IR calibrations for water determination in olivine,r-GeO<Subscript>2</Subscript>, and SiO<Subscript>2</Subscript> polymorphs     

Sylvia-Monique?ThomasEmail author  Monika?Koch-Müller  Patrick?Reichart  Dieter?Rhede  Rainer?Thomas  Richard?Wirth  Stanislav?Matsyuk 《Physics and Chemistry of Minerals》2009,36(9):489-509

Mineral-specific IR absorption coefficients were calculated for natural and synthetic olivine, SiO₂ polymorphs, and GeO₂ with specific isolated OH point defects using quantitative data from independent techniques such as proton–proton scattering, confocal Raman spectroscopy, and secondary ion mass spectrometry. Moreover, we present a routine to detect OH traces in anisotropic minerals using Raman spectroscopy combined with the “Comparator Technique”. In case of olivine and the SiO₂ system, it turns out that the magnitude of ε for one structure is independent of the type of OH point defect and therewith the peak position (quartz ε = 89,000 ± 15,000  \textl \textmol_{\textH2\textO}^-1 \textcm^-2\text{l}\,\text{mol}_{{\text{H}_2}\text{O}}^{-1}\,\text{cm}^{-2}), but it varies as a function of structure (coesite ε = 214,000 ± 14,000  \textl \textmol_{\textH2\textO}^-1 \textcm^-2\text{l}\,\text{mol}_{{\text{H}_2}\text{O}}^{-1}\,\text{cm}^{-2}; stishovite ε = 485,000 ± 109,000  \textl \textmol_{\textH2\textO}^-1 \textcm^-2\text{l}\,\text{mol}_{{\text{H}_2}\text{O}}^{-1}\,\text{cm}^{-2}). Evaluation of data from this study confirms that not using mineral-specific IR calibrations for the OH quantification in nominally anhydrous minerals leads to inaccurate estimations of OH concentrations, which constitute the basis for modeling the Earth’s deep water cycle.  相似文献   

Empirical Relationships for Debris Flows   总被引：40，自引：10，他引：30  

Rickenmann  Dieter 《Natural Hazards》1999,19(1):47-77

The assessment of the debris flow hazard potential has to rely on semi-quantitative methods. Due to the complexity of the debris-flow process, numerical simulation models of debris flows are still limited with regard to practical applications. Thus, an overview is given of empirical relationships that can be used to estimate the most important parameters of debris-flow behavior. In a possible procedure, an assessment of a maximum debris-flow volume may be followed by estimates of the peak discharge, the mean flow velocity, the total travel distance, and the runout distance on the fan. The applicability of several empirical equations is compared with available field and laboratory data, and scaling considerations are used to discuss the variability of the parameters over a large range of values. Some recommendations are made with regard to the application of the presented relationships by practicing engineers, apart from advocating field reconnaissance and searching for historic events wherever possible.  相似文献   

Internal morphology, habit and U-Th-Pb microanalysis of amphibolite-to-granulite facies zircons: geochronology of the Ivrea Zone (Southern Alps)   总被引：52，自引：2，他引：50  

Gerhard Vavra  Rolf Schmid  Dieter Gebauer 《Contributions to Mineralogy and Petrology》1999,134(4):380-404

Several types of growth morphologies and alteration mechanisms of zircon crystals in the high-grade metamorphic Ivrea Zone (IZ) are distinguished and attributed to magmatic, metamorphic and fluid-related events. Anatexis of pelitic metasediments in the IZ produced prograde zircon overgrowths on detrital cores in the restites and new crystallization of magmatic zircons in the associated leucosomes. The primary morphology and Th-U chemistry of the zircon overgrowth in the restites show a systematic variation apparently corresponding to the metamorphic grade: prismatic (prism-blocked) low-Th/U types in the upper amphibolite facies, stubby (fir-tree zoned) medium-Th/U types in the transitional facies and isometric (roundly zoned) high-Th/U types in the granulite facies. The primary crystallization ages of prograde zircons in the restites and magmatic zircons in the leucosomes cannot be resolved from each other, indicating that anatexis in large parts of the IZ was a single and short lived event at 299 ± 5 Ma (95% c. l.). Identical U/Pb ages of magmatic zircons from a metagabbro (293 ± 6 Ma) and a metaperidotite (300 ± 6 Ma) from the Mafic Formation confirm the genetic context of magmatic underplating and granulite facies anatexis in the IZ. The U-Pb age of 299 ± 5 Ma from prograde zircon overgrowths in the metasediments also shows that high-grade metamorphic (anatectic) conditions in the IZ did not start earlier than 20 Ma after the Variscan amphibolite facies metamorphism in the adjacent Strona–Ceneri Zone (SCZ). This makes it clear that the SCZ cannot represent the middle to upper crustal continuation of the IZ. Most parts of zircon crystals that have grown during the granulite facies metamorphism became affected by alteration and Pb-loss. Two types of alteration and Pb-loss mechanisms can be distinguished by cathodoluminescence imaging: zoning-controlled alteration (ZCA) and surface-controlled alteration (SCA). The ZCA is attributed to thermal and/or decompression pulses during extensional unroofing in the Permian, at or earlier than 249 ± 7 Ma. The SCA is attributed to the ingression of fluids at 210 ± 12 Ma, related to hydrothermal activity during the breakup of the Pangaea supercontinent in the Upper Triassic/Lower Jurassic. Received: 7 July 1998 / Accepted: 4 November 1998  相似文献   

Sorption and Chemical Reactions of PAHs with Dissolved Humic Substances and Related Model Polymers     

Frank‐Dieter Kopinke  Anett Georgi  Katrin Mackenzie 《洁净——土壤、空气、水》2001,28(7):385-399

Sorption coefficients measured for PAHs on dissolved humic substances by SPME and FQT were found to be inevitably different and method‐dependent – SPME provides activity‐based and FQT concentration‐based sorption coefficients. Poly(acrylic acid) esters as well‐defined model polymers were used in sorption experiments, leading to the conclusion that short aliphatic chains are more effective in binding PAHs than aromatic moieties. FQT was inappropriate to measure sorption coefficients for the interaction of pyrene with poly(acrylic acid) esters but the experiments revealed a characteristic shift in the fluorescence spectrum. Using pyrene as a probe for the molecular environment in the sorbed state, the observed spectral shift indicated a highly hydrophobic microenvironment. The empirical relationships between lg K_DOC and lg K_OW were generalized on the basis of a modified Flory‐Huggins concept. Introducing only one sorbent‐specific parameter, the solubility parameter δ_DOM, the calculation of sorption coefficients became possible for a wide range of HOCs using fundamental data readily available from the literature. Long‐term experiments showed that reactive PAHs (such as acenaphthylene and 9‐methylanthracene) are able to react with HAs under strictly abiotic and anoxic conditions, whereas less reactive PAHs (such as naphthalene and dihydroanthracene) do not form bound residues. The HA reveals two functions in the interaction, behaving as a reaction partner and as a protecting ligand.  相似文献   

Prograded foredunes of Western Australia's macro‐tidal coast – implications for Holocene sea‐level change and high‐energy wave impacts          下载免费PDF全文

Max Engel  Simon Matthias May  Anja Scheffers  Peter Squire  Anna Pint  Dieter Kelletat  Helmut Brückner 《地球表面变化过程与地形》2015,40(6):726-740

The Holocene evolution of the Canning Coast of Western Australia has largely been overlooked so far mainly due to its remoteness and low population density. We report on new data from a sequence of foredunes inside the macro‐tidal Admiral Bay, 110 km southwest of Broome. Based on sediment cores, differential global positioning system (dGPS)‐based elevation transects, and stratigraphical analyses on outcrops of the relict foredunes, we aim at reconstructing Holocene coastal changes and relative sea levels (RSLs), as well as identifying and dating imprints of extreme‐wave events. Sedimentary analyses comprise the documentation of bedding structures, foraminiferal content and macrofaunal remains, grain size distribution, and organic matter. The chronological framework is based on 26 carbon‐14 accelerator mass spectrometry (¹⁴C‐AMS) datings. Marine flooding of the pre‐Holocene surface landward of the 2.5 km‐wide foredune barriers occurred 7400–7200 cal bp , when mangroves colonized the area. After only 200–400 years, a high‐energy inter‐tidal environment established and prevailed until c. 4000 cal bp , before turning into the present supralittoral mudflat. During that time, coastal regression led to beach progradation and the formation of aligned foredunes. Drivers of progradation were a stable RSL or gradual RSL fall after the mid‐Holocene and a positive sand budget. The foredunes overlie upper beach deposits located up to >2 m above the present upper beach level and provide evidence for a higher mid‐Holocene RSL. Discontinuous layers of coarse shells and sand are intercalated in the foredunes, indicating massive coastal flooding events. One such layer was traced over three dune ridges and dated to c. 1700–1550 cal bp . However, it seems that most tropical cyclones induce net erosion rather than deposition at aligned foredunes and thus, they are only suitable for reconstructing temporal variability if erosional features or sedimentation reliably tied to these events can be identified and dated accurately. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Morphodynamics of steep mountain channels          下载免费PDF全文

Francesco Brardinoni  Luca Mao  Alain Recking  Dieter Rickenmann  Jens M. Turowski 《地球表面变化过程与地形》2015,40(11):1560-1562

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Removal of uranium(VI) from the aqueous phase by iron(II) minerals in presence of bicarbonate     

Simona Regenspurg  Dieter Schild  Thorsten Schfer  Florian Huber  Maria E. Malmstrm 《Applied Geochemistry》2009,24(9):1617-1625

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Compositional zoning of garnet porphyroblasts from the polymetamorphic Wölz Complex, Eastern Alps     

Martina Bestel  Timo Gawronski  Rainer Abart  Dieter Rhede 《Mineralogy and Petrology》2009,97(3-4):173-188

We employ garnet isopleth thermobarometry to derive the P–T conditions of Permian and Cretaceous metamorphism in the Wölz crystalline Complex of the Eastern Alps. The successive growth increments of two distinct growth zones of the garnet porphyroblasts from the Wölz Complex indicate garnet growth in the temperature interval of 540°C to 560°C at pressures of 400 to 500 MPa during the Permian and temperatures ranging from 550°C to 570°C at pressures in the range of 700 to 800 MPa during the Cretaceous Eo-Alpine event. Based on diffusion modelling of secondary compositional zoning within the outermost portion of the first garnet growth zone constraints on the timing of the Permian and the Eo-Alpine metamorphic events are derived. We infer that the rocks remained in a temperature interval between 570°C and 610°C over about 10 to 20 Ma during the Permian, whereas the high temperature stage of the Eo-Alpine event only lasted for about 0.2 Ma. Although peak metamorphic temperatures never exceeded 620°C, the prolonged thermal annealing during the Permian produced several 100 µm wide alteration halos in the garnet porphyroblasts and partially erased their thermobarometric memory. Short diffusion profiles which evolved around late stage cracks within the first garnet growth zone constrain the crack formation to have occurred during cooling below about 450°C after the Eo-Alpine event.  相似文献   

南海张裂过程及其对晚中生代以来东南亚构造的启示——IODP建议书735-Full介绍   总被引：2，自引：1，他引：1  

李春峰  汪品先  Dieter Franke  李家彪  许树坤  Peter Michael  周祖翼  翦知湣  李前裕  刘志飞  耿建华  木村学  阎贫  丘学林  王嘹亮  解习农  吴时国  吴能友 《地球科学进展》2009,24(12):1339-1351

南海的形成揭示了大陆边缘张裂和盆地形成的复杂模式,尽管已经进行了广泛研究,但是关于基底岩石和深海盆沉积层的精确年代数据还很缺乏,这使得对南海张裂年代的估计存在很大的误差,对张裂机制和历史的各种假设没有得到验证.同时只有对南海的张裂过程有了精确地分析与刻画,才能更好地理解西太平洋边缘海盆地的形成以及它们在印支块体受印度-欧亚板块碰撞而向东南挤出、青藏高原隆升中可能起到的作用.2009年正式提交的国际综合大洋钻探计划(IODP)建议书735-Full建议在南海深海盆内的4个站位上实施钻探.这4个站位分布在南海盆地4个不同的次级构造单元上(南海东北部、西北次海盆、东部次海盆和西南次海盆),这样的站位设计会确保完成本建议书的整体研究目标,即揭示南海的张裂历史和它对晚中生代以来东南亚构造的启示.位于南海盆地最东北部的站位有助于确定该区域地壳的属性和验证古南海是否存在,位于西北次海盆的站住可能会提供南海的最早张裂年代,另外2个分别位于东部次海盆和西南次海盆的站位将重点确定2个次海盆的绝对年龄、基底矿物成分与磁化率以及2个次海盆的相对张裂次序.这些站位的水深大约在2 910～4 400 m,钻探深度预计到海底以下大约700～2 200 m,总的钻透深度为5 959 m,其中5 359 m穿透沉积层,另外600 m或400 m钻入基底.所有这些站位的位置是由已有的地球物理观测数据所确定,目前计划收集更多的地质与地球物理数据以满足IODP对井位调查数据的要求.  相似文献   

Charcoal as evidence of palaeo‐wildfires in the Late Triassic of SW Germany     

Dieter Uhl  Michael Montenari 《Geological Journal》2011,46(1):34-41

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