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1.
呼斯特岩体是新疆西天山博罗科努岛弧带上的一个与矽卡岩成矿有关的复式杂岩体,由二长花岗岩、花岗闪长岩、正长花岗岩、花岗细晶岩、闪长玢岩、辉长岩和中基性包体等组成。本文对该岩体不同岩相岩石开展了岩石学、锆石LAICP-MS U-Pb同位素定年和Hf同位素研究,探讨岩石成因及构造意义。锆石U-Pb定年结果表明,正长花岗岩、闪长玢岩、花岗闪长岩和二长花岗岩加权平均年龄分别为380.2±4.6Ma、372.8±5.9Ma、367.7±4.5Ma和366.2±4.5Ma,岩体侵位时代为晚泥盆世,在大约15Myr期间,至少发生了3~4次岩浆侵入。在地球化学组成上,除辉长岩外,岩体为准铝质-弱过铝质、高钾钙碱性-低钾(拉斑)系列的I型花岗岩,轻重稀土分馏明显,具Eu负异常;富集Th、U,亏损Ba、P和高场强元素(如Nb、Ta、Zr、Ti),为晚古生代北天山洋向南俯冲于伊犁地块背景下岩浆活动的产物。二长花岗岩锆石Hf同位素组成较为均一,εHf(t)值为1.3~3.0,二阶段Hf模式年龄为1171~1280Ma,远大于成岩年龄,说明原始岩浆从地幔分异后经历了较长时间的地壳滞留。研究认为,高钾中酸性岩(花岗岩、闪长玢岩和中基性包体)由元古代新生基性下地壳部分熔融而成,伴有受俯冲沉积物熔体交代的幔源岩浆混合。低钾花岗闪长岩高Sr、低Y和Yb,属O型埃达克岩,与同源的辉长岩一起由俯冲的大洋板片部分熔融形成,源岩为低钾的拉斑玄武岩。 相似文献
2.
通过1∶5万区域地质调查,对祁连山哈拉湖地区火山岩进行了野外地质、岩石学、锆石U-Pb同位素年龄、地球化学等研究。LA-ICP-MS锆石U-Pb同位素定年结果显示,该火山岩年龄为466.3±2.4Ma(n=9,MSWD=1.4),形成于中奥陶世。岩石地球化学研究表明,哈拉湖地区火山岩为低钾拉斑玄武系列,绝大多数样品的亲石元素Rb、Th、U、Ce、Zr、Nd和稀土元素La、Sm富集明显;高场强元素(Sr、P、Ti)强烈亏损,Zr、Hf微弱富集,Ba明显亏损。总的特征显示,少数火山岩具有过渡型洋脊玄武岩的特征,大多数火山岩样品显示岛弧火山岩的特征。此外,哈拉湖地区的岛弧火山岩与晚奥陶世的岛弧花岗岩伴生在一起。这些特征表明,与俯冲有关的奥陶纪岛弧岩石可能与拉脊山地区古大洋的闭合有关。 相似文献
3.
班公湖带多不杂富金斑岩铜矿床斑岩-火山岩的地球化学特征与时代:对成矿构造背景的制约 总被引:35,自引:13,他引:22
西藏多不杂铜矿床是班公湖-怒江带北侧新近发现的具有超大型远景的、典型的富金斑岩型铜矿床.本文对含矿斑岩、玄武质火山岩进行了系统的地球化学分析,甄别出三套岩石系列:埃达克岩、高Nb玄武岩和正常的岛弧玄武安山岩.三套岩石SiO2含量47%~68%,Al2O3含13%~18%,MgO含量1.4%~8.5%,FeOt含量2.3%~8.1%和CaO含量2.1%~10%,属于钙碱系列.MgO、CaO和FeOt与SiO2呈负相关,K2O与SiO2基本呈正相关.高Nb玄武岩和正常的岛弧玄武安山岩富Na,Na2O/K2O在0.9~7之间,而埃达克岩是相对富K,Na2O/K2O比为0.8.稀土元素总量∑REE为29×10-6-203×10-6,从基性到酸性岩乏REE是逐渐减小的,高Nb玄武岩的稀土元素含量最高,而埃达克岩最低.球粒陨石标准化配分曲线为轻稀土富集型,LREE/HREE为7.0~12.4,(La/Yb)N为3.2~13,δEu为0.9~2.1.埃达克岩和正常的岛弧玄武岩富集大离子亲石元素(LILE:如Rb、Ba、K、Sr)和活泼的高场强元素(如:U、Th),相对亏损其它高场强元素(HFSE:如Nb、Ta、Zr、Hf、Ti),表明具有俯冲带之上岛弧岩浆的特征.而高Nb玄武岩具有明显Nb、Ta正异常,且TiO2含量高(>2%),(La/Nb)PM<2.微量元素地球化学特征和Sr、Nd同位素结果表明该区埃达克岩直接来源于俯冲洋壳的部分熔融,但可能有俯冲沉积物成分的加入;而高Nb的玄武岩则可能来源于埃达克质熔体交代或者超临界流体交代而产生富Nb、Ta的地幔源区,可能有软流圈地幔的加入;而正常的岛弧火山岩则来源于俯冲流体交代过的地幔楔.另外,多不杂矿区埃达克岩和高Nb玄武岩(HNB)空间共生的"埃达克质岩浆交代的火山岩系列",表明多不杂铜矿床形成于典型的岛弧俯冲构造背景.对与成矿密切相关的花岗闪长斑岩进行精确的SHRIMP锆石U-Pb年代学研究,其锆石具有明显的岩浆结晶环带,Th/U比值范围为0.51~0.90,均大于0.1,为岩浆成因锆石,其SHRIMP U-Pb年龄为121.6±1.9Ma,表明至少在大约120Ma期间班公-怒江洋盆正在向北俯冲,洋盆闭合时间应晚于早白垩世中期. 相似文献
4.
半坡杂岩体位于滇西澜沧江构造岩浆带南段,岩体主要由橄榄岩、辉石岩、辉长岩和辉长闪长岩等镁铁 超镁铁质岩组成。通过ID-TIMS锆石U-Pb年代学方法对半坡杂岩体中辉长闪长岩进行精确定年,获得其结晶年龄为(294.9±2.6) Ma,表明半坡杂岩体的形成时代为早二叠世。半坡杂岩体中不同类型岩石微量元素、稀土元素和同位素组成相似,均呈现轻稀土元素(LREEs)相对于重稀土元素(HREEs)弱到中等富集,高场强元素Nb、Ta、Zr和Hf相对亏损的特征,εNd(t=295 Ma)为正值,在+3.4~+6.6,接近亏损地幔值,这些特征与典型的大洋岛弧玄武岩的特征相似。混合计算表明,半坡杂岩体母岩浆为地幔楔部分熔融,加上约2%~7%源于大洋俯冲沉积物的富硅熔浆和蚀变洋壳流体形成的岛弧玄武质岩浆。上述年龄和同位素数据提供了早二叠世早期南澜沧江地区洋内俯冲的可靠证据。 相似文献
5.
青海冷湖盐场北山花岗闪长岩年代学、地球化学及其Hf同位素特征 总被引:1,自引:0,他引:1
盐场北山花岗闪长岩位于柴北缘西端青海冷湖地区。岩体高Si(71.19%~71.81%),富Na(4.52%~4.85%)。铝饱和指数平均为1.02,属弱过铝质花岗岩。岩体富集大离子亲石元素(K、Rb、Sr、Th),亏损高场强元素(Nb、Ta),具弧型花岗岩特征。LA-ICP-MS锆石U-Pb测年结果表明岩体形成于(265±2)Ma。锆石Hf同位素初始比值176 Hf/177 Hf分布于0.282 962 0~0.283 048 7,并具有的正εHf(t)值(12.54~15.19),其平均两阶段模式年龄TDM2(Hf)为367 Ma,反映岩体源区可能为新生的镁铁质下地壳,另外,εHf(t)基本位于亏损地幔演化线附近,指示该玄武质下地壳来源于亏损地幔。结合区域地质背景和岩石地球化学特征,认为盐场北山花岗闪长岩与泥盆纪镁铁-超镁铁岩有关,由于宗务隆裂谷小洋盆的向南俯冲,引发其上覆玄武质新生地壳发生熔融形成,进而揭示晚二叠世末柴北缘处于火山弧或活动陆缘的构造环境。 相似文献
6.
包尔汉图 白乃庙岛弧岩浆岩带分布于兴蒙造山带南缘,是古亚洲洋与华北板块之间早古生代俯冲作用的岩浆记录,以往工作大多集中在岛弧侵入岩和东段白乃庙群火山岩,岛弧西部包尔汉图群火山岩的研究相对较少。本文对内蒙古达茂旗北部出露较完整的包尔汉图群火山岩进行了锆石U Pb年代学、Lu Hf同位素组成和岩石地球化学分析,以完善兴蒙造山带早古生代演化的认识。包尔汉图群火山岩为一套中基性—中酸性火山岩系列,其中英安岩获得锆石U Pb年龄为447. 3±2. 5 Ma,为晚奥陶世岩浆活动的产物。地球化学组成上,火山岩均富集轻稀土元素(LREE)和Rb、Ba、Th、U等大离子亲石元素(LILE),亏损Nb、Ta等高场强元素(HFSE)和Ti元素,具有较弱的Eu负异常,类似岛弧岩浆岩地球化学特征。岩石学及地球化学分析表明,中基性火山岩为岛弧环境下遭受俯冲板片熔体交代的地幔楔熔融产物,并可能有大洋沉积物的加入;而中酸性火山岩偏低的Nb/U值(1. 45~3. 63)和明显亏损的锆石εHf(t)值(+2. 2~+11. 0),显示其源区为俯冲板片流体交代的新生基性下地壳。结合前人资料和新近研究成果,中酸性火山岩亏损的锆石Hf同位素特征和二阶段模式年龄tDMC集中在1637~839 Ma,佐证了包尔汉图岛弧可能存在与华北板块北缘具有亲缘性的前寒武纪陆壳基底,表明早古生代兴蒙造山带南缘属于安第斯型活动大陆边缘,即古亚洲洋以陆缘弧形式向华北北缘俯冲,形成了包尔汉图 白乃庙岛弧岩浆岩带。 相似文献
7.
青草山北花岗闪长岩体位于班公湖-怒江缝合带北侧、羌塘陆块南缘,呈岩脉、岩株状与晚二叠世龙格组碳酸盐岩呈侵入接触。本文对该花岗闪长岩的锆石进行了LA-ICP-MS U-Pb年代学和岩石地球化学研究,其岩浆锆石U-Pb年龄为154.8±1.2Ma(MSWD=1.7),属晚侏罗世,与热那错埃达克质英安岩年龄高度一致,岩石地球化学特征显示,青草山北花岗闪长岩属于准铝质、高钾钙碱性系列,富集轻稀土元素、大离子亲石元素,亏损重稀土元素、高场强元素,具弱Eu负异常,显示出典型岛弧岩浆岩特征;锆石原位微量元素分析表明,锆石总体富集重稀土,相对亏损轻稀土,在锆石Nb/Ta-Y图解中样品点落入金伯利岩区域,而在岩石地球化学构造环境判别图解中,样品点同样指示其可能来源于幔源岩浆。青草山北花岗闪长岩班公湖-怒江洋壳晚侏罗世北向俯冲到一定深度后,俯冲洋壳发生部分熔融,形成的岩浆在上升的过程中与地幔楔发生混染,其中,部分岩浆在侵位的过程中形成中酸性的花岗闪长质岩浆房,部分岩浆则喷出地表,形成热那错组英安岩。 相似文献
8.
内蒙古中部达茂旗地区三叠纪花岗岩和钾玄岩的地球化学、年代学和Hf同位素特征 总被引:2,自引:1,他引:1
内蒙古索伦山缝合带南侧达尔罕茂明安联合旗北部分布有车根达来花岗闪长岩-闪长岩和西别河火山岩。车根达来花岗闪长岩为高钾或中钾钙碱性系列岩石,化学成分相当于埃达克岩。闪长岩为中钾钙碱性系列岩石,呈大小不等的包体产于花岗闪长岩中,化学成分相当于正常岛弧深成岩。但是,花岗闪长岩[εHf(t)=-4.56~-1.56]和闪长岩[εHf(t)=-5.01~-1.88]锆石Hf同位素组成指示其源区为古老的(镁铁质)陆壳或富集地幔。锆石SHRIMPU-Pb定年给出车根达来花岗闪长岩的年龄为245Ma±1Ma,闪长岩包体的形成年龄为239Ma±2Ma。西别河火山岩为钾玄岩,喷发年龄为224Ma±2Ma。火山岩以大量的、年龄分散的捕虏晶(260~1556Ma)为特征,指示了大陆背景。这些三叠纪侵入岩和火山岩形成于古亚洲洋闭合(中晚二叠世)之后,没有明显的构造变形,应为中亚造山带的造山后演化的岩浆岩记录。 相似文献
9.
塞勒肯特岩体出露于谢米斯台中东部,岩性主要为二长花岗岩、石英闪长岩及花岗闪长岩。本文通过锆石U-Pb年代学、岩石地球化学和Sr-Nd-Hf同位素等研究,探讨其形成的构造环境及岩石成因。结果表明,二长花岗岩(400.9±4.3Ma)和石英闪长岩(398.1±4.5Ma)形成于早泥盆世,花岗闪长岩(381.7±2.9Ma)形成于晚泥盆世。岩体整体富碱,属于准铝质-弱过铝质高钾钙碱性花岗岩类。轻重稀土分馏较明显且富集轻稀土((La/Yb)_N=5.09~9.22),Eu异常不明显,相对富集Rb、Th、U、K等元素,亏损Nb、Ta、Ti等高场强元素;二长花岗岩和石英闪长岩具有低的(~(87)Sr/~(86)Sr)_i值(0.7040~0.7043),正ε_(Nd)(t)值(+4.85~+6.18),年轻的t_(DM1)(Nd)年龄(663~732Ma),二长花岗岩锆石ε_(Hf)(t)值为+7.94~+12.12,t_(DM2)(Hf)=648~889Ma;花岗闪长岩也具有低的(~(87)Sr/~(86)Sr)_i值(0.7045~0.7046),正ε_(Nd)(t)值(+4.61~+4.80),年轻的t_(DM1)(Nd)年龄(731~749Ma),花岗闪长岩锆石εHf(t)值为+4.26~+11.69,tDM2(Hf)=631~1103Ma。综合研究表明,塞勒肯特岩体形成于俯冲背景下的大陆边缘弧环境,可能是俯冲板片脱水交代地幔楔产生的玄武质岩浆上涌,导致新生下地壳发生部分熔融。二长花岗岩及石英闪长岩均来源于新生下地壳的部分熔融;花岗闪长岩主要来源于新生下地壳的部分熔融,并有少量幔源物质的加入,花岗闪长岩中的暗色微粒包体可能是幔源物质与新生下地壳部分熔融的岩浆未发生完全混合,最终冷凝结晶的产物。谢米斯台地区与俯冲相关的中酸性岩浆活动至少从晚奥陶世一直延续至晚泥盆世。 相似文献
10.
新疆阿舍勒盆地中阿舍勒组火山岩主要为英安质、流纹质火山角砾岩,凝灰岩、沉凝灰岩等火山角砾岩及火山熔岩,顶部为玄武岩及碧玉岩、灰岩。玄武岩亏损Nb,Ta,Ti等高场强元素,富集Ba,Th,U,Sr等大离子亲石元素,具岛弧玄武岩特征;英安岩为钙碱性系列,富集Rb,Ba,Th,U等大离子亲石元素,Nb,P,Ti亏损十分明显,具火山弧英安岩特征。玄武岩和英安岩中分别获得(387±2.8)Ma和(398.1±6.9)Ma的锆石U-Pb年龄。Hf同位素研究表明,玄武岩、英安岩物质主要来自亏损地幔,受部分熔融地壳的混染。地球化学特征显示,早中泥盆世阿舍勒组火山岩形成于俯冲构造环境。 相似文献
11.
Inter-regional correlation of transgressions and regressions in the Cretaceous period 总被引:1,自引:0,他引:1
T. Matsumoto 《Cretaceous Research》1980,1(4):359-373
Well investigated platforms have been selected in each continent, and the history of Cretaceous transgressions and regressions there is concisely reviewed from the available evidence. The factual records have been summarized into a diagram and the timing of the events correlated between distant as well as adjoining areas.On a global scale, major transgressions were stepwise enlarged in space and time from the Neocomian, via Aptian-Albian, to the Late Cretaceous, and the post-Cretaceous regression was very remarkable. Minor cycles of transgression-regression were not always synchronous between different areas. Some of them were, however, nearly synchronous between the areas facing the same ocean.Tectono-eustasy may have been the main cause of the phenomena of transgression-regression, but certain kinds of other tectonic movements which affected even the so-called stable platforms were also responsible for the phenomena. The combined effects of various causes may have been unusual in the Cretaceous, since it was a period of global tectonic activity. The slowing down of this activity followed by readjustments may have been the cause of the global regression at the end of the Cretaceous. 相似文献
12.
The Afyon stratovolcano exhibits lamprophyric rocks, emplaced as hydrovolcanic products, aphanitic lava flows and dyke intrusions, during the final stages of volcanic activity. Most of the Afyon volcanics belong to the silica-saturated alkaline suite, as potassic trachyandesites and trachytes, while the products of the latest activity are lamproitic lamprophyres (jumillite, orendite, verite, fitztroyite) and alkaline lamprophyres (campto-sannaite, sannaite, hyalo-monchiquite, analcime–monchiquite). Afyon lamprophyres exhibit LILE and Zr enrichments, related to mantle metasomatism. 相似文献
13.
K.Naganjaneyulu 《地学前缘(英文版)》2014,5(1):1-2
正The Precambrian shields and associated suture zones of the globe preserve important records of continental growth and destruction,the formation and closure of ocean basins,and the early evolution of the Earth in terms of tectonics,resources,and environment.They also offer critical clues on the nature and style 相似文献
14.
Daniel Harlov 《地学前缘(英文版)》2014,5(5):621-625
正1.Introduction This special issue of Geoscience Frontiers is a tribute volume honoring the life and career of Jacques Touret.A set of research papers has been assembled,which broadly reflect his research interests over his 50 plus year career.These papers focus on the role that fluids play during the formation and evolution of the Earth's crust.Below I provide a brief summary of the life of Jacques Touret,along with a select bibliography of his more important papers.This is then followed by a brief introduction to the papers assembled for this special issue. 相似文献
15.
《地学前缘(英文版)》2014,(1):139-141
正1 AIM AND SCOPE GEOSCIENCE FRONTIERS(GSF)is a bi-monthly international journal that publishes in English high quality original research articles and timely reviews in interdisciplinary fields of Earth and Planetary Sciences.GSF aims to bridge innovative,provocative and challenging concepts and models related to various fields of research including petrology and geochemistry in understanding lithospheric architecture and mantle dynamics,global tectonics,economic geology and fuel exploration,geophysics,stratigraphy and paleontology with new 相似文献
16.
正The world petroleum exploration suggests that,about70%of the world’s potash resources were discovered during oil and gas exploration(Zheng et al.,2007).The Kuqa depression in the Tarim basin is abundant with petroleum exploration data,and 相似文献
17.
正Qarhan Salt Lake is located in the eastern part of the Qaidam Basin,which is first discovered the large potash deposit in the late 1950s.The Bieletan section is located in the west of Qarhan Salt Lake,where saline sediment 相似文献
18.
正With the approach of the 45th World Earth Day,China’s Ministry of Land and Resources issued the status of the Chinese geological survey and environments on 22nd April 2013.Regional geological survey in 2013 achieved new results—(why was oceanic in twice?)polar and oceanic expedition were fully completed,a national census of geography was begun,and 相似文献
19.
正1 Introduction The Lop Nor playa,located in the eastern end of the Tarim Basin,capped with a thick salt crust covering an area of approximately 5,500 km2(Ma 2007)that closely resembles a"Great Ear"in satellite images.Understanding the formation of the salt crust can provide important 相似文献
20.
In Liaoning, Hunan, Guangxi, Guizhou, Gansu, Sichuan, Anhui, Jilin and other provinces in China, there is a wide occurrence of metal quantity over 1000 tons of refractory gold ores, principally because of low gold recoveries and become "stay mine". Features of refi'actory gold ores are: gold in micro-particles or a microscopic state that is wrapped in pyrite, presence of arsenopyrite and other sulfide minerals or disseminated in the crystal lattice of sulfide minerals; harmful impurity elements such as arsenic, carbon, mercury, antimony, copper with high content are closely related with the gold, and these elements affect the contact reaction between the gold and solvent extraction, making the recovery of the gold extraction process low. In the past 20 years, overseas countries have developed the application of the roasting oxidation method, hot acid (alkali) oxidation, bacterial oxidation and flash chlorination oxidation technology to solve this problem.Among these, biological oxidation has developed rapidly in the domestic market and gold enterprises abroad because of its low investment in infrastructure, low production costs, less environmental pollution, simple process and easy control, etc. 相似文献