共查询到20条相似文献，搜索用时 15 毫秒
1.
Kevin J. Grant Simon C. Kohn Richard A. Brooker 《Contributions to Mineralogy and Petrology》2006,151(6):651-664
The solubility of water in coexisting enstatite and forsterite was investigated by simultaneously synthesizing the two phases in a series of high pressure and temperature piston cylinder experiments. Experiments were performed at 1.0 and 2.0 GPa at temperatures between 1,100 and 1,420°C. Integrated OH absorbances were determined using polarized infrared spectroscopy on orientated single crystals of each phase. Phase water contents were estimated using the calibration of Libowitzky and Rossman (Am Mineral 82:1111–1115, 1997). Enstatite crystals, synthesized in equilibrium with forsterite and an aqueous phase at 1,350°C and 2.0 GPa, contain 114 ppm H2O. This is reduced to 59 ppm at 1,100°C, under otherwise identical conditions, suggesting a strong temperature dependence. At 1,350°C and 1.0 GPa water solubility in enstatite is 89 ppm, significantly lower than that at 2.0 GPa. In contrast water solubility in forsterite is essentially constant, being in the range 36–41 ppm for all conditions studied. These data give partition coefficients
in the range 2.28–3.31 for all experiments at 1,350°C and 1.34 for one experiment at 1,100°C. The incorporation of Al2O3 in enstatite modifies the OH stretching spectrum in a systematic way, and slightly increases the water solubility. 相似文献
2.
Roland Stalder Andreas Kronz Klaus Simon 《Contributions to Mineralogy and Petrology》2008,156(5):653-659
The incorporation of hydrogen in enstatite in a hydrous system containing various amounts of NaCl was investigated at 25 kbar.
The hydrogen content in enstatite shows a clear negative correlation to the NaCl-concentration in the system. The most favourable
explanation is the reduction of water fugacity due to dilution. Other reasons for the limited hydrogen incorporation at high
NaCl levels, such as a significant influence of Na+ on the defect chemistry or an exchange between OH- and Cl−in enstatite, appear much less important. A partition coefficient D
Na
En/Fluid = 0.0013 could be determined, demonstrating that Na is less incompatible in enstatite than H. The new results support the
idea that dissolved components have to be considered when the total hydrogen storage capacity in nominally anhydrous minerals
is estimated, especially in geological settings with high levels of halogens, such as subduction zones. 相似文献
3.
Clinopyroxene + liquid equilibria to 100 kbar and 2450 K 总被引：5，自引：1，他引：4
Keith Putirka 《Contributions to Mineralogy and Petrology》1999,135(2-3):151-163
One of the most active issues in igneous petrology is the investigation of mantle melting, and subsequent differentiation.
To evaluate alternative hypotheses for melting and differentiation it is essential to accurately predict clinopyroxene compositions
in natural systems. Expressions have thus been derived that describe clinopyroxene-melt equilibria, and allow equilibrium
clinopyroxene compositions to be calculated. These equations were constructed from least-squares regression analysis of experimental
clinopyroxene-liquid pairs. The calibration database included clinopyroxenes synthesized from both natural and synthetic basalt
compositions; experimental conditions ranged from 0 to 100 kbar and 1350 to 2450 K. Regression equations were based on thermodynamic
functions. Empirical expressions were also derived, since such models yield more precise estimates of clinopyroxene compositions,
and may be easily incorporated into existing liquid line-of-descent models. Such equations may be useful for calculation of
high pressure liquid fractionation, or for constraining P-T conditions for basalts produced by partial melting of a pyroxene-bearing source. Models of mantle melting often rely on expressions
involving simple element ratios. Partition coefficients (K
d
cpx/liq
) for the minor elements, Na and Ti, were thus also calibrated as a function of P, T and composition. K
Ti
cpx/liq
, while sensitive to composition was relatively insensitive to P and T. In contrast, K
Na
cpx/liq
increases substantially with increasing P, and exceeded 1 in some experiments. Since oceanic basalts show variations in Na/Ti ratios, the potential exists for partial
melting depths to be inferred from K
Na
cpx/liq
.
Received: 28 May 1997 / Accepted: 20 November 1998 相似文献
4.
Experimental study of the phase and melting relations of homogeneous basalt + peridotite mixtures and implications for the petrogenesis of flood basalts 总被引：20，自引：0，他引：20
Gregory M. Yaxley 《Contributions to Mineralogy and Petrology》2000,139(3):326-338
Flood basalt provinces may constitute some of the most catastrophic volcanic events in the Earth's history. A popular model
to explain them involves adiabatic ascent of plumes of anomalously hot peridotite from a thermal boundary layer deep in the
mantle, across the peridotite solidus. However, peridotitic plumes probably require unreasonably high potential temperatures
to generate sufficient volumes of magma and high enough melting rates to produce flood volcanism. This lead to the suggestion
that low melting eclogitic or pyroxenitic heterogeneities may be present in the source regions of the flood basalts. In order
to constrain petrogenetic models for flood basalts generated in this way, an experimental investigation of the melting relations
of homogeneous peridotite + oceanic basalt mixtures has been performed. Experiments were conducted at 3.5 GPa on a fertile
peridotite (MPY90)–oceanic basalt (GA1) compositional join. The hybrid basalt + peridotite compositions crystallised garnet
lherzolite at subsolidus temperatures plus quenched ne-normative picritic liquids at temperatures just above the solidus, over the compositional range MPY90 to GA150MPY9050. The solidus temperature decreased slightly from ∼1500 °C for MPY90 to ∼1450 °C for GA150MPY9050. Compositions similar to GA130MPY9070 have 100% melting compressed into a melting interval which is approximately 50–60% smaller than that for pure MPY90, due
to a liquidus minimum. During adiabatic ascent of hybrid source material containing a few tens of percent basalt in peridotite,
the lower solidus and compressed solidus–liquidus temperature interval may conspire to substantially enhance melt productivity.
Mixtures of recycled oceanic crust and peridotite in mantle plumes may therefore provide a viable source for some flood volcanics.
Evidence for this would include higher than normal Fe/Mg values in natural primary liquids, consistent with equilibration
with more Fe-rich olivine than normal pyrolitic olivine (i.e. <Fo89–92). Modelling of fractionation trends in West Greenland picrites is presented to demonstrate that melts parental to the Greenland
picrites were in equilibrium at mantle P–T conditions with olivine with Fo84–86, suggesting an Fe-enriched source compared with normal peridotite, and consistent with the presence of a basaltic component
in the source.
Received: 29 October 1999 / Accepted: 3 February 2000 相似文献
5.
Talita Lammoglia Bemardino R Figueiredo Alice M. Sakuma M.L. Buzzo I.A. Okada C.S. Kira 《中国地球化学学报》2006,25(B08):66-66
During the last century, several lead mines and a metal smelter were in production in the Upper Ribeira Valley, southeastern Brazil. After fifty years of activity, the refinery was shut down in November 1995 and, thereafter the last mines in production were closed. Since 1998, a multidisciplinary research group has carried out an ambitious investigation among the population of five municipalities in the Ribeira Valley （sampled population of 472 children and 523 adults） to assess the human exposure to lead. The highest blood lead levels were found among the population of two villages in the vicinity of the smelter where soil and indoor-dust are highly contaminated. During the present study, the lead contents of several food species that are part of local population diet were investigated. Greens, vegetables, corn, chicken eggs and cow milk, were sampled in two occasions, July 2004 and February 2005. The analytical procedures included burning of organic matter, pre-concentration of lead and, finally, determination by AAS using background correction. The quantification limit was 0.05 μg/g Pb. Soil samples were also collected and analyzed by X-ray fluorescence spectroscopy with a quantification limit of 2 μg/g Pb. The results are very impressing since 100% of greens, vegetables and eggs yielded lead concentrations exceeding the upper limits established by Brazilian regulations whereas milk and maize samples presented lead contents below the regulated limit of 0.05 μg/g Pb. Lead concentrations in soil varied between 156 and 1292 μg/g Pb, resembling the results of previous studies and far exceeding the threshold of 200 μg/g Pb indicated as the intervention value. Lead contents in some species vary consistently with lead concentrations in soils, however, other factors may account for the bioavailability of lead and its intake by plants, like the soil pH, its cationic exchange capacity, clay and organic matter contents, characteristics of the plant species itself, climate, among others. 相似文献
6.
Chiaki Igarashi Naotatsu Shikazono Haruhiro Otani 《中国地球化学学报》2007,26(1):35-45
The major element composition of sound-producing sand is reported together with rare-earth elements (REE) and other selected elements for the first time. Rare-earth element concentrations in beach sands from Miyagi and Tottori in Japan were determined by induction-coupled, argon-plasma spectrometry (ICP-MS) to characterize the REE of sound-producing and silent sands relative to the parental rocks. Sound-producing sand beaches are very common and all over in Japan: five beaches in Miyagi and 2 in Tottori are selected with other silent sand beaches in the areas. Both sound-producing sand and silent sand samples from Miyagi and Tottori contain more than 60wt% of SiO2 and are composed mainly of quartz and feldspar. Miyagi sand samples are characterized by light REE enrichment and flat chondrite-normalized patterns that are similar to those of local source sandstone. However, all sand samples from Miyatojima in Miyagi show positive Eu anomalies, a characteristic feature not shown in other sand samples from Miyagi. Tottori sand samples also are characterized by high REE contents and remarkable positive Eu anomalies. The sands containing lower REE contents are due to high quartz and feldspar contents. Miyatojima sand samples and Tottori sand samples have high REE contents and show remarkable positive Eu anomalies due to the presence of feldspar. The best results are obtained using all of the geological methods and the Principal Component Analysis (PCA) as a measure of the similarity between sound-producing sand and silent sand. The difference between sound-producing sand and silent sand is obtained from the PCA results. 相似文献
7.
正It is significant for recognizing the origin of chromitites to research the primary mineral inclusions in chromitites.A large number of primary mineral inclusions including CPXs,OPXs,olivines,aspidolites,Na-Cr pargasites,CPX 相似文献
8.
9.
Brian Gulson Karen Mizon Michael Korsch Honway Louie Michael Wu Jenny Stauber J. Michael Davis Alan Taylor 《中国地球化学学报》2006,25(B08):62-62
This is a 4-year longitudinal study to evaluate changes to the environment and exposure of young children associated with the introduction of methylcyclopentadienyl manganese tricarbonyl （MMT） into Australia in 2000. The cohort includes 57 females and 56 males; age range of 0.29 to 3.9 years. Samples are collected every 6 months from children in residences located at varying distances from major traffic thoroughfares in Sydney. Environmental samples： air, house and day care dustfall, soil, dust sweepings and gasoline. Samples from children： blood, urine, handwipes prior to and after playing outdoors, and a 6-day duplicate diet. All samples are analyzed for a suite of 20 elements using ICP-MS. Results are presented for the first three 6-month sampling periods for Pb and Mn. For dustfall accumulation, there was no significant change over the 3 sampling periods （time） for Pb or Mn, and a positive relationship between ‘traffic exposure＇ （traffic volume and proximity to the road） and Pb but not Mn. For handwipes, Pb and Mn in wipes taken from children after playing outdoors were usually significantly greater than for wipes taken prior to playing. There was no significant association between Pb or Mn in handwipes with traffic exposure. Dustfall accumulation was a significant predictor for Pb in the handwipes, and dust sweepings were a significant predictor of Mn in handwipes. 相似文献
10.
Thermal expansion has been measured by laboratory and synchrotron X-ray powder diffraction for end-member åkermanite (ak, Ca2MgSi2O7) and gehlenite (ge, Ca2Al2SiO7) in the range 20–1,500 K. In ak in the range 340–390 K, there is a negative linear thermal expansion in [001] direction. This is related to the phase transition from an incommensurate modulated structure (IC) to a normal one (N). The volumetric mean thermal expansion coefficients for ak and ge, obtained with a linear fit of the experimental data in the temperature range 298–1,400 K, are respectively 32.1×10–6 and 28.3×10–6 K–1 . The variation of the c/a ratio with temperature, due to different thermal expansion along the crystallographic axes, can be related to the different behaviour of the tetrahedral layers in the N and IC phases. Analysis of the variation of the superstructure peaks intensity across the phase transition confirms the tricritical behaviour of the IC/N transition in ak. 相似文献
11.
Liu Xiaoliang Chen Congyun Yang Xuezeng Yang Sen Zhang Jiongfei Gao Yuhua Shenyang Institute of Geology Mineral Resources Chinese Academy of Geological Sciences Shenyang Liaoning Sun Sheping 《《地质学报》英文版》1992,66(4):427-442
The Ordovician Changtu Fauna is recently discovered in the Xia' ertai and Hulan Groups in northernLiaoning-central Jilin. The fauna, containing 10 genera and 14 species (including 3 new genera, 9 new speciesand an unidentified species), is closely related in evolution with the Early Cambrian Qinghezhen Fauna. Thediscovery of this fauna is significant to the study on the age of the strata, Ordovician biostratigraphy and geo-logical evolution of the tectonostratigraphical terrane on the northern margin of the Sino-Korean plate. 相似文献
12.
1 The rise of the problem The region of western Shandong has been attracting more and more attention of geologists because of its unique geological features and abundant mineral resources, and it has been well geologically documented (Lin Jingqian et al.… 相似文献
13.
《中国地球化学学报》2006,(Z1)
Chemical and biological reactions occurring in lake sediments (early diagenesis) can influence the vertical distribution of trace metals and compromise the use of sediment profiles as historical records of anthropogenic metal pollution. There is thus a ne… 相似文献
14.
X. Chris Le Xiufen LU Meiling LU Nicole Orr Zhongwen WANG Chungang YUAN 《中国地球化学学报》2006,25(B08):77-78
Arsenic is the 20th most abundant element in the Earth crust. Humans are exposed to naturally occurring and anthropogenic sources of arsenic compounds in the environment. A wide variety of adverse health effects have been attributed to chronic exposure to high levels of arsenic. More than two-dozen arsenic compounds （species） are present in the environment and in biological systems. The various arsenic species have dramatically different behavior and toxicity. This presentation briefly describes arsenic speciation analysis, human exposure to and metabolism of arsenic species. Environmental issues on arsenic in Canada are briefly discussed. These include （1） the arsenic waste left from previous gold mining and smelting activities; （2） the domestic use of wood treated with chromated copper arsenate; and （3） use of well water as the source of drinking water by approximately one third of the Canadian population. 相似文献
15.
Mohammad Rasul Jan Mahmood A Khawaja Jasmin Sha Kashif Gul 《中国地球化学学报》2006,25(B08):182-182
Due to the persistent nature of DDT, a persistent organic pollutant and its adverse environmental and health impacts, the present study was undertaken to examine the residual DDT in and around DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. The factory was established in 1963 and remained in operation till 1994. Composite samples of soil, sediments and water were collected in and around the factory area, nearby DDT stores, main factory drain leading to river and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analysis. Physical parameters for the collected water samples measured were temperature, pH and conductance. Extraction of each sample for DDT analyses was carried out in triplicates using soxhlet extraction apparatus. The extract was transferred to well washed, clean; dry glass vial, sealed and put in the refrigerator. Gas Chromatograph with electron capture detector and capillary column was used for analysis. DDT in the samples was identified on the basis of their retention time and quantified on the basis of peak areas. It is evident from the analytical data obtained in the present study that both water and soil in and around the factory area are still contaminated with DDT, despite the closure of the factory since the past few years. 相似文献
16.
TheMiddleandUpper~aninNorthCabhasbeenextenSiVelystudiedfor~yearSinbiostratigraphy(LuandDong,1953;Xiangatal.,1981;An,1982;Met,1993a,1993b).Ho~,thelithOStratigraphictntSwereunfortunatelydefinedbytrilobitezonesotherthanlithologitalcriteria,owingtothecomplicatedChangeSandt~itioninlithofades.CbnseqUentiy,thebio--,litho~andchronostrstigraphictntS~confuSed,asPOintedOuttosomeextentbyLuetal.(1994).Nevertheless,thezoningfossilsoftrilobiteSoCCUrredatthehorizonsSeparatedfromeachotherinseveralt… 相似文献
17.
Hechun PIAO Congqiang LIU 《中国地球化学学报》2006,25(B08):169-170
In consideration of the poor correlation between soil and plant nutrient levels, biogeochemists often focus on nutrient stoichiometry, which is mostly used in ecology to indicate the limitation of nutrients in environments. The previous work indicated that the studies of nutrient cycles must go beyond linkage between environmental conditions and plant nutrient concentrations to consider plant internal processes such as growth and nutrient stoichiometry. The plant species composition in calcareous soils with higher pH, generally to be considered P-limited conditions, is expected to differ from that in acidic soils. Many vascular plant species are unable to colonize limestone soils. Thus, floristic composition and soil properties of adjacent limestone and sandstone altitudinal gradients differ greatly in Southwest China. Until now, mechanisms regulating this differing ability of plants to colonize limestone sites have not been elucidated. It is reported that the inability of many plants to establish in limestone sites seems to be related to a low capacity of such plants to solubilize phosphate from these soils. It is reported that the toxicity of manganese and the deficiency of iron were also closely correlated with floristic compositions. We focus on whether similar trends of nutrient distributions occur across different experimental plots during legume growing, 相似文献
18.
Chen Fajing Wang Xinwen Zhang Guangya Cao Shoulian Luo ChuanrongDepartment of Geology Energy Resources China University of Geosciences Beijing 《中国地质大学学报(英文版)》1995,(2)
About 26 sedimentary basins bearing oil and gas are developed in China. They can be classified into two main types , extensional basins and foreland basins . The former are chiefly distributed in the eastern part and the latter in the central and northwestern parts of the country . The present paper discusses the structural characteristics of these basins , including subsidence history , thermal history and structural style and kinematics . Combined with tectonic setting analysis of geophysical data and eruptive rocks , the geodynamic setting of the basins is established , and the formation mechanism of the basins is deduced to have been related to the subduction of the Izanagi and west Pacific plates and the closing of the Tethys ocean. 相似文献
19.
20.
Geoffrey S. Plumlee 《中国地球化学学报》2006,25(B08):75-76
Large volumes of solid, gaseous, or liquid materials that are of potential concern from an environmental or public health perspective are commonly produced by natural or anthropogenic disasters, such as earthquakes, volcanic eruptions, wildfires, urban fires, landslides, hurricanes, tsunamis, floods, windstorms, industrial spills, and terrorist attacks. Geochemical processes play key roles in the environmental and health impacts of these materials. Yet, process-focused environmental geochemistry expertise and characterization methods are often underutilized in disaster response and planning. In part, the scientific studies needed for detailed process characterization are difficult to plan and implement while the events are still underway, and delayed responses can miss key transient processes and byproducts. Further, emergency responders are focused primarily on identifying the types, amounts, and health hazards of contaminants produced by the event, thus the responders do not have the time or the need to collect the full range of appropriate geological, geochemical, microbiological and other data necessary to understand the full range of physical and chemical processes that influence contamination from these extreme events. A thorough characterization and understanding of geochemical and environmental processes that occur during specific disasters can be used to better anticipate effects of and plan for similar future disasters. A broad spectrum of environmental geochemistry capabilities can be applied to help emergency response authorities and the public health community in their initial hazardous materials assessments immediately following disasters. 相似文献