蓬莱与宽甸新生代碱性玄武岩及其深源包体和巨晶矿物的稀土元素

本文应用现代仪器分析方法——质谱同位素稀释法测定了辽宁宽甸和山东蓬莱碱性玄武岩及其深源超镁铁岩包体和巨晶矿物中的稀土元素REE,测定结果用Nakamura数值进行了球粒陨石标准化计算。根据所得REE丰度和分布模式特征,推测了两地区的尖晶石二辉橄榄岩属残渣型地幔岩包体,榴辉岩属原始型地幔岩包体。两地区的镁铝榴石巨晶可能是早期液相线上的产物,后期的变质作用对整个REE没有明显的影响。富铝普通辉石巨晶则是比镁铝榴石较晚期的结晶产物。两地区的碱性玄武岩及其超镁陕岩包体和巨晶矿物在REE丰度和分布模式上十分相似,表明了两地区所处的大地地质构造以及熔融和分异作用的物理化学条件的相似性。     

安徽女山幔源橄榄岩捕虏体Re-Os 同位素地球化学

Re-Os同位素体系可以为研究大陆岩石圈地幔形成和演化提供重要制约.女山12个地幔橄榄岩全岩样品测得Re含量为19×10-12~306×10-12,Os含量为0.81×10-9~2.42×10-9,187Os/188Os比值为0.114 90~0.131 02,187Re/188Os比值为0.037~1.517.两个石榴子石-尖晶石二辉橄榄岩的Os同位素组成与原始上地幔(PUM)的现代值0.129 6相似,其余的尖晶石二辉橄榄岩、方辉橄榄岩,和角闪石、金云母-尖晶石二辉橄榄岩等的Os同位素组成都低于PUM现代值,Os同位素模式年龄为早元古代.实性和隐性地幔交代作用对女山幔源橄榄岩捕虏体的Os同位素组成没有明显影响.橄榄岩捕虏体代表的女山地区岩石圈地幔是元古代岩石圈地幔经过减薄作用后的残留部分.橄榄岩中Re-Os体系扰动是近期事件.     

山丹县白水泉北金矿地质特征及找矿前景浅析

山丹县白水泉北金矿位于甘肃省山丹县东北100°方位,直线距离约18 km。目前工作区通过1∶2.5万沟系次生晕测量工作,圈出Au、Co、Ni、Cu、Zn等元素综合异常11处;根据全区浓度克拉克值与变异系数的分析,Au、Ni元素在工作区相对分散,但变异系数大,表明Au、Ni元素在有利地质条件下有富集成矿的可能性,同时已圈出金矿体3条(Au2-1、Au2-2、Au2-3),钴矿化体1条(Co1)。金矿体赋存于混合花岗岩质碎裂岩中的破碎蚀变带,矿体长80 m,品位1.14～2.42 g/t,矿体走向近东西。因此该区有较好的成矿地质条件,找矿前景较好。     

红树植物繁殖器官发育过程中铁钼锌元素的含量变化

探讨了显胎生红树植物木榄(Bruguiera gymnorrihiza)、秋茄(Kandelia obovata)、隐胎生红树植物白骨壤(Avicennia marina)、桐花树(Aegiceras corniculatum)和非胎生红树植物木果楝(Xylocarpus grantum)的繁殖器官发育过程中铁(Fe)、钼(Mo)、锌(Zn)元素的含量变化.结果表明:在花蕾期,除白骨壤外,其他种类Fe元素含量相近,在0.035 2～0.045 4 μg/mg之间.隐胎生红树植物白骨壤、桐花树中Fe元素含量在种子期最高,分别为0.090 2和0.073 3 μg/mg,萌发后呈现降低的趋势,在胚轴成熟期达到最低.在种子期,Mo元素含量在胎生红树植物中差异不大,在0.288 2～0.302 0 ng/mg之间,平均为0.294 5 ng/mg,明显高于非胎生红树植物木果楝0.105 6 ng/mg.种子萌发后,胎生红树植物中Mo元素含量下降.在同一时期,胎生红树植物种子的Mo元素含量明显大于木果楝.在木果楝的繁殖器官发育过程中,Zn元素含量逐渐下降,且比同期的胎生红树植物低.     

浙赣皖相邻区燕山期花岗质岩类含矿性及其氧逸度特征*

对浙赣皖相邻区燕山期两类花岗岩的岩石学、地球化学及成矿元素研究发现,燕山早期岩体主要岩石类型为花岗闪长岩,岩石偏中性,成矿元素方面更富含Au、Ag、Cu、Mo、Ni等深源元素,研究区大部分铜金钼矿床都与其有关;燕山晚期岩体主要岩石类型是花岗（斑）岩,岩石偏酸性,成矿元素相对缺乏Au、Ag、Cu、Mo、Ni等深源元素,与之伴生的铜金钼矿床罕见。可见,花岗质侵入体与研究区的金、铜、钼等成矿作用密切相关。通过锆石Ce异常计算出的岩浆氧逸度结果显示,早期花岗质侵入体的氧逸度范围介于FMQ （铁橄榄石-磁铁矿-石英缓冲对）和MH （磁铁矿-赤铁矿缓冲对）之间,平均值为FMQ＋2.7,氧逸度较高;晚期氧逸度小于FMQ,平均值为FMQ-1.1。因此,氧逸度对部分元素（如铜、金、钼）的成矿有重要影响,氧逸度高,更有利于形成铜、金、钼等矿床。由于锆石成分分析的普及,获得锆石中的稀土微量元素含量越来越便利,利用锆石成分来计算岩浆的氧逸度具有非常广阔的应用前景。     

地幔流体参与宁芜玢岩铁矿成矿 ——碳、锶同位素证据

磷灰石为宁芜玢岩铁矿标志性矿物之一,玢岩铁矿磷灰石δ13CPDB值处于-9.6‰—-0.6‰间,除T-06-1和J-06-3两个样品外,其余所有样品δ13CPDB值落入-2‰—-9‰地幔碳区间.玢岩铁矿各种类型磷灰石87Sr/86Sr比值介于0.706326—0.707577,相对比较集中,与火山岩、次火山岩Sr同位素初始比基本相同.比典型幔源岩浆成因磷灰石87Sr/86Sr值(≈0.7040)高得多,很显然成矿时有壳源物质的加入.磷灰石包体中δ13C和Sr同位素的特征表明玢岩铁矿形成时幔源物质和幔源流体参与了成矿作用.这被区域地质构造、区域地球物理场和宁芜火山岩、次火山岩地球化学特征所证实.     

房山岩体的岩浆来源、形成机制及动力学意义

房山岩体是华北东部典型的燕山期中酸性侵入杂岩体,其地球化学特征为富Si、Na、Al、Sr,亏损高场强元素(Nb、Ta),轻重稀土分异强烈,Sr-Nd同位素具有类似EMI型富集地幔的特点,表明其岩浆来自于加厚下地壳的部分熔融,并且中生代华北东部下地壳已经被早先的富集岩石圈地幔置换.不同基性程度岩浆的不完全混合是形成微粒闪长质包体的原因.侵入杂岩的角闪石压力计显示下地壳部分熔融形成的中酸性岩浆先后在19~8 km里的深度范围内结晶就位.古太平洋板块在地幔过渡带深度于早白垩世水平俯冲至太行山一线,洋壳脱水导致上覆地幔部分熔融,后者成为加热下地壳部分熔融的热源.     

内蒙古四子王旗中新世含包体玄武岩的深部地质环境分析

内蒙古四子王旗东八号地区出露一套含深源包体的中新世玄武岩, 寄主岩石具有高钾( 1.16%< K O 含量 < 3. 36% ) , 高钛( 2. 25% < TiO2 含量 < 2. 51% ) 的特征; 其母岩浆富集 LREE 和 HFSE, 强烈富集 Nb, Ta 和 La, 相对亏损 K, Rb 和 Ba。其母岩浆来源于经历低度部分熔融, 残留石榴石和金云母的软流圈地幔, 运移过程中在高压环境下发生了分离结晶作用, 分异相主要为单斜辉石和斜长石。玄武岩中出现橄榄岩和麻粒岩包体:橄榄岩包体为尖晶石二辉橄榄岩, 富集 LREE, 平衡温压范围为:1050 ～1100℃, 1. 64 ～2. 37 GPa, 代表富集的或发生过富集事件的上地幔; 麻粒岩包体为中基性麻粒岩, 平衡温压范围为: 960 ～1000℃, 0. 82 ～1. 13 GPa, 其原岩包括原生的下地壳物质和与玄武质岩浆有关的产物。说明华北克拉通北缘的岩石圈受到地幔柱作用的影响, 中新世时处在减薄状态。     

微波消解ICP-MS法测定藏药德君芒觉却毛中的无机元素

目的:建立藏药德君芒觉却毛中无机元素含量的测定方法.方法:样品经微波消解后,以铑、铼为内标,用电感耦合等离子体质谱(ICP-MS)测定样品中Na、Mg、Al、K、Ca、V、Cr、Mn、Fe、Ni、Cu、Zn、As、Se、Mo、Ag、Cd、Au、Hg、Pb等20种元素的含量.结果:该方法对各元素的检出限0.0033~2.418μg·g-1,加标回收率在87.27%~106.5%之间.结论:所建立的方法快速、准确、灵敏度高,可以用于测定德君芒觉却毛中无机元素的含量.     

赶黄草中营养素含量的测定

测定赶黄草中蛋白质、糖类、矿物质、维生素C和β-胡萝卜素含量以及脂肪含量。采用分光光度计法测定赶黄草中蛋白质、维生素C和β-胡萝卜素、含量;通过硫酸-苯酚法测定赶黄草总糖含量;并以硝酸-高氯酸为消解体系,电感耦合等离子体-原子发射光谱(ICP-AES)法测定赶黄草中的Ni、Fe、Cu、Mg、Ca、Cd等矿物质元素的含量;最后用酸水解法测定脂肪含量。结果显示赶黄草中蛋白质的含量为4. 00 mg/g;维生素C的含量为26. 94μg/g;β-胡萝卜素的含量为29. 04μg/g;总糖的质量分数为3. 40%;矿物质元素含量从低到高依次为Cd(0. 01 mg/g)、Ni(0. 01 mg/g)、Cu(0. 02 mg/g)、Fe(0. 15 mg/g)、Mg(1. 35 mg/g)和Ca(2. 68 mg/g);脂肪的含量为6. 43 mg/g。     

Laserprobe oxygen isotope analysis of minerals from mantle-derived rocks in eastern China

Oxygen isotope analyses were carried out by the laserprobe technique for mineral separates from mantle xenolith and megacryst in Cenozoic basalts, East China. The results not only give the δ I8O range consistent with that reported for peridotites in the world, but also yield oxygen isotope equilibrium between coexisting minerals.     

Noble gas abundances and isotopic compositions in mantle-derived xenoliths, NE China

Following the researches of helium isotopic compositions in mantle-derived xenoliths in eastern China,this study reported noble gas abundances and isotopic compositions of mantle-derived xenoliths from Kuandian of Liaoning Province, Huinan of Jilin Province and Hannuoba of Hebei Province. Compared with the middle ocean ridge basalt (MORB) and other continental areas, mantle-derived xenoliths in NE China are characterized by slightly low noble gas abundances, 3He/4He equivalent to or lower than that of MORB, 40Ar/36Ar lower than that of MORB, 38Ar/36Ar and Ne-Kr-Xe isotopic ratios equivalent to those of atmosphere. These results indicate the heterogeneity of subcontinentai lithospheric mantle beneath northeastern China, that is, a MORB reservoir-like mantle beneath Kuandian and an enriched/metasomatized mantle beneath Huinan. Low 40Ar/36Ar ratios in the three studied areas may imply that a subducted atmospheric component has been preserved in the subcontinental lithospheric mantle.``     

Hydrogen isotope compositions of mantle-derived amphibole megacrysts from Qilin, Guangdong and its tectonic significance

Hydrogen isotope compositions of mantle-derived amphibole megacrysts from Qilin, Guangdong Province have been obtained by ion micro-probe. δD and H contents are constant both among different samples and within single sample, demonstrating that their formation condition is very stable. High δD values suggest the presence of a component recycled from crust which is possibly related to the subduction of Pacific Plate beneath Eurasian Plate in Mesozoic.     

Structural OH in mantle-derived clinopyroxene megacrysts from Nushan

Thirteen clinopyroxene megacrysts from Nushan Cenozoic basalts have been investigated by Fourier transform infrared spectrometer(FTIR). The results demonstrate that all samples contain trace amount of structural OH. Clinopyroxenes from Nushan show four groups of absorption bands, in which, 3 472–3 506 cm⁻¹ is the major characteristic one. It is suggested that the position of major band is probably related to AI content: the position of major characteristic band for high-AI samples is around 3 470 cm⁻¹, whereas that for low-AI samples around 3 620 cm⁻¹.     

Multi-origin alkanes related to CO2-rich, mantle-derived fluid in Dongying Sag, Bohai Bay Basin

With the newly obtained carbon isotope data for the natural gas, a pilot study of multiple-sourced alkanes related to the mantled-derived fluid is presented. The carbon isotope values of alkanes in the Dongying Sag possess thefea tures indicating a general organic origin. However, there are two sub-populations in the isotopic data set, which reflect two specific types of origins. In gene ral, the sub-population with high δ13CCH4 values is related to the CO2-rich, mantle-derived fluid, and it is distributed in the belts where mantle-derived fluid flow and basic volcanic activities have occurred. Geological and geochemical studies demonstrate that this variation of methane carbon isotope values in the Dongying Sag is unrelated with the basin bury and thermal histories, types of source rocks, and reactions between basin fluid and rocks. Mixing of mantle-derived fluid and organic sourced hydrocarbons is probably the cause for the variation .     

Osmium isotope determination on mantle-derived peridotite xenoliths from Panshishan with N-TIMS

The¹⁸⁷Os/¹⁸⁸Os ratios of spinel lherzolite xenoliths from Panshishan determined with N-TIMS are lower than that of the primitive mantle, which shows depleted mantle characteristics. Their positive correlation with Al₂O₃/MgO suggests that the geochemical behavior of trace elements Re and Os is similar to that of Al₂O₃ and MgO respectively during the magmatic evolution and Re-Os isotopic system is largely immune to mantle metasomatism. A model age of 2.8–3.4 Ga obtained by¹⁸⁷Os/¹⁸⁸Os-Al₂O₃/ MgO correlation might represent the homogeneous age of the mantle lithosphere beneath the area.     

四川盆地西部海相碎屑岩-陆相碎屑岩的转换过程

四川盆地是一个叠合盆地,经历了海相碳酸盐岩到海相碎屑岩、海相碎屑岩到陆相碎屑岩的转换和变迁.这两个转换过程最终结束均发生在四川盆地西部.海相碎屑岩到陆相碎屑岩的转换发生在晚三叠世末,相对应的地层单位为上三叠统须家河组.通过对须家河组厚度和沉积相变化,以及龙门山前砾岩的分布特征研究,认为这一转换主要发生于须家河组沉积末期(T_3x~4-T_3x~6),时间上随地区不同而不同,空间上具有由北往南的先后顺序.这揭示龙门山造山带的造山隆升过程具有由北往南的特点.这一转换过程导致川西前陆盆地内南、北段油气地质条件存在差异.寻找河口沙坝、三角洲平原河道砂等形成的优质储层应是须家河组油气勘探的关键.     

煤巷围岩稳定性综合分类及锚杆支护形式合理选择

提出一种围岩稳定性综合分类法，用此法研究平顶山矿区煤巷稳定性变化规律，得到了综合评价围岩稳定性的统计判据，可根据巷道条件及实测信息评价巷道稳定程度，并绘制出多指标围岩分类图。文中相应阐述了煤巷锚杆支护形式选择原则。