Geologische und geochemische Untersuchungen im Zentralgneis und in der Greiner Schiefer Serie (Zillertaler Alpen,Tirol)

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.

     

Temperaturen und Drucke bei der regionalen Metamorphose: Prinzipielle und praktische Hinweise

The author's concept (1970, 1974) of evaluating metamorphic conditions is explained on the basis of most recent petrologic data. The major points treated are:

1. Instead of usual petrographic mapping, petrographic work in the field is aimed at specific “targets”, i.e., rock compositions. This is so because only specific rocks may give petrogenetically relevant information in the four metamorphic grades.
2. There are very many mineral reactions in metamorphism but only a few are petrogenetically significant. These are important to know, and they are graphically demonstrated. Any mineral assemblage that is formed by a significant mineral reaction must be verified as a paragenesis of mutually contacting minerals. Only such parageneses deserve to be mapped in the field as isograds or isoreactiongrads.
3. Crossing isograds or isoreactionsgrads provide data on temperature and pressure during metamorphism for that part of a metamorphic terrane where the crossing has been observed.
4. The sequence of isograds or isoreaction-grads may be a pressure indicator. Moreover, such a sequence provides geodynamic information whether a larger metamorphic area has been lifted up evenly or has been tilted while it was uplifted after metamorphism.

     

Sedimentmikrobioiogie und ihre geologischen Aspekte

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. p_H-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.     

Geochemistry and origin of granitic rocks,Scourian Complex,NW Scotland

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.     

Tonminerale in normalsedimenten,hydrothermal beeinflu\ten sedimenten und Erzschlämmen des Roten Meeres

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.     

Kyanite eclogites

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.

     

The Araguainha astrobleme/Central Brazil

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.

     

Quartz-grain surfaces of debris flow material in the marginal mountains of Tibet

Debris flow is a natural phenomenon which occurs on steep slopes of mountain regions. Very often morainic material and nonmorainic sediments, such as debris flow material, fluvial and other sediments, are mixed in the marginal mountain systems of the Tibetan Plateau. The study of quartz-grain surface features of debris flow has an important significance for differentiating between different origins of Quaternary sediments. Features of quartz-grain in debris flow will be described as below:

1. The predominant shapes of quartz grains are irregular.
2. The degree of roundness of grains is in general are angular to subangular in shape.
3. The textures of quartz-grains in debris flows are conchoidal fractures, parallel steps and mechanical V-marks. Parallel steps are especially abundant. Their presence is the most characteristic indicator of debris flow sand, aiding in the differentiation between debris flow and glacial sand.
4. Fresh cleavage planes are extremely flat.

     

Die Strukturgeschichte der Zentralsahara

The author has investigated paleogeographic and structural problems in the middle part of the Sahara desert since 1959. Detailed studies of thickness changes, of disconformities and unconformities and of structural events resulted in the definition of the different tectonical eras and their individual paleogeographic elements. The middle part of North Africa is characterized by three major periods of structural development:

1. Folding and consolidation in Precambrian time.
2. Formation of NW to NNW striking horsts during Cambrian time, which became the core of uplifts (separated by troughs) in Silurian and Devonian time. This structural relief of the early Paleozoic era possibly is the result of regional stretch in NE-SW direction.
3. Formation of uplifts and troughs striking NE during late Paleozoic and Mesozoic time. Blockfaulting occurred along the edge of some uplifts during Jurassic time or at the Jurassic-Cretaceous transition. These movements were the result of regional compression from SE toward NW. The formation of this large scale undulation of the earth's crust coincides with the separation of the Sahara platform from the so-called Tethys (geosynclinal area in NW Africa, the Mediterranean and parts of Asia). This separation most probably began in Northwest Africa during late Carboniferous or early Permian time, it reached Northeastern Libya in Jurassic time. The Sirte grabens were formed as the result of east-west shearing movements, during Upper Cretaceous. Finally, in late Tertiary to Pleistocene time, volcanic activity formed large basalt plateaus. Volcanism occurs mainly along well defined old structural elements.

The results of this analysis were used to interpret structural aspects of larger parts of Africa. The structural relief of the early Paleozoic Era seems to extend far southeast into areas of the old African shield indicating that there is no principal structural difference between the shield and the Sahara platform. The orientation of the late Paleozoic to Mesozoic large scale undulation indicates that the reason for the SE-NW compression is the rotation tendency of Africa which began in late Carboniferous time and culminated during the Tertiary, when Africa was separated from Asia along the Red Sea graben. At approximately the same time, the Atlas area of Northwest Africa was folded.     

Gravimetrische Feldmessungen und Modellberechnungen im Gebiet des Krimmler Ache-Tales und Obersulzbachtales (Großvenediger Gebiet / Österreich)

Gravity measurements in the Krimmler Ache Tal and Obersulzbachtal (Oberpinzgau/ Austria) have been carried out. The results of the measurements are presented as follows:

1. Profiles of Bouguer anomalies (BA),
2. Profiles of regional and residual anomalies.

Superficial geological structures are simulated by synthetic models and taken into account for correcting geologically the measured BA's. By the aid of a three-dimensional underground model a first estimation concerning deapth and position of geological structures is possible.     

Rauhwacken und ihre Entstehung

This publication comprises the results of a detailed investigation of rauhwackes regarding both their stratigraphic/tectonic positions and their macroscopic/microscopic aspects. The conclusion drawn is that rauhwackes are carbonate breccias of tectonic origin, which usually suffered extensive recrystallization and calcitization. Moreover, these breccias became strongly weathered as a result of which they acquired a typical porous to cavernous appearance. Rauhwackes were formed by way of brecciation of carbonate rocks with a comparatively slight cohesion of their constituting grains; these rocks have been deposited in a saline environment. Rauhwackes may be divided into two main varieties:

1. monomict rauhwaekes, formed by fragmentation of only one type of rock (usually a sucrose dolostone), and
2. polymict rauhwackes, formed by fragmentation and mixing of two or more types of rock.

The typical boxwork rauhwackes represent a subtype of monomict rauhwackes. They originated from fractured dolostones and are extensively developed in only slightly tectonized regions, e. g. in the German Zechstein and Muschelkalk. Polymict rauhwackes represent intraformational crush-breccias which were formed by sliding (décollement) parallel to the bedding. Examination of polymict rauhwackes occurring in the metamorphic nappes of Tertiary orogenes may increase our knowledge about the relation existing between the tectonic evolution and Alpine metamorphism in these orogenes.     

Continental and marine paleoenvironments reflected by west Pacific clay sedimentation

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.

     

Über die Vergleichbarkeit von Lösungsformen auf Chlorid-, Sulfat- und Karbonatgestein — Überlegungen zu Fragen der Nomenklatur und Methodik der Karstmorphologie

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.

     

Petrogenesis of the Elzevir batholith and related trondhjemitic intrusions in the grenville province of eastern Ontario,Canada

The Elzevir batholith belongs to a suite of trondhjemitic intrusions emplaced at ca. 1,240 Ma in the Grenville Province of eastern Ontario. New major and trace element data, including REE, combined with isotopic and petrographic data indicate that:

1. the batholith has calc-alkalic affinities;
2. the Elzevir parental magma is very similar to that of dacites in the nearby, coeval metavolcanic rocks; the magma formed by partial melting of crustal material at granulite grade;
3. chemical differences between the plutonic and volcanic rocks can be best explained by accumulation of plagioclase in the plutonic environment;
4. fractionation was dominated by plagioclase and quartz, with lesser biotite and epidote, and minor zircon and apatite.

It is suggested that melting of sialic crust took place during the ‘docking’ of a partly-evolved, originally ensimatic arc system against the main cratonic mass to the northwest.     

Forest condition and forest damages — contribution of remote sensing to different inventory approaches

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

     

Die Liegendschichten der devonischen Pyrit- u. Schwerspat-Lager von Eisen (Saarland), Meggen und des Rammelsberges

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.

     

The structural geology of the Dalradian rocks of Slieve Gamph,Cos. Mayo and Sligo,Western Ireland

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.     

Environmental impacts by input of substances in landscapes of the District (Bezirk) of Leipzig,Germany

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.     

Low temperature\lg f_{O_2 } - pH diagrams of sulfur isotope evolution in an equilibrium hydrothermal system

According to Sakai-Ohmoto's theory regarding the evolution of sulfur isotopes in hydrothermal systems, in conjunction of new data on chemical resaction equilibrium constants and equilibrium isotopic fractionation factors as well as on individual ion activity coefficients of aqueous sulfur species, the following lgfo₂.-pH diagrams are constructed:

1. mole fractions of aqueous sulfur species (X _i ),
2. stability fields of some minerals in the Fe-S-O system,
3. diagram depicting the oxidation-reduction-state ratio for aqueous sulfur species (R′)
4. isotopic compositions of sulfur compounds ( \(\delta S_1 ^{34} \) ).