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1.
The development of immunodetection method of 2, 2-Bis （4-chlorophenyl） acetic acid （DDA）, the decomposition product of organochlorine insecticide DDT, was performed in this study. DDA was conjugated with bovine serum albumin （BSA） and ovualbumin （OVA） for the use of immunogen to produce antibodies and coating ligands to measure the titration level of antibody and the displacement of free analytes. Evaluation of the antisera by antibody capture assay showed that the antibody titer of antisera raised against DDA-OVA was higher than 1 ： 80000. Using 5#PAb, an indirect competitive enzyme immunoassay was developed for measurement of DDA. The working range for quantitative measurement of DDA and the quantitative limit for DDA were estimated to be 2.5-2000 ng/mL and 2.5 ng/mL for seawater, 12.5 ng/g for shellfish, respectively.  相似文献   

2.
Conceptual geological repositories are generally used for disposing spent nuclear wastes containing both high and low level of nuclear radiation and heat. Due to its long-lasting effect, it is imperative to analyze its long-term effect on the surrounding rock. Before analyzing radiation and thermal effect, it is important to have structurally stable cavern because designing an opening in rock is a more difficult problem than designing the structure made of steel. Underground rocks are under stress because of the weight of the overlying rock, and in addition, an underground opening will produce a stress concentration and stress relaxation in the surrounding rock. If the induced stress in the surrounding rock exceeds its strength, the opening will fail either by fracturing or by deforming more than the tolerable limit. In this paper, the stability of four different shapes of excavation has been examined for conceptual geological repositories in Indian context. This has been done using equivalent continuum numerical model which has been incorporated in the commercial finite difference code-FLAC-3D. Effects of opening shapes on stress distribution, subsidence of crown and side wall, and their stability have been analyzed and discussed. The validation of FLAC3D software for its applicability in conceptual underground geological repositories has been done with a published literature.  相似文献   

3.
In geosciences the necessity of combining geological and geophysical information as well as applying tools for designing 3D geological and geophysical models is well accepted. Nevertheless, in most cases this demand is only put into practice by file transfer between the applications. The creation of a common 3D model is complicated by the inflexible handling of new and reinterpreted data and by changing applications, heterogeneous operating systems and/or hardware platforms. We present a new approach for a component based GIS which is coupled with an object oriented database management system. The original data, as well as the derived data and the 3D models, are stored in the extensible database. Geological and geophysical 3D modeling tools have direct access to the database via the Common Object Request Broker Architecture (COREA). By this means, we obtained both the integration of the software components and independence from changing software applications and changing platforms, finally resulting in an interoperable 3D GIS.  相似文献   

4.
Zusammenfassung Die Sandsteine und Eisenoolithe im Schwäbischen Jura sind im allgemeinen unvollständig verkittet.An der Eisenerzlagerstätte von Geislingen (Steige), einem etwa 2 m mächtigen, langgestreckten Eisenoolithkörper im Oberen Braunen Jura, sind Verkittungserscheinungen besonders auffallend und wurden eingehend untersucht.Die verkitteten Teile können überall im Flözprofil auftreten, insgesamt ist die Verkittung aber oben ausgedehnter als unten. Es wird der Nachweis geführt, daß der Kalkzement primär ± homogen im Profil verteilt war und bei der diagenetischen Mobilisierung vorzugsweise nach oben gewandert ist. Für die Sandsteinhorizonte des Braunen Jura und z. T. des Schwarzen Jura gilt ähnliches.Da der unverkittete Oolith im Korngefüge Setzungserscheinungen zeigt, der verkittete dagegen nicht, läßt sich die Zeit der Verkittung als frühdiagenetisch angeben.Es wird angenommen, daß die Mobilisierung des Kalkzements im Rahmen der Setzungsentwässerung der liegenden Tonschichten erfolgte.Durch Wechsel von Zementation und Erosion ist am Dach des Lagers eine konglomeratische Schicht entstanden. Die Entstehung der konkretionär entstandenen Konglomeratkomponenten wird zu den Verkittungsvorgängen im Flöz in Beziehung gesetzt.  相似文献   

5.
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6.
Zusammenfassung Silurische Riffe von Gotland wurden im Detail untersucht. Es fand Biohermbildung in einem warmen, untiefen, epikontinentalen Flachmeere statt. Verschiedene Typen von Riffen werden beschrieben. Unterschiede zu den heutigen Riffen, dem heutigen reef complex, und den Riffen geosynklinaler Faziesbereiche gegenüber werden diskutiert.  相似文献   

7.
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8.
Summary Early tentative hypotheses, that regional metamorphism may be genetically associated with the formation of mineral deposits are now reasonably confirmed, and the class of metamorphogenic mineral deposits is widely accepted. Two end member models define a range of possibilities occurring in nature: the prograde devolatilization model, and the retrograde leaching model. In the first, the mineralizing fluids are thought to have been generated and to have acquired their solute content within source rocks undergoing prograde metamorphism. Then they flow towards lower pressure zones, possibly accompanied by further reactions with country rocks. Finally, changes in the chemical or physical environment along the flow conduits potentially induce mineral precipitation. Retrograde leaching occurs after peak metamorphism, when a still-hot metamorphic complex is flooded and cooled by waters from outside; this will normally happen during uplift and extensional tectonics, and the resulting convection cells are open to the surface. Metamorphogenic deposits cannot be recognized as such in the field, where they appear as examples of epigenetic hydrothermal mineralization. Only the application of a broad spectrum of laboratory methods allows a correct genetic classification. It is expected that future research will increasingly quantify the evolution of metamorphic terranes through time, similar to modern basin analysis in petroleum geology.
Das Erkenen metamorphogener Lagersätten-eine Einleitung
Zusammenfassung Frühe Beobachtungen über enge Zusammenhänge zwischen regionaler Metamorphose und Lagerstättenbildung wurden in jüngerer Zeit bestätigt, so daß die Klasse der metamorphogenen Lagerstätten nunmehr nahezu gesichert ist. Zwei verschiedene genetische Modelle bilden die Endglieder eines in der Natur vorkommenden Spektrums solcher Lagerstättenbildung: das Modell der prograden Devolatilisierung und das Modell einer retrograden Laugung. Im ersten Fall wurden die lagerstättenbildenden Fluide innerhalb eines Gesteinskörpers gebildet, während dieser eine prograde Metamorphose erlitt; gleichzeitig nahmen die Fluide ihre kennzeichnende Lösungsfracht auf. Danach fließen sie einem Druckgefälle folgend aus dem Bildungsraum ab, z.T. unter weiteren Reaktionen mit Nebengesteinen. Chemische oder physikalische Zustandsänderungen im Verlauf der Fließwege induzieren den Mineralabsatz. Retrograde Laugung hingegen findet statt, wenn ein noch heier metamorpher Komplex nach Durchlaufen der maximalen p/T-Bedingungen durch von außen zufließende Wässer geflutet und abgekühlt wird; dies wird gewöhnlich mit Aufstieg und Dehnungstektonik verbunden sein, weshalb die resultierenden Konvektionszellen zur Oberfläche offen sind. Metamorphogene Lagerstätten können nicht nur mit Feldmethoden als solche erkannt werden, da sie dort einfach als epigenetische hydrothermale Mineralisationen erscheinen. Nur die Anwendung eines breiten Spektrums geeigneter Labormethoden erlaubt eine richtige Zuordnung. Es wird erwartet, daß zukünftige Forschung dadurch wesentliche Fortschritte erzielt, daß die Entwicklung metamorpher Komplexe in Zeit und Raum quantitativ untersucht wird, ähnlich wie jene sedimentärer Becken in der modernen Erdölgeologie.

This paper was presented at the IGCP 291 Project Symposium Metamorphic Fluids and Mineral Deposits, ETH Zürich, March 21–23, 1991.  相似文献   

9.
Over the past two decades, whenever a copy of Journal of Geological Society of lndia has reached my hand, the first thing I have done is read the editorial. No matter what their topics are, these essays are never dull but lively and precise presentations of various earth science issues facing the developing countries and oftentimes the world as well.Coming from the pen of Dr. B. P. Radhakrishna,  相似文献   

10.
Ohne Zusammenfassung  相似文献   

11.
《Gondwana Research》2014,25(1):30-47
The ca. 2.45–2.0 Ga supracratonic record of six cratonic terranes (Superior Province, Hearne Domain, Fennoscandian crustal segment, and São Francisco, Pilbara and Kaapvaal cratons) is investigated. A <~2415–2420 basal unconformity appears pervasive, floored by basement lithologies for the three “Kenorland-related” terranes (Superior, Hearne and Fennoscandian) and by passive margin chemical sedimentary platform deposits for the apparently “non-amalgamated” cratons. Palaeosols are locally associated with this unconformity, and glacigenic lithologies, for all of the “non-amalgamated” cratons as well as for Superior. A relatively complete sedimentary record is recorded for the three Kenorland supercontinent terranes, including at least two glacial events, whereas hiatuses characterise the Pilbara and São Francisco cratons, with an incomplete record for Kaapvaal. Evidence for geodynamic reactivation at ca. 2.2 Ga includes widespread mafic dykes and volcanics, orogenies in Pilbara and São Francisco, glaciation in Kaapvaal and Pilbara, and significant transgressions thereafter on many of the cratonic terranes. While the overall ca. 2.45–2.2 Ga records studied here are at least compatible with the postulated global magmatic slowdown of Condie et al. (2009), distinct differences between the records associated with “Kenorland-related” and “non-amalgamated” cratons might reflect thermal subsidence and associated sedimentation accompanying the slowdown for the former group (where thermal blanketing likely played a role), while elevated freeboard and concomitant erosive regimes accompanied the inferred slowdown for the latter group.  相似文献   

12.
The results of correlation between geological events in the period of 2.8?2.0 Ga provide grounds to assume that the Sarmatia lithospheric megablock definable in the southern part of the East European Craton belonged to the ancient Vaalbara supercontinent consisting of the Pilbara and Kaapvaal cratons. In the period of 2.8?2.6 Ga, all of them represented fragments of the continental crust consolidated at approximately 2.8 Ga and subjected to continental rifting, which was accompanied by intense basite volcanism. In the period of 2.50?2.45 Ga, these three cratons were characterized by similar tectonic settings and accumulation of banded iron formations. Precisely these banded iron formations of the largest Transvaal, Hamersley, Kursk, and Kremenchug?Krivoi Rog iron ore basins accumulated in the period of 2.50?2.45 Ga in a single oceanic basin serve as a basis for adequate paleotectonic reconstructions of the Vaalbara supercontinent. In the period of 2.45?2.20 Ga, all three cratons were subjected to a long-lasting break in sedimentation followed by activation of continental rifting with terrigenous sediment deposition, which terminated with basite volcanism ca. 2.2 Ga. These events gave start to the Vaalbara breakup, which represented a multistage process with alternating divergence and convergence phases of supercontinent fragments until the Kaapvaal and Zimbabwe, Pilbara and Yilgarn, and Sarmatia and Volgo-Uralia cratons, respectively, became eventually united.  相似文献   

13.
Understanding the geologic history and position of the North China craton in the Paleoproterozoic Columbia supercontinent has proven elusive. Paleoproterozoic orogenic episodes (2.00–1.85 Ga) are temporally associated with ultimate stabilization of the North China craton (NCC), followed by the development of extensive craton-wide rift systems at 1.85–1.80 Ga. The age difference between the sedimentary cover and the metamorphic basement is up to 500–700 Ma, suggesting that uplift and doming of cratonic basement occurred in the latest Paleoproterozoic. Mafic dike swarms (1.80–1.77 Ga) and anorogenic magmatism (1.80–1.70 Ga) record the extensional breakup and dispersal of the North China craton during this stage. The late Paleoproterozoic tectonic framework and geological events documented provide important constraints for reconstruction of the NCC within the Late Paleoproterozoic supercontinent of Columbia.An east-west striking thousand kilometer long belt of khondalites (granulite facies metapelites) stretches along the northern margin of the North China craton, on the cratonward side of the Northern Hebei orogenic belt. This granulite belt includes Mg–Al (sapphirine bearing) granulites that reached ultrahigh-temperature “peak” metamorphic conditions of  1000 °C at 10 kbars at 1927 ± 11 Ma. Following peak ultrahigh-temperature conditions, the rocks underwent initial isobaric cooling and subsequent isothermal decompression, and these trajectories are interpreted to be part of an overall anti-clockwise P-T evolution indicating that the northern margin of the craton experienced continental collision at 1.93–1.92 Ga. The position of the khondalite belt south of the Northern Hebei orogenic belt makes it analogous to Tibet, a continental collision-related plateau characterized by double crustal thicknesses and granulite facies metamorphism at depth. We suggest that the tectonic evolution of the NCC during this period was closely related to the assembly and break-up of the Columbia supercontinent, and that the NCC was adjacent to the Baltic and Amazonian cratons in the period 2.00–1.70 Ga. Craton-wide extension occurred within 100–150 Ma of collision along the northern margin of the craton at 1.93–1.92 Ga. It is concluded that mantle upwellings are chiefly responsible for the breakup of the NCC from the Paleoproterozoic supercontinent.  相似文献   

14.
Zegers  de Wit  Dann  & White 《地学学报》1998,10(5):250-259
The only remaining areas of pristine 3.6–2.7 Ga crust on Earth are parts of the Kaapvaal and Pilbara cratons. General similarities of their rock records, especially of the overlying late Archean sequences, suggest that they were once part of a larger Vaalbara supercontinent. Here we show that the present geochronological, structural and palaeomagnetic data support such a Vaalbara model at least as far back as 3.1 Ga, and possibly further back to 3.6 Ga. Vaalbara fragmented prior to 2.1 Ga, and possibly as early as 2.7 Ga, suggesting supercontinent stability of at least 400 Myr, consistent with Neoproterozoic and Phanerozoic analogues.  相似文献   

15.
Based on a new method of paleomagnetic data analysis, a reconstruction of the Kaapvaal, Karelian, Pilbara, and Superia cratons in the Neoarchean was tested. The most likely positions of these cratons within the Kenorland supercontinent, which existed in the Neoarchean, have been proposed. New paleomagnetic data obtained on the basis of the Neoarchean complexes allowed the motion of cratons to be calculated at 4–9 cm per year. The paleomagnetic reconstruction is in good agreement with the structural-geological peculiarities of the coeval complexes.  相似文献   

16.
Northwestern Fujian Province is one of the most important Pre-Palaeozoic areas in the Cathaysia Block of South China. Metavolcano-sedimentary and metasedimentary rocks of different types, ages and metamorphic grades (granulite to upper greenschist facies) are present, and previously were divided into several Formations and Groups. Tectonic contacts occur between some units, whereas (deformed) unconformities have been reported between others. New SHRIMP U–Pb zircon ages presented here indicate that the original lithostratigraphy and the old “Group” and “Formation” terminology should be abandoned. Thus the “Tianjingping Formation” was not formed in the Archaean or Palaeoproterozoic, as previously considered, but must be younger than its youngest detrital zircons (1790 Ma) but older than regional metamorphism (460 Ma). Besides magmatic zircon ages of 807 Ma obtained from metavolcano-sedimentary rocks of the “Nanshan Formation” and 751–728 Ma for the “Mamianshan Group”, many inherited and detrital zircons with ages ranging from 1.0 to 0.8 Ga were also found in them. These ages indicate that the geological evolution of the study area may be related to the assembly and subsequent break-up of the Rodinia supercontinent. The new zircon results poorly constrain the age of the “Mayuan Group” as Neoproterozoic to early Palaeozoic (728–458 Ma), and not Palaeoproterozoic as previously thought. Many older inherited and detrital zircons with ages of 3.6, 2.8, 2.7, 2.6–2.5, 2.0–1.8 and 1.6 Ga were found in this study. A 3.6 Ga detrital grain is the oldest one so far identified in northwestern Fujian Province as well as throughout the Cathaysia Block. Nd isotope tDM values of eight volcano-sedimentary and clastic sedimentary rock samples centre on 2.73–1.68 Ga, being much older than the formation ages of their protoliths and thus showing that the recycling of older crust played an important role in their formation. These rocks underwent high grade metamorphism in the early Palaeozoic (458–425 Ma) during an important tectono-thermal event in the Cathaysia Block.  相似文献   

17.
Two Neoarchean supercontinents? Evidence from the Paleoproterozoic   总被引：10，自引：0，他引：10  
An unresolved question in Precambrian geology is the relationship between Archean crustal fragments that are now separated by younger orogens: were they once contiguous? Williams et al. (1991) proposed the name ‘Kenorland' for a speculative Neoarchean supercontinent comprising the Archean provinces in North America. Recently, a large number of ca. 2.5–2.0 Ga magmatic, metamorphic, detrital and xenocrystic ages have been reported from North America. We interpret that the wide geographic distribution and temporal spread of these ages may signify long-lived, regional-scale mantle upwelling, and anorogenic magmatic and metamorphic processes related to the protracted breakup of Kenorland. Breakup may have extended from ca. 2.5 to 2.1 Ga, culminating with dispersion of continental fragments at ca. 2.1–2.0 Ga. In North America, ca. 2.5–2.1 Ga intracratonic basin successions (e.g. Hurwitz Group) formed in the interior of Kenorland before dispersion, and passive margin sequences flanking the Superior Province (e.g. Huronian Supergroup) and the Wyoming Province (e.g. Snowy Pass Supergroup) defined the edges of Kenorland. Earliest Paleoproterozoic magmatic and sedimentary rocks, which include voluminous quartz arenites and glacigenic deposits, are consistent with a high-standing supercontinent and a mantle superplume. The Paleoproterozoic record from the Baltic and Siberian shields is similar to that of North America, suggesting inclusion in Kenorland. A slightly different record from the southern continents suggests a second, coexisting supercontinent that included the Zimbabwe, Kaapvaal, and Pilbara cratons, (‘Zimvaalbara' of I.G. Stanistreet), the São Francisco Craton, and possibly, cratonic blocks in India. Attenuation of this second supercontinent started earlier than in Kenorland (ca. 2.65 Ga) and was accompanied by high sea level and deposition of vast Lake Superior-type iron formations. Immediately thereafter, both supercontinents became emergent and were subject to global cooling and glaciation.  相似文献   

18.
New paleomagnetic and isotope-geochronological data obtained for the Onega granulite complex of Neoarchean age are used to reconstruct the position of the Karelian craton in the structure of the Kenorland supercontinent in the Neoarchean. Geological correlations are made for the Karelian, Kaapvaal, Pilbara, Superior, and Slave cratons. Comparison of independent geological and paleomagnetic data allow us to propose a new configuration of the Kenorland supercontinent in the Neoarchean. The position of the ancient core of the Karelian craton (the Vodlozero terrane), located in the Northwestern margin of the supercontinent, is reconstructed based on the earlier paleomagnetic data for the Neoarchean Panozero sanukitoid massif and new data for granulites of the Onega complex.  相似文献   

19.
Plume–lithosphere interactions (PLI) have important consequences both for tectonic and mineralogical evolution of the lithosphere: for example, Archean metallogenic crises at the boundaries of the West African and Australian cratons coincide with postulated plume events. In continents, PLI are often located near boundaries between younger plates (e.g., orogenic) and older stable plates (e.g., cratons), which represent important geometrical, thermal and rheological barriers that interact with the emplacement of the plume head (e.g., Archean West Africa, East Africa, Pannonian–Carpathian system). The observable PLI signatures are conditioned by plume dynamics but also by lithosphere rheology and structure. We address the latter problem by considering a free-surface numerical model of PLI with two stratified elasto-viscous–plastic (EVP) lithospheric plates, one of which is older and thicker than another. The results show that: (1) plume head flattening is asymmetric, it is blocked from one side by the cold vertical boundary of the older plate, which leads to the mechanical decoupling of the crust from the mantle lithosphere, and to localized faulting at the cratonic margin; (2) the return flow from the plume head results in sub-vertical down-thrusting (delamination) of the lithosphere at the margin, producing sharp vertical cold boundary down to the 400 km depth; (3) plume head flattening and migration towards the younger plate results in concurrent surface extension above the centre of the plume and in compression (pushing), down-thrusting and magmatic events at the cratonic margin (down-thrusting is also produced at the opposite border of the younger plate); these processes may result in continental growth at the “craton side”; (4) topographic signatures of PLI show basin-scale uplifts and subsidences preferentially located at cratonic margins. Negative Rayleigh–Taylor instabilities in the lithosphere above the plume head provide a mechanism for crustal delamination. Inferred consequences of PLI near intra-continental plate boundaries, such as faulting at cratonic edges and enhanced magmatic activity, could explain plume-related metallogenic crises, as suggested for West Africa and Australia.  相似文献   

20.
克拉通演化的超大陆背景与克拉通盆地的成因机制   总被引：1，自引：0，他引：1       下载免费PDF全文
席怡  何登发  孙衍鹏  苏艳 《地质科学》2014,49(4):1093-1112
研究表明克拉通的形成与超大陆的汇聚和裂解有着重要关系。本文对近年来超大陆重建的研究进行了分析对比,对克拉通发展与超大陆事件的关系做出了总结。前人对超大陆的研究表明,其形成与地幔动力有直接联系,地幔柱重组的旋回导致了超大陆的旋回。Phillips and Bunge（2007）在前人三维球体地幔对流模型的基础上加入大陆进行了模拟实验,结果显示周期性的超大陆旋回只发生在理想模型中,而Senshu et al.（2009）对代表陆壳的英云闪长岩-奥长花岗岩-花岗岩（TTG）地壳进行了研究,提出随着俯冲的TTG地壳产热速率的下降,超大陆旋回的周期随之变长;更有许多学者指出,历史上哥伦比亚超大陆存在时间明显较长,因此超大陆的旋回并不具有周期性。对近年来不同学者提出的哥伦比亚、 罗迪尼亚、 冈瓦纳、 潘基亚4个超大陆新的重建证据进行分析,大致确定出上述4个超大陆的形成时间、 格局及演化过程。此外,对华北、 东欧、 西伯利亚、 亚马孙、 刚果、 西非6个克拉通各自的演化进行分析,也显示出克拉通演化与超大陆汇聚及裂解在时间与空间上有对应关系。通过分析得出克拉通演化与超大陆旋回有关,且确定出克拉通演化的4个超大陆旋回。本文最后讨论了克拉通盆地的成因机制以及3种端元类型,并将盆地的发育与超大陆演化的巨旋回相联系。  相似文献   

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