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31.
The distribution of cadmium, copper, iron, manganese, lead, and zinc in sediments of Port Phillip Bay, Victoria, Australia was investigated, and the impact of industrial discharges studied. The pre-cultural levels for these metals are in nearly all cases far less than the post-cultural levels, especially in those sediments deposited in the last half century in the vicinity of urbanized areas. 相似文献
32.
Nicholas DODD 《中国海洋工程》1999,(2)
-A nonlinear model of mean free surface of waves or wave set-up is presented.The model isbased on that of Roelvink(1993),but the numerical techniques used in the solution are based on theWeighted-Average Flux(WAF)method(Watson et al,1992),with Time-Operator-Splitting(TOS)usedfor the treatment of the source terms.This method allows a small number of computational points to beused,and is particularly efficient in modeling wave set-up.The short wave(or primary wave)energy equa-tion is solved by use of a more traditional Lax-Wendroff technique.A nonlinear wave theory(James,1974)is introduced.The model described in this paper is found to be satisfactory in most respects whencompared with the measurements conducted by Stive(1983)except in modeling the mean free surface veryclose to the mean shoreline. 相似文献
33.
在原η坐标模式基础上,利用1995年8月23日和1998年4月28日四川西部两次强降水过程为例,通过改变水平分辨率和具有不同分辨率的地形资料,以及固定边界、单向影响嵌套边界,进行了一些数值试验。结果表明:(1)较低水平分辨率的η模式,采用较高分辨率的地形资料不一定能改善预报结果;(2)具有较高水平分辨率,并引入较高分辨率的地形资料,以及单向嵌套侧边界的η模式,对预报结果有较明显的改进 相似文献
34.
应用电镜扫描石英颗粒结构分析,对西藏高原洞穴碎屑沉积及其相关的地表沉积物进行了研究。其结论是:绝大部分样品的物质来源于附近的火成岩和变质岩基岩,这些沉积物的石英颗粒表面并未显示经受冰川的、河流的或风的搬运作用所造成的变形痕迹,也缺乏成土作用或热带湿热环境的化学变形证据。很明显,目前的环境难于在石英颗粒表面产生物理的或化学的结构形态。 相似文献
35.
Ian Parsons Charles W. Magee Charlotte M. Allen J. M. G. Shelley Martin R. Lee 《Contributions to Mineralogy and Petrology》2009,157(5):663-687
Perthitic alkali feldspar primocrysts in layered syenites in the Klokken intrusion in South Greenland, underwent dissolution–reprecipitation
reactions in a circulating post-magmatic aqueous fluid at ~450°C, and are to a large degree pseudomorphs. These ‘mutual replacement’
reactions provide a perfect natural experiment with which to study trace element partitioning between sodium and potassium
feldspars growing simultaneously. The reactant ‘phase’ was a cryptoperthitic feldspar consisting of low albite and low microcline
in a coherent sub-μm ‘braid’ intergrowth and the product phases were ‘strain-free’ incoherent subgrains of low albite and
low microcline forming microporous patch perthites on scales up to 200 μm. The driving force for the reaction was reduction
of coherency strain energy. The mechanisms of this process are described in Part I. Five mixed braid perthite–patch perthite
crystals were analysed for major and trace elements using laser ablation-inductively coupled plasma mass spectrometry with
a 19 μm beam diameter. This gave bulk analyses of the braid texture, which were in the range Ab73–54Or45–27An4.3–0.8, but could resolve Ab- and Or-rich patches in patch perthite. The major element bulk compositions of the crystals were retained
during the replacement reactions. Major components in patches plot on tielines in the Ab–Or–An ternary system that pass through
or very close to the parent braid perthite composition and indicate local equilibrium on the scale of a few tens of mm. Many
trace elements, including REE, were lost to the fluid during the deuteric reactions, but the effect is large only for Fe and
Ti. Cs, Pb and Sr were added to some crystals. Plots of log distribution coefficient D for Rb, Ba, Pb, Eu2+, La and Ce between Or- and Ab-rich patches against ionic radius are straight lines, assuming eightfold coordination, and
to a first approximation are independent of ionic charge. K also lies on these lines, and the smaller ions Na and Ca lie close
to them. The best linear fits were obtained using ionic radii for [8]K and [8]Ca, but there is ambiguity as to whether [7]Na or [5]Na is most appropriate. The linear relationship shows that the listed trace elements are in the feldspar M-site rather than
in inclusions. Tl is in M although an exact D could not be obtained. The very large Cs ion partitions strongly into the Or-rich phase but its D value appears to be less than predicted by extrapolation. The near-linearity arises because partitioning is occurring between
two solids into sites which have similar Young’s moduli, so that the parabolas that normally represent trace element partitioning
between crystals and liquids (which have negligible shear strength) approximately cancel out. Ga and Be are in T-sites, as
well as some of the Fe and Ti present, although part is in oxide inclusions. The site of Sc is unclear, but if structural
it is likely to be T. Partitioning on M-sites is a potential geothermometer but because the effective size of the irregular
M-site is defined by its K and (Na + Ca) contents, which are controlled by ternary solvus relationships, its calibration is
not independent of conventional two-feldspar geothermometers. Trace elements may however provide a useful means of confirming
that feldspar pairs are in equilibrium, and of recognising feldspar intergrowths produced by non-isochemical replacement rather
than exsolution. Two-feldspar geothermometry for the ternary phases in the low-albite microcline patch perthites gives temperatures
above the stability range of microcline, markedly so if a correction is made for Si–Al ordering. This is probably because
current geothermometers are too sensitive to low concentrations of An in ordered Or-rich feldspars. This interpretation is
supported by two-feldspar assemblages growing at known temperatures in geothermal systems and sedimentary basins.
This paper and the earlier Part I are dedicated in the memory of J. V. Smith and W. L. Brown, both of whom died in 2007, in
acknowledgement of their unrivalled contributions to the study of the feldspar minerals over more than half a century.
An erratum to this article can be found at 相似文献
36.
Seismic reflection data image now-buried and inactive volcanoes, both onshore and along the submarine portions of continental margins. However, the impact that these volcanoes have on later, post-eruption fluid flow events (e.g., hydrocarbon migration and accumulation) is poorly understood. Determining how buried volcanoes and their underlying plumbing systems influence subsurface fluid or gas flow, or form traps for hydrocarbon accumulations, is critical to de-risk hydrocarbon exploration and production. Here, we focus on evaluating how buried volcanoes affect the bulk permeability of hydrocarbon seals, and channel and focus hydrocarbons. We use high-resolution 3D seismic reflection and borehole data from the northern South China Sea to show how ca. <10 km wide, ca. <590 m high Miocene volcanoes, buried several kilometres (ca. 1.9 km) below the seabed and fed by a sub-volcanic plumbing system that exploited rift-related faults: (i) acted as long-lived migration pathways, and perhaps reservoirs, for hydrocarbons generated from even more deeply buried (ca. 8–10 km) source rocks; and (ii) instigated differential compaction and doming of the overburden during subsequent burial, producing extensional faults that breached regional seal rocks. Considering that volcanism and related deformation are both common on many magma-rich passive margins, the interplay between the magmatic products and hydrocarbon migration documented here may be more common than currently thought. Our results demonstrate that now-buried and inactive volcanoes can locally degrade hydrocarbon reservoir seals and control the migration of hydrocarbon-rich fluids and gas. These fluids and gases can migrate into and be stored in shallower reservoirs, where they may then represent geohazards to drilling and impact slope stability. 相似文献
37.
I. S. T. Tsong U. Knipping C. M. Loxton C. W. Magee G. W. Arnold 《Physics and Chemistry of Minerals》1985,12(5):261-270
We have conducted detailed studies of the behavior of carbon on the surfaces of MgO and olivine single crystals using various surface analytical techniques: viz. secondary ion mass spectrometry (SIMS), Auger electron spectrometry (AES) and X-ray photoelectron spectrometry (XPS). In order to distinguish without ambiguity the effect of diffusion of carbon from the bulk to the surface and the effect of surface contamination by carbon-containing species, the experiments were conducted in ultrahigh vacuum, i.e. 10?11–10?9 torr. In addition to MgO and olivine single crystals, we have conducted the same studies on TiO2, MnO, SiO2 and Ta2O5 which serve as blank samples. The MgO and olivine samples were also intentionally implanted with known doses of carbon and the mobility of this particular carbon was investigated in detail. Our results show that the bulk carbon content in MgO is around 40 wt. ppm, considerably lower than the quantities quoted by Freund and co-workers in the past. We also show that the carbon in both MgO and olivine does not display any rapid diffusion behaviour leading to surface segreation in the temperature range 78–723 K, in contrast to the previous findings of Freund and co-workers. 相似文献
38.
Marcel Schmid HR. Bürgi Rudolf Müller 《Aquatic Sciences - Research Across Boundaries》1980,42(1):86-87
Ohne Zusammenfassung 相似文献
39.
Synthesis and Preliminary Characterisation of New Silicate, Phosphate and Titanite Reference Glasses 总被引:3,自引:0,他引:3
Stephan Klemme Stefan Prowatke Carsten Münker Charles W. Magee Yann Lahaye Thomas Zack Simone A. Kasemann E. Joan A. Cabato Benjamin Kaeser 《Geostandards and Geoanalytical Research》2008,32(1):39-54
Eleven synthetic silicate and phosphate glasses were prepared to serve as reference materials for in situ microanalysis of clinopyroxenes, apatite and titanite, and other phosphate and titanite phases. Analytical results using different micro-analytical techniques showed that the glass fragments were homogeneous in major and trace elements down to the micrometre scale. Trace element determinations using inductively coupled plasma-mass spectrometry (ICP-MS), multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) and secondary ionisation mass spectrometry (SIMS) showed good agreement for most elements (Li, Be, B, Cs, Rb, Ba, Sr, Ga, Pb, U, Th, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Tm, Yb, Lu, Zr, Hf, Ta, Nb) studied and provide provisional recommended values. 相似文献
40.