火山岩。火山岩的形成时间具有从内陆向沿海变新的特点,早第三纪三水和珠江口盆地火山岩具有由玄武岩与粗面岩-流纹岩构成的双峰式特点。其中玄武岩和粗面岩的微量元素和稀土元素的配分形式相似,富集大离子亲石元素并且有相似的εNd(T)同位素组成(2.34～6.4),说明它们来自相同的地幔源区,为同源岩浆演化的产物。玄武岩和粗面岩经历了不同的结晶分异过程,其中玄武岩在较深部岩浆房中经历橄榄石和单斜辉石为主的分离结晶作用,而粗面岩则是在浅部岩浆房中由玄武岩浆分异形成的过渡性岩浆再经过强烈的钾长石和斜长石、以及磷灰石的结晶分异形成的。晚第三纪珠江口盆地和北部湾火山岩、雷琼半岛第四纪火山岩则由碱性和拉斑玄武岩构成。这些火山岩的形成时间和地球化学和同位素特征表明它们经历了连续的软流圈地幔上涌和部分熔融过程,受控于自晚中生代以来的地幔柱构造。南海的形成是地幔柱活动引起的地幔上涌和大陆裂解作用的结果。 相似文献
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《Chemie der Erde / Geochemistry》2016,76(1):77-93
The Mid to Late Miocene intraplate alkaline volcanic suites of western Bohemia are relict of the intensive voluminous volcanism accompanied by large-scale uplift and doming. The association with the uplift of the NE flank of the Cheb–Domažlice Graben (CDG) is uncertain in view of the mostly transpressional tectonics of the graben. The volcanism is most probably of the Ohře/Eger Rift off-rift settings. Two cogenetic volcanic suites have been recognised: (i) silica-saturated to oversaturated consisting of olivine basalt–trachybasalt-(basaltic) trachyandesite–trachyte–rhyolite (13.5 to 10.2 Ma) and (ii) silica-undersaturated (significantly Ne-normative) (melilite-bearing) olivine nephelinite–basanite–tephrite (18.3 to 6.25 Ma). A common mantle source is suggested by similar primitive mantle-normalised incompatible element patterns and Sr–Nd–Pb isotopic compositions for the assumed near-primary mantle-derived compositions of both suites, i.e., olivine basalt and olivine nephelinite. Apparently, they were generated by different degrees of partial melting of a common mantle source, with garnet, olivine and clinopyroxene in the residuum. Negative Rb and K anomalies indicate a residual K-phase (amphibole/phlogopite) and melting of partly metasomatised mantle lithosphere. The evolution of the basanite–olivine basalt–trachybasalt-(basaltic) trachyandesite–trachyte–rhyolite suite suggests the presence of an assimilation–fractional crystallization process (AFC). Substantial fractionation of olivine, clinopyroxene, Fe–Ti oxide, plagioclase/alkali feldspar and apatite accompanied by a significant assimilation of magma en route by crustal material is most evident in evolved member, namely, trachytes and rhyolites. The magmas were probably sourced by both sub-lithospheric and lithospheric partly metasomatised mantle. The evolution of the (melilite-bearing) olivine nephelinite–basanite–tephrite suite is less clear because of its limited extent. Parental magma of both these rock suites is inferred to have originated by low-degree melting of the mantle source initiated at ca. 18 Ma and reflects mixing of asthenosphere-derived melts with isotopically enriched lithospheric melts. The older Oligocene alkaline rocks (29–26 Ma) occur within the Cheb–Domažlice Graben (CDG) locally but are significant in the closely adjacent neighbouring western Ohře Rift. The Sr–Nd–Pb isotopic composition of primitive volcanic rocks of both suites is similar to that of the European Asthenospheric Reservoir (EAR). Initial Pb isotopic data plot partly above the northern hemisphere reference line at radiogenic 206Pb/204Pb ratios of ∼19 to 20, and indicate the presence of a Variscan crustal component in the source. 相似文献
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Friedrich Lucassen Dieter Pudlo Gerhard Franz Rolf L. Romer Peter Dulski 《International Journal of Earth Sciences》2013,102(1):183-205
Chemical and Sr, Nd and Pb isotopic compositions of Late Cenozoic to Quaternary small-volume phonolite, trachyte and related mafic rocks from the Darfur volcanic province/NW-Sudan have been investigated. Isotope signatures indicate variable but minor crustal contributions. Some phonolitic and trachytic rocks show the same isotopic composition as their primitive mantle-derived parents, and no crustal contributions are visible in the trace element patterns of these samples. The magmatic evolution of the evolved rocks is dominated by crystal fractionation. The Si-undersaturated strongly alkaline phonolite and the Si-saturated mildly alkaline trachyte can be modelled by fractionation of basanite and basalt, respectively. The suite of basanite–basalt–phonolite–trachyte with characteristic isotope signatures from the Darfur volcanic province fits the compositional features of other Cenozoic intra-plate magmatism scattered in North and Central Africa (e.g., Tibesti, Maghreb, Cameroon line), which evolved on a lithosphere that was reworked or formed during the Neoproterozoic. 相似文献
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南天山托云盆地晚白垩世——早第三纪玄武岩的地球化学特征 … 总被引：18，自引：0，他引：18
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
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响岩代表了陆内火山岩省钠质碱性岩浆最终端的演化产物,揭示其成因机制对认识陆内火山岩省的岩浆演化过程具有重要意义。文章对出露在我国境内西南天山托云中新生代火山岩盆地的响岩开展了系统的矿物学、岩石学和地球化学研究,以揭示托云火山岩岩浆系列特征和岩浆演化过程。托云响岩以发育碱性长石、单斜辉石、铁橄榄石和角闪石斑晶为特征,在基质中可见霞石。在地球化学组成上,托云响岩以高的Na2O含量(7.9%～8.6%)和K2O含量(5.2%～6.3%)为特征,∑REE变化范围为408×10-6～470×10-6,稀土元素配分曲线具有明显的Eu异常,在原始地幔标准化的微量元素蛛网图上,样品显示出Ba、Sr、P、Ti的负异常和Nb、Ta、Zr、Hf的正异常特征。亏损的Nd同位素组成表明其成因与共生的碧玄岩有紧密的成因联系,经MELTS热力学模拟,响岩可由碧玄岩经碱性长石(36%)、单斜辉石(21%)、尖晶石(10%)、铁橄榄石(6%)和角闪石(5%)的分离结晶作用形成,进一步的EC-AFC模拟表明,响岩在形成过程中受到一定程... 相似文献
15.
PRICE RICHARD C.; COOPER ALAN F.; WOODHEAD JON D.; CARTWRIGHT IAN 《Journal of Petrology》2003,44(11):2053-2080
The Port Chalmers Breccia is a vent-filling, clastic volcanicunit exposed within the Miocene Dunedin Volcano of South Island,New Zealand. Clasts (up to in excess of 1 m but generally <20cm) are supported in ash and fine lapilli of phonolitic (ne-benmoreiteor tephro-phonolite) composition and the dominant clast type(55 to almost 100%) is also phonolitic. Less abundant lithologiesinclude ne-normative basalt (basanite), hawaiite, mugeariteand trachyandesite, syenites and microsyenites, coarse-grainedmafic (gabbros) and ultramafic rocks (pyroxenites, hornblendites),schists and sediments. The breccias were emplaced as diatremesassociated with localized, but highly explosive, eruptive eventsin which mantle-derived CO2 was an important component. Thesyenitic and ultramafic clasts could represent intrusive suitesproduced by crystal fractionation acting on parental ne-benmoreitemagmas that may themselves have been derived by crystal fractionationfrom basanitic precursors. An alternative variation on thismodel is that the parental ne-benmoreites were generated throughpartial melting of an alkalic igneous underplate. Sr, Nd andPb isotopic compositions are strikingly similar to those ofintraplate igneous rocks, ranging in age from 100 to less than10 Ma, from elsewhere in the South Island, and New Zealand'ssub-Antarctic islands, the south Tasman Sea and the Ross Searegion. This regional, HIMU-influenced, isotopic signature isbelieved to be derived from within the lithospheric mantle. KEY WORDS: phonolite; diatreme; nepheline syenite; Dunedin Volcano; alkalic rocks; fractional crystallization 相似文献
16.
南极泰勒谷及罗斯岛地区火山岩的微量元素地球化学研究表明,它们可以分为两大类,博尼湖南岸、克雷克特山和鸟角的碧玄岩或碱玄岩是地幔平衡部分熔融作用的结果;罗德角和伊万思角的安粗岩是岩浆分离结晶作用的结果,其母岩浆相当于本区的碧玄岩。５个采样地区火山岩具有相同的地幔来源,地幔源区为轻稀土富集型,并富集重稀土元素。 相似文献
17.
皖南逍遥岩体的年代学、地球化学特征及其成因分析 总被引：3，自引：0，他引：3
皖南绩溪县逍遥岩体侵位于新元古界南华系、震旦系和下古生界海相沉积盖层中,岩性为花岗闪长岩。测得该岩体LA-ICP-MS锆石U-Pb同位素加权平均值年龄为(149.3±2.3)和(148.6±1.9)Ma,表明:岩体侵位于晚侏罗世。逍遥花岗闪长岩体的电子探针分析显示其黑云母为镁质黑云母。岩石地球化学研究表明:其为高钾钙碱性系列,准铝质—过铝质,属于I型花岗岩;微量元素特征显示其富集轻稀土而亏损重稀土元素,富集Ba、Sr等大离子亲石元素。综合地质、年代学、电子探针和岩石主微量元素分析,逍遥岩体形成于晚侏罗世,其岩浆来源于有幔源物质加入的下地壳,在形成过程中经历了较强的部分熔融作用,该岩体具有火山弧花岗岩特点。 相似文献
18.
Trace Element Geochemistry of Tertiary Continental Alkali Basalts from the Liuhe—Yizheng Area,Jiangsu Province,China 总被引：5，自引：0，他引：5
支霞臣 《中国地球化学学报》1991,10(3):204-216
Reported in this paper are the chemical compositions and trace element (REE,Ba,Rb,Sr,Nb,Zr,Ni,Cr,V,Ga,Y,Sc,Zn,Cu,etc)abundances of Tertiary continental alkali basalts from the Liube-yizheng area,Jiangsu Province,China.The olivine basalt,alkali olivine basalt and basanite are all derived from evolved melts which were once af-fected by different degrees of fractional crystallization of olivine and clinopyroxene(1:2)under high pres-sures.The initial melts were derived from the garnet lherzolite-type mantle source through low-degree par-tial melting.The mantle source has been affected by recent mantle-enrichment events(e.g.mantle metasomatism),resulting in incompatible trace element enrichment and long-term depletion of radiogenic isotopic compositions of Sr and Nd. 相似文献
19.
S. Harangi 《Lithos》1994,33(4):303-321
Early Cretaceous volcanic rocks (basanite to phonolite) from the Mecsek Mountains (South Hungary) represent the products of Late Mesozoic extension-related alkaline magmatism at the southern margin of the European plate. Two mafic groups have been distinguished: ankaramite-alkali basalt and Na-basanite-phonotephrite. Phonolites could have been formed from the Na-basanitic magma by low-pressure fractionation. The major and trace element characteristics of the Mecsek basalts are similar to those of alkaline basalts of other intraplate areas and have a St. Helena-type OIB affinity. The mantle source of the Mecsek volcanics could be similar to that proposed by Wilson and Downes (1991) as one of the mantle endmembers for extension-related Tertiary-Quaternary alkaline basalts in Europe. Geochemical modelling indicates that the primary magmas of the Na-basanite series were formed by about 4% partial melting, whereas ankaramites and alkali basalts originated by about 6% partial melting of a garnet-peridotite source. 相似文献
20.
WANG Yanbin WANG Yong LIU Xun FU Derong XIAO Xuchang QI Longshui . Institute of Geology Chinese Academy of Geological Sciences Beijing . Hebei College of Technology Tangshan 《Continental Dynamics》2001,(1)
1. Introduction The Tianshan Mountains is a typical intercontinental orogenic belt in the world. From late Carboniferous to Permian, the old Tianshan formed during the tectonic amalgamation of the Tarim block, Tianshan block and Siberia craton (Carroll et al, 1990). Mid-Cenozoic basalts are widely distributed in both the Tuyon basin of southwest Tianshan and its western part of Tianshan in Jierjisi in late Cretaceous-Paleogene period, which indicates the activation of the old Tianshan.… 相似文献