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1.
Detailed petrographic and geochemical investigations on the rocks underlying the Devonian stratiforme pyrite and barite deposits of Eisen (Saar district), Meggen (Westphalia), and Rammeisberg (Harz Mountains) in the Rhenish Schiefergebirge have led to the following conclusions:
  1. These deposits are tied to dark shales of the pelagic basin facies. In all cases a local depression of the sea floor coincides largely with the spatial extension of the overlying pyrite and barite bodies. These depressions are marked by a large number of sand and silt intercalations, accumulations of reef debris and a significant lower carbonate content.
  2. The dark shales underneath the deposits have conspicuously high, but strongly varying contents of Mn, Zn and Pb. This, corresponding with the low carbonate content, is characteristic for the presence of hydrothermal, metalliferous emissions.
  3. Predepositional phases of sulfide and barite emplacement are indicated by small layers and lenses.
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2.
Detailed sedimentological investigations were performed on sediments from DSDP-Site 594 (Chatham Rise, east of New Zealand) in order to reconstruct the evolution of paleoclimate and paleoceanographic conditions in the Southwest Pacific during the last 6 million years. The results can be summarized as follows:
  1. High accumulation rates of biogenic opal and carbonate and the dominance of smectites in the clay fraction suggest increased oceanic productivity and an equable dominantly humid climate during the late Miocene.
  2. During Pliocene times, decreasing contents of smectites and increasing feldspar/quartz ratios point to an aridification in the source area of the terrigenous sediments, culmunating near 2.5 Ma. At that time, accumulation rates of terrigenous components distinctly increased probably caused by increased sediment supply due to intensified atmospheric and oceanic circulation, lowered sea level, and decreased vegetation cover.
  3. A hiatus (1.45 to 0.73 Ma) suggests intensified intermediate-water circulation.
  4. Major glacial/interglacial cycles characterize the upper 0.73 Ma. During glacial times, oceanic productivity and terrigenous sediment supply was distinctly increased because of intensified atmospheric and oceanic circulations and lowered sea level, whereas during interglacials productivity and terrigenous sediment supply were reduced.
  5. An increased content of amphibols in the sediments of Site 594 indicates increased volcanic activities during the last 4.25 Ma.
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3.
Mn-activated cathodoluminescence can be used in several fields of carbonate petrography. It may, for instance, be possible to recognize
  1. cement sequences and their correlation (Tab. 1, Figs. 1, 2, 4; Tab. 2, Fig. 1)
  2. growth fabrics of skeletons (Tab. 2, Figs. 2, 3, 4; Tab. 3, Figs. 1, 2)
  3. dolomitisation processes and problems (Tab. 1, Figs. 1, 2; Tab. 4, Fig. 2)
  4. transformation paths from Mg-calcite to calcite and from aragonite to calcite (Tab. 2, Fig. 1; Tab. 3, Figs. 3, 4; Tab. 4, Fig. 1)
  5. growth structures in certain types of ooids (Tab. 1, Fig. 4; Tab. 3, Fig. 3; Tab. 4, Fig. 1)
  6. reworked skeletal particles (Tab. 3, Fig. 4)
  7. phantom grains and fossil-outlines in a micro- or macrocrystalline groundmass (Tab. 4, Figs. 2, 3)
  8. healed fissures crossing micro- or macrocrystalline carbonate rocks (Tab. 4, Fig. 4).
These are, however, no general luminescence criteria indicating the depositional environment. Luminescence of calcite and dolomite requires 20–40 ppm Mn, with the equipments used in this study. Aragonite is not yet investigated systematically. Zonal luminescence in carbonate cements may indicate changes of the chemical composition of the aquifer and may be used for “cement stratigraphy”. In skeletons it rather indicates physiological changes. While aragonitic skeletons lose their luminescence Zonation during replacement by calcite, Mg-calcite skeletons may keep parts of it, because their replacement preserves the original crystal fabric. Blotchy luminescence developes in Mg-calcitic particles during their adjustment to lower Mg-calcites by dissolution-precipitation processes in solutions with changing Mn/Fe-ratios.  相似文献   

4.
The data obtained can be summed up in 6 points:
  1. The sediment consists of varying amounts of quartz (14–23 weight percent, mean value 18%), aragonite, dolomite, Mg-rich calcite, Mg-poor calcite, Na-rich plagioclase (7–10%, m.v. 8%), chlorite (18–32%, m.v. 22%), kaolinite (4–29%, m.v. 13%), illite and mixedlayered illite-montmorillonite (20–42%, m.v. 34%) and organic matter (0.7–2.5%, m.v. 1.1%).
  2. The composition of the carbonate fraction suggests a detrital origin for the carbonates deposited along the Persian Coast.
  3. The clay mineral distribution follows gradients perpendicular to the long half-axis of the Persian Gulf. This favours detrital origin. The kaolinite distribution suggests an additional detritus from Euphrates and Tigris,
  4. Enrichments of trace elements with regard to mean values in clays (Turekian and Wedepohl, 1961) are estimated for Fe, Co, Mo, Ni, V, Zr and Br; impoverishments are recorded for Cu, Mn, K. The contents of Rb, Ti and Zn comply with mean values of clays. The enrichments distribute as follows: chlorite concentrates Mn and Fe, kaolinite Ti and Zr, illite and mixedlayered illite-montmorillonite Rb, V, M, Zn, Mo and Co.
  5. The high Br-contents (up to 420 ppm) in the sediment give positive correlations with the concentrations of organic carbon. The X-ray analysis of isolated kerogen confirms an enrichment of Br in this fraction of the organic matter.
  6. The distribution of elements in the sediment to a large extent is controlled by a) detritus of Euphrates and Tigris, b) influence of organic matter.
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5.
Prior experimental work has shown that in the laboratory the mineralogy of eclogites is sensitive to the ratio of CaO ∶ MgO ∶ FeO and that the reaction pyroxene + kyanite?garnet + quartz proceeds to the right at high pressures in rocks rich in magnesium and to the left in rocks rich in calcium and iron. Typical basalts crystallized at high pressure never contain kyanite. The chemistry and mineralogy of a large number of naturally occurring eclogites show they belong to three classes.
  1. Kyanite-free magmatic eclogites, rich in magnesium, from:
  2. kimberlites
  3. dunites and serpentinites.
  4. Kyanite-bearing eclogites and grosspydites rich in CaO and low in FeO with intermediate MgO from:
  5. kimberlites
  6. gneisses.
  7. Kyanite-free eclogites of metamorphic origin rich in iron with low magnesium and intermediate amounts of calcium from:
  8. glaucophane schists
  9. gneisses.
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6.
The study deals with the comparison of corrosion forms in differently soluble rocks from different climatic regions, namely forms of the naked karst (lapies), depressions, and corrosive plains. The far-reaching morphographic conformity of corresponding forms permits some general conclusions:
  1. The forms in question have the same genesis, there is no casual convergence of forms. It would be convenient to term them as forms of the salt-, gypsum-, and carbonate karst. There is no justification for a fundamental distinction between the “karstification” of limestone and the “leaching” of gypsum and salt.
  2. The different liability to karstification (Karstgunst) of rocks can be compensated by a different liability to karstification due to climatic factors.
  3. Similarly the other factors of karstification vary gradually; they add up or compensate each other. A classification of climatic-morphological karst provinces seems to be possible only by means of analysis and balance of the single factors and their effects.
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7.
The following facts have supported the origin of the Araguainha circular structure in Central Brazil by a meteoritic impact:
  1. the almost circular contour
  2. the impact-morphologic sequence including a central uplift, ring walls and a basin rim of escarpments
  3. outcrops of suevites and mixed breccias
  4. the evidence of shock metamorphism
  5. the presence of shatter cones, and
  6. negative anomalies of the total intensity of the magnetic field at the center of the ring structure.
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8.
The “South-Italian city” is characterized at four different levels as an independent cultural-genetic city-type:
  1. The characteristics arrangement of the functional areas and the residential areas of different social groups is represented in a model.
  2. From the model, developments and changes in the arrangement of the functional areas can be identified which clearly deviate from those which are derived from the universal city model.
  3. Some of the structural individuality can be directly explained by the peculiar features of the respective social and economic history.
  4. Some of the special features must, however, be traced back to a wider historico-cultural background. Through this run processes which flow through the universal city development in similar forms, to the deviating structure of the “South-Italian city”.
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9.
Geologic, petrological and geochemical investigations have been carried out in the western part of the “Zillertaler Alpen”. Important results are:
  1. The premetamorphic material of the Greiner series consists of conglomerates, breccias, arcosic-sandstones or greywackes, bituminous shales, volcanic lavas and tuffs.
  2. The southern part of the “Zentralgneis” shows a differentiation trend from alkaline granite to quarzdiorite with predomination of granodiorite.
  3. Chemical relationships of granodiorite to its restitic inclusions allow the supposition of a palingenetic origin of the granitic rocks.
  4. At least two stages of metamorphism can be differentiated.
  5. Parts of the Greiner series, covered by triassic metasediments, are supposed to be of Permian age. A lower age boundary can not yet be given.
  6. Some vertical, northeast striking faults with throws of more than 1 or 2 kilometers produced southward verging drag folds.
  7. Geodynamic aspects, revealed from regional metamorphism and tectonics, are discussed.
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10.
H. Kenneweg 《GeoJournal》1994,32(1):47-53
The development of inventory activities in the field of forest damage assessment and monitoring during the last decade in Germany and the present state are recorded as far as remote sensing has been involved. Any forest inventory is influenced by external factors, and the resulting difficulties for an introduction of new technologies are described. The following tasks and/or methods are discussed:
  • -global approaches to deforestation monitoring
  • -working experience from local and regional case studies
  • -vegetation and vegetation-damage monitoring in ”urban forestry”
  • -sampling approaches for large areas
  • -the contribution of spectral signatures and satellite remote sensing to damage assessment
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    11.
    From 14 deeps and other regions of the Red Sea totally 226 samples from 28 cores recovered during the VALDIVIA cruises (1971, 1972) were investigated according to their clay mineral content (<2μm resp. < 6.3 μm) after carbonate dissolution. Three facies groups are to distinguish:
    1. normal sediments: dominance of chlorite, kaolinite, illite, small amounts of smectite and sepiolite. Two palygorskite types are present only in a few samples.
    2. normal sediments with hydrothermal influence: clay mineral paragenesis similar like that of normal sediments; but increase of smectite and presence of goethite in each sample; partly small contents of talc.
    3. heavy metal deposits: dominance of iron-bearing smectite, partly with amorphous components resp. pure ore mineral assemblages with authigenic silicates (talc, quartz, opal, chrysotile, sepiolite, palygorskite, chlorite).
    Crystallinity of the clay and ore minerals is independent from sedimentary overburden. Sepiolite shows in small amounts a wide distribution; palygorskite2 (d110=11.3 Å) yields locally an increased concentration in the range of pteropod layers cemented by aragonite. The environment of ore deposits is characterized by iron-bearing smectite besides the ore minerals.  相似文献   

    12.
    Principe is one of the volcanic centres comprising the Cameroun line in West Africa. The volcanic rocks can be divided into two stratigraphic units:
    1. Younger lava series — basanite and nephelinite overlying.
    2. Older lava series — transitional to mildly alkaline basalt and hawaiite.
    These units lie on a basement of palagonite breccias of tholeiitic affinities. The basic lavas are intruded by plugs ranging in composition from tristanite to phonolite and are overlain by phonolite lavas. These rocks form two chemically and mineralogically distinct suites:
    1. Phonolites which evolved by low pressure crystal fractionation of the younger lava series basanitic magma, and
    2. Tristanite — trachyte — trachyphonolite suite which may have evolved by high pressure crystal fractionation of the older lava series magma.
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    13.
    Problems of landscape and resource protection resulting from the intensification of land-use can be mastered only by intersectoral planning and a land management considering (landscape-)ecological principles right from the beginning. In the district of Leipzig ecological studies in the '80ies have focussed on:
    1. Determination of the regional pattern of atmospheric immissions;
    2. Registration of heavy metals in soil and vegetation;
    3. Soil compaction, soil erosion;
    4. Study of stress indicators in the aeration zone and in the top-most aquifer in order to examine barrier effects in the percolation process.
    First results are discussed.  相似文献   

    14.
    According to their material sources, China’s pegmatities can be divided into two broad types: (1) the crust-source pegmatites derived mainly from the upper continental crust, which can be subdivided into metamorphic differentiated, mixed metasomatic and anatectic magmadifferentiated pegmatites, and (2) the mantle-source pegmatites generated from the mantle, including those related to late differentiates and carbonatites. In space, carbonatites are usually accompanied with alkaii syenite. The criteria of discriminating the two-source pegmatites of China are listed as follows:
    1. Rock-forming minerals (micas and feldspars);
    2. REE distribution patterns;
    3. Zr/Hf ratios in zircons; and
    4. Species of apatite and REE contents.
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    15.
    The influence of bacteria on recent sediments was first discussed in 1885, whenFischer andGazert were discussing the cycle of substances in the sea as well as in sediments. The influence of bacteria on the cycling of C, N, S, P in recent sediments and the open sea was soon accepted by marine geologists. Nevertheless, only very few experiments have, so far, shown more than qualitative and quantitative data collection in various restricted areas. This is due to the extensive and complicated chain of reactions on the surface of sediments and in the sediment itself. Biologists are asking for the amount of organic and inorganic matter which is reworked and released to the sea. Geologists usually emphasize the amount of substances which are sedimentated. For biologists the sediment is only part of their dominant ecosystem (the sea). While, for geologists the “sea” is only furnishing and influencing their first range system sediment. How much then, are bacteria involved in the slow process of conversion from a recent sediment to sedimentary rocks? Bacteria influence more or less strongly and to a more or less advanced degree of diagenesis:
    1. The organic matter in sediments and the final form in which it is found.
    2. The anions CO3 2?, NO3 ?, OH-, SO4 2?, PO4 3? as well as their intermediate stages and the resulting minerals.
    3. The cations H+, NH4 +, Ca2+, Fe2+, Fe3+, and a series of metals which are dissolved or precipitated by microbial activities as for example Fe, Mn, Cu, Ag, V, Co, Mo, Ni, U, Se, Zn.
    4. The equilibrium of silicium. At least diatoms and radiolarians are precipitating silica, while other reactions which have been proved are not yet shown to influence marine sediments.
    5. pH-values and oxidation-reduction potentials of the sediment.
    6. The composition of interstitial waters.
    7. The surface activity of minerals, since bacteria are growing especially on particle surfaces.
    8. The energy content and temperature of sediments.
    9. The texture of fine grained sediments.
    10. The fossilization of microfauna, macrofauna and trace fossils.
    Sedimentology and mineralogy may also influence the bacterial activities and the composition of the microflora within sediments. Methods and problems of sediment microbiology are demonstrated by some investigations in the German Bay (North Sea) in connection with the first German Underwater Station (UWL). Ecological work proves to be difficult in various directions. The main cause of difficulties in microbiological work on sediments are the great variety of different factors influencing the environment (microbial, chemical, physical, mineralogical), the difficulty of taking representative samples, and the small amount of data which has been collected so far.  相似文献   

    16.
    Systematic natural hazard mapping in Japan was started after WW II using aerial photographs. Analysing the interaction between disaster occurrence and land conditions is the most useful method for establishing the disaster prediction system for three types of disaster, flood disaster, mass-movement disaster, and earthquake disaster, which are strongly related to land conditions. A series of maps on natural hazards were established based on the results analysed. In our opinion, the following problems of natural hazard mappings remain so far unsolved:
    1. No clear distinction is made between natural hazard mapping and land classification.
    2. Organization of information for natural hazard prevention is not yet established.
    3. There is no established earthquake disaster prevention map.
    4. Utilization of new machines and tools is inadequate.
    5. Effect of human activity is not estimated.
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    17.
    Concordant granite sheets from the granulite facies Scourian Complex, N.W. Scotland exhibit the following features:
    1. a common planar fabric with their host pyroxene granulites;
    2. the presence of an exsolved ternary feldspar phase;
    3. a low-pressure, water-saturated minimum composition;
    4. K/Rb ratios (450–1,350) distinctly higher than most upper crustal granites but similar to the surrounding granulites;
    5. low absolute concentrations of the rare earth elements (REEs), light REE enrichment, and large positive Eu anomalies.
    It is proposed that the granite sheets have originated by anatexis of gneisses undergoing granulite facies metamorphism — gneisses that were already essentially dry and depleted in incompatible elements. Their unusual trace element chemistry may be explained by either disequilibrium melting and/or sub-solidus reequilibration of the granite sheets with the surrounding gneisses. Isotopic and trace element data suggest that cross-cutting, potash-rich pegmatites represent reworking of the granite sheets during a later amphibolitization.  相似文献   

    18.
    The wet tropical weathering of Precambrian spessartite quartzites leads to the formation of secondary oxidized ores. These ores result from different successions of superimposed elementary processes, among them:

  • garnet hydrolysis: Mn, Ca, and Fe are leached, and only an amorphous, silicoaluminous phase remains.
  • lithiophorite neoformation: Added manganese combines with alumina of the amorphous, Si-Al products.
  • leaching: Voids appear in the central part of the weathered garnets. They may widen, leaving only the quartz matrix with polyhedric voids.
  • epigenic replacement: The quartz is replaced by cryptomelane, while the garnets may remain unweathered.
    • The various ore types are characterized by the sequence of transformations and by the volumes that each transformation affects. These transformations are old because they are observed not only in situ ores but also in removed detrital ores. In the same way the major part of the accumulated stocks of oxidized ores must be old.  相似文献   

    19.
    The analysis of the martian relief leads to the conclusion that some of the most important relief elements are either concentrically or radially arranged with respect to a central structure and hence form aureoles. In this paper four different types of aureoles are identified and described:
    1. impact aureoles (as result of extradynamics),
    2. volcanic aureoeles (as result of lava flow through vents),
    3. tectonic aureoles (as result of isostatic adjustment and/or settlement),
    4. permafrost-related aureoles and mega-aureoles (as result of migration above thawing permafrost in areas with high relief).
    The spatial distribution of these different types of aureoles indicates the predominant type of relief-forming dynamics in the area of their distribution (impact-related aureoles occur predominantly in the area of the Southern Uplands; volcanic, tectonic and permafrost-related aureoles in the area of large-scale updomings-TaNoVa, Elysiumand their volcanic provinces).  相似文献   

    20.
    A series of K-plagioclases have been produced metastably by ion-exchanging the plagioclases in KCl-melt. Chemical analyses and re-exchange experiments (with NaCl-melt) have proved that the K-plagioclases are truly isomorphous with plagioclases. Because of their isomorphous nature it was possible to mix them in different proportions and homogenise them, thereby producing ternary feldspars of different compositions in the system Or-Ab-An. A comparative study of the lattice constants of plagioclases, their K-equivalents and the different ternary feldspars calculated using powder data leads to the following conclusions:
    1. It is possible to dertermine by X-ray methods the anorthite content of a plagioclase to an accuracy of ±1% An.
    2. The influence of the ionic size of the bigger cations Na, Ca, and K and that of order/disorder are different on different lattice constants and it is possible to distinguish these two effects.
    3. The b-parameter indicates a definite structural change in plagioclases at about 25–30% An.
    4. It is possible to predict the average Al/Si-distributions in the four different positions T1(o), T1(m), T2(o) and T(m) of all plagioclases of all stable structural states, using the c-parameter of their K-equivalents.
      相似文献   

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