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青藏高原岩石圈演化的记录:藏北超钾质及钠质火山岩的岩石学与地球化学特征 总被引:56,自引:12,他引:44
藏北鱼鳞山超钾质火山岩为一中等规模的熔岩被, 可分为三期。前两期主要为霞石黝方白榴石响岩、霞石白榴斑岩等, 后期主要为方钠石霓石粗面岩、霓霞粗面岩等。时代为18~30 Ma。本区超钾质岩浆 Si O2 强烈不饱和、强碱性、高度富集 L R E E及 L I L E、放射成因 Sr、 Pb 及非放射成因 Nd 同位素 (86 Sr/87 Sr= 0708766~0709162, 206 Pb/204 Pb= 18882888~ 19104751, 207 Pb/204 Pb= 15642037 ~ 15828458, 208 Pb/204 Pb= 39138921 ~ 39686835 及143 Nd/144 Nd= 0512116 ~0512342),其上述特征指示岩浆源区为受到地壳物质强烈交代的富集 E M I I型地幔。藏北拉嘎拉钠质碱性橄榄玄武岩为高原面上的剥蚀残丘, 时代为60 Ma。其岩石学、 R E E、微量元素及 Sr Nd Pb 同位素指示了岩浆源区为受到洋壳俯冲物质交代的轻度富集地幔。本研究结果指示, 羌塘高原南部富集地幔的形成可能是受到印度板块俯冲的影响。 相似文献
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陕西商县—丹凤地区丹凤群变质玄武岩的微量元素和同位素地球化学 总被引:26,自引:10,他引:26
丹凤祥变质玄武岩可以分为两类:一类是LREE富集型的钙碱性玄武岩,另一类是LREE平坦型的拉斑玄武岩。LREE富集型的变质玄武岩[(Ce/Yb)N为5~20]贫Ti、Nb、Ta,Th>Ta,Nb/La<0.8,Hf/Th>8,Zr/Y<3,表明其形成于消减带之上的洋内岛弧环境。该玄武岩的εNd(t)=+4.9~+7.3,εSr(t)=3.0~+32,可能是亏损地幔端元(DMM)与第二类富集地幔端元(EMⅡ)混合形成的。大多数玄武岩的(206Pb/204Pb)i比值(16.5~17.6)较低,(208Pb/204Pb)i和(207Pb/204Pb)i比值(分别为36.2~36.9和15.3~15.5)较高,ε18O变化较大(5.5‰~9.2‰)。因此,根据微量元素和同位素地球化学资料,丹凤群变质玄武岩的源区可能包括下述组分:1)亏损的软流圈地幔(DM);2)富集地幔(EM);3)洋内岛弧下地壳(镁铁和超镁铁质岩);4)消减带岩片带入的组分。而LREE亏损的拉斑玄武岩具MORB的特征,Th/Ta和La/Ta比值近似等于1,TiO2=1.65%,Ti/V=22,指示来自亏损的软流圈地幔,形成在与消减作用无关的拉张 相似文献
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武当地块基性岩墙群及耀岭河群基性火山岩的Sr,Nd,Pb,O同位素研究 总被引:9,自引:2,他引:7
武当地块基性岩墙群与耀岭河群基性火山岩的Sr、Nd、Pb同位素特征反映它们具相同的混合地幔源区。前者的(^87Sr/^86Sr)i=0.6905 ̄0.7061,εNd(t)=-1.9 ̄5.0,Δ^208Pb/^204Pb=35.49 ̄190.26,Δ^207Pb/^204Pb=4 ̄85,Th/Ta低,La/Yb变化大;后者的(^87Sr/^86Sr)i=0.6487 ̄0.7075,εNd(t)=0 相似文献
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武当地块基性岩墙群及耀岭河群基性火山岩的Sr、Nd、Pb、O同位素研究 总被引:15,自引:4,他引:11
武当地块基性岩墙群与耀岭河群基性火山岩的 Sr、 Nd、 Pb 同位素特征反映它们具相同的混合地幔源区。前者的(87 Sr/86 Sr)i= 06905~07061, ε N d (t) = - 19~50, Δ208 Pb/204 Pb= 3549~19026, Δ207 Pb/204 Pb= 4~85, Th/ Ta 低, La/ Yb 变化大;后者的(87 Sr/86 Sr)i= 06487~07075,ε N d(t)= 011~394, Δ208 Pb/204 Pb= - 8158~21995, Δ207 Pb/204 Pb= 444~1668, Th/ Ta 和 La/ Yb 较高。这指示它们的源区以岩石圈亏损地幔和第2 类富集地幔为主要混合组分, 耀岭河群基性火山岩曾遭受地壳物质的混染。结合它们具大陆拉斑玄武岩地球化学特征, 代表同源异相裂谷环境的产物推断, 南秦岭基底陆块在新元古代时曾发生过一次重要裂解作用, 并向早古生代秦岭洋盆转变。 相似文献
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汉诺坝玄武岩中辉石岩类包体Nd、Sr、Pb同位素及其成因信息 总被引:13,自引:1,他引:13
对汉诺坝地区的12个辉石岩和1个麻粒岩包体进行了Nd、Sr、Pb同位素测定,发现辉石岩组成有很大变化,143Nd/144Nd比值为0.51160—0.51314,87Sr/86Sr比值为0.7029—0.7086,206Pb/204Pb比值为15.942—18.683,207Pb/204Pb比值为15.264—15.569,208Pb/204Pb比值为36.213—38.744,显示了其复杂成因q推测具有高Sr、低Nd和低Pb同位素组成的辉石岩是地幔早期富集的产物,与麻粒岩、辉长岩包体有类似成因;具有弱至中等亏损的Nd、Sr同位素和高放射成因Pb的辉石岩是亏损地幔近期富集或交代的产物 相似文献
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南极罗斯岛及泰勒谷地区火山岩的地球化学特征及成因讨论 总被引:2,自引:0,他引:2
利用微量元素和Sr,Nd,Pb同位素资料,得出了南极罗斯岛及泰勒谷地区火山岩来自于上地幔,五个地区火山岩具有相同的源区。岩石具有大洋岛屿玄武岩(OIB)的特征。来自地幔的火山喷发的岩浆未遭受地壳物质的混染作用。地幔源区是具有高μ(=206Pb/204Pb)比值的地幔组分HIMU与亏损地幔组分DMM混合作用的结果,其中以HIMU组分为主,原生岩浆由具HIMU组分特征的深部地幔柱与浅部的DMM混合而成。 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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冀西北水泉沟正长岩杂岩体的成因 总被引:11,自引:5,他引:11
水泉沟碱性正长岩杂岩体侵入于太古宇桑干群变质岩中,岩体主要由碱性长石正长岩、角闪碱长正长岩、正长岩、石英碱长正长岩等组成,属碱性岩系列,在岩石的石英颗粒中见有熔融包体的存在。岩石的稀土元素分布模式呈平滑的右倾模式,无明显的铕异常。岩石的Pb同位素组成为206Pb/204Pb=16.457~18.286、207Pb/204Pb=15.270~15.472、208Pb/204Pb=36.539~37.393,石英的δ18O值为8.0‰~8.5‰,(87Sr/86Sr)i≈0.705,岩石的tDM为1.6~1.9Ga,εNd(t)为-7.45~-13.1,明显大于区域基底的εNd(t)值(-20±)。以上结果表明,岩体为上地幔和下地壳物质部分熔融的产物。岩体角闪石39Ar-40Ar年龄327Ma,为海西期岩浆作用的产物 相似文献
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青藏高原岩石圈演化的记录:藏北超钾质及钠质火山岩的岩石学与地球?… 总被引:14,自引:0,他引:14
藏北鱼鳞山超钾质火山岩为一中等规模的熔岩被,可分为三期。前两期主要为霞石黝方白榴石响岩、霞石白榴斑岩等,后期主要为防方钠石霓石粗面岩、霓霞粗岩等。时代为18 ̄30Ma。本区超钾质岩浆SiO2强烈不饱和、强碱性、高度富集LREE及LILE、放射成因Sr、Pb及非放射成因Nd同位素(^86Sr/^87Sr=0.708766 ̄0.709162,^206Pb/^204Pb=18.882888 ̄19.104 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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正1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and 相似文献
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正On 22nd April 2014,with the approach of the 45th World Earth Day,China’s Ministry of Land and resources issued the status of China’s mineral resources in 2013.The first task of the prospecting breakthrough strategy action implemented in the last five years has been completed,and China’s security capacity for mineral resources has been significantly improved.In the 相似文献
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正There are more than 700 salt lakes with area of more than 1km2 on the Qinghai-Tibet Plateau of China.In recent years,an oilfield brine was also found in the Nanyishan Section of Qaidam Basin in the Qinghai-Tibet 相似文献
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正1 Introduction Physical and numerical models are constructed to investigate the evolution and mechanism of salt migration driven by tectonic processes.In recent years,we have designed and ran series of models to simulate salt 相似文献
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YUAN Qin LI Jianguo QIN Zhanjie WEI Haicheng SHENG Shurong SHAN Fashou 《《地质学报》英文版》2014,88(Z1):276-276
正The study of Cretaceous-Palaeogene salt-bearing strata of the Khorat Basin Laos and the Lanping-Simao Basin in Yunnan,China has an great significance not only in explaining the basin evolution and the genesis of potash 相似文献
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正Potash is one of the long-term scare deposits in China,and potash prospecting has long been listed as a key brainstorm project for our nation and geological prospecting units.There have been considerable studies in search for potash deposits in the Kuqa depression of the Tarim basin(Jackson et al.,1991;Gemmer et al.,2004;Vendeville,2005;Vendeville and Jackson,1992a,1992b), 相似文献
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正1 Introduction Qaidam Basin in Qinghai,including 43 salt lakes with multiple dominant mineral such as potassium,magnesium,lithium etc.,is the most intensive distribution of Saline 相似文献