K比例H点标准加入吸光光度法同时测定矿样中铌和钽

从样品分解方法入手,探讨了最佳测试条件。用盐酸-氟化氢铵-硝酸-高氯酸溶解试样,在10%的盐酸介质中,用火焰原子吸收光谱仪于波长328.1 nm处,以空气-乙炔火焰测定铅精粉中的银量,克服了用铅析或灰吹法测定的步骤冗长等缺点。用铅精粉国家一级标准物质GBW 07167分析验证,测定结果与标准值吻合。方法精密度(RSD,n=12)为2.2%~4.3%,方法检出限为1.2μg/g。方法分析快速,简单。     

Evidence for carbonate platform failure during rapid sea‐level rise; ca 14 000 year old bioclastic flow deposits in the Lesser Antilles

Bioclastic flow deposits offshore from the Soufrière Hills volcano on Montserrat in the Lesser Antilles were deposited by the largest volume sediment flows near this active volcano in the last 26 kyr. The volume of these deposits exceeds that of the largest historic volcanic dome collapse in the world, which occurred on Montserrat in 2003. These flows were most probably generated by a large submarine slope failure of the carbonate shelf comprising the south‐west flank of Antigua or the east flank of Redonda; adjacent islands that are not volcanically active. The bioclastic flow deposits are relatively coarse‐grained and either ungraded or poorly graded, and were deposited by non‐cohesive debris flow and high density turbidity currents. The bioclastic deposit often comprises multiple sub‐units that cannot be correlated between core sites; some located just 2 km apart. Multiple sub‐units in the bioclastic deposit result from either flow reflection, stacking of multiple debris flow lobes, and/or multi‐stage collapse of the initial landslide. This study provides unusually precise constraints on the age of this mass flow event that occurred at ca 14 ka. Few large submarine landslides have been well dated, but the slope failures that have been dated are commonly associated with periods of rapid sea‐level change.     

小尺度环境地形相对高度认知及影响因素——以南京大学浦口校区为例

地形认知虽然是探讨人地互动的重要命题, 但目前研究甚少。本文选取南大浦口校园 为案例地, 在实验设计基础上, 采用非概率和分层比例抽样, 使用问卷调查和深度访谈的数 据收集方法, 历时两年, 共访谈调查了644名被试, 并运用定性与定量数据分析方法, 得出 小尺度环境地形认知一致性、参照体系特征、个体日常环境对认知的影响性等特点, 具体结 论如下:(1)认知一致性:被试在地形相对高度的认知方式与状况、地形特征点的辨识方面 具有较高一致性;且认知偏误率在空间上呈现一定的分布规律。(2)参照体系特征:被试使 用的环境参照物附近的地形多呈凹陷状且地势较低、空间临近特征显着, 并且它们多是被试 熟悉, 视觉通达性较好, 到访率较高的场所。(3)个体日常环境对认知的影响性:地形特征 的辨识及其相对高度认知受地理环境、认知、行为、情绪和态度等多方面因素影响, 其中决 定性因素是个体的日常生活环境。     

The effects of source lithology, transport, deposition and sampling scale on the composition of southern California sand

The Transverse Ranges of southern California represent an uplifted and variably dissected Mesozoic magmatic arc, and Mesozoic to Holocene sedimentary and volcanic strata deposited in convergent and transform tectonic settings. Modern sand within part of the Western Transverse Ranges represents: first-order sampling scale of the Santa Monica and the San Gabriel Mountains; second-order sampling scale of the Santa Clara River draining both mountain ranges; and third-order sampling scale of the beach system between the mouth of the Santa Clara River and the eastern Santa Monica Mountains, and turbidite sand of the Hueneme-Mugu submarine fan. Source lithology includes plutonic and metamorphic rocks of the San Gabriel Mountains, and sedimentary and volcanic rocks of the Santa Monica Mountains. First-order sands have large compositional variability. Sand from local coastal drainage of the Santa Monica Mountains ranges from basaltic feldspatholithic to quartzofeldspathic. Sand of the San Gabriel Mountains local drainages has three distinct petrofacies, ranging from metamorphiclastic feldspatholithic to mixed metamorphi/plutoniclastic and plutoniclastic quartzofeldspathic. Second-order sand is represented by the main channel of the Santa Clara River; the sand has an abrupt downstream compositional change, from feldspathic to quartzofeldspathic. Third-order sand (beaches and deep-sea turbidite samples) of the Santa Monica Basin is quartzofeldspathic. Beach sand is more quartz-rich than is Santa Clara river sand, whereas turbidite sand is more feldspar-rich than is beach sand. Deep-sea sand has intermediate composition with respect to second-order samples of the Santa Clara River and third-order samples of the beach system, suggesting that (1) the Santa Clara River is the main source of sediments to the marine environment; and (2) local entry points from canyons located near local drainages may generate turbidity currents during exceptional flood conditions. Petrologic data of modern sand of the study area are highly variable at first- and second-order scale, whereas third-order sand is homogenized. The homogenized composition of deep-marine sand is similar to the composition of most ancient sandstone derived primarily from the Mesozoic dissected magmatic arc of southern California. This study of the Western Transverse Ranges illustrates the effects of source lithology, transport, depositional environment, and sampling scale on sand composition of a complex system, which provides insights regarding actualistic petrofacies models.     

Chemical Variation within and between Volcanic Rock Series--A Statistical Approach

Using the statistical method of principal component analysisa new type of variation diagram is developed which combinessimplicity with a large amount of available information. Withthe aid of this principal latent vector variation diagram thedifferentiation processes within the alkali and sub-alkali volcanicrock series and the origin of basic magma types are discussed.A study of the frequency distribution of the oxides within thealkali and sub-alkali volcanic rock series leads to the unexpectedconclusion that the differentiation processes within the twoseries must be fundamentally different. By means of simple discriminantfunctions rock analyses of the alkali series can be distinguishedfrom those of the sub–alkali series with a high degreeof certainty. The mean of the discriminant values of a provincecan be used as an indication of the ‘degree of alkalinity’of that province. Techniques such as these are ideally suitedto the interpretation and comparison of the vast numbers ofcomputerised chemical analyses that will invitably be obtainedfrom X-ray fluorescence analysis and allied methods.     

Variational data analysis with control of the forecast bias

We propose a methodology for the treatment of the systematic model error in variational data assimilation. The principle of the method is to add a systematic error correction term in the model equations and to include it in the variational assimilation control vector.
This method is applied to a simplified ocean circulation model in an identical twin experiment framework. It shows a noticeable improvement compared to the result of a classical variational assimilation scheme in which the systematic error is not corrected. The estimated systematic error correction term is sufficiently consistent with that needed by the model that it allows improvements not just to the analysis, but also during the forecast phase.     

Fabry-perot Hα-interferometric observations of some HII regions. I. SH2-152 and SH2-153

H -interferometric observations of the HII-regions Sh2-152 and Sh2-153 are carried out with a high resolution (1 pixel=2.13×2.13 arcsec). They confirm the results on the structure of those formations obtained earlier. Individual radial velocities determined in different points for each of these HII-regions show that the inner motions of ionized matter relative to the exciting stars are, in general, of expanding character. It gives ground to assume that in both these star forming regions the dissipation of matter takes place.Published in Astrofizika, Vol. 37, No. 2, pp. 175–186, April–June, 1994.     

The Geochemistry of Lavas from the Gomores Archipelago, Western Indian Ocean: Petrogenesis and Mantle Source Region Characteristics

New mineral and bulk-rock analyses, as well as Nd, Sr and Pbisotope compositions are presented for lavas from Grande Comore,Moheli and Mayotte, thru of the four main islands of the ComoresArchipelago in the western Indian Ocean, and these data an usedto evaluate the petrogenesis, evolution and mantle source regioncharacteristics of Comorean lavas. The typically silica-undersaturated,alkaline lavas from all three islands can be grouped into twodistinct types: La Grille-type (LGT) lavas, which display strongrelative depletions in K, and Karthala-type (KT) lavas, whichdo not. With the exception of the lavas erupted by La Grillevolcano on Grande Comore, which exhibit the petrographic andgeochemical characteristics expected of primary mantle-derivedmagmas, all Comorean lavas analysed have experienced compositionalmodifications after they segregated from their source regions.Much of this variation can be explained quantitatively by fractionalcrystallization processes dominated by the fractionation ofolivineand clinopyroxene. Semi-quantitative modelling shows that theconsistent and fundamental difference in composition betweenK-depleted LGT lavas and normal KT lavas can be attributed topartial melting processes, provided amphibole is a residualmantle phase after extraction of LGT magmas at low degrees ofmelting. Low absolute abundances of the heavy rare earth elementsin LGT magmas are interpreted to reflect partial melting withinthe garnet stability field In contrast, KT magmas, which donot show relative K depletions, are considered to be the productsof somewhat larger degrees of partial melting of an amphibolefreesource at comparatively shallower depths. Whereas the Nd andSr isotopic compositions of Comorean lavas (which show a significantrange: ⁸⁷Sr/⁸⁶Sr = 0.70319–0.70393; ¹⁴³Nd/Nd = 0.51263–0.51288)bear evidence for a time-averaged depletion in incompatibleelements, the high incompatible element abundances of the lavasare interpreted to reflect the effects of a recent mantle enrichmentevent. At depths well within the garnet stability field thismantle enrichment is interpreted to have taken the form of modalmetasomatism with the introduction of amphibole (giving riseto the source of LGT magmas), whereas cryptic metasomatism tookplace at shallower levels (giving rise to the source of KT lavas).The Nd, Sr and Pb isotope signature of the majority of Comoreanlavas (both LGT and KT) is proposed to be the result of predominant4contributions from a somewhat heterogeneous source4 4 4 presentativeof the ambient sub-Comorean mantle, comprising a mixture betweena HIMU component and a component on the depleted portion ofthe mantle array (possibly the source of Indian Ocean MORB),with only limited contributions from an EM I plume component.The lavas erupted by Karthala volcano (the youngest Comoreanlavas), however, have significantly different isotopic compositionsfrom all other Comorean lavas (lower ¹⁴³Nd/¹⁴⁴Nd and higher⁸⁷Sr/⁸⁶Sr), suggesting increased contributions from the EM Icomponent. KEY WORDS: basalt petrogenesis; Comores; mantle geochemistry; ocean island basalts ^*Telephone: 27-21-6502921. Fax: 27-21-6503781 e-mail: alr{at}geology.uct.ac.za.     

TMI被动微波遥感资料用于地表洪涝特征分析试验

星载被动微波遥感资料为云天条件下地表洪涝特征分析提供了可能。微波极化比 (PR)可以有效刻画地表洪涝特征 ,宏观反映地表湿度信息。正演模拟分析结果表明地表粗糙度、地表植被覆盖状况和地表湿度对上行微波亮温有影响 ;TRMM/TMI低频微波通道微波极化比能减弱大气因素的影响 ,清晰反映地表的洪涝特征。合理确定分类阈值 ,对 1 998年长江流域洪涝区进行地表洪涝特征分析 ,可以在TMI像元尺度 ,将洪涝区分类为不同等级。洪涝区分类结果与经过天 -地校验过的机载和星载SAR资料地表洪涝分类实况对比 ,TRMM/TMI低频微波通道微波极化比 1 0GHz的PR1 0和 1 9GHz的PR1 9的分类正确率不低于 75 %。     

一个新的交叉学科——绿色化学

绿色化学致力于节约资源，从源头上防止污染物的生成，它是涉及整个化学领域的一个交叉学科。本文介绍绿色化学的提出、发展和研究内容，作者认为高校是绿色化学发展的重要力量。