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1.
内蒙古达茂旗花岗岩类LA-ICP-MS
锆石U-Pb年龄及其地质意义 总被引：2，自引：1，他引：1
对内蒙古达茂旗北部构造单元的巴特敖包岛弧带2个花岗闪长岩岩体样品和南部构造单元一个花岗岩岩体的2件样品进行了LA-ICP-MS锆石U-Pb定年。北部构造单元采自2个花岗闪长岩岩体的样品锆石206Pb/238U年龄分别为468Ma±2Ma和452Ma±3Ma,代表了这2个岩体的侵位时间,表明古亚洲洋向华北克拉通之下俯冲不晚于468Ma±2Ma;南部构造单元采自同一花岗岩岩体的2件样品获得的锆石206Pb/238U年龄分别为268Ma±2Ma和264Ma±2Ma,和该单元西部岩体已有的锆石年龄相符。这为华北克拉通北缘岩浆作用研究提供了新的年代学证据。 相似文献
2.
河南焦作云台山早前寒武纪变质基底锆石SHRIMP U-Pb年龄 总被引：4，自引：0，他引：4
应用离子探针技术,对华北太行山南缘钾长石化长英质副片麻岩和钾长石化片麻状奥长花岗岩进行了锆石年龄测定。钾长石化长英质副片麻岩的变质原岩为泥砂质碎屑沉积岩,其形成时代很可能为新太古代。碎屑锆石普遍存在强烈铅丢失,靠近上交点的5个数据点207Pb/206Pb加权平均年龄为3399Ma±8Ma,代表了物源区组成的时代。钾长石化片麻状奥长花岗岩2组锆石207Pb/206Pb加权平均年龄分别为2511Ma±13Ma(岩体形成时代)和2735Ma±16Ma(残余锆石年龄),分别代表该岩体形成时代和残余锆石年龄。新的资料支持了华北克拉通中部造山带太古宙地质体与其东部陆块存在亲缘关系的认识。 相似文献
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湖南骑田岭芙蓉矿田成岩成矿时代的厘定及其地质意义 总被引：22，自引：4，他引：22
通过对湖南骑田岭岩体芙蓉超单元南溪单元中粒斑状角闪石黑云母二长花岗岩、芙蓉矿田白腊水矿区的10号矿脉中蚀变花岗岩型锡矿石、19号矿脉中矽卡岩型矿石矿物、42号含矿花岗斑岩体和ZK801钻孔(80~90m)的细粒花岗岩的Rb-Sr、Sm-Nd和锆石SHRIMP U-Pb同位素年代学研究,分别获得南溪单元弱蚀变花岗岩全岩Rb-Sr等时线年龄为146±10Ma(95%可信度)和岩体锆石SHRIMP U-Pb年龄为155±6Ma(95%可信度),蚀变矿化花岗岩锆石SHRIMP U-Pb年龄为156±5Ma(95%可信度),10号蚀变花岗岩型矿脉矿石的Rb-Sr等时线年龄为137±5Ma(95%可信度),19号矽卡岩型矿脉的矿石—矿物Sm-Nd等时线年龄为133±15Ma(95%可信度);42号含矿花岗斑岩体锆石SHRIMP U-Pb年龄为146±5Ma(95%可信度);ZK801钻孔中细粒花岗岩全岩的Rb-Sr等时线年龄为140±7Ma(95%可信度)。上述精确的年代学研究结果表明,芙蓉超单元花岗岩侵位时间为燕山早期,而不是印支期。由此推测骑田岭芙蓉超单元花岗岩形成于早—中侏罗世,它的构造环境可能为地壳处于强烈剪切挤压晚期,而区内花岗斑岩和细粒花岗岩岩浆活动可能发生在140~145Ma之间,其构造环境可能为地壳由挤压剪切向拉张伸展转化的时期形成的;白腊水矿区不同类型矿床年代学研究结果(133~141Ma)清楚地表明,其成矿作用的时间与区内花岗斑岩和细粒花岗岩的岩浆活动时间有明显的耦合关系。据此推断,骑田岭芙蓉锡矿是在晚侏罗世,地壳由挤压剪切向拉张伸展转化的时期形成的。而与芙蓉花岗岩主体侵入岩浆活动无直接成生关系。 相似文献
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内蒙古北山地区小狐狸山钼矿辉钼矿Re-Os年龄
和LA-ICP-MS锆石U-Pb年龄 总被引：2，自引：1，他引：1
小狐狸山钼矿是内蒙古北山地区近年来新发现的一个中型规模的斑岩型矿床。通过对成矿斑岩锆石和成矿晚阶段石英脉型钼矿的同位素研究,获得小狐狸山含矿花岗岩锆石LA-ICP-MS U-Pb年龄216.9Ma±0.5Ma（MSWD=0.41）,与斑岩型钼矿化的时间220Ma±2.2Ma在误差范围内基本一致,为该矿床主要为一个斑岩型钼矿床提供了同位素年代学的佐证;晚成矿阶段辉钼矿单矿物Re-Os模式年龄加权平均值为213.2Ma±4.6Ma(MSWD=1.3)。小狐狸山钼矿床成矿岩体的展布受控于沿黑河展布的北东东向构造,该组构造切割了早期形成的北西向区域构造,暗示216~220Ma为北山地区由后碰撞进入板内伸展环境提供了初步的年龄约束,北山地区印支期的成矿作用值得重视。 相似文献
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内蒙古林西地区上二叠统林西组砂岩碎屑锆石的年龄及其大地构造意义 总被引：1，自引：0，他引：1
林西地区林西组的主体岩性以碎屑岩为主,对其中代表性岩石组合——长石石英砂岩进行了年代学研究。 50粒碎屑锆石样品的LA-ICP-MS U-Pb年代学测试结果显示2个主要年龄区间：(256±2～322±3)Ma,峰值年龄为279Ma±2Ma;(357±7～497±4)Ma,峰值年龄为441Ma±3Ma。另有3颗锆石的年龄分别为797Ma±6Ma、1413Ma±38Ma、1661Ma±24Ma。其中256 Ma±2Ma的年龄限定了林西组原岩年龄应为晚二叠世;第二组年龄(357±7～497±4)Ma,峰期年龄441Ma±3Ma,与东北地区的主要泛非期事件年龄一致,表明主要的物源区为东北地块(佳蒙地块)。而797Ma±6Ma、1413Ma±38Ma、1661Ma±24Ma等年龄反映了东北地块基底年龄的信息。这些年龄数据表明, 林西组应为东北地块的一部分,并进一步限制了华北与西伯利亚两大板块的缝合线应位于林西组发育地区的南部,即西拉木伦河断裂,而拼合时代应晚于晚二叠世,可能为早三叠世。 相似文献
6.
华北克拉通南缘龙王Chuang碱性花岗岩U—Pb年龄及其地质意义 总被引：6，自引：3，他引：6
华北克拉通南缘发育一系列碱性岩体,前人曾划出3个碱性岩带,龙王碱性岩位于中带,对该岩体形成的确切时代仍有较大争议。一些学者将该岩体作为晋宁期伸展体制下形成的碱性岩,并认为这期岩浆活动与扬子北缘同时代的裂解型岩浆活动可以对应。作者等进行了TIMS和SHRIMP法锆石U-Pb年代学研究。样品(T26)采自河南省栾川县庙子镇之北的卢氏管村西的钠铁闪石正长花岗岩。TIMS法U-Pb上交点年龄为1637Ma±33Ma,SHRIMP法206Pb/238U和207Pb/206Pb表面年龄平均值分别为1611Ma±19Ma和1625Ma±16Ma,3组年龄在误差范围内一致。我们选择SHRIMP法207Pb/206Pb表面年龄平均值1625Ma±16Ma作为龙王正长花岗岩的形成时代。因此,龙王碱性花岗岩是华北克拉通1.8～1.6Ga裂解过程中最晚期碱性岩浆活动的产物。石童石童石童 相似文献
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冀东唐杖子、牛心山花岗岩体锆石SHRIMP U-Pb定年及其地质意义 总被引：4，自引：0，他引：4
冀东地区是一个金矿聚集区，但与国内外的矿集区相比，冀东地区却“只见星星不见月亮或少见月亮”，这可能是因为某些具有地区性特征的找矿标志尚未被人们所认识。本次工作采用SHRIMP锆石U-Pb法测得唐杖子金矿的花岗斑岩株的形成年龄为173Ma±2Ma，牛心山红色花岗岩的年龄为173Ma±2Ma，与峪耳崖岩体红色花岗岩的年龄174Ma±3Ma相吻合，同属中生代燕山早中期，应是同一岩浆活动的产物。如果金矿与该岩浆活动有关，那么这3个矿床就具有成因上的联系，即它们（也许包括更多的矿点）可能由一个热中心分异矿化形成，后经多次地壳活动形成目前的格局。 相似文献
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青海柴达木山岩体LA-ICP-MS锆石U-Pb定年
及Hf同位素特征 总被引：3，自引：1，他引：2
柴达木山岩体是柴北缘地区最大的岩体之一。为确定柴达木山岩体成因及其与柴北缘早古生代造山作用的关系,采用LA-ICP-MS方法对柴达木山眼球状花岗岩和花岗闪长岩中的锆石进行了U-Th-Pb同位素及Hf同位素研究。柴达木山眼球状花岗岩及花岗闪长岩206Pb/238U年龄加权平均值分别为436.9Ma±2.8Ma及440.8Ma±7.3Ma,Th/U值均大于0.2,代表了岩浆的形成年龄。眼球状花岗岩和花岗闪长岩锆石Hf同位素地球化学特征相近,45个锆石Hf同位素分析值中42个锆石176Lu/177Hf值均介于0.000735~0.002786之间,176Hf/177Hf值变化范围为0.282264~0.282439,εHf(t)变化于-8.5~-2.5之间,Hf同位素两阶段模式年龄为1.44~1.77Ga。研究表明,柴达木山岩体形成于437~446Ma,具有多期侵位特点,其原岩来自柴达木板块基底下地壳;结合柴北地区缘早古生代构造演化特点认为,柴达木山岩体为陆陆碰撞的产物。 相似文献
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江西武功山穹隆复式花岗岩的锆石U-Pb年代学研究 总被引：21，自引：4，他引：17
采用锆石U-Pb法对武功山穹隆复式花岗岩中广泛分布的花岗质岩石开展精细定年研究,结果表明:山庄、张佳坊和武功山岩体的锆石U-Pb年龄分别为460.5±1.5 Ma、427.9±1.2 Ma和428.0±1.0-462.3±2.3 Ma,属早古生代晚期花岗岩;而雅山、温汤和明月山等岩体的锆石U-Pb年龄分别为161.0±1.0 Ma、143.8±1.6 Ma和126.3±6.4.Ma,属晚侏罗世-早白垩世花岗岩。因此认为武功山穹隆复式花岗岩中花岗岩分属早古生代晚期及晚侏罗世-早白垩世岩浆活动产物。从一个侧面说明华南地区大地构造演化过程中可能存在早古生代晚期构造一岩浆作用事件及晚侏罗世-早白垩世构造-岩浆作用事件,为华南大地构造演化研究提供了新的依据。结合前人在武功山地区花岗质片麻岩中白云母40Ar/39Ar法定年(225-233 Ma)资料,说明本区韧性变形形成于晚i叠世,可能意味着武功山伸展构造的启动时间,而晚侏罗世-早白垩世花岗岩浆的形成及向上运移,使周围的岩石软化乃至部分熔融,使得围岩环境更有利于伸展构造发展,并在早白垩世最终形成武功山花岗岩穹隆伸展构造。 相似文献
11.
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
12.
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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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
16.
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
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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
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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
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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