冀北凹陷高于庄组与洪水庄组在岩芯、露头中多赋存态生物标志物的对比

利用气相色谱-质谱联用仪对采自燕山地区冀北凹陷的中元古界长城系高于庄组(Chg)灰岩和蓟县系洪水庄组(Jxh)泥页岩露头和岩芯中不同赋存状态生物标志物进行了分析.正构烷烃和萜类生物标志物显示从高于庄组(Chg)到洪水庄组(Jxh)生源由浮游类和底栖类为主转变为浮游类为主,而沉积水体的盐度则由高变低.露头样品和相应岩芯中...     

金牙金矿载金矿物及金的赋存状态研究

应用电子探针、电子衍射、电子顺磁共振和化学分析等多种现代方法和手段，综合研究载金矿物的特征及金的赋存状态，认为金牙金矿中载金矿物主要是毒砂和黄铁矿，金的主要赋存形式是超显微包体金，为解决金芽金矿床难处理的原生矿石提供了科学数据资料。     

Faulting parameters of earthquakes in the New Madrid, Missouri, region

The advent of high-resolution digital seismic recording and advances in computer technology enable the combination of traditional regional seismic network observations with direct seismogram modeling to improve estimates of small earthquake faulting geometry, depth, and size. We illustrate a combined modeling approach using observations from three earthquakes that occurred within the environs of the New Madrid Seismic Zone: two Missouri earthquakes from September 26, 1990 and May 4, 1991; and the southern Illinois earthquake of February 5, 1994. We also re-examine the faulting geometry for two events from the 1960s that are inconsistent with the current estimate of the regional stress field. Based on direct modeling of the long-period seismograms associated with these events, we revise earlier estimates of the earthquake parameters for the March 3, 1963 and July 21, 1967 Missouri earthquakes. Comparing the new and revised results with existing earthquake mechanisms in the region, we find that tension-axes are generally aligned in a N-S to NW-SE direction, while the compression-axes trend in a NE to E direction. An interesting exception to this pattern are the March 3, 1963 and two nearby earthquakes that lie within a well-defined 30-km long left step in seismicity near New Madrid.     

荒沟蓄能电站地下厂房地应力状态与工程稳定性研究

为了解黑龙江荒沟抽水蓄能电站地下厂房区应力状态,在探洞内布置了4个地应力测点,利用空芯包体应力计进行地应力测量.测量结果表明:最大主应力近于水平,最大主应力量值为9.6 MPa,最大主应力方向为N78°W.根据实测结果对该区应力作用特征进行了分析,测量结果与现今区域构造应力场相吻合.在地应力实测和岩石力学性质试验基础上,对地下厂房周边应力状态进行了有限元分析,为地下厂房轴线的选择提出了建设性意见.     

The redox state of subduction zones: insights from arc-peridotites

Spinel peridotites from a variety of island arcs have been utilised to calculate the redox state of the mantle wedge above subduction zones. Oxygen fugacities (f_O2 values) calculated from the ferric iron content of spinels, measured by Electron Microprobe (EMP) using secondary standards [Wood, B.J., Virgo, D., 1989. Upper mantle oxidation state: ferric iron contents of lherzolite spinels by ⁵⁷Fe Mössbauer spectroscopy and resultant oxygen fugacities. Geochim. Cosmochim. Acta, 53, 1277–1291.], yield values which range from 0.3 to 2.0 above the fayalite–magnetite–quartz (FMQ) buffer. These data provide further evidence that the mantle wedge is ubiquitously oxidised relative to oceanic and ancient cratonic mantle. There is no correlation between f_O2 values and the presence of hydrous phases and, in fact, the most oxidised samples contain no hydrous phases. Within individual suites there is no correlation between f_O2 and degree of depletion as indicated by spinel Cr#, except for a suite of reacted forearc-peridotites. However, when the data is viewed as a whole there is broad a positive correlation between f_O2 and spinel Cr# suggesting that partial melting processes may influence the redox state of the mantle wedge. We suggest that the ultimate source of the oxygen which oxidises the mantle wedge is from the subducted slab. It is not clear whether this oxidising agent is a solute-rich hydrous fluid or a water-bearing silicate melt. However, our data does indicate that silicate melts are effective oxidisers of the depleted shallow upper mantle. Simple mass balance calculations based on the ferric iron content of primitive subduction zone magmas indicates that the source region must contain 0.6–1.0 wt.% Fe₂O₃. This amount of Fe₂O₃ in a fertile spinel peridotite yields an oxygen fugacity of 0.5–1.7 log units above FMQ in the IAB source. If water is the sole oxidising agent in the mantle wedge then 0.030–0.075 wt.% H₂O is required which is considerably less than the 0.25% H₂O envisaged by Stolper and Newman [Stolper, E.M., Newman, S., 1994. The role of water in the petrogenesis of Mariana trough magmas. Earth Planet. Sci. Lett., 121, 293–325.], suggesting water is not necessarily an efficient oxidising agent. Alternatively, ferric iron may be added to the mantle wedge by addition of a ferric iron-rich sediment melt or more likely as a solute-rich hydrous fluid. This model would produce spinel, orthopyroxene or amphibole in the wedge with only a slight increase in f_O2 of the source region. Although it is unclear which model is correct the maximum f_O2 of the fertile mantle wedge is unlikely to be above FMQ+2 and therefore some decompression melting in the mantle wedge is required to explain the higher f_O2 values of primitive arc lavas than arc-peridotites.     

高压密闭消解技术在土壤有效态样品前处理中的应用

土壤样品经有机酸浸提后,浸提出的溶液中存在大量有机酸及有机质,如未进行破坏处理,进入电感耦合等离子体发射光谱仪(ICP-OES)进样系统后容易堵塞雾化器、中心管、矩管等,或有颗粒黏附于中心管壁和矩管壁上,造成测定结果精密度和准确度差、空白高等问题,进而影响土壤有效态的综合评价。本文将土壤样品用有机酸(DTPA、草酸-草酸铵、柠檬酸等)浸提后,过滤或离心,吸取上清液加入高压密闭消解罐中,经电热板上处理,再加2mL浓硝酸,于180℃烘箱中保温至少3h,采用ICP-OES测定有效态元素铜锌铁锰镉铅镍铬钼硅的含量。本方法采用高压密闭消解技术处理土壤样品,各元素测定结果的相对标准偏差(RSD)为2.5%～5.9%,相对误差为-2.1%～5.2%,回收率为90.1%～103.2%,方法检出限为0.32μg/kg～0.038mg/kg;而采用以往高温炉中灼烧法、硝酸-高氯酸(硫酸)敞开消解法等技术手段,回收率为89.2%～100.5%,方法检出限为0.50μg/kg～0.050mg/kg,两者相比,本方法的测定结果稳定、空白低,分析周期短,适合批量样品的连续分析。     

元素活动态提取条件和分析方法的应用研究

元素活动态分析作为深穿透地球化学的新方法,得到了广泛的应用。实验对水提取态、黏土吸附态、有机结合态和铁锰氧化物结合态四种元素活动态的提取条件进行了系统研究,分别考察了提取时间、液固比、离心转速、提取液放置时间对提取效果的影响,确定了元素活动态的最佳提取条件:提取时间为24h,液固比为10:1,离心转速4000rpm;提取液采用新型的高分辨率等离子体质谱法(HR-ICP-MS)测定,该仪器具有强大的动态线性范围(10^-12～10¹²)和高灵敏度,使可同时测定的元素拓展至50余种,可以大大提高工作效率。对HR-ICPMS的主要工作条件:辅助气流量、样品气流量和采样深度等利用响应面法进行了优化。本法将传统的过滤法改为离心法,避免了滤纸或穿滤引入的误差;将新型的高分辨率等离子体质谱法(HR-ICP-MS)应用到提取液的测定,提升了多元素同时分析能力,大大提高工作效率,同时也降低了该方法的检出限,改善了测定结果的精密度。依据实验结果,建立了HR-ICP-MS对四种元素活动态的分析方法,分别得到了四种活动态中各元素的方法检出限和方法精密度,水提取态、黏土...     

The compressibility of Fe- and Al-bearing phase D to 30 GPa

High-pressure in situ X-ray diffraction experiment of Fe- and Al-bearing phase D (Mg_0.89Fe_0.14Al_0.25Si_1.56H_2.93O₆) has been carried out to 30.5 GPa at room temperature using multianvil apparatus. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields values of V ₀ = 86.10 ± 0.05 ų; K ₀ = 136.5 ± 3.3 GPa and K′ = 6.32 ± 0.30. If K′ is fixed at 4.0 K ₀ = 157.0 ± 0.7 GPa, which is 6% smaller than Fe–Al free phase D reported previously. Analysis of axial compressibilities reveals that the c-axis is almost twice as compressible (K _c  = 93.6 ± 1.1 GPa) as the a-axis (K _a  = 173.8 ± 2.2 GPa). Above 25 GPa the c/a ratio becomes pressure independent. No compressibility anomalies related to the structural transitions of H-atoms were observed in the pressure range to 30 GPa. The density reduction of hydrated subducting slab would be significant if the modal amount of phase D exceeds 10%.     

一类新型的散粒型土体本构理论

详细地介绍了国际上近30才发展起来的具有独特建模思想的一类新型的散粒型土体本构建模理论--亚塑性本构理论。将该理论与经典的弹塑性理论进行比较后发现,亚塑性理论的本构表达式自动隐含了弹塑性理论中相对应的一些基本概念和假定,无需额外引入,因此增加了模型的客观性。以Gudehus-Bauer亚塑性模型为例,分析了模型在临界状态时的本构特征。此外,通过三轴试验和循环剪切试验的亚塑性数值模拟表明,亚塑性本构模型能很好地反映无黏性散粒型土体的非弹性、非线性及剪胀（剪缩）性等主要应力-应变特性。     

福建尤溪梅仙铅锌矿山地质环境现状及防治建议

通过尤溪县梅仙铅锌矿山开采造成矿山周围地质环境的破坏和可能诱发的各种地质灾害的危害性作分析,并提出相应的工程治理措施、矿山地质环境保护和防治建议。