Biomass burning in the tropical savannas of Ivory Coast: An overview of the field experiment Fire of Savannas (FOS/DECAFE 91)   总被引：1，自引：0，他引：1  

J. P. Lacaux  J. M. Brustet  R. Delmas  J. C. Menaut  L. Abbadie  B. Bonsang  H. Cachier  J. Baudet  M. O. Andreae  G. Helas 《Journal of Atmospheric Chemistry》1995,22(1-2):195-216

FOS/DECAFE 91 (Fire of Savannas/Dynamique et Chimie Atmosphérique en Forêt Equatoriale) was the first multidisciplinary experiment organized in Africa to determine gas and aerosol emissions by prescribed savanna fires. The humid savanna of Lamto in Ivory Coast was chosen for its ecological characteristics representative of savannas with a high biomass density (900 g m^–2 dry matter). Moreover the vegetation and the climate of Lamto have been studied for more than twenty years. The emission ratios (X/CO₂) of the carbon compounds (CO₂, CO, NMHC, CH₄, PAH, organic acids and aerosols), nitrogen compounds (NO_x, N₂O, NH₃ and soluble aerosols) and sulfur compounds (SO₂, COS and aerosols) were experimentally determined by ground and aircraft measurements. To perform this experiment, 4 small plots (100×100 m) and 2 large areas (10×10 km) were prepared and burnt in January 1991 during the period of maximum occurrence of fires in this type of savanna. The detailed ecological study shows that the carbon content of the vegetation is constant within 1% (42 g C for 100 g of vegetal dry matter), the nitrogen content (0.29 g N for 100 g of dry matter) may vary by 10% and the sulfur content (0.05 g S/100 d.m.) by 20%. These variations of the biomass chemical content do not constitute an important factor in the variation of the gas and particle emission levels. With the emission ratios characteristic of humid savanna and flaming conditions (CO/CO₂ of 6.1% at the ground and 8% for airborne measurements), we propose a set of new emission factors, taking into account the burning efficiency which is about 80%: 74.4% of the carbon content of the savanna biomass is released to the atmosphere in the form of CO₂, 4.6% as CO, 0.2% as CH₄, 0.5% as NMHC and 0.7% as aerosols. 17.2% of the nitrogen content of the biomass is released as NO_x, 3.5% as N₂O, 0.6% as NH₃ and 0.5% as soluble aerosols.  相似文献   

Stable boundary layers: observations,models and variability part II: Data analysis and averaging effects     

S. H. Derbyshire 《Boundary-Layer Meteorology》1995,75(1-2):1-24

As argued in Part I (Derbyshire, 1995), variability is a key issue in stable boundary layers, and differences in variability between observations and idealized models may imply sytematic biases. Here we discuss how data analysis can be geared to allow for variability and thus consistency with models. Instrumental errors, smoothing methods and vertical discretization are considered. We then show how statistical averaging broadly improves the agreement of heterogeneous results in Part I with the Brost-Wyngaard closure. Recommendations are made for the information needed to analyze apparent differences between homogeneous and heterogeneous stable boundary layers.Part of UK Meteorological Office Atmospheric Processes Research Division  相似文献   

A fast response,open path,infrared hygrometer,using a semiconductor source     

A. E. Green  W. Kohsiek 《Boundary-Layer Meteorology》1995,74(4):353-370

Investigations were carried out as to the feasibility of using a semiconductor source in the design of a new rapid response, open-path hygrometer. A single-beam instrument was constructed employing an infrared light emitting diode (LED) as a source instead of the usual high energy, wideband filament. The spectral emission envelope encompassed the 1.87 m water absorption band. Electronic modulation and thermoelectrical cooling of the diode eliminated the conventional chopper wheel and stabilized the peak wavelength emission. Path length was 200 mm. Over a water vapour concentration range of 0–16 g m^–3, absorption varied by 2% in a linear fashion. At 10 Hz, the noise level was 0.1 g m^–3 rms. Hygrometer resolution and stability are constrained by the detector noise level, the small source emission in the absorption band and low frequency drift in the optical filter. Despite these problems, the new instrument showed comparable performance characteristics to a commercial Lyman- hygrometer. Latent heat fluxes measured with both instruments and a Kaijo-Denki, 3-D sonic anemometer agreed to within 4% over a range 0–350 W m^–2. Further improvements in performance can be anticipated with advances in detector and LED technology.  相似文献   

A multifractal analysis of lidar measured water vapour     

J. E. Pinzón  C. E. Puente  M. B. Parlange  W. Eichinger 《Boundary-Layer Meteorology》1995,76(4):323-347

Accurate and fast-response measurements of space-time observations of specific humidity were made above a drying land surface at the University of California at Davis, using the Los Alamos water Raman-lidar. In an attempt to quantify the space-time intermittency features of turbulent flows in the lower atmosphere, a multifractal analysis of these water vapour measurements was performed. The structure of the specific humidity, (x, t), was analyzed quantifying a scalar gradient measure both in time and space, for all possible one-dimensional cuts, i.e. and . The results confirm the multifractal nature of this scalar gradient measure (a type of scalar dissipation rate) and show that humidity measurements at fixed times (x) are more intermittent (e.g. have less entropy dimension) than those at fixed locations in space (t). Similar multifractal behaviour of the spatial data, with and without a transformation from the observed wind velocities, supports the validity of Taylor's hypothesis for the studied fields.  相似文献   

Particulate content of savanna fire emissions   总被引：9，自引：0，他引：9  

Hélène Cachier  Catherine Liousse  Patrick Buat-Menard  Annie Gaudichet 《Journal of Atmospheric Chemistry》1995,22(1-2):123-148

As part of the FOS-DECAFE experiment at Lamto (Ivory Coast) in January 1991, various aerosol samples were collected at ground level near prescribed fires or under local background conditions, to characterize the emissions of particulate matter from the burning of savanna vegetation. This paper deals with total aerosol (TPM) and carbon measurements. Detailed trace element and polycyclic hydrocarbon data are discussed in other papers presented in this issue.Near the fire plumes, the aerosols from biomass burning are primarily of a carbonaceous nature (C%70% of the aerosol mass) and consist predominantly of submicron particles (more than 90% in mass.) They are characterized by their organic nature (black to total carbon ratio Cb/Ct in the range 3–20%) and their high potassium content (K/Cb0.6). These aerosols undergo aging during their first minutes in the atmosphere causing slight alterations in their size distribution and chemical composition. However, they remain enriched in potassium (K/Cb=0.21) and pyrene, a polycyclic aromatic hydrocarbon, such that both of these species may be used as tracers of savanna burning aerosols. We show that during this period of the year, the background atmosphere experiences severe pollution from both terrigenous sources and regional biomass burning (44% of the aerosol). Daynight variations of the background carbon concentrations suggest that fire ignition and spreading occur primarily during the day. Simultaneous TPM and CO₂ real-time measurements point to a temporal and spatial heterogeneity of the burning so that the ratio of the above background concentrations (TPM/CO₂) varies from 2 to 400 g/kg C. Smoldering processes are intense sources of particles but particulate emissions may also be important during the rapidly spreading heading fires in connection with the generation of heavy brown smoke. We propose emission factor values (EF) for aerosols from the savanna biomass burning aerosols: EF (TPM)=11.4±4.6 and 69±25 g/kg C_{dry plant} and EF(Ct)=7.4±3.4 and 56±16 g C/kg C_{dry plant} for flaming and smoldering processes respectively. In these estimates, the range of uncertainty is mostly due to the intra-fire variability. These values are significantly lower than those reported in the literature for the combustion of other types of vegetation. But due to the large amounts of vegetation biomass being burnt in African savannas, the annual flux of particulate carbon into the atmosphere is estimated to be of the order of 8 Tg C, which rivals particulate carbon emissions from anthropogenic activities in temperate regions.  相似文献   

Geology of the volcanic-hosted Brockman rare-metals deposit,Halls Creek Mobile Zone,northwest Australia. l. Volcanic environment,geochronology and petrography of the Brockman volcanics     

Dr. W. R. Taylor  R. W. Page  G. Esslemont  N. M. S. Rock  D. I. Chalmers 《Mineralogy and Petrology》1995,52(3-4):209-230

Summary Rare-metals mineralization of the Brockman deposit (Halls Creek Mobile Zone, NW Australia) is hosted in a fluorite-bearing, rhyolitic volcaniclastic unit informally termed the Niobium Tuff. The Tuff, more correctly described as a tuffaceous volcaniclastic deposit, is the lowermost unit of a sequence of trachyte-to-rhyolite lavas, trachyandesite subvolcanic rocks, and volcaniclastic units of the Brockman volcanics located within the Halls Creek Group, a thick, early Proterozoic volcano-sedimentary sequence. High precision SHRIMP ion-microprobe zircon dating of the Niobium Tuff gives an eruption age of 1870 ± 4 Ma. Regional geochronological constraints indicate the Niobium Tuff was deposited about 15 Ma before major orogenic activity affected the area. Despite folding, faulting and low-grade metamorphism, the Brockman volcanics show excellent preservation of primary volcanological features, including pillow-lavas and pillow-breccias, that suggest a dominantly subaqueous, below-wave-base emplacement environment. The style of eruption products and magma volume constraints suggest the trachyte-dominated volcanics were erupted from a small shield volcanic complex probably in a rift-related basin in a shallow-marine setting. The tectonic setting was intraplate but differs from most Tertiary to recent trachyte volcanic complexes which are largely subaerial, are built on relatively thick continental crust, and show no post-eruptive orogenic history. Brockman-style rare-metal deposits are characterized by preservation of subaqueous volcanics beneath a thick sedimentary sequence, eruption of early incompatible-element enriched products followed by less differentiated magmas, and fine-grained mineralogy influenced by alteration processes. Prospects exist for discovery of analogous deposits, particularly in early Proterozoic mobile belts and Tertiary intraplate shield volcanic provinces.

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Geologie der an Vulkanite gebundenen Seltene-Metalle-Lagerstätte Brockman, Halls Creek Mobile Zone, Nordwest-Australien. I. Vulkanologie, Geochronologie und Petrographie der Brockman-Vulkanite

Zusammenfassung Selten-Metall-Vererzung der Brockman-Lagerstätten (Halls Creek Mobile Zone, NW Australien) sitzt in einer Fluorit-führenden, rhyolitischen vulkanoklastischen Einheit auf, die informell als der Niob-Tuff bezeichnet wird. Es handelt sich hier um ein vulkanoklastisches Tuff-Sediment; dieses ist die unterste Einheit einer Abfolge vor Trachyt bis Rhyolit-Laven, trachyandesitischen Subvulkaniten and vulkanoklastischen Einheiten der Brockman Vulkanite innerhalb der Halls Creek Gruppe, einer mächtigen frühproterozoischen vulkanosedimentdren Abfolge. Prüzisionsdatierungen des Niob Tuffs mit der SHRIMP Ionen-Mikrosonde ergeben ein Eruptionsalter von 1870 +-4 Millionen Jahren. Regionale geochronologische Zusammenhänge zeigen, daß der Niob Tuff etwa 15 Millionen Jahre vor einer größeren Orogenese, die das Gebiet betroffen hat, abgelagert wurde. Trotz Faltung, Bruchtektonik and niedriggradiger Metamorphose zeigen die Brockman-Vulkanite einen hervorragenden Erhaltungszustand primärer vulkanologischer Erscheinungen. Diese urnfassen auch Kissenlaven und KissenBreckzien, die eine vorwiegend subaquatische Ablagerung in ruhigem Wasser erkennen lassen. Die Art der Eruptionsprodukte and das Magmavolumen zeigen, daß die Trachytdominierten Vulkanite von einem kleinen Schildvulkan stammer, wahrscheinlich in einem Becken in einer Rift-Situation im seichten marinen Milieu. Die tektonische Situation war intraplate, aber unterscheidet sich von den meisten tertiären bis rezenten trachytischen Vulkan-Komplexen, die hauptsächlich subaerisch sind, auf einer relativ mächtigen kontinentalen Kruste aufsitzen, and keine post-eruptive orogene Entwicklung zeigen. Seltene-Metalle-Lagerstatten des Brockman-Typs rind durch die Erhaltung subaquatischer-Vulkanite unterhalb einer machtigen sedimentdren Abfolge gekennzeichnet; welters durch frühe Eruptionsprodukte, die an inkompatiblen Elementen angereichert sind, auf die dann weniger differenzierte Magmen folgten, und schließlich durch einen feinkörnigen Mineralbestand, der vor Umwandlungsprozessen betroffen war. Es besteht die Möglichkeit der Entdeckung analoger Lagerstätten, besonders in frühproterozoischen mobilen Gürteln und in tertidren intraplate Schildvulkan Provinzen.

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Deceased  相似文献   

Early miocene post-collisional calc-alkaline magmatism along the easternmost segment of the periadriatic fault system (Slovenia and Croatia)   总被引：1，自引：0，他引：1  

Dr. R. Altherr  Dr. B. Lugović  Dr. H. -P. Meyer  Dr. V. Majer 《Mineralogy and Petrology》1995,54(3-4):225-247

Summary Early Miocene calc-alkaline igneous rocks from the easternmost segment of the Periadriatic fault system can be subdivided into two series of different alkalinity: (1) Volcanics which occur in the vicinity of the Velenje-Rogatec Line range from high-alumina basalt via low-K and medium-K andesites to medium-K dacites. (2) In the Pohorje Mountains mafic rocks are lacking. A high-K tonalitic pluton crystallized at pressures of about 0.7 GPa as indicated by Al-in-hornblende barometry and accessory magmatic epidote. Rapid exhumation of the tonalite during dextral transtension along the Periadriatic fault system is indicated by tonalitic pebbles in Helvetian (?) clastic sediments. High-K andesitic to dacitic volcanics are interlayered with, and dikes cut, the clastic sediments.Compositional variations shown by the volcanics from the Velenje-Rogatec Line are consistent with fractionation of the observed phenocryst assemblages (olivine, plagioclase, clinopyroxene, orthopyroxene, titanomagnetite). Substantial fractionation of plagioclase is indicated by decreasing Sr/Nd and Sr/Y values and increasing negative Eu anomalies with increasing SiO₂. All samples have chondrite-normalized HREE > 9.6 and low (Tb/Yb)_n ratios (1.29–1.08). With increasing SiO₂, the abundances of HREE and Y (18 to 39 ppm) increase and those of Sc (32.5 to 20.9 ppm) decrease slightly. These features, together with low Hf/Lu and Zr/Y values (10.1–5.7 and 5.7–3.6, respectively), rule out garnet as a major fractionating phase. Since (La/Yb)_n values (3.24–6.59) do not increase with SiO₂ and chondrite-normalized REE patterns do not show concave-upward shapes, fractionation of amphibole was probably insignificant. Although Rb/Cs values ( 18) are generally low, a significant contribution by continental crustal materials to the magmas by an AFC process is suggested by negative correlations of Nb/U(7.16 to 3.14) and Nb/Th(2.14 to 0.87) values with SiO₂, as well as by low Hf/Ta(7.8–3.4), and in part also by K/Rb (340-71) and Zr/Rb (5.0–1.7) values.Rocks from the Pohorje Mountains have high abundances of U. Values of Nb/U and Nb/Th are low (3.55 to 1.85 and 1.27 to 0.64, respectively) and are negatively correlated with SiO₂. These features, in combination with high values of Ba/Nb (56 to 93), Ba/La (23–30), and Rb/Cs (19–56), as well as with previously published ¹⁸O values ( 9) for the tonalite indicate a substantial contribution of the continental crust to these magmas. High Sr abundances (455 to 984 ppm) and moderate negative Eu anomalies suggest that fractionation of plagioclase was of minor importance. Although the rocks have relatively low Sc (9.3 to 3.8 ppm) and Y (21 to 14 ppm) contents, low (Tb/Yb)_n values (1.67–1.14) indicate that garnet was not a major fractionating phase. Instead, fractionation of amphibole is a viable mechanism to explain the combination of high (La/Yb)_n (21.8–13.1) and low (Tb/Yb)_n.

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Untermiozäner, kalkalkaliner Post-Kollisions-Magmatismus entlang des östlichsten Segmentes des periadriatischen Störungssystems (Slowenien und Kroatien)

Zusammenfassung Untermiozäne Kalkalkali-Magmatite aus dem östlichen Bereich des Periadriatischen Lineaments gliedern sich in zwei Serien unterschiedlicher Alkalinität: (1) Entlang der Velenje-Rogatec-Linie treten High-Al-Basalte, Low-K- und Medium-K-Andesite und Medium-K-Dazite auf. (2) Im Pohorje-Gebirge, wo basische Magmatite fehlen, kristallisierte ein High-K-Tonalit bei Drücken von ca. 0.7 GPa (Al-in-Hornblende-Barometer, magmatischer Epidot). Gerölle dieses Tonalits in einer untermiozänen (Helvet?) klastischeu Abfolge belegen eine schnelle Heraushebung des Tonalits durch dextrale Transtension im östlichsten Bereich des periadriatischen Lineaments. Eingeschaltet in die klastischen Sedimente sind andesitische bis dazitische Pyroklastika und Laven sowie diskordante dazitische Gänge, die alle der High-K-Serie angehören.Die chemische Variation innerhalb der Vulkanitserie von der Velenje-Rogatec-Linie läßt sich durch Fraktionierung der Einsprenglingsminerale Olivin, Plagioklas, Klinopyroxen, Orthopyroxen und Titanomagnetit erklären. Abnehmende Sr/Nd- und Sr/Y-Werte und zunehmende negative Eu-Anomalien mit steigendem SiO₂ weisen auf eine bedeutende Plagioklas-Fraktionierung hin. Alle Vulkanite besitzen hohe Gehalte an schweren Seltenen Erden (chondritnormiert > 9.6) und geringe (Tb/Yb)_n-Werte (1.29–1.08). Mit zunehmendem SiO₂ nehmen die Gehalte an Yb(2.02 bis 4.30 ppm) und Y(18 bis 39 ppm) zu, während die Sc-Gehalte (32.5 bis 20.9 ppm) nur geringfügig abnehmen. Diese Charakteristika, zusammen mit geringen Hf/Lu- und Zr/Y-Werten (10.1–5.87 bzw. 5.7–3.6), schließen Granat als wesentliche, fraktionierende Phase aus. Da die (La/Yb)_n-Verhältnisse (3.24–6.59) nicht mit SiO₂ korrelieren und die chondritnormierten SeltenenErden-Muster keine nach oben konkaven Formen aufweisen, spielte die Fraktionierung von Amphibol keine wesentliche Rolle. Trotz geringer Rb/Cs-Werte ( 18) wird eine beträchtliche krustale Kontamination der Magmen angenommen. Für einen AFC-Prozeß sprechen negative Korrelationen von Nb/U(7.16–3.14) und Nb/Th(2.14–0.87) mit SiO₂ (bei steigenden Nb-, U- und Th-Gehalten), geringe Hf/Ta-Werte (7.8–4.3) und teilweise auch geringe K/Rb- (340-71) und Zr/Rb-Verhältnisse (5.0–1.7).Die Magmatite des Pohorje-Gebirges weisen hohe U-Gehalte sowie geringe Nb/U-und Nb/Th-Verhältnisse auf (3.55–1.85 bzw. 1.27–0.64), die eine schwache negative Korrelation mit SiO₂ zeigen. Zusammen mit hohen Ba/Nb-(56–93), Ba/La-(23-30) und Rb/Cs-Verhältnissen (19–56) sowie bereits publizierten ⁸O-Werten ( 9) weisen diese Eigenschaften auf einen beträchtlichen Anteil assimilierten Krustenmaterials in den Magmen hin. Hohe Sr-Gehalte (455–984 ppm) und relativ geringe negative Eu-Anomalien machen es unwahrscheinlich, daß während des AFC-Prozesses in der Unterkruste wesentliche Mengen an Plagioklas fraktioniert wurden. Obwohl die Gehalte an Sc (9.3–3.8 ppm) und Y (21–14 ppm) relativ gering sind, scheidet Granat aufgrund der geringen (Tb/Yb)_n- Verhältnisse (1.67–1.14) als dominierende Fraktionierungsphase aus. Die Kombination von hohen (La/Yb)_n- Verhältnissen (21.8–13.1) und geringen (Tb/Yb)_n-Verhältnissen deutet eher auf Amphibol als wichtige, fraktionierende Phase hin.

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Textures exhibited by feldspars in the Giant Mottled Anorthosite (GMA) of the bastard unit in the Upper Critical Zone,Western Bushveld Complex     

W. J. de Klerk 《Mineralogy and Petrology》1995,54(1-2):25-34

Summary The Bastard Unit, overlying the Merensky Unit, is the uppermost and most complete of the cyclic units in the Upper Critical Zone and its upper contact is taken as the boundary between the Critical and Main Zones (as recommended by SACS, 1980). The Unit is different from underlying units for three reasons: it does not have a well-defined top contact (with an overlying unit); it is much thicker than the Merensky and Footwall Units; and it has an unusually thick sequence of mottled anorthosite at its top. This distinctive composite anorthositic sequence is termed the Giant Mottled Anorthosite (GMA) which is predominantly made up of poikilitic anorthosite. The GMA can broadly be subdivided into three distinct parts; the Lower Giant Mottled Anorthosite (LGMA), Giant Mottled Middling (GMM) and the Upper Giant Mottled Anorthosite (UGMA).Petrographic examination of 82 samples taken in the GMA from 11 borehole profiles around the western limb of the Complex revealed that the LGMA and GMM are essentially adcumulates while the UGMA is orthocumulate in character. By its very nature the dominant phase throughout the GMA is cumulus plagioclase feldspar ( 85%) with the balance being made up of intercumulus orthopyroxene and clinopyroxene and minor biofite — all of which constitute the darker mottles. Intercumulus inverted pigeonite occurs in the upper part of the GMM, throughout the UGMA and for c. 30 m into the Main Zone. K-feldspar also joins the paragenesis within the UGMA and occurs both as intercumulus orthoclase and antiperthite. Cumulus plagioclase grains, showing varying degrees of complex oscillatory-zonal growth are common in the upper part of the GMA. These grains are interpreted as records of growth episodes during earlier influxes of magma which were responsible for the development of the underlying cyclic units, but escaped incorporation into the cumulate pile.

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Feldspat-Texturen im Giant Mottled Anorthosite der Bastard-Einheit in der oberen kritischen Zone des westlichen Bushveld-Komplexes

Zusammenfassung Die Bastard-Einheit, die die Merensky-Einheit überlagert, ist die oberste und am besten entwickelte der zyklischen Einheiten in der oberen kritischen Zone; ihr oberer Kontakt gilt als die Grenze zwischen der Kritischen und der Main-Zone (entsprechend den Empfehlungen von SACS, 1980). Die Einheit unterscheidet sich aus drei Gründen von den Einheiten im liegenden: sie hat keinen gut definierten oberen Kontakt (mit einer darüberliegenden Einheit), sie ist wesentlich mächtiger als die Merensky und die Footwall-Einheiten, und sie hat eine ungewöhnliche mächtige Abfolge von Mottled Anorthosite als obersten Teil der Abfolge. Diese wohldefinierte anorthositische Abfolge wird als Giant Mottled Anorthosite (GMA) bezeichnet, und besteht hauptsächlich aus poikilitischem Anorthosit. Die GMA kann in 3 Teile, den unteren (LGMA), den mittleren (GMM) un den oberen (UGMA) unterteilt werden.Die petrographische Untersuchung von 82 Proben in der GMA aus 11 Bohrlöchern im Westteil des Bushveld-Komplexes zeigt, daß LGMA und GMM im wesentlichen Adkumulate sind, während die UGMA ein Orthokumulat darstellt. Die Hauptphase in der gesamten GMA ist Kumulus-Plagioklas ( 85 %); der Rest besteht aus Intercumulus-Orthopyroxen, Klinopyroxen, und geringen Mengen von Biotit. Diese sind die Komponenten der dunkleren mottles. Intercumulus invertierter Pigeonit kommt im oberen Teil der GMM, in der gesamten UGMA und in den unteren 30 Metern der Main-Zone vor. Innerhalb der UGMA tritt K-Feldspat hinzu, dieser kommt als Intercumulus Orthoklas und Antiperthit vor. Körner von Cumulusplagioklas mit verschiedenen Intensitäten komplexer Zonierung sind im oberen Teil der GMA verbreitet. Diese Körner werden als Hinweise auf Wachstumsepisoden während früherer Magmenzufuhr-Phasen interpretiert, die für die Entwicklung der zyklischen Einheiten im Liegenden verantwortlich waren, aber selbst nicht Teil der Cumulatabfolge wurden.

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Characterizing heterogeneous permeable media with spatial statistics and tracer data using sequential simulated annealing     

Akhil Datta-Gupta  Larry W. Lake  Gary A. Pope 《Mathematical Geology》1995,27(6):763-787

Characterizing heterogeneous permeable media using flow and transport data typically requires solution of an inverse problem. Such inverse problems are intensive computationally and may involve iterative procedures requiring many forward simulations of the flow and transport problem. Previous attempts have been limited mostly to flow data such as pressure transient (interference) tests using multiple observation wells. This paper discusses an approach to generating stochastic permeability fields conditioned to geologic data in the form of a vertical variogram derived from cores and logs as well as fluid flow and transport data, such as tracer concentration history, by sequential application of simulated annealing (SA). Thus, the method incorporates elements of geostatistics within the framework of inverse modeling. For tracer-transport calculations, we have used a semianalytic transit-time algorithm which is fast, accurate, and free of numerical dispersion. For steady velocity fields, we introduce a transit-time function which demonstrates the relative importance of data from different sources. The approach is illustrated by application to a set of spatial permeability measurements and tracer data from an experiment in the Antolini Sandstone, an eolian outcrop from northern Arizona. The results clearly reveal the importance of tracer data in reproducing the correlated features (channels) of the permeability field and the scale effects of heterogeneity.  相似文献   

Geochemical and structural evolution of micas in the Rožná and Dobrá Voda pegmatites,Czech Republic     

P. Černý  R. Chapman  J. Staně  M. Nová  H. Baadsgaard  M. Rieder  M. Kavalová  L. Ottolini 《Mineralogy and Petrology》1995,55(1-3):177-201

Summary The chemistry, structural parameters, polytypism, optical properties and Rb-Sr isotopes were examined in 11 to 60 samples of biotite, muscovite and lepidolite from the pegmatites at Roná (the type locality of lepidolite; 323 ± 4Ma) and Dobrá Voda (306 ± 9Ma) in western Moravia. At both localities, early endocontact biotite is followed inwards by muscovite and lepidolite, which is concentrated in and around the core. At Roná, a 1M lepidolite follows after 2M₁ muscovite but all later generations of lepidolite are 2M₂, close to Tri₅₀ Ply₅₀ and in part associated with muscovite 2M₁. At Dobrá Voda, all lepidolite types are 1M and free of muscovite, and the late varieties approximate Tri₃₀ Ply₇₀. At both localities, a trend of increasing HF is indicated during the progress of mica crystallization, culminating in precipitation of topaz. Polytypism of lepidolite is not correlatable with any compositional or growth feature, or their combination. Throughout the mica crystallization, Rb/Cs decreases but K/Rb becomes reversed after an initial decrease. Boron is partitioned preferentially into muscovite (up to 1.10 wt.% B₂O₃) but Be, Zn, Mn and Sc are enhanced in lepidolite. A slight increase in Fe, Ba and Cl in the last generation of lepidolite might be possibly due to mixing of residual pegmatite fluids with metamorphic pore solutions.

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Geochemische und strukturelle Entwicklung der Glimmer in den Pegmatiten von Roná und Dobrá Voda, Tschechische Republik

Zusammenfassung In 11 bis 60 Proben von Biotit, Muskovit und Lepidolith aus den Pegmatiten von Roná (Typlokalität des Lepidoliths; 323 ± 9 Ma) in Westmähren wurden Chemie, Struktur-parameter, Polytypie, optische Eigenschaften und Rb-Sr-Isotopie untersucht. An beiden Lokalitäten wird früher Biotit an Endokontakten nach Innen von Muskovit und Lepidolith gefolgt, letzterer ist in und um den Kern konzentriert. In Roná folgt 1M-Lepidolith auf 2M₁-Muskovit, aber alle späteren Lepidolithgenerationen sind 2M₂, nahe Tri₅₀Ply₅₀ und zum Teil mit 2M₁-Muskovit vergesellschaftet. In Dobrá Voda sind alle Lepidolithe vom Typ 1M und frei von Muskovit, die späten Varietäten kommen Tri₅₀Ply₅₀ nahe. An beiden Lokalitäten ist während des Fortschreitens der Glimmerkristallisation eine Tendenz von steigendem HF angezeigt, die in der Ausfällung von Topas ihren Höhepunkt findet. Die Polytypie des Lepidoliths kann nicht mit irgendeiner Eigenheit der Zusammensetzung oder des Wachstums korreliert worden, auch nicht mit einer Kombination von diesen. Während der ganzen Glimmerkristallisation nimmt Rb/Cs ab, aber die Tendenz von K/Rb ändert sich nach anfänglichem Abfall. Das Bor verteilt sich bevorzugt auf den Muskovit (bis zu 1.10 Gew. -% B₂O₃), aber die Be-, Zn-, Mn- und Sc-Gehalte sind im Lepidolith erhöht. Ein leichter Ansteig von Fe, Ba und Cl in der letzten Lepidolithgeneration könnte vielleicht durch eine Mischung von pegmatitischen Restlösungen mit metamorphen Porenlösungen verursacht sein.

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