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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.
The following conclusions can be drawn from the work reported in this paper:
  1. Sixteen samples were determined for uranium by spectrophotometric method. The uranium content in the sea floor sediments of the Bohai Gulf ranges from 1.6 to 6.3 ppm, with an average of 4.3 ppm.
  2. Statistical data show close relationship between U concentration and grain size. Relatively larger amount of uranium was found accumulated in mud than in sand. The bulk of uranium is assumed to be derived from terrestrial detrital minerals.
  3. A positive correlation between U and Fe is recognized. Similar relation also can be seen between U and Al. The plot of U concentration vs. Fe is linear, and can be expressed by the linear regression equation:Y=?0.37+1.35X. The plot of U against Al gives an equation ofY=?2.48+1.01X.
  4. The average U/Corg. ratio for these sediments is 7×10?4, and the average ratios of U/P, U/Mn, and U/CaCO3 are 100×10?4, 50×10?4 and 2×10?4, respectively.
  5. Compared with the abundances of other shelf sediments, the average concentration of U in the area under consideration is close to that of sediments on the selves of Japan and the Gulf of Mexico, and the Black Sea. Uranium concentration in the Bohai Gulf sediments is comparable to that of the continental crust, but differs from that of deep-sea clay.
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3.
In Hungary loess has long been used for soil reclamation. The main steps of the method are: horizon A and B are removed from a suitable area and their material is stockpiled at the margins of the resulting pit. The loess (horizon C), this way exposed, is excavated and spread over the salt affected soils to be improved then mixed with their upper layer. The pit is named in Hungarian digó (pit). The name of the reclamation process is the digo method or spreading of yellow earth. Digó method is mainly used for the amelioration of salt affected soils with an acid A horizon and its benefits are as follows:
  1. The acidity of the horizon A is eliminated
  2. The soil structure is improved
  3. The amount of calcium (a plant nutrient) is increased
  4. Soil fertility is improved continuously
  5. The soil depth is extended which adds to the relative volume of the ground water table.
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4.
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   

5.
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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6.
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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7.
Paleocurrent directions can be reconstructed by determining optically the preferred orientation of longest grain axes of sediments; this can be estimated by measuring the anisotropy of magnetic susceptibility (Rees, 1965). In order to check the applicability of both methods, the orientation of large- and small-scale sedimentary structures (cross-bedding, sole markings, grain orientation) was compared with the “magnetic fabric” of some sand and silt layers of different ages and origins:
  1. Rosario Formation (Late Cretaceous), La Jolla: thin siltstone layers with small-scale current-ripple cross-lamination;
  2. Monterey and Topanga Formations (Miocene, Los Angeles Basin): graded and laminated sandstone beds (“turbidites”);
  3. Holocene submarine La Jolla Fan: graded and cross-laminated sand layers (Rees, v.Rad &Shepard, 1968).
Most of the investigated sand layers have a “primary-style” magnetic fabric, characterized by well-grouped, horizontal maximum susceptibility axes, sometimes slightly imbricated upcurrent, minimum susceptibilities normal to the bedding, and intermediate values of the factor q (about 0.1–0.5), suggesting moderately strong current conditions during deposition. The orientation of maximum susceptibility axes correlates with the directions of sand transport, inferred from cross-lamination foresets and sole markings (a). Also conventional optical grain orientation measurements give very similar directions as maximum susceptibilities (b). In Recent deep-water sand layers (c) cross-lamination foresets and maximum susceptibility axes are parallel, and influenced by the local morphology (e. g. fan-valley axis). Since current-parallel orientation of the longest grain axes and maximum susceptibility axes is prevailing in deep-water sands, the magnetic method is a useful tool for palcocurrent analysis. Characteristic differences of the magnetic fabrics from different depositional environments may also give clues to the mechanisms of sediment transport.  相似文献   

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.
The groundwater reserves in Kharga Oases have been studied for the long-term socioeconomic development in the area. The Nubian Sandstone, which consists of a thick sequence of coarse clastic sediments of sandstone, sandy clay interbedded with shale, and clay beds, forms a complex aquifer system. The Nubian Aquifer has been providing water to artesian wells and springs in the Kharga Oases for several thousand years. Groundwater in the Kharga Oases is withdrawn from springs and shallow and deep artesian wells Nearly all the wells originally flowed, but with the exploitation of ground-water from deep wells for irrigation beginning about 1959. the natural flows declined as more and more closely spaced deep wells were drilled By 1975 many deep wells had ceased to flow The water demand in the area has been met by pumping both shallow and deep wells The total annual extraction from deep wells has fluctuated over the year, however, the annual withdrawal from deep wells has exceeded extraction from shallow wells About 17 billion m3 of water was withdrawn from the combination of shallow and deep wells during the period 1960–1980 The Nubian complex aquifer in the Kharga Oases has a very large groundwater potential that could be exploited and beneficially used for a long-term agricultural development in the area, provided proper well spacing and management are implemented Other major environmental considerations for which precise hydrogeologic data are needed include
  1. Determination of the long-term yield available from properly constructed and producing artesian wells that will support a planned migration of population from the overcrowded Nile delta and flood plain areas
  2. Development of an effective management program and adequate staff to maintain groundwater production over an extended period of years
  3. The impact on climate caused by extensive irrigation in the oases of the Western Desert of Egypt
  4. Protection against water logging of soils from irrigation practices
  5. Protection against salinization of soils from irrigation practices
  6. Development of effective surface and subsurface drainage practices
  7. The impact of farming and pest control practices on the shallow groundwater of the oases
  8. Determination of the long-term development of the artesian water on the quality of the water from the aquiter systems in the Western Desert
This paper addresses items 1, 2 and 8.  相似文献   

10.
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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11.
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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12.
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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13.
During the “Heidelberg-Ellesmere-Island-Expedition” to Oobloyah Valley, N-Ellesmere Island, NWT, Canada in 1978 the summerly water balance of this high arctic catchment area with continuous permafrost was investigated. The following results will be presented:
  1. Three hydrogeological areas with different physical parameters, thawing depths and drainage are distinguished and studied on slope I, II and slope III.
  2. The climatic situation of summer 1978 was mainly influenced by the change of radiating and cloudy periods. Due to air temperatures (2 m above ground), which never went below 0°C, these periods regulated the thawing of the glaciers and the respective run-off.
  3. Most of the winterly snow cover melted before July, thereafter soil thawing and its drainage began. In none of the sediments the latter reached field capacity.
  4. Considering the course of daily discharge and soil water balance the three studied streams were characterized by the “Dry-Weather-Discharge-Line”, DWL, of Peri-Creek the “Radiation-Weather-Discharge-Line”, RWL, and the “Cloudy-Weather-Discharge-Line”, CWL, of Nukapingwa River and Heidelberg River.
  5. The periglacial streams never had a measurable sediment load not even during snow melt, whereas the glacial and mixed glacial-periglacial streams as Nukapingwa River and Heidelberg River showed a sediment drift depending on their run-off. Only in Peri-Creek the ion concentrations were correlated to discharge.
  6. Precipitation (snow plus rain) add up to 51% of the summerly water balance. The glaciers contributed up to 48%, and the actual evapotranspiration is only 1%.
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14.
The ferruginous deposits of north-western Nigeria occur extensively capping sediments which outcrop over thousands of square kilometers. These deposits could be subdivided into 3 major groups:
  1. Ferruginous oolites;
  2. Crusty/Concretionary laterites;
  3. Ferruginous sandstones.
The iron-rich oolites are primary deposits and deposition of ferruginous materials occurred during the late Paleocene. All gradations can be traced between a pure oolitic ironstone and concretionary laterite with scattered oolitic grains of limonite. The crusty laterites and Ferruginous sandstone were formed during the late Tertiary or early Quaternary. They are definitely post Miocene in age and consists of abundant angular quartz grains embedded in a matrix of gothite, haematite, limonite and clay. The laterites and oolites posses different element concentrations which indicate formation under different environmental conditions ranging from deep Marine through shallow near shore marine to continental (fluviatile and lacustrine). The crusty laterites and ferruginous sandstones in northwestern Nigeria attain a thickness of approximately 4 meters or more forming the crust of flat-topped hills or mesas. They are almost certainly equivalent to the laterites covering much of the Northern plains and the Fluvio-volcanic series of the Jos Plateau. In northwestern Nigeria the laterites are restricted to outcrops of sediments of appropriate composition and drainage properties. These ferruginous deposits are usually massive with almost horizontal bedding planes marked by abrupt or gradual changes in morphology and lithology. Cross bedding and ripple-marks can be observed at Gundumi and Imasa as well as in Birnin Kebbi and large scale stratification of the laterites occur at Kalambaina. Laminations are generally localised.  相似文献   

15.
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
  •   相似文献   

    16.
    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   

    17.
    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   

    18.
    Various stratigraphic and paleoenvironmental results arise from mineralogical, geochemical and micromorpho logical investigations on Late Cretaceous and Cenozoic sediments recovered by the Deep Sea Drilling Project in the West Pacific:
  • Stratigraphic correlations. The deep pelagic red clays deposited on either side of the Shatsky Rise contain a variety of clay minerals, which point to the importance of eolian detrital supply and allow rough stratigraphic correlations.
  • Climate and paleocirculation. Neogene sediments of the Lord Howe Rise area reflect closely the relationship between the evolution of the Antarctic ice sheet and related aridification stages, and the atmospheric and oceanic circulation pattern since 14 my.
  • Regional and global tectonics. The post-Eocene deposits around New Zealand express a sequence of tectonic events and of relaxation stages, associated with changes in the circulation regime. Along the inner wall of the Japan Trench, clay mineral successions document the existence of an outer continental landmass until the late Oligocene, its collapse associated with volcanism close to the Paleogene-Neogene boundary, and an increased detrital influence from Japan since the early-middle Miocene.
  • Volcanism, diagenesis and detrital supply. The Aptian to Maastrichtian sediments in the Mariana Basin document a complex sequence of geochemical and geodynamical events: proximal volcanism and local supply from subaerial archipelagoes; early marine diagenesis during lithospheric subsidence and plate migration; and finally the occurrence and evolution of terrigenous input from distant sources distributed by marine currents.
  •   相似文献   

    19.
    Stoichiometric mixtures of tremolite and dolomite were heated to 50° C above equilibrium temperatures to form forsterite and calcite. The pressure of the CO2-H2O fluid was 5 Kb and \(X_{{\text{CO}}_{\text{2}} }\) varied from 0.1 to 0.6. The extent of the conversion was determined by the amount of CO2 produced. The resulting mixtures of unreacted tremolite and dolomite and of newly-formed forsterite and calcite were examined with a scanning electron microscope. All tremolite and dolomite grains showed obvious signs of dissolution. At fluid compositions with \(X_{{\text{CO}}_{\text{2}} }\) less than about 0.4, the forsterite and calcite crystals are randomly distributed throughout the charges, indicating that surfaces of the reactants are not a controlling factor with respect to the sites of nucleation of the products. A change is observed when \(X_{{\text{CO}}_{\text{2}} }\) is greater than about 0.4; the forsterite and calcite crystals now nucleate and grow at the surface of the dolomite grains, thus indicating a change in mechanism at medium CO2 concentrations. As the reaction progresses, the dolomite grains become more and more surrounded by forsterite and calcite, finally forming armoured relics of dolomite. Under experimental conditions this characteristic texture can only be formed if the CO2-concentration is greater than about 40 mole %. These findings make it possible to estimate the CO2-concentration from the texture of the dolomite+tremolite+forsterite+calcite assemblage. The results suggest a dissolution-precipitation mechanism for the reaction investigated. In a simplified form it consists of the following 4 steps:
    1. Dissolution of the reactants tremolite and dolomite.
    2. Diffusion of the dissolved constituents in the fluid.
    3. Heterogeneous nucleation of the product minerals.
    4. Growth of forsterite and calcite from the fluid.
    Two possible explanations are discussed for the development of the amoured texture at \(X_{{\text{CO}}_{\text{2}} }\) above 0.4. The first is based upon the assumption that dolomite has a lower rate of dissolution than tremolite at high \(X_{{\text{CO}}_{\text{2}} }\) values resulting in preferential calcite and forsterite nucleation and growth on the dolomite surface. An alternative explanation is the formation of a raised CO2 concentration around the dolomite grains at high \(X_{{\text{CO}}_{\text{2}} }\) values, leading to product precipitation on the dolomite crystals.  相似文献   

    20.
    The paper presents novel information on the Caledonian orogeny in Ireland. A series of Dalradian (Upper Precambrian-Lower Cambrian) metasedimentary rocks occur as an envelope to a granitic igneous complex at Slieve Gamph, Western Ireland. These metasedimentary rocks have been deformed at several distinct times and evidence is shown for the following sequence of events:
    1. formation of major nappe structures and a tectonic slide. The axial-plane traces of the folds probably trended N. E.-S. W.
    2. formation of upright, gently plunging folds with axial-plane traces of the folds trending N. E.-S. W. Emplacement of the components of the Slieve Gamph igneous complex.
    3. formation of a conjugate set of folds:
      1. Open folds with N. N. E.-S. S. W. trending axial-planes which dip to the east,
      2. Open folds with E.W. trending axial-planes which dip to the north.
    4. formation of kink-bands, open and conjugate folds with an axialplane trace trending N. W.-S. E.
    Late phase of faulting. No isotopic dates are available for these structural events.  相似文献   

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