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Boulders of the assemblage ruby—sapphire corundum, chromianmuscovite, margarite, tourmaline (chromian chlorite, Zn—Mnchromite and Mn—Ti magnetite) occur in glacial moraineand rivers of north Westland, South Island of New Zealand. Thelocation, Cr-rich composition of the boulders and the presenceof rare serpentinite rinds indicate that they are derived fromultramafic rocks (Pounamu Ultramafics) that occur within AlpineSchist of the Southern Alps. The largest sample is progressivelyzoned outwards from a corundum—margarite core, throughan intermediate zone of Cr-muscovite, to an outer zone of Cr-chloritethat is in contact with serpentinite. Most finds consist oferosion-resistant corundum-rich cores. In the corundum, Cr2O3content ranges from 0.5 to 13%, with red coloration becomingmore intense with increasing Cr. In addition to the dominantCr3+ Al3+ substitution, those of (Fe, V)3+ Cr3+ and (Ti4++Fe2+) 2Cr3+ result in spectacular colour zoning from colourlessto deep ruby red-carmine and pale blue to dark blue—violet.Corundum has grown by replacement of the micaceous matrix thatconsists of chromian muscovite (0.10–4.10% Cr2O3) andchromian margarite (0.46–1.20% Cr2O3). Both micas containa significant paragonite component (up to 21.5% in muscoviteand up to 40.8% in margarite). Late phase muscovite is Ba richwith up to 4.77% BaO, and margarite has up to 0.66% SrO. Tourmalineoccurs as veins, vein outgrowths and larger poikilitic crystalsthat replace the mica matrix. Chromium content ranges between0.82 and 3.6% Cr2O3. High bulk rock Al (up to 78% Al2O3), K,Ca, Cr and Na, and low Si (14.5–23.1% SiO2), suggest thatthe corundum—Cr-silicate rocks are the products of extrememetasomatic alteration of quartzofeldspathic schist enclavesin serpentinite. Isocon analysis indicates that conversion ofthe schist to the micaceous matrix of the corundum rocks involvesconservation of Ca, Al, K, volatiles and Sr, a mass loss of59% and a volume reduction of 69% consequent on removal of 70–80%Si and all other elements (most >80%), with enrichment ofbetween 900 and 1800% Cr. The formation of corundum from themica matrix involved a further mass—volume reduction anddecrements in Si, Ca, K, volatiles and Sr from reaction sites.Concentric mineral zonation in single rock samples and zoning—replacementin minerals, e.g. Cr in corundum and chromite, Ti, Fe2+ in corundum,Ba in muscovite, Sr in margarite, and Mn and Zn in chromiteand magnetite, imply element redistribution during metasomatism.Experimental reaction between quartzofeldspathic schist andserpentinite at 450C and 2 kbar produced reaction sequencescontaining newly formed Ca-plagioclase—phlogopitic micachloriteand muscovite—chlorite that in terms of composition areanalogous with the observed (corundum—margarite)—muscovite—chloritezonation. The temperature of metamorphism of garnet zone rocks(45020C) that contain the corundum—Cr-silicate rocksis well below that of the breakdown of muscovite and margariteto form corundum and indicates the importance of fluid composition,particularly the cation—hydrogen variables aCa2+/H+, aK+/H+and aS1O2. Introduction of boron into the schist (from serpentinite),and boron released from the breakdown of original tourmalinein the schist, resulted in tourmaline veining and reaction ofthe mica matrix to form tourmaline that invoved both a massand volume increase and addition of Fe, Mg together with B. KEY WORDS: corundum—Cr-silicate rocks; metasomatism; New Zealand; Southern Alps
*Corresponding author. 相似文献
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Dry deposition of particles 总被引：5，自引：0，他引：5
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某废弃煤矿竖井经倾倒有机废液,导致环境污染事件,造成巷道及采空区内地下水污染。本文结合场地实际情况,选取倾倒竖井(事故井)及周边区域为中试区域,采用“抽出处理+原位氧化循环”两阶段联合修复技术对污染场地开展中试研究。本文介绍了场地污染概况、地下水修复中试方案设计和实施,以及对修复效果进行评价。结果表明,中试处理后地下水中COD和二氯甲烷最高去除率分别为97.88%和99.74%。中试试验表明, “抽出处理+原位氧化循环”两阶段修复技术,对处理矿区内巷道及采空区等复杂地层结构下深层地下水中有机污染物具有较好的去除效果,可以结合现场实际情形对整个污染场区进行规模应用。 相似文献
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KEN J. WOOLFE 《地球表面变化过程与地形》1996,21(5):477-478
Duck's recent finding (R. W. Duck, Earth Surface Processes and Landforms, 1994, 19 , 525–529) that QDa and Md parameters derived from pipette and SediGraph analysis of sediments from Loch Tummel returned similar results can be interpreted in two ways. The observed consistency could result from (i) a general agreement between the methods (as is suggested by Duck) or (ii) from the use of inappropriate parameters (Md and QDa) to describe polymodal distributions. 相似文献
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The Generation of Kimberlites, Lamproites, and their Source Rocks 总被引：18，自引：8，他引：10
Measurements of rare earth element (REE) concentrations in SouthAfrican kimberlites and in the Argyle lamproite from WesternAustralia constrain the composition of the source rocks fromwhich these melts originate. To account for the concentrationsof Tm, Yb, and Lu in these magmas, their sources must firsthave been strongly depleted by 20% melting in the garnet stabilityfield, and then enriched by a metasomatic melt rich in lightREE and other incompatible elements. The calculated source compositionsclosely resemble those of coarse, low-temperature, depletedperidotite nodules that are the commonest nodules in kimberlites.Rarer nodule types have undergone either more or less depletionthan have the source regions of kimberlites and lamproites.The REE composition of the metasomatic melt calculated fromthe diopsides and garnets in the sheared nodules, from the diopsidemegacrysts, and from majorite garnet inclusions in diamonds,is in excellent agreement with that expected for a melt producedby melting 0.5% of the source region of ocean ridge basalts.The initial depletion event requires the extraction of 20% meltfrom a region in which garnet and chrome-spinel were stable.The melt distribution obtained from inversion of komatiite compositionssatisfies both these conditions. Kimberlite source rocks areshallower than the layer from which fertile nodules originate.Such nodules must therefore be transported by entrainment ofthe lower boundary of the layer that becomes unstable. Thisproposal can account for their strong fabric. 相似文献
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Although GIS are used extensively in modern socio-economic studies, their application to historical analysis, especially of relatively early periods, is in its infancy. Yet, as this paper demonstrates, GIS has particular utility both for combining information from disparate and unstandardized historical sources and for reconstructing broad distribution patterns from spatially discontinuous data. When combined with cluster analysis, it also provides a powerful tool for analysing and classifying data sets and representing the results thereby obtained. This paper describes the stages whereby data extracted from almost 10 000 original Inquisitiones Post Mortem, dating from 1300 to 1349, are ultimately transformed into a national land-use classification map for the critical period immediately prior to the Black Death of 1348. 相似文献
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The aim of FLOODNET is to provide a communications and data distribution facility specifically designed to meet the demanding temporal requirements of flood monitoring within the European Union (EU). Currently, remotely sensed data are not fully utilized for flood applications because potential users are not familiar with the procedure for acquiring the data and do not have a defined route for obtaining help in processing and interpreting the data. FLOODNET will identify the potential user groups within the EU and will, by demonstration, education and the use of telematics, increase the awareness of users to the capabilities of earth observation (EO) and the means by which they can acquire EO data. FLOODNET will act as a filter between users and satellite operation planners to help assign priorities for data acquisition against previously agreed criteria. The network will encourage a user community and will facilitate cross-sector information transfer, particularly between ‘flood experts’ and administrative decision makers. The requirement for two levels of flood mapping is identified: (1) a rapid, ‘broad-brush’ approach to assess the general flood situation and identify areas at greatest risk and in need of immediate assistance; (2) a detailed mapping approach, less critical in time, suitable for input to hydrological models or for flood risk evaluation. A likely networking technology is outlined, the basic functionality of a FLOODNET demonstrator is described and some of the economic benefits of the network are identified. © 1997 John Wiley & Sons, Ltd. 相似文献
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KEN TREMAINE 《New Zealand geographer》2000,56(2):42-46
This was the Second Annual Lecture of the Auckland Branch of the New Zealand Geographical Society. It was delivered at the University of Auckland on 12 October 1999. The Annual Lecture is intended as a contribution to debate about significant issues or developments of immediate or potential interest to Aucklanders. 相似文献
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