论河北丰宁牛圈银(金)矿床的成矿时限问题

对河北牛圈银(金)矿区细粒钾长花岗岩株和含矿隐爆角砾岩墙钾长石样品进行了详细的40Ar/39Ar同位素年龄测定。细粒钾长花岗岩株钾长石样品主要加热阶段所获得数据构成一条相关性很好的直线,其对应的同位素等时线年龄值为(216.6±3.2)Ma(2σ),40Ar/39Ar初始比值为297±28。相比之下,含矿隐爆角砾岩墙钾长石样品特定加热阶段(1200～1300℃和1360～1450℃)所获数据同样也构成两条直线,其对应的同位素等到时线年龄值分别为(227.9±4.8)Ma(2σ)和(216.7±6.1)Ma(2σ),40Ar/39Ar初始比值分别为307±41和269±39。考虑到所测样品均采自未受到明显后期构造-岩浆活动或其他热事件影响的岩(矿)体,因此,细粒钾长花岗岩株和含矿隐爆角砾岩墙的形成时代为216Ma,与印支期富钾岩浆作用具有密切成因联系。根据含矿隐爆角砾岩墙的野外地质证据,结合矿物共生组合关系和钾长石同位素年龄数值,可以推测牛圈银(金)矿区早期成矿作用发生在(227.9±4.8)Ma,而主要成矿期为(216.7±6.1)Ma,是印支期多阶段富碱质成矿流体活动的产物。牛圈银(金)矿区成矿作用时间的厘定对于提高该区成矿理论研究水平和寻找隐伏金属矿床均具重要意义。     

内蒙古柳坝沟金矿床40Ar-39Ar年代学及铅同立素

内蒙古柳坝沟金矿床是华北地台北缘成矿带上,以广泛发育钾长石化为特色的大型金矿床.金矿体中钾长石的40 Ar-39Ar同位素和矿石的铅同位素特征表明:40Ar-39Ar年龄密度图中260～360 Ma峰值区反映了岩浆活动的主要时限,与区内岩体侵位年龄(220～350 Ma)相符.40Ar-39Ar坪年龄为(217.9±3...     

东川汤丹铜矿床石英真空击碎及其粉末阶段加热^40Ar—^39Ar年龄谱的含义

采用真空击碎技术提取东川汤丹铜矿床石英流体包裹体进行40Ar-39Ar法年龄测定,获得了逐渐下降的阶梯形年龄谱,表明流体包裹体含有过剩氩;数据点在40Ar／36Ar-39Ar／36Ar图解上构成等时线,等时线年龄为（712±33）Ma,代表了矿床的形成年龄。随后对其粉末进行40Ar-39Ar阶段加热（100—800℃）分析,形成相对比较平坦的年龄谱,坪年龄为（317±6）Ma（39Ar占45％,含真空击碎分析在内）,粉末加热分析全部数据点构成的等时线年龄为（321±13）Ma。电子探针分析和显微镜观察证实了该石英样品中含有粒径大于100μm,K2O含量为8％-10％,形成时间明显晚于石英的白云母类富钾矿物,粉末阶段加热分析结果表明～320Ma应为后期白云母类矿物的年龄。     

石英击碎与粉末加热40Ar-39Ar定年及其含义讨论

采用真空击碎技术提取东川汤丹铜矿床石英流体包裹体，进行40Ar-39Ar法年龄测定，获得了逐渐下降的阶梯形年龄谱，表明流体包裹体含有过剩氩；数据点在40Ar/36Ar-39Ar/36Ar图解上构成等时线，年龄为712±33Ma，这一年龄值代表了矿床的形成年龄[1]。随后对其粉末进行40Ar/39Ar阶段加热（100-800℃）分析，形成相对比较平坦的年龄谱，坪年龄为317±6Ma(39Ar占45%，含真空击碎分析在内)，全部加热分析数据点构成的等时线年龄为321±13Ma，这一年龄初步解释为流体包裹体内子     

澄江动物群产出层位^40Ar—^39Ar年龄谱

澄江动物群,产于云南下寒武统筇竹寺组玉案山段黄绿色粉砂质页岩中,大部分风化较强,给同位素年龄测定带来困难.笔者应用40Ar/39Ar快中子活化法,测得澄江地区大坡头剖面玉案山段下部伊利石40Ar-39Ar年龄为559.22±0.77Ma;晋宁地区昆阳磷矿剖面玉案山段下部伊利石40Ar-39Ar年龄为559.63±0.98Ma.该年龄代表澄江动物群的下限同位素年龄值.     

云南个旧老卡岩体钾长石与“玄武岩型”铜矿金云母~(40)Ar-~(39)Ar年龄及其地质意义

个旧变玄武岩系中热液型铜锡多金属矿床主要分布于老厂、卡房矿田西部。文章利用40Ar-39Ar同位素测年方法对老卡隐伏花岗岩体的钾长石、老卡矿田"玄武岩型"铜矿的金云母进行年龄测试。结果显示,老卡岩体钾长石的40Ar-39Ar同位素坪年龄为71.6±0.29 Ma;老厂和卡房"玄武岩型"铜矿蚀变矿物金云母坪年龄分别为81.99±0.85 Ma和82.46±0.85 Ma,表明其形成时代皆为晚白垩世。结合区域资料,指出个旧锡-铜多金属矿田经历了较长的岩浆-热液演化时期,"玄武岩型"铜多金属矿床与燕山晚期花岗岩浆活动相关,为晚白垩世软流圈上涌、岩石圈大规模伸展减薄的产物。     

华北地块南缘中段中生代花岗质岩石的40Ar-39Ar年代学研究

对华北地块南缘4个中生代花岗质岩体中的角闪石和黑云母进行了40Ar-39Ar定年研究。结果表明,陕西黑山村岩体黑云母花岗闪长岩中黑云母的40Ar-39Ar坪年龄为126. 6±0. 3Ma,河南马家湾岩体细粒黑云母花岗闪长岩中黑云母的40Ar-39Ar坪年龄为126. 6±0. 2Ma,河南洛宁南八百坡岩体黑云母二长花岗岩中角闪石的40Ar-39Ar坪年龄为128. 3±0. 3Ma,山西蚕坊岩体花岗闪长岩中角闪石的40Ar-39Ar坪年龄为129. 2±0. 2Ma。上述结果显示华北地块南缘中生代的岩浆活动主要发生在早白垩世。该期岩浆的产生应与中国东部早白垩世的伸展环境相联系。     

鄂东南地区大型矽卡岩型铁矿床金云母40Ar-39Ar同位素年龄及其构造背景初探

鄂东南地区铜铁多金属矿床是长江中下游地区金属成矿带的重要组成部分,但其精确的成矿时代和构造背景的研究显得较少.本文选择与磁铁矿密切共生的金云母为研究对象,利用40Ar-39Ar阶段加热同位素定年方法对该地区典型大型程潮和金山店矽卡岩铁矿床中金云母进行了成矿时代的研究,获得了金云母的40Ar-39Ar同位素坪年龄分别为132.6±1.4Ma和131.6±1.2Ma,对应等时线年龄为136±4Ma和132.0±2.8Ma.结合矿物共生组合特征和流体包裹体温度的分析,认为金云母的40Ar-39Ar坪年龄分别代表程潮和金山店矽卡型铁矿床的成矿时代,结果与大冶矽卡岩型铁矿床和鄂东南地区斑岩-矽卡岩型铜多金属矿床的成矿时代可以对比.在整合已有的岩石学、地球化学和地球物理学资料基础上,笔者认为鄂东南大型矽卡岩型铁矿床形成于区域岩石圈伸展和减薄构造环境.     

变斑晶石榴石40Ar—39Ar年龄谱的含义与华北高压麻粒岩变质时代

采用40AAr-39Ar阶段加热法研究华北桑干地区高压基性麻粒岩的变斑晶石榴石,获得40Ar-39Ar坪年龄1852土8Ma,40Ar-39Ar等时线年龄1862±37Ma.这组年龄相当于高压麻粒岩的变质作用年龄.这一结果表明,虽然变斑晶石榴石中仅仅在显微矿物包体、流体包裹体和晶格缺陷中赋存少量的K+,但其生成的40Ar*仍然能够形成稳定的年龄谱.如果退变质的影响较小,40Ar-39Ar坪年龄可以代表石榴石生长阶段的变质作用年龄.     

湖北省随州三里岗地区二长花岗岩Rb-Sr、40Ar/39Ar同位素年龄

三里岗二长花岗岩与花山蛇绿混杂岩中的基性火山岩呈侵入接触关系,其年龄的确定可解决花山蛇绿混杂岩中基性岩形成年龄的上限问题. 本文对三里岗二长花岗岩分别进行了Sm、Nd同位素研究及Rb-Sr、40Ar/39Ar同位素年龄测定.3个全岩样品的Nd模式年龄平均值为1 064±105 Ma;12个全岩样品的Rb-Sr等时线年龄为422±53(2σ)Ma;二长花岗岩中所含角闪石矿物的40Ar/39Ar坪年龄为141.4±0.3 Ma,等时线年龄为142±2 Ma.这些结果暗示了花山蛇绿混杂岩中基性火山岩的形成年龄不可能晚于422 Ma.     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

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.     

硅酸盐类样品中硅、铁、铝、钛、锰、钙、镁、钾、钠和磷的x射线荧光光谱测定

本文拟定了一种以熔融法制备样片,用X射线荧光光谱测定硅酸盐类样品中Si、Fe、Al、Tj、Mn、Ca、Mg、K、Na、P等元素的分析方法。在对不同靶材X光管和分光晶体实验对比的基础上,选择了最佳的测量条件。该法具有快速、准确,测量范围广,检测限低,价格便宜等优点。经过近百个各种类型标样或管理样品的分析对比表明,本法不仅适用于硅酸盐类岩石样品的分析,还适用于铁矿、铝土矿、碳酸盐类岩矿样品以及水泥、耐火材料等样品的分析。     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

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     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

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.     

Viscous, cohesive, non-Newtonian, depositing, radial slurry flow

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.     

硅酸盐中铁、锰、钛、钙、钾、磷、硅、铝、镁、钠、锶、铷、钡的X-射线荧光光谱定量测定

本文介绍样品经四硼酸锂熔融制成玻璃小饼。采用Lachance模式和理论a系数来校正元素间的效应,由3080E型X-射线荧光谱仪和DF-350B数据处理系统完成硅酸盐中十三个项目的测定。     

Bellechester,Minnesota, USA,lagoon collapses

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.     

Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA

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.     

滇东南花岗岩与锡、银、铜、铅、锌多金属矿床的成因关系

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.     

岩石密度和超高压岩石折返速率

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。