红外显微镜红外光强度对测定不透明矿物中流体包裹体盐度的影响：以辉锑矿为例   总被引：2，自引：0，他引：2  

格西  苏文超  朱路艳  武丽艳 《矿物学报》2011,31(3):366-371

红外显微镜是研究不透明矿物中流体包裹体的重要手段,但红外光发热可能对不透明矿物中流体包裹体的盐度和均一温度测定有影响。本文以辉锑矿中流体包裹体为例,系统评价了红外光强度对测定辉锑矿中流体包裹体冰点的影响。结果表明,红外光强度对辉锑矿中流体包裹体的冰点测定有显著影响,导致过高估计流体包裹体的盐度,并提出了解决这一问题的方法。  相似文献   

基于纳米尺度的碎屑岩骨架矿物结构研究     

杨少春  王惠娟 《西安地质学院学报》2011,(4):331-336

对胜利油田胜坨地区碎屑岩储层岩芯样品和岩石薄晶片分别采用场发射扫描电镜、透射电镜进行镜下观察与能谱测试分析。结果表明：碎屑岩中骨架矿物石英和长石中存在纳米尺度的结构特征;石英镜下可见类蚀像凹坑、雏晶单晶、平行脊线、晶体位错、类包裹体晶内核等5种纳米尺度的结构;长石镜下可见晶面平行凹痕、溶蚀针、纳米级薄层断阶、长石高岭石化、晶体位错和超微包裹体等6种纳米尺度的结构;这些结构大多在几百纳米的尺度范围内,有的甚至只有几十纳米;矿物在纳米尺度上表现出的结构特征与其本身的硬度变化、晶体品格缺陷、晶体生长过程以及成岩作用的显微表现和显微构造应力改造作用有关。对碎屑岩骨架矿物中纳米尺度结构特征的进一步研究有望为岩石显微变形的应力作用机制和方式以及溶解作用等成岩作用模式做出有效分析,进而为油气勘探开发提供新的探索方式。  相似文献   

Assessment and characterization of heavy metal resistance in Palk Bay sediment bacteria     

Nithya C  Gnanalakshmi B  Pandian SK 《Marine environmental research》2011,71(4):283-294

The present study aimed at characterizing the heavy metal resistance and assessing the resistance pattern to multiple heavy metals (300 mmol L?1) by Palk Bay sediment bacteria. From 46 isolates, 24 isolates showed resistance to more than eight heavy metals. Among the 24 isolates S8-06 (Bacillus arsenicus), S8-10 (Bacillus pumilus), S8-14 (B. arsenicus), S6-01 (Bacillus indicus), S6-04 (Bacillus clausii), SS-06 (Planococcus maritimus) and SS-08 (Staphylococcus pasteuri) exhibited high resistance against arsenic, mercury, cobalt, cadmium, lead and selenium. Plasmid curing confirmed that the heavy metal resistance in S8-10 is chromosomal borne. Upon treatment with the heavy metals, the strain S8-10 showed many morphological and physiological changes as shown by SEM, FTIR and AAS analysis. S8-10 removed 47% of cadmium and 96% of lead from the growth medium. The study suggests that sediment bacteria can be biological indicators of heavy metal contamination.  相似文献   

The future of three‐dimensional microscopic imaging in marine biology     

Renaud Boistel  Jim Swoger  Uroš Kržič  Vincent Fernandez  Brigitte Gillet  Emmanuel G. Reynaud 《Marine Ecology》2011,32(4):438-452

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Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope   总被引：1，自引：0，他引：1  

Laura A. Stern  Thomas D. LorensonJohn C. Pinkston 《Marine and Petroleum Geology》2011,28(2):394-403

Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5 m to 760.1 m depth, and sections investigated here were retrieved from 619.9 m and 661.0 m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 70-75% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20-120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas.  相似文献   

Xylem anatomy and hydraulic conductivity of three co-occurring desert phreatophytes     

A. RzepeckiF. Zeng  F.M. Thomas 《Journal of Arid Environments》2011,75(4):338-345

The tree species Populus euphratica, the shrub Tamarix ramosissima and the sub-shrub Alhagi sparsifolia are phreatophytes that grow along the southern fringe of the Taklamakan Desert (NW China). We hypothesised that in the shoot xylem of these species, the fraction of conduits with a large cross-sectional area and the hydraulic conductivity decrease in the sequence A. sparsifolia > T. ramosissima > P. euphratica according to the different ground water distances at the typical sites of the species’ occurrence. The theoretical hydraulic conductivity related to the total cross-sectional xylem area (k_ttot) or to the cross-sectional area of the conduits (k_tcond) was computed using a modified Hagen-Poiseuille equation. The percentage of wide conduits and k_tcond were highest in A. sparsifolia, and smallest, in P. euphratica. With regard to k_ttot, the diffuse-porous to semi-ring-porous P. euphratica occupied an intermediate position due to an increased percentage of conducting area related to the total cross-sectional xylem area. This figure as well as k_ttot were lowest in the semi-ring-porous to ring-porous T. ramosissima. The k_ttot values corresponded to the leaf area-related hydraulic conductivity calculated from measurements in the field. Altogether, our results match the typical occurrence of the species with respect to the ground water depth.  相似文献   

Structural features and mechanical behaviour of a pyroclastic weak rock     

Manuela Cecconi  Giulia MB Viggiani 《国际地质力学数值与分析法杂志》2001,25(15):1525-1557

The results of an extensive programme of laboratory testing on intact and reconstituted samples of a pyroclastic weak rock from the volcanic complex of the Colli Albani (Central Italy) are presented. The deposit is known as Pozzolana Nera and may be assimilated to a bonded coarse grained material. The nature of bonds and the micro‐structural features were examined by means of diffractometry, optical and electron microscopy. As bonds are made of the same constituents of grains and aggregates of grains, bond deterioration and particles breakage upon loading are indistinguishable features of the mechanical behaviour. The testing programme consisted mainly of one‐dimensional and drained and undrained triaxial compression tests in a wide range of confining pressures up to 58 MPa. As confining stress increases, the mechanical behaviour of the material changes from brittle and dilatant to ductile and contractant; for both brittle and ductile behaviour failure is associated with the formation of shear surfaces separating the sample in several parts at the end of test. The experimental stress–dilatancy relationships are compared with the classical stress–dilatancy theories for a purely frictional material and for a material with friction and cohesion between particles. The analysis of the data indicates that peak strength results from the interplay between degradation of inter‐particle bonds, increasing friction between particles and increasing rate of dilation. Copyright © 2001 John Wiley & Son, Ltd.  相似文献   

The history of Erica erigena R. Ross,an Irish plant with a disjunct European distribution     

Peter J. Foss  Gerard J. Doyle 《第四纪科学杂志》1990,5(1):1-16

Scanning electron microscopy combined with pollen, spore, rhizopod and fungal analyses of two peat profiles at Claggan Mountain, Co. Mayo, sheds new light on the Holocene history of Erica erigena in western Ireland. This heather is referred to the Mediterranean-Atlantic group in the Irish flora, and is remarkable for its disjunct distribution in Europe, where it occurs in Ireland, Bordeaux in France, and in Spain and Portugal. Scanning electron microscopy has proved a powerful tool, allowing the unambiguous identification of ericoid pollens to species level and it is used to identify the first occurrence of Erica erigena pollen in the peat profiles. Radiocarbon dating of the profiles shows that Erica erigena is a relatively recent arrival at Claggan Mountain, appearing for the first time in the historic period at 1431 AD. The details of vegetational changes associated with the expansion of E. erigena have been explored by conventional pollen, spore, rhizopod and fungal analyses. Drying of the peat surface and replacement of bog vegetation by ericaceous heathland during a period of marked agricultural activity in the region was associated with its spread. The relatively recent arrival of E. erigena at Claggan Mountain, suggests that introduction might explain its presence here, and its disjunct distribution in Europe. Documented trade and pilgrimage routes between Ireland and those areas in Europe where the heather occurs may have allowed its recent introduction into Ireland. Further pollen analysis work, using SEM techniques, will be required if an earlier occurrence for the heather in Ireland is to be proved. The combination of techniques described here may prove useful in the study of the history of other plants with pollen that is difficult to identify using conventional light microscopy.  相似文献   

Freeze–thaw processes degrade post-fire water repellency in wet soils     

Ekaterina Rakhmatulina  Sally Thompson 《水文研究》2020,34(26):5229-5241

Wildfires are a cause of soil water repellency (hydrophobicity), which reduces infiltration whilst increasing erosion and flooding from post-fire rainfall. Post-fire soil water repellency degrades over time, often in response to repeated wetting and drying of the soil. However, in mountainous fire-prone forests such as those in the Western USA, the fire season often terminates in a cold and wet winter, during which soils not only wet and dry, but also freeze and thaw. Little is known about the effect of repeated freezing and thawing of soil on the breakdown of post-fire hydrophobicity. This study characterized the changes in hydrophobicity of Sierra Nevada mountain soils exposed to different combinations of wet–dry and freeze–thaw cycling. Following each cycle, hydrophobicity was measured using the Molarity of Ethanol test. Hydrophobicity declined similarly across all experiments that included a wetting cycle. Repeated freezing and thawing of dry soil did not degrade soil water repellency, but freeze–thaw cycles decreased hydrophobicity in wet soils. Total soil organic matter content was not different between soils of contrasting hydrophobicity. Macroscopic changes such as fissures and cracks were observed to form as soil hydrophobicity decayed. Microscopic changes revealed by scanning electron microscope imagery suggest different levels of soil aggregation occurred in samples with distinct hydrophobicities, although the size of aggregates was not clearly correlated to the change in water repellency due to wet–dry and freeze–thaw cycling. A 9-year climate and soil moisture record from Providence Critical Zone Observatory was combined with the laboratory results to estimate that hydrophobicity would persist an average of 144 days post-fire at this well-characterized, typical mid-elevation Sierra Nevada site. Most of the breakdown in soil water repellency (79%) under these climate conditions would be attributable to freeze–thaw cycling, underscoring the importance of this process in soil recovery from fire in the Sierra Nevada.  相似文献   

热液矿床矿物微形貌与晶体生长环境研究   总被引：5，自引：2，他引：3  

叶荣  涂光炽  马喆生  赵伦山 《地学前缘》2005,12(2):240-246

应用高分辨率扫描隧道显微镜(STM)和场效应扫描电镜(FEG SEM),对取自山西义兴寨金矿等4处热液矿床的黄铁矿、方铅矿、赤铁矿等矿物的表面生长微形貌进行了观察研究,并与实验合成的黄铁矿、方铅矿等矿物的微形貌特征进行对比。发现了自然矿物结晶三维成核成因的黄铁矿微球状晶,在合成和自然矿物的晶面观察到漏斗状晶和胞状结构等生长形貌。合成黄铁矿表面发育平整光滑的生长台阶,反映静态无扰动、接近平衡的晶体生长环境;而大量产于热液矿床的黄铁矿、方铅矿等晶体普遍发育胞状或拉长的胞状结构表面,并总体呈台阶状排列的表面结构,证明自然成矿热液体系的高过饱和度和流动生长环境。研究表明,热液成矿过程中矿物结晶作用有从成核、台阶状晶体生长、到形成“平衡”多面体生长的一个演化过程;形成于复杂条件的矿物晶体表面微观结构,包含丰富的成矿环境信息。  相似文献