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大别造山带南缘蕲春混杂岩带构造属性和地质时限存在争议.本文在1/5万区域地质调查和岩石地层学研究的基础上,通过对实测剖面中四个变质沉积岩基质样品进行了碎屑锆石LA-ICP-MS U-Pb测年和原位Hf同位素分析,为混杂带的形成和演化提供约束.结果表明,碎屑锆石年龄谱主要集中在802-911 Ma,1331-1536 Ma,1776-2224 Ma,2302-2789 Ma和2868-3401 Ma等区间,存在四个明显的特征年龄峰值:～811 Ma、～1385 Ma、～2020 Ma和 ～2479 Ma;碎屑锆石εHf(t)值介于-16.2～+4.5之间,主要为负值,两阶段模式年龄变化范围在1.4-3.8 Ga之间.最年轻的岩浆成因碎屑锆石年龄约束其最晚形成时代应该不早于 ～800 Ma.综合对比区域研究结果,认为变质沉积岩的物源可能主要来自于秦岭-大别造山带中早前寒武纪基底物质和近源的新元古代岛弧带,南大别地区可能存在新元古代时期的俯冲增生记录. 相似文献
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为探讨镁铁质-超镁铁质岩的岩石学特征及成岩成矿作用时间序列, 完善区域成岩成矿年代学格架, 对平川地区的镁铁质-超镁铁质岩进行了元素地球化学分析和LA-ICP-MS锆石U-Pb定年.测试结果显示, 黄草坪辉长岩成岩年龄为259.7±1.2 Ma, 其捕获锆石结晶年龄为269.8±2.4 Ma, 辉绿(玢)岩等次火山岩参考成岩年龄为248± Ma, 其变质锆石年龄为67± Ma.研究结果表明, 平川地区的镁铁质-超镁铁质岩产出于大陆裂谷环境, 岩浆源区来自上地幔尖晶石相二辉橄榄岩, 为一套同源异相有利于铁矿化形成的富钠质拉斑玄武质岩石系列.岩浆活动开始孕育时间不晚于269.8±2.4 Ma, 大规模岩浆活动发生于259.7±1.2 Ma, 其约束了岩浆分异型和火山喷发(溢)沉积型矿化的成矿时间, 次火山岩的成岩年龄约束了次火山热液型矿化的成矿时间上限, 变质锆石U-Pb年龄记录了平川地区经历了喜马拉雅期陆内造山作用.平川地区构造岩浆活动具有爆发性、阶段性和成矿专属性等特点, 镁铁质-超镁铁质岩的形成可能与岩石圈的大规模减薄作用有关, 攀西地区海西-印支期的成岩-成矿作用为同源岩浆受区域统一深部地球动力学背景约束演化的异相产物. 相似文献
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沉积物源对油气储层发育具有重要影响.为研究丽水-椒江凹陷西斜坡明月峰组上段物源的岩性组成及其分布特征,选取4口钻井4个砂岩样品进行碎屑锆石U-Pb定年,并对陆上潜在物源区岩层(体)的岩性和年龄进行统计分析.结果显示:(1)样品中碎屑锆石以岩浆锆石为主,主要的年龄区间为125~90 Ma、145~125 Ma及170~145 Ma,还有少量变质锆石,其年龄区间为235~210 Ma及2 087~1 653 Ma;(2)陆上潜在物源区中以火山岩占绝对优势(173~94 Ma),局部区域可能有较大规模白垩系永康群沉积岩,而变质岩(＞210 Ma)和侵入岩(107.0~87.8 Ma)仅零星出露.综合分析认为:研究区东北部明月峰组上段的物源以永康群火山-沉积岩和九里坪组火山岩为主,含有少量晚白垩世侵入岩;西南部以九里坪组、西山头组火山岩及元古代区域变质岩为主,侏罗纪火山岩为辅,这一区域可能更有利于优质储层的发育. 相似文献
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扬子地块西南缘大红山群石榴白云母-长石石英片岩的白云母40Ar-39Ar定年及其地质意义 总被引：1，自引：1，他引：0
大红山群是扬子地块西南缘出露的古元古代结晶基底,主要经历了绿片岩相-低角闪岩相变质作用.本研究对大红山群老厂河组变质中酸性岩和变质沉积岩——石榴白云母-长石石英片岩中的白云母进行了40Ar-39Ar测年,得到三个样品的坪年龄和40Ar/39Ar等时线年龄结果较统一,坪年龄代表的变质年龄分别为837.7±4.2Ma、839.6±4.2Ma和844.2±4.2Ma.变质沉积岩和变质中酸性岩的变质时代类似,均介于837～845Ma.大红山群变质基性岩中变质锆石的U-Pb定年年龄为849±12Ma(杨红等,2012),40Ar-39Ar测年数据与锆石定年数据相结合,说明大红山群古元古代结晶基底中的火山岩和沉积岩均在新元古代经历了同期变质作用,其主期低角闪岩相变质作用发生于新元古代837～850Ma.结合前人发表的扬子西缘～750Ma的变质年龄,扬子西缘从北向南的区域变质作用时限可扩展到750 ～850Ma.此外,扬子西缘存在750～850Ma的岩浆事件,本文研究结果说明,扬子地块西缘在新元古代不仅发生了大规模岩浆作用,也发生了750～850Ma的区域变质作用,扬子西缘存在新元古代的岩浆-变质事件.岩浆事件与变质事件之间可能存在相关性,即新元古代岩浆作用引起了扬子西缘的区域动力热流变质作用. 相似文献
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松潘-甘孜造山带东缘的三叠纪-侏罗纪中酸性花岗岩,如塔公岩体,为晚三叠世的碰撞造山以及燕山期的构造演化提供了重要信息.区域地质调查填图表明,塔公岩体为石英闪长岩、花岗闪长岩、黑云母二长花岗岩.其地球化学特征表明岩石主体属高钾钙碱性系列、准铝质-过铝质过渡系列,稀土配分曲线显示其轻稀土富集、重稀土亏损,具有壳源岩浆特征,稀土-微量元素投点结果表明花岗岩形成于造山时期后碰撞阶段.对塔公花岗岩体采集的4件同位素样品的年龄数据质量较高,为214±1 Ma、214±1 Ma、215±1 Ma、216±1 Ma;该组年龄可以作为限制印支晚期扬子、华北和昌都板块之间碰撞时限的证据.基于塔公花岗岩类的岩石地球化学特征、同位素年代学特征,结合区域研究资料,认为松潘-甘孜造山带东缘类似塔公岩体的晚三叠世花岗岩类形成于昌都、扬子和华北地块后碰撞阶段的岩石圈拆沉作用. 相似文献
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阿尔金山地区铜金矿化富集规律 总被引：8，自引：0，他引：8
阿尔金走滑断裂系不同级次构造控制阿尔金山地区铜、金成矿带、矿田及矿床的分布,区域上可以划分为阿尔金北缘金-铜-铁多金属成矿带和阿尔金铁-铜-金多金属成矿带.通过岩石铜、金含量数理统计和40Ar/39Ar热年代学研究结果,将其划分为两个主成矿期,年龄分别为502.3Ma士10.1Ma和207.6Ma±4.2Ma;构造应力场和矿化富集过程分为3期:前中生代--挤压期;中生代--伸展期和新生代--走滑期.相对低应力值区为矿化富集的有利部位. 相似文献
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内蒙古扎兰屯地区林西组以砂板岩组合为重要特征,形成时代为晚二叠世.对扎兰屯地区林西组粉砂质泥质板岩、粉砂岩2个样品进行了LA-ICP-MS锆石U-Pb测年.结果显示,150个谐和-近谐和年龄主要分布于6个年龄区间：259.7~281.9 Ma （n=18）,加权平均年龄为273.3 Ma;291.3~311.5 Ma （n=110）,加权平均年龄为298.1 Ma;319.2~334.5 Ma （n=10）,加权平均年龄为327.0 Ma;340.3~375.2 Ma （n=9）,加权平均年龄为356 Ma;399.7~400.7 Ma （n=2）,加权平均年龄为400.2 Ma;728.5~765.4 Ma （n=2）,加权平均年龄为750.0 Ma,上述6组年龄峰值与区域上的岩浆事件基本吻和.林西组主要物质供给区为研究区内早二叠世侵入岩及大石寨组火山岩,占碎屑物总含量的85%,少部分来自于晚石炭世之前的古生代侵入岩及扎兰屯群等地质体.林西组与宝力高庙组分别记录了晚古生代250~270 Ma及310~325 Ma之间发生的两次重要的区域隆升事件. 相似文献
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西藏墨竹工卡县甲马多金属矿床几组年龄数据的比较与成因研究 总被引：6，自引：1，他引：5
甲马矿床是西藏腹地冈底斯带已投入开采的大型多金属矿床,有关其成因的研究直接影响着该带多金属矿床的区域找矿方向及对冈底斯带地球动力学过程的成矿效应研究.目前对该矿床成因尚无统一的认识,关键在于未获得成矿年龄的可靠结果.本文比较了前人和本文获得的Rb-Sr(260Ma和54Ma)、裂变径迹(>25～22Ma)和Re-Os(模式年龄15.4～15.5Ma,等时线年龄15.18Ma和模式年龄15.23～15.62Ma,等时线年龄15.41Ma)等年龄数据,认为Re-Os同位素年龄数据最为可靠,应作为矿床的成矿年龄.矿床Re-Os同位素年龄与矿区外围花岗闪长斑岩全岩K-Ar同位素年龄一致,显示甲马夕卡岩及其中的多金属矿床为斑岩-多底沟组灰岩接触带岩浆热液交代-充填成因,该矿床属冈底斯中段的后碰撞岩浆热液成矿系统.预计该区深部及外围存在斑岩型-夕卡岩型-脉型含金多金属矿化. 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
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Between 1985 and 1991, two new mountain protected areas (MTNPA) covering more than 35,000 km2 and based on participatory management models — the Makalu-Barun National Park and Conservation Area, Nepal, and Qomolangma Nature Preserve, Tibet Autonomous Region — were successfully established through the collaborative efforts of Woodlands Mountain Institute and conservationists in China and Nepal. Characteristics common to both projects include the importance of establishing (1) effective rationales, (2) local support constituencies, (3) a senior advisory group, (4) a task force, (5) linkages between conservation and development, and (6) fund raising mechanisms. The lessons derived from the experiences of Woodlands Mountain Institute are of significant value to others in preserving MTNPA. Increased collaboration and communication between all interested in conservation, however, will remain a critical component for expanding mountain protected area coverage to throughout the world. 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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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