共查询到20条相似文献，搜索用时 218 毫秒
1.
冀东地区新太古代晚期的岩浆事件与地壳增生:来自岩石地球化学和锆石年龄及Hf同位素的制约 总被引：3，自引：2，他引：1
在华北克拉通东部冀东的遵化-迁西-迁安地区广泛分布有新太古代晚期的斜长角闪岩(基性火山岩)、TTG片麻岩和紫苏闪长岩/紫苏花岗岩。锆石U-Pb同位素测定表明,该区的斜长角闪岩、TTG片麻岩和紫苏闪长岩/紫苏花岗岩几乎同时形成于2529±30Ma到2555±14Ma期间。这是华北克拉通新太古代晚期一次重要的岩浆事件,并紧随有2.5Ga左右的麻粒岩相变质作用。阴极发光图像显示,TTG片麻岩和紫苏闪长岩/紫苏花岗岩中一些锆石的核部为灰黑色,具杉树叶结构或无内部结构,意味着这些锆石核部的U-Th-Pb同位素体系在变质作用期间受到了干扰或重置,因此岩浆锆石核部的207Pb/206Pb加权平均年龄通常被解释为代表岩浆事件最年轻的年龄。新太古代晚期TTG片麻岩和紫苏闪长岩/紫苏花岗岩的岩浆锆石具有正的εHf(t)值(-0.08~9.49),计算的tDM1(Hf)模式年龄介于2572~2896Ma之间,峰值年龄为2.72Ga。这表明,TTG片麻岩和紫苏闪长岩/紫苏花岗岩的母岩浆是从亏损地幔源分异出来的,且2.7Ga是研究区和华北克拉通最重要的一次地壳增生事件。地球化学和岩石成因研究表明,本区的TTG片麻岩和紫苏闪长岩/紫苏花岗岩是由来自新生地壳基性岩石部分熔融形成的岩浆通过结晶分离形成的,其中角闪石是主要的分离相矿物。地幔柱模式更有利于解释本区TTG片麻岩和紫苏闪长岩/紫苏花岗岩的成因以及冀东地区的许多其他地质特征。 相似文献
2.
太古代麻粒岩地体中通常主要分布的是紫苏花岗岩—紫苏花岗闪长岩套。这套岩石地球化学特征类似于太古代克拉通的英云闪长质—奥长花岗质—花岗闪长质片麻岩(TTG)。开放系统的结晶分异模式认为,TTG地壳是由浅部英云闪长质岩浆结晶生成的。按照这个模式,我们认为,上述麻粒岩可能是对流循环的同一岩浆库的底部结晶生成的。随着深度增加流体的溶解度增大,这意味着在厚大对流岩浆库的底部H_2O和CO_2是不饱和的。这样就可以形成紫苏花岗岩组合。深部结晶作用可包括脱挥发份—熔融反应的逆过程,即耗损钾长石、斜方辉石和流体产生黑云母和石英。这种反应在结晶期间减弱了水的活动性,但不减少CO_2的活动性,因此,在逐渐固结过程中出溶的流体多半是富CO_2的。 相似文献
3.
赵国春 《矿物岩石地球化学通报》1991,(1)
冀东地区的紫苏花岗岩主要出露于迁西的太平寨、鱼户寨、丘丈子和迁安的水厂等地。紫苏花岗岩呈块状地体侵入到具有强烈变质变形特点的紫苏斜长片麻岩之中。具有粗粒花岗 相似文献
4.
北山南带沙枣园复式岩体由中细粒黑云母花岗闪长岩、细粒黑云母石英闪长岩、中粒黑云母二长花岗岩和中粗粒黑云母正长花岗岩4个岩相单元组成。LA-ICP-MS锆石U-Pb定年结果表明,中细粒黑云母花岗闪长岩、细粒黑云母石英闪长岩和中粒黑云母二长花岗岩侵位于晚二叠世(252.1±1.9Ma、252.2±2.1Ma和248.8±3.5Ma),为海西晚期的产物;而中粗粒黑云母正长花岗岩侵位于早三叠世(246.4±2.0Ma),为印支早期的产物。该花岗质岩石均具有稀土元素的球粒陨石标准化配分曲线呈右倾型,轻重稀土分馏大,轻稀土富集且分异明显,而重稀土亏损且分异不显著特征。中细粒黑云母花岗闪长岩和细粒黑云母石英闪长岩具有较高的SiO_2、Al_2O_3和Na_2O含量,以及较低的MgO含量,强烈富集Sr而亏损Yb和Y,具轻微的铕异常(δEu=0.75～1.16),表现出典型的埃达克岩特征;中粒黑云母二长花岗岩和中粗粒黑云母正长花岗岩总体富硅(SiO_2)、富钾(K_2O)、富碱(K_2O+Na_2O),Al_2O_3含量中等,铕分别呈现负异常(δEu=0.45～0.73)和强负异常(δEu=0.02～0.08)。年代学及地球化学特征研究表明:①中细粒黑云母花岗闪长岩和细粒黑云母石英闪长岩属准铝质-弱过铝质的钙碱性Ⅰ型花岗岩,并具有典型的埃达克岩特征,中粒黑云母二长花岗岩属弱过铝质的高钾钙碱性Ⅰ型花岗岩,中粗粒黑云母正长花岗岩属弱过铝质的高钾钙碱性A2型花岗岩;②中细粒黑云母花岗闪长岩、细粒黑云母石英闪长岩和中粒黑云母二长花岗岩的岩浆来源于下地壳玄武质岩石部分熔融源区,并在上升过程中混染了下地壳物质,而中粗粒黑云母正长花岗岩的岩浆来源于年轻地壳中富含黑云母的变质泥岩部分熔融源区;③中细粒黑云母花岗闪长岩、细粒黑云母石英闪长岩和中粒黑云母二长花岗岩是俯冲-碰撞构造背景条件下的岩浆产物,而中粗粒黑云母正长花岗岩是同碰撞-碰撞后构造背景条件下的岩浆产物。 相似文献
5.
冀东太古宙克拉通线性岩浆-构造混杂岩区内分布有一种具英云闪长岩-花岗闪长岩成分的角闪斜长片麻岩,空间上与紫苏花岗闪长岩密切伴生。角闪斜长片麻岩是紫苏花岗闪长岩受构造变形影响,沿一组共轭构造(N45°E,E15°S)发生退化变质的产物。退变质作用在有水参与的等化学体系内完成,并受最强期变形事件控制。 相似文献
6.
辽西新太古代钓鱼台花岗岩成因及演化过程:来自岩石组构的证据 总被引：2，自引：2，他引：0
辽西兴城钓鱼台地区分布一套花岗质杂岩,是新太古代"绥中花岗岩"的重要组成部分。花岗质杂岩以似斑状花岗闪长岩和石英闪长岩为主,少量细粒黑云闪长岩(包体)及脉状花岗岩,各类岩石接触关系明确,本文定义为"钓鱼台花岗岩"。锆石U-Pb同位素测试结果显示似斑状花岗闪长岩、石英闪长岩、脉状花岗岩的形成年龄分别为2538±20Ma、2476±56Ma、2470±18Ma,同为新太古代末期热事件的产物。通过该花岗岩组合的宏观-微观组构解析表明,似斑状花岗闪长岩表现为均匀块状构造,具有深熔花岗质岩浆的典型堆晶结构;细粒黑云闪长岩为细粒结构,呈小型暗色包体分布在似斑状花岗闪长岩中,包体的塑性变形、捕掳晶、淬冷边及反向脉等组构发育,具有铁镁质基性岩浆加入同深熔花岗闪长岩并快速冷却的特征;暗色的石英闪长岩主要分布在似斑状花岗闪长岩之下,接触带附近似斑状花岗闪长岩中的钾长石变斑晶明显增多,显示闪长质岩浆"底垫"侵位加热的特征;脉状花岗岩同时穿切似斑状花岗闪长岩和石英闪长岩,具有熔体富集脉体的结构特征。各类岩石中变形组构均不发育。钓鱼台花岗岩记录了新太古代末期地壳深熔和壳幔相互作用过程,岩石组构研究表明新太古代地壳再造作用是一个"静态"多期次的缓慢深熔过程,伴有同期幔源基性物质加入并混合,以及随后大规模的基性岩浆底侵。由此推断钓鱼台花岗岩形成的构造背景为幔源岩浆垂向底侵过程,可能是与俯冲带关联不明显的岩浆弧环境。 相似文献
7.
本文从地质事件的角度出发,根据岩石成因类型,变质作用强度、期次,变形作用方式、构造样式,区域地球物理场特征及同位素地质年代学和矿化资料,将冀东太古宙结晶基底区划分为高压紫苏花岗片麻岩区、低压紫苏花岗片麻岩区、TTG杂岩区和岩浆构造混杂岩区四个构造单元,并提出高压紫苏花岗片麻岩区和低压紫苏花岗片麻岩区是冀东太古宙地壳同一时期不同深度层次或压力环境下的产物。岩浆构造混杂岩区是叠加于高压紫苏花岗片麻岩区背景之上长期活动的弧形线性巨型构造活动带。而TTG杂岩区是太古宙末期形成于地壳较浅部层次的花岗杂岩穹窿。 相似文献
8.
山东招掖一带是我国重要金矿产区之一。金矿与花岗质岩石关系密切,因此对于花岗质岩石的研究显得极为重要。与金矿关系密切的花岗质岩石主要有玲珑花岗岩和郭家岭花岗质闪长岩。对于这两类岩石的成因前人有以下几种看法: 1 认为玲珑花岗岩和郭家岭花岗闪长岩均为岩浆型花岗质侵入体,玲珑花岗岩为印支期,郭家岭花岗闪长岩为燕山早期。 相似文献
9.
冀东太平寨紫苏花岗岩类深熔成因的矿物标志 总被引：1，自引：0，他引：1
冀东太平寨地区紫苏花岗岩的矿物学研究结果表明,该类岩石中的主要组成矿物具有残晶相和结晶相矿物共存特点。残晶相和结晶相矿物与围岩中同类矿物对比研究表明,该区的紫苏花岗岩类是由其围岩—石英闪长质-英云闪长质紫苏斜长片麻岩深熔而成。 相似文献
10.
《地学前缘》2017,(6):25-45
光石沟铀矿床是中国重要的伟晶岩型铀矿,铀矿体产在黑云母花岗伟晶岩和黑云斜长片麻岩的接触带上。本文对矿区出露的花岗岩、花岗伟晶岩开展了详细的年代学和岩石地球化学研究以约束花岗质岩石的成因和形成环境。LA-ICP-MS锆石U-Pb测年获得了黑云母花岗闪长岩、黑云母正长花岗岩、产铀黑云母花岗伟晶岩、非矿黑云母花岗伟晶岩的加权平均年龄,分别为(440.3±2.6)Ma、(420.4±2.7)Ma、(415.1±2.6)Ma和(413.6±2.4)Ma。地球化学数据显示,从矿区花岗岩到花岗伟晶岩分异程度逐渐升高,富集LILE(Rb、Ba、Sr),亏损HFSE(Nb、Ta、Ti),并且具有I型花岗岩的特征。花岗伟晶岩为具有稀土元素四分组效应(TE1,3=1.06~1.14)的NYF型(NbTa、Y、F)伟晶岩,指示了熔体与出溶的富挥发分流体间强烈的相互作用。黑云母花岗闪长岩、黑云母正长花岗岩、黑云母花岗伟晶岩的锆饱和温度TZr分别为730~765℃、700~723℃和518~640℃。花岗质岩浆在深成中等还原(ΔO_x=-0.54~-0.25)的环境上升侵位,源区为石榴石和斜长石稳定区。黑云母花岗闪长岩的岩石成因与混入幔源物质的加厚下地壳部分熔融有关。伴随汇聚挤压作用的减弱,同源母岩浆的缓慢分离结晶形成了黑云母正长花岗岩-花岗伟晶岩组合。产铀黑云母花岗伟晶岩中较高含量的FeO~T、MgO、TiO_2、MnO、LILE(Rb、Ba、K)和较低的HFSE(Nb、Ta)是伟晶岩浆和黑云斜长片麻岩发生化学交换的结果。伟晶岩浆的同化分离结晶(AFC)导致了U在接触带的饱和,在中等还原的环境下富集成矿。光石沟花岗岩和花岗伟晶岩形成于北秦岭同造山-造山晚期。 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.
13.
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
14.
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
15.
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
16.
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