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1.
阿拉善地块南缘是镁铁质—超镁铁质岩体的重要分布区,自北向南可分为北大山岩带、龙首山岩带和北海子岩带。本文主要以北大山岩带为研究对象,通过对野芨里岩体、青疙瘩岩体及鄂博沟岩体的岩石学、岩石地球化学、微量元素、稀土元素等研究,探讨了北大山镁铁质—超镁铁质岩体的成因类型和形成构造环境。3个岩体主量元素特征显示Mg#=76~87,橄榄岩类w(Al2O3)=3.2%~5.2%,但辉长岩、辉绿岩类明显高于该值,说明北大山镁铁质—超镁铁质岩熔融程度整体不高,该区岩体属于镁质超基性岩,并且具有富铁趋势;稀土元素特征显示稀土总量(ΣREE)在5.68×10-6~11.5×10-6之间,野芨里岩体LREE稍富集,而青疙瘩及鄂博沟岩体LREE明显富集;微量元素特征显示北大山镁铁质—超镁铁质岩体的成岩构造环境为板内拉张环境,岩浆在侵位过程中受到上地壳的混染作用,微量元素原始地幔标准化蛛网图显示Ni明显亏损,有利于镍成矿。 相似文献
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青海南部杂多地区超镁铁质-镁铁质岩石的特征及Ar—Ar定年 总被引：7，自引：0，他引：7
通过野外地质研究和室内岩相学、岩石地球化学研究,在位于青藏高原中部的青海杂多地区的双湖-澜沧江结合带中发现了一套超镁铁质岩、镁铁质岩。该超镁铁质岩、镁铁质岩沿北西—南东向区域构造线多呈岩脉状侵入在早石炭世杂多群中,局部呈构造透镜体分布在断裂带中或呈包体分布在白垩纪花岗岩中,出露规模不大,局部侵入体具有层状侵入杂岩体的特征。主要岩石类型为辉石橄榄岩、辉长岩、辉长辉绿岩,岩石地球化学具高Ti、Fe、Al、Ga和LREE中等富集的特征。橄榄岩中角闪石的~(40)Ar/~(39)Ar同位素测年得到275.3Ma±1.9Ma的坪年龄,表明这套超镁铁—镁铁质岩石可能为早、中二叠世弧后盆地拉张的产物。 相似文献
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秦祁交接部位天水新阳镇细尾子沟新发现一套镁铁—超镁铁质岩,超镁铁质岩主要由蛇纹石化橄辉岩和透辉石岩组成,岩石具有低Si O2含量、高Mg O含量、稀土元素和微量元素与原始地幔含量相当的特点。镁铁质岩主要由变辉长岩和变辉长闪长岩组成,岩石具有堆晶岩的特点,具有低Si O2和Ti O2含量、高Mg O含量和Mg#值,具有较低的Ti/V比值(20±)、较高的稀土元素丰度和HREE较平坦的稀土元素配分模式;镁铁质岩属于拉斑玄武岩系列,其岩浆源区是受地壳物质交代改造过的富集型岩石圈地幔,具有E-MORB的特征。综合构造环境和区域大地构造背景,认为细尾子沟镁铁—超镁铁质岩为较典型的岛弧SSZ型蛇绿岩。LA-ICP-MS锆石U-Pb测年结果表明细尾子沟岛弧SSZ型蛇绿岩形成于晚奥陶世晚期(443.6±1.8Ma)。细尾子沟岛弧SSZ型蛇绿岩的形成与"天水—武山"古洋盆自南向北的俯冲作用密切相关,表明秦祁交接部位早古生代构造格局是一个完整的洋—弧—盆体系。 相似文献
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浪木日镁铁质-超镁铁质岩体位于东昆仑造山带东段,临近昆中断裂,主要由橄榄岩、橄榄辉石岩、辉石岩和辉长岩组成,且局部发育星点状和浸染状硫化物矿化。辉石岩和橄榄辉石岩获得的锆石U-Pb年龄分别为(421.2±1.2)Ma和(421.10±0.96)Ma,表明岩体侵位于晚志留世。岩石地球化学特征显,浪木日镁铁质-超镁铁质岩具有较高的Mg#(Mg#>80),富集LILE(Rb、Th、U等),亏损HFSE(Nb、Ta、Ti等),轻、重稀土元素分馏程度较强((La/Yb)N=6.28～50.91,(La/Sm)N=1.45～4.15,(Gd/Yb)N=1.43～9.71),具有弱的负Eu异常(δEu=0.226～0.824)。锆石Lu-Hf(εHf(t)=-2.9～-10)和全岩Sr-Nd(εNd(t)=-10.3～-8.9)同位素特征显示,其岩浆源区主要来自富集地幔,与俯冲洋壳脱水交代上覆地幔楔活动有关。综合研究表明,浪木日镁铁质-超镁铁... 相似文献
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江南造山带西南段梵净山地区镁铁质-超镁铁质岩:形成时代、地球化学特征与构造环境 总被引：1，自引：0，他引：1
梵净山地区位于江南造山带的西南缘,这里新元古代的镁铁质-超镁铁质岩浆岩广泛发育,岩性包括枕状熔岩、超镁铁质-镁铁质岩床群以及浅成侵入的辉长岩,成分属拉斑玄武岩系列。其中枕状熔岩以富集轻稀土元素和Rb、Ba、Th、U等强不相容元素,亏损高场强元素Nb和Ta,低的εNd(t)值为特征,明显不同于洋脊玄武岩,推测其成因可能与富集型地幔的部分熔融有关,形成于与俯冲有关的弧后小洋盆环境。超镁铁质-镁铁质岩床群主要由辉绿岩和碳酸辉橄岩组成,其中超镁铁质岩床群中出现大量的原生碳酸盐矿物,指示它们形成于拉张(甚至裂谷)的构造环境。辉长岩可能是区内最晚形成的岩浆岩,其SHRIMP锆石U-Pb年龄为821±4Ma。由枕状熔岩经超镁铁质-镁铁质岩床群到辉长岩,高场强元素Nb和Ta的亏损程度减弱、轻稀土元素的富集程度降低、εNd(t)值由负值变为正值,指示随时间的由早到晚,来自亏损地幔的物质不断增加。推测梵净山地区新元古代岩浆作用的顺序大致为:枕状熔岩(～840Ma)→白云母花岗岩(～838Ma)→碳酸超镁铁质岩床群→镁铁质岩床群→辉长岩(～821Ma),构造环境由俯冲-碰撞到拉张-裂谷。 相似文献
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四顶黑山岩体主要由超镁铁质岩和镁铁质岩组成。超镁铁质岩由橄榄岩、角闪橄榄岩、辉橄岩、辉石岩等组成;镁铁质岩由辉长岩、角闪辉长岩、橄榄辉长岩等组成。本次对辉长岩进行了全岩Sm-Nd同位素分析,得到的等时线年龄为327±9.0Ma,初始εNd（t）=＋3.97,表明镁铁质—超镁铁质岩中辉长岩形成于早石炭世末。属于富集地幔向亏损地幔过渡类型。这一年龄的确定,为探讨北山—天山结合部晚古生代镁铁质—超镁铁质岩的成因机制和该区的区域地质演化提供了有效的年代学依据。 相似文献
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大别造山带中镁铁质——超镁铁质岩石和榴辉岩有关问题的讨论 总被引：21，自引：3，他引：18
根据近年来积累的文献资料及研究讨论指出：（１）大别山造带镁铁质－－超镁铁质岩石可分成两大类;一类以任家湾、童家冲、祝家铺道士冲、青山、沙河等辉石辉长岩类为代表,它们具有相同的牲和成岩年龄,可能与华北、华南地块聚敛碰产生的岛弧或大陆岩浆岩有关;另一类以铙拔寨,大化坪、碧溪岭和毛屋岩体为代表,虽然它们的成岩年龄均在前寒武纪,但却有着不同的成岩时代和成岩环境。（２）大别造山带榴辉岩等多属异地来源,具有不 相似文献
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为探讨内蒙古中部地区镁铁质-超镁铁质岩形成时代及地球化学特征,完善区域成岩成矿年代学格架,本文对克布、黄花滩和小南山岩体进行了锆石U-Pb年代学及全岩地球化学分析。LA-ICP-MS锆石U-Pb测年获得克布和黄花滩镁铁质-超镁铁质岩结晶年龄分别为258±2 Ma(MSWD=2.3)和262±1 Ma(MSWD=0.51),属于中-晚二叠世,小南山辉长岩应形成于中-晚二叠世(～273 Ma)。全岩地球化学分析表明,三个岩体样品m/f值介于0.96～3.54之间,主要为镁铁质-超镁铁质岩,其稀土和微量元素曲线基本表现为轻稀土元素(LREE)和大离子亲石元素(LILE)相对富集,高场强元素(HFSE)相对亏损的相似性特征,但也有明显的区别,显示各岩体岩浆演化或分异程度可能不尽相同。综合区域研究资料表明,内蒙古中部地区晚古生代镁铁质-超镁铁质岩浆活动可能至少始于早二叠世(294Ma),持续至中-晚二叠世(273～258Ma),且二叠纪时期中亚造山带南缘较大范围内均发育较为活跃的幔源岩浆活动。克布、黄花滩和小南山岩体应形成于后碰撞伸展环境,其岩浆源区可能混染了俯冲流体交代改造的地幔楔物质,使3个岩体的岩石样品均显示具有富含大离子亲石元素和轻稀土元素,贫高场强元素等部分岛弧岩浆特征的信号。 相似文献
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内蒙古乌拉特中旗地处华北陆块北缘西段,大地构造分区属于狼山-白云鄂博陆缘裂谷。区域上,镁铁质-超镁铁质岩呈东西向带状分布,断续出露长约300km,宽约30km。该镁铁质-超镁铁质岩带内铜镍矿床(点)较为发育,克布为该带内一个中-小型铜镍硫化物矿床。克布镁铁质-超镁铁岩体出露面积约45km2,主要由辉长岩相和橄榄岩相组成,辉长岩相为岩体的主要岩相,橄榄岩相为主要的赋矿岩石,两个相带相伴产出,呈渐变过渡关系。本文采用LA-ICP-MS锆石U-Pb法测年,获得克布斜长方辉橄榄岩年龄为258.1±1.8Ma(MSWD=2.3),属于晚二叠世。岩石主、微量及稀土元素分析结果表明,岩石样品属铁质镁铁质-超镁铁质岩,具有拉斑玄武岩系列演化趋势,并相对富集大离子亲石元素(Rb、Sr、Ba),亏损高场强元素(Nb、Ta、Zr、Hf、Ti),以及具有轻稀土富集[(La/Yb)N=2.47~11.29]的右倾型稀土配分模式。以橄榄石-熔体平衡原理估算克布镁铁质-超镁铁质岩体母岩浆的MgO含量为10.1%,FeO为12.1%,应为高镁的拉斑玄武质岩浆。综合分析认为,克布镁铁质-超镁铁质岩体应形成于后碰撞伸展阶段,岩浆源区由被消减板片交代的地幔楔物质和软流圈物质组成。橄榄石和辉石等富镁铁矿物的分离结晶和富硅地壳物质的混染可能对硫化物熔离富集成矿起到了关键性作用。 相似文献
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石头坑德镁铁-超镁铁质岩体位于东昆仑造山带东段五龙沟地区,邻近昆中大断裂,主要岩性为辉石岩、橄辉岩、橄榄岩、辉长岩等,铜镍矿体主要赋存于Ⅰ号岩体的辉石岩、橄辉岩和橄榄岩中。岩石地球化学特征表明,其镁铁比值(m/f)变化范围在2.77~6.01之间,属铁质系列的镁铁-超镁铁岩,有利于成铜镍矿。稀土总量总体较低,轻稀土元素之间分馏强,重稀土元素之间分馏弱。岩石总体富集LILE(Rb、Ba、Th、U),贫HFSE(Nb、Ta、Zr、Y),具有明显的Rb、U正异常及Nb、Ta的负异常。超镁铁岩类橄榄石中的Ni普遍亏损,指示深部存在硫化物的熔离作用,在橄榄石结晶之前,大量的Ni进入到硫化物中,极有利于形成富矿岩浆或矿浆。可见,伴随同化混染作用的发生,岩浆中S达到过饱和,进而硫化物发生不混溶作用,富含硫化物的岩浆运移至东昆仑造山带邻近昆中断裂构造薄弱的部位成岩成矿。铜镍矿体多赋存在含橄榄石的超镁铁质岩体内,指示石头坑德岩体深部存在高度富集铜镍的部位,是下一步的找矿方向。 相似文献
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S. Viswanathan K. Surya Prakash Rao B. Mahabaleswar 《Journal of the Geological Society of India》2013,82(6):621-627
Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours. 相似文献
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奥地利安东帕有限公司 《岩矿测试》2009,28(3):306-306
最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提 相似文献
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E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献
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Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance. 相似文献
17.
岩石密度和超高压岩石折返速率 总被引：1，自引：3，他引：1
在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。 相似文献
18.
滇东南锡、银、铅、锌多金属矿床主要分布在个旧、白牛厂、都龙3个矿区,而滇东南较大的3个花岗岩体又分别出露在3个矿区或附近.花岗岩体均形成于燕山晚期,岩石化学、矿物成分相似,富含锡、银、铅、锌、钨、铜等成矿元素.矿床主金属元素组合与岩体之间的距离由远而近出现由锡、钨、(铍、铌、钽)→锡、钨、(铁)、铜、铟→锡、铅、锌、银、铟、(锑)有规律的变化.花岗岩浆是成矿物质来源和成矿热源.岩浆侵入初期使上覆地层隆起产生背斜(凹陷部位成向斜);同时使地层产生一系列裂隙、压性断层或层间断裂;岩浆侵入晚期,这些断层再次活动,表现为张性,岩浆产生的含矿热液沿由其活动所造成的断裂迁移、充填、交代、沉淀而形成矿床. 相似文献
19.
Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA 总被引：1，自引：0，他引：1
The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources. 相似文献
20.
Alexander E. C. Broberg J. S. Kehren A. R. Graziani M. M. Turri W. L. 《Environmental Geology》1993,22(4):353-361
Bellechester, Minnesota, is a small community of approximately 155 residents located on the county line between Goodhue and Wabasha counties in southeast Minnesota's karst region. Bellechester is served by a 21-year-old wastewater treatment facility (WWTF) consisting of three waste-stabilization ponds. On 28 April 1992 six sinkholes were discovered to have drained cell 2 of the WWTF resulting in the loss of approximately 8.7×106 1 of partially treated effluent and about 600 m3 of soil into previously undetected subsurface voids of unknown dimensions. In the week following the collapse, approximately 200 water wells located within a 5-km radius of the WWTF were sampled in an after-the-fact, emergency sampling program. Twelve samples with elevated fecal coliform levels, 18 samples with nitrate-nitrogen greater than the 10 mg/1 standard, and no samples with elevated chlorides were found. However, the elevated levels could not be unambiguously attributed to the WWTF collapse. This is the third WWTF to fail by sinkhole collapse in southeast Minnesota since 1974. All three collapsed lagoons have been located in similar geomorphic and stratigraphic settings. However, at least two lagoons have collapsed in the adjacent area in northeast Iowa, and these lagoons are located at different stratigraphic positions. Twenty-two WWTFs constructed in southeast Minnesota's karst region in the last 25 years have been identified as subject to potential sinkhole collapse. An unknown but significant number of manure storage lagoons, flood control structures, etc., have also been constructed in the karst region and are at risk. Public agencies are beginning to develop plans to deal with the risk associated with existing and future waste lagoons in this environment. The critical hydrogeologic parameters that can be used to prioritize the risk of collapse at existing facilities include: (1) the lithology of the first bedrock beneath each lagoon, (2) the thickness of surficial materials between the lagoon and the bedrock surface, (3) the presence and construction of liners (seepage rate), and (4) the proximity to existing sinkholes. 相似文献