Deformationsmechanik eines offenen Konglomeratgefüges—Ein Beitrag zur statischen Tektonik

Zusammenfassung Offene Faltung in proterozoischen Tilliten der Huronian Supergroup führte zu geringen Differentialverschiebungen zwischen Matrix und Grobkomponenten innerhalb von konglomeratischen Schichtgliedern. Einmessung der aus der Bewegung resultierenden Striemungen und feiner Risse erlaubt die Bestimmung der regionalen Spannungsachsen (₁ > ₂ > ₃).

---

Deformation mechanics of an open conglomerate fabric—A contribution to static tectonics

Summary Open folding of Proterozoic tillites (Huronian Supergroup) caused minor differential displacements between matrix and clasts within conglomeratic units. Detailed measurements of striations and ruptures along the clast surface permitted the deduction of regional stress axes (₁ > ₂ > ₃).

---

---

Mit 6 Abbildungen

---

Herrn Prof. Dr. Dr. h. c.B. Sander zum 90. Geburtstag gewidmet.     

Statistical Properties of Ideal Rock Textures: Relationship Between Crystal Size Distribution and Spatial Correlation of Minerals

The concept of an ideal rock texture, in which crystals are distributed randomly in space, is proposed for use in general analysis of rock textures. The spatial correlation function for the ideal rock texture was examined and the function, a specific kind of spatial correlation function, is related to crystal size distribution and to some extent to crystal boundaries. The function is unity at distance zero, and monotonically decreases with increasing distance for the ideal texture. This behavior of the function is observed for any size distribution. In an ideal texture, the function is directly related to crystal size distribution and crystal shape. It is important in stereology because the crystal size distribution in three dimensions may be deduced from analyzing a function that is obtained from analyzing two-dimensional section images. Crystal shape is also related to the function. If crystals are concave in shape, or have inclusions of other phases, the function may show a hump or plateau when plotted against distance. However, the crystal shape effect cannot produce values smaller than zero. If values become negative, the texture is no longer considered ideal. The ideal textures for two model size distributions—step and delta functions—are considered. The rate of decrease of values is more strongly dependent on size distribution than on system dimension.     

Electrical conductivity,thermopower and <Superscript>57</Superscript>Fe Mössbauer spectroscopy of aegirine (NaFeSi<Subscript>2</Subscript>O<Subscript>6</Subscript>)

DC and AC electrical conductivities were measured on samples of two different crystals of the mineral aegirine (NaFeSi₂O₆) parallel () and perpendicular () to the [001] direction of the clinopyroxene structure between 200 and 600 K. Impedance spectroscopy was applied (20 Hz–1 MHz) and the bulk DC conductivity _DC was determined by extrapolating AC data to zero frequency. In both directions, the log _DC – 1/T curves bend slightly. In the high- and low-temperature limits, differential activation energies were derived for measurements [001] of E_A 0.45 and 0.35 eV, respectively, and the numbers [001] are very similar. The value of _DC [001] with _DC(300 K) 2.0 × 10^{–6 –1}cm^–1 is by a factor of 2–10 above that measured [001], depending on temperature, which means anisotropic charge transport. Below 350 K, the AC conductivity () (/2=frequency) is enhanced relative to _DC for both directions with an increasing difference for rising frequencies on lowering the temperature. An approximate power law for () is noted at higher frequencies and low temperatures with () ^s, which is frequently observed on amorphous and disordered semiconductors. Scaling of () data is possible with reference to _DC, which results in a quasi-universal curve for different temperatures. An attempt was made to discuss DC and AC results in the light of theoretical models of hopping charge transport and of a possible Fe²⁺ Fe³⁺ electron hopping mechanism. The thermopower (Seebeck effect) in the temperature range 360 K < T <770 K is negative in both directions. There is a linear – 1/T relationship above 400 K with activation energy E 0.030 eV [001] and 0.070 eV [001]. ⁵⁷Fe Mössbauer spectroscopy was applied to detect Fe²⁺ in addition to the dominating concentration of Fe³⁺.     

Analysis of the variability of unconfined compression tests of rock

Summary The laboratory testing program reported herein describes the statistical correlations of unconfined compressive strength ( _c ), Young's modulus (E _t50), and modulus ratio (MR) to their coefficients of variation (CV( _c ), CV(E _t50), and CV(MR)). Negative correlation of both _c andE _t50 to CV( _c ) indicates that data scatter tends to decrease with increasing strength and stiffness. A positive correlation between MR and CV( _c ) indicates that stiffer rocks are more variable for a given compressive strength.     

An internal variable model for the creep of rocksalt

Summary The creep strain rate of rocksalt, like that of other ductile crystalline materials, can be described by a power law equation of the type ( ) ⁿ , where the active stress is the difference between the total deviatoric applied stress and an internal stress _i . In this paper, the origin and the nature of this internal stress, which develops during inelastic deformation of the material, are discussed. It is shown that this internal stress can serve as an internal (or state) variable in the constitutive model of rocksalt, which reflects the microstructure evolution of the material under the competitive action of hardening and recovery mechanisms.An analysis of experimental data, both our own and those taken from the literature, demonstrates that such a law is able to correctly reproduce rocksalt creep test results in the steady-state domain. The proposed model is in accordance with the macroscopic and microscopic behavior of salt, and with direct measurements of the internal stresses made by others on this material.     

Dreiaxiale verformungen an Solnhofener Kalkstein im Temperaturbereich von 20–650° C. Röntgenographische Gefügeuntersuchungen mit dem Texturgoniometer

Axial-symmetric and real triaxial deformation tests on Solnhofen limestones were made in the range of 20 to 650° C. Stress, strain and time observations as functions of temperature and the ratios of the external stresses are plotted as stress-strain and strain-time curves. Mechanical twinning on e (01¯12) and syntectonic recrystallization (at temperatures above 500° C) is assumed to be the dominant flow mechanism. On samples of high permanent strain the textural changes and development of preferred orientations were investigated by means of the X-ray diffractometer. In all tests the symmetry of the polefigures is exactly identical with the symmetry of the external stress-field.In tests with ₁>₂=₃ the poles of the planes investigated (10¯11; 10¯12; 11¯20) occupy girdles about the unique principle compressive axis. When all principle stresses are different (₁>₂>₃) the poles of the planes investigated tend to maxima (in the case of plane strain) ore to girdle-occupations about the principle axis of maximum extension. The deduced c-diagrams show a fairly similar tendency of the spacial orientations.The pole figures (as well as the calculated orientation of the c-axis) must be explained by the superposition of reflected intensities on planes in twinned and untwinned grains. In every diagram partial occupations—possibly representing the orientations of twinned grains-are in fairly good agreement with the orientation predicted by the theory of Brace-MacDonald for the stable orientation of anisotropic minerals in a non-hydrostatic stress-field.

---

---

Herrn Prof. Dr. F. Karl danke ich sehr herzlich für zahlreiche Diskussionen sowie für die kritische Durchsicht des Manuskripts. Mein Dank gilt auch der Deutschen Forschungsgemeinschaft, welche die Untersuchung durch eine Sachbeihilfe unterstützte.     

Petrographic and geochemical evidence for hydrothermal evolution of the North Deposit,Mt Tom Price,Western Australia

High-grade iron mineralisation (>65%Fe) in the North Deposit occurs as an E-W trending synclinal sheet within banded iron formation (BIF) of the Early Proterozoic Dales Gorge Member and consists of martite-microplaty hematite ore. Three hypogene alteration zones between unmineralised BIF and high-grade iron ore are observed: (1) distal magnetite-siderite-iron silicate, (2) intermediate hematite-ankerite-magnetite, and (3) proximal martite-microplaty hematite-apatite alteration zones. Fluid inclusions trapped in ankerite within ankerite-hematite veins in the hematite-ankerite-magnetite alteration zone revealed mostly H₂O–CaCl₂ pseudosecondary and secondary inclusions with salinities of 23.9±1.5 (1, n=38) and 24.4±1.5 (1, n=66) eq.wt.% CaCl₂, respectively. Pseudosecondary inclusions homogenised at 253±59.9°C (1, n=34) and secondary inclusions at 117±10.0°C (1, n=66). The decrepitation of pseudosecondary inclusions above 350°C suggests that their trapping temperatures are likely to be higher (i.e. 400°C). Hypogene siderite and ankerite from magnetite-siderite-iron silicate and hematite-ankerite-magnetite alteration zones have similar oxygen isotope compositions, but increasingly enriched carbon isotopes from magnetite-siderite-iron silicate alteration (–8.8±0.7, 1, n=17) to hematite-ankerite-magnetite alteration zones (–4.9±2.2, 1, n=17) when compared to the dolomite in the Wittenoom Formation (0.9±0.7, 1, n=15) that underlies the deposit. A two-stage hydrothermal-supergene model is proposed for the formation of the North Deposit. Early 1a hypogene alteration involved the upward movement of hydrothermal, CaCl₂-rich brines (150–250°C), likely from the carbonate-rich Wittenoom Formation (¹³C signature of 0.9±0.7, 1, n=15), within large-scale folds of the Dales Gorge Member. Fluid rock reactions transformed unmineralised BIF to magnetite siderite-iron silicate BIF, with subsequent desilicification of the chert bands. Stage 1b hypogene alteration is characterised by an increase in temperature (possibly to 400°C), depleted ¹³C signature of –4.9±2.2 (1, n=17), and the formation of hematite-ankerite-magnetite alteration and finally the crystallisation of microplaty hematite. Late Stage 1c hypogene alteration involved the interaction of low temperature (~120°C) basinal brines with the hematite-ankerite-magnetite hydrothermal assemblage leaving a porous martite-microplaty hematite-apatite mineral assemblage. Stage 2 supergene enrichment in the Tertiary resulted in the removal of residual ankerite and apatite and the weathering of the shale bands to clay.Editorial handling: B. Lehmann     

The Candelaria silver deposit,Nevada — preliminary sulphur,oxygen and hydrogen isotope geochemistry

The pre-Cenozoic geology at Candelaria, Nevada comprises four main lithologic units: the basement consists of Ordovician cherts of the Palmetto complex; this is overlain unconformably by Permo-Triassic marine clastic sediments (Diablo and Candelaria Formations); these are structurally overlain by a serpentinitehosted tectonic mélange (Pickhandle/Golconda allochthon); all these units are cut by three Mesozoic felsic dike systems. Bulk-mineable silver-base metal ores occur as stratabound sheets of vein stockwork/disseminated sulphide mineralisation within structurally favourable zones along the base of the Pickhandle allochthon (i.e. Pickhandle thrust and overlying ultramafics/mafics) and within the fissile, calcareous and phosphatic black shales at the base of the Candelaria Formation (lower Candelaria shear). The most prominent felsic dike system — a suite of Early Jurassic granodiorite porphyries — exhibits close spatial, alteration and geochemical associations with the silver mineralisation. Disseminated pyrites from the bulk-mineable ores exhibit a ³⁴S range from — 0.3 to + 12.1 (mean ³⁴S = +6.4 ± 3.5, 1, n = 17) and two sphalerites have ³⁴S of + 5.9 and + 8.7 These data support a felsic magmatic source for sulphur in the ores, consistent with their proximal position in relation to the porphyries. However, a minor contribution of sulphur from diagenetic pyrite in the host Candelaria sediments (mean ³⁴S = — 14.0) cannot be ruled out. Sulphur in late, localised barite veins ( ³⁴S = + 17.3 and + 17.7) probably originated from a sedimentary/seawater source, in the form of bedded barite within the Palmetto basement ( ³⁴S = + 18.9). Quartz veins from the ores have mean ¹⁸O = + 15.9 ± 0.8 (1, n = 10), which is consistent, over the best estimate temperature range of the mineralisation (360°–460°C), with deposition from ¹⁸O-enriched magmatic-hydrothermal fluids (calculated ¹⁸O fluid = + 9.4 to + 13.9). Such enrichment probably occurred through isotopic exchange with the basement cherts during fluid ascent from a source pluton. Whole rock data for a propylitised porphyry ( ¹⁸O = + 14.2, D = — 65) support a magmatic fluid source. However, D results for fluid inclusions from several vein samples (mean = — 108 ± 14, 1, n = 6) and for other dike and sediment whole rocks (mean = — 110 ± 13, 1, n = 5) reveal the influence of meteoric waters. The timing of meteoric fluid incursion is unresolved, but possibilities include late-mineralisation groundwater flooding during cooling of the Early Jurassic progenitor porphyry system and/or meteoric fluid circulation driven by Late Cretaceous plutonism.     

Mean and turbulent velocity measurements of supersonic mixing layers

The behavior of supersonic mixing layers under three conditions has been examined by schlieren photography and laser Doppler velocimetry. In the schlieren photographs, some largescale, repetitive patterns were observed within the mixing layer; however, these structures do not appear to dominate the mixing layer character under the present flow conditions. It was found that higher levels of secondary freestream turbulence did not increase the peak turbulence intensity observed within the mixing layer, but slightly increased the growth rate. Higher levels of freestream turbulence also reduced the axial distance required for development of the mean velocity. At higher convective Mach numbers, the mixing layer growth rate was found to be smaller than that of an incompressible mixing layer at the same velocity and freestream density ratio. The increase in convective Mach number also caused a decrease in the turbulence intensity ( _u /U).List of Symbols a speed of sound - b total mixing layer thickness betweenU ₁ – 0.1U andU ₂ + 0.1U - f normalized third moment ofu-velocity,f u ³/(U)³ - g normalized triple product ofu ² v,g u ² v/(U)³ - h normalized triple product ofu v ², h uv' ²/(U)³ - l _u axial distance for similarity in the mean velocity - l _u axial distance for similarity in the turbulence intensity - M Mach number - M _c convective Mach number (for ₁=₂),M _c (U ₁–U ₂)/(a ₁+a ₂) - P static pressure - r freestream velocity ratio,rU ₂/U ₁ - Re unit Reynolds number,Re U/ - s freestream density ratio,s ₂/ ₁ - T _t total temperature - u instantaneous streamwise velocity - u deviation ofu-velocity,u u–U - U local mean streamwise velocity - U ₁ primary freestream velocity - U ₂ secondary freestream velocity - U average of freestream velocities, ¯U (U ₁ +U ₂)/2 - U freestream velocity difference,U U ₁ –U ₂ - v instantaneous transverse velocity - v deviation ofv-velocity,v v – V - V local mean transverse velocity - x streamwise coordinate - y transverse coordinate - y ₀ transverse location of the mixing layer centerline - ensemble average - ratio of specific heats - boundary layer thickness (y-location at 99.5% of free-stream velocity) - similarity coordinate, (y –y ₀)/b - compressible boundary layer momentum thickness - viscosity - density - standard deviation - dimensionless velocity, (U –U ₂)/U - 1 primary stream - 2 secondary stream A version of this paper was presented at the 11th Symposium on Turbulence, October 17–19, 1988, University of Missouri-Rolla     

Deformation und Gefügeregelung von Steinsalz im Temperaturbereich 20–200° c

Cubic specimens of fine-grained artifical polycristalline rock salt were deformed at different principal stresses in the range of 20–200° C. The data from different types of tests are compared by plotting ₁–₃ against ₁, ₂, ₃. The deformation behavior is highly influenced by the intermediate principal stress ₂. An increase of the intermediate stress from compression (₁>₂=₃) to extension (₁=₂>₃) lowers the rate of deformation. An increase of temperature always gives rise to an increase of deformation rate.Translation gliding on (110) is assumed to be the dominant flow mechanism. Textural changes and development of preferred orientation were investigated by means of the X-ray diffractometer. Intensities were measured for (110), (111), and (100). Compression leads to girdle occupations about the unique principle compressive axis, extension to girdles about the unique principle axis of extension. When all principle stresses are different the polfigures tend to a position intermediate between the two occupations.     

The genesis of emeralds and their host rocks from Swat,northwestern Pakistan: a stable-isotope investigation

Emerald deposits in Swat, northwestern Pakistan, occurring in talc-magnesite and quartz-magnesite assemblages, have been investigated through stable isotope studies. Isotopic analyses were performed on a total of seven emeralds, associated quartz (seven samples), fuchsite (three samples) and tourmaline (two samples) from the Mingora emerald mines. The oxygen isotopic composition ( ¹⁸O SMOW) of emeralds shows a strong enrichment in¹⁸O and is remarkably uniform at + 15.6 ± 0.4 (1,n = 7). Each of the two components of water in emerald (channel and inclusion) has a different range of hydrogen isotopic composition: the channel waters being distinctly isotopically heavier (D = –51 to –32 SMOW) than the other inclusion waters (D = –96 to –70 SMOW). Similarly the oxygen isotopic compositions of tourmaline and fuchsite are relatively constant ( ¹⁸O = + 13 to + 14 SMOW) and show enrichment in¹⁸O. The ¹⁸O values of quartz, ranging from + 15.1 to + 19.1 SMOW, are also high (+ 16.9 ± 1.4 1, n = 7). The meanD of channel waters measured from emerald (–42 ± 6.6 SMOW) and that of fluid calculated from hydrous mineralsD_calculated (–47 ± 7.1 SMOW) are consistent with both metamorphic and magmatic origin. However, the close similarity between the measuredD values of the hydroxyl hydrogen in fuchsite (–74 to –6 SMOW) and tourmaline (–84 and –69 SMOW) with pegmatitic muscovite and tourmaline suggests that the mineralization was probably caused by modified (¹⁸O-enriched) hydrothermal solutions derived from an S-type granitic magma. The variation in the carbon and oxygen isotopic composition of magnesite, locally associated with emerald mineralization, is also very restricted ( ¹³ –3.2 ± 0.7%, PDB; ¹⁸O + 17.9 ± 1.27 SMOW). On the basis of the isotopic composition of fluid ( ¹³C –1.8 ± 0.7 PDB; ¹⁸O + 13.6 ± 1.2 SMOW calculated for the 250-550 °C temperature), it is proposed that the Swat magnesites formed due to the carbonation of previously serpentinized ultramafic rocks by a CO₂-bearing fluid of metamorphic origin.     

Paleomagnetic constraints on Zn–Pb ore genesis of the Pillara Mine, Lennard Shelf, Western Australia

The Pillara Zn–Pb deposit is the largest of several known Mississippi Valley-type (MVT) deposits in the Lennard Shelf of the Canning Basin. Paleomagnetic and rock magnetic measurements are reported for 294 specimens from 23 sites in mineralization and its carbonate host rocks from the deposit as well as on 15 artificial specimens of zinc and lead concentrate and of tailings. Pyrrhotite carries the characteristic remanent magnetization (ChRM) in nearly all specimens. The ChRM postdates most faulting as shown by breccia tests and most minor regional tilting as shown by the degraded fit on tilt correction. The mean ChRM direction for all sites is D=20.6°, I=–27.5° (N=23, ₉₅=5.3°, k=34.1), yielding an age of 358±5 Ma (2) that is similar to the comparable age of 354±8 Ma (2) for the Kapok MVT deposit. Host rock diagenesis with attendant secondary remagnetization yields an age of 361±5 Ma (1) and the MVT mineralization with a primary chemical remanent magnetization gives an age of 356±3 Ma (1), co-eval with a published Rb–Sr sphalerite age of 357±3 Ma. Interpretation of this temporal data suggests that the MVT deposits of the southeastern Lennard Shelf originated during extension, probably in response to rift-related topography-driven fluid flow.Editorial handling: C. Brauhart     

Hydrothermale Lösungen

Zusammenfassung Das hydrothermale Auflösungsverhalten der vorwiegend als Gangarten auf-tretenden Mineralphasen Fluorit (CaF₂), Baryt (BaSO₄), Cölestin (SrSO₄) und Anglesit (PbSO₄) läßt sich übersichtlich in einem Temperatur-Löslichkeitsdiagramm darstellen und mit dem bekannten, qualitativ ähnlichen System SiO₂-H₂O vergleichen.Gegenüber dem molekulardispers gelösten SiO₂ ergeben sich aber für die in Ionen dissoziierten Lösungen der schwerlöslichen Sulfate und des Fluorits beträchtliche Verschiebungen der Sättigungsgleichgewichte, insbesondere bei Anwesenheit von Elektrolyten als Lösungsgenossen.Diese Beeinflussung, die für die genetischen Verhältnisse der Minerallagerstätten von entscheidender Bedeutung ist, wird für 0,1–2,0 normale NaCl-Lösungen im NaCl-Konzentrations-Löslichkeits-Diagramm der Minerale Fluorit, Baryt, Cölestin und Anglesit isotherm bis zum Siedepunkt der wäßrigen Mischphasen untersucht.Ferner wird das Löslichkeitsverhalten in den ternären Systemen BaSO₄-NaCl-H₂O und SrSO₄-NaCl-H₂O für Baryt und Cölestin gegen 2,0n NaCl-Lösungen entlang der Grenzkurve des Dreiphasengebietes und für die Isochoren 0,326 bis 0,6 bis 600° C und 2000 Bar dargestellt und mit den entsprechenden Verhältnissen der reinen wäßrigen Systeme verglichen.Ein abweichendes inkongruentes Auflösungsverhalten von Alumosilikaten mit Schichtgitterstruktur läßt sich am Beispiel des Muskovits durch die experimentelle Bestimmung der nichtstöchiometrischen Molekularverhältnisse SiO₂/K₂O und SiO₂/Al₂O₃ in den gesättigten Lösungen für den hydrothermalen Existenzbereich des Muskovits nachweisen.

---

The behaviour of solubility for some minerals, which were for the most part found as vein minerals, was determined experimentally and is represented by summarizing diagrams.In the temperature-solubility diagram the hydrothermal solubility of fluorite, barite, celestine and anglesite is compared to the solubility of quartz and muskovite for the boundary curve of the three-phase region and for some isochores. As opposed to SiO₂, which is molecularly dispersed in solution, the ionic solutions of the systems CaF₂-H₂O, BaSO₄-H₂O, SrSO₄-H₂O and PbSO₄-H₂O show considerable displacement of the saturation equilibrium when other components are present in the solution.This influence on the solubility, significant for the genetic relations of mineral deposits, was quantitatively analyzed for 0.1–0.2 n-NaCl solutions. The results are isothermally shown in the NaCl-concentration solubility diagram within the boundaries of room temperature and the boiling point of the aqueous mixed phases.In the tenary systems BaSO₄-NaCl-H₂O and SrSO₄-NaCl-H₂O, the hydro-thermal solubility of barite and celestine in 2.0 n-NaCl solutions is also shown for the range of the boundary curve of the three-phase region and for the isochores 0.326–0.6 up to a temperature of 600° C and a pressure of 2000 bar. These solubilities are then compared with the diagrams of solubility for pure aqueous solutions.The irregular and incongruent behaviour of the solubility of aluminium-silicates of a layered-lattic structure is demonstrated for the system KAl₂(OH)₂-AlSi₂O₁₀-H₂O in the presence of muscovite by experimental determination of the non-stoechiometric molecular proportions of SiO₂K₂O and SiO₂ Al₂O₃. Such determination was conducted in saturated solutions for the hydrothermal range of the existence of muscovite.The geological importance of the knowledge of hydrothermal data of solubility and their application to the process of the hydrothermalmagmatic series and hydrothermalmetamorphosis is discussed.

---

Résumé Le comportement de dissolution expérimentalement déterminé de certains minéraux trouvés surtout en filons est exposé en le résumant par diagrammes.La solubilité hydrothermique de fluorine, barytine, célestine et anglésite est comparée pour la courbe limitante (de la région triphasée) et pour les isochores 0,326–0,6 g.cm³ du diagramme température-solubilité avec le comportement de dissolution du quartz et de la muscovite. Les solutions ioniques des systèmes CaF₂H₂O, BaSO₄-H₂O, SrSO₄-H₂O et PbSO₄-H₂O montrent, comparées au SiO₂ dissous en dispersion moléculaire, de différences importantes d'équilibres de saturation en présence d'associés de solution.Cette influence sur la solubilité qui est d'une importance décisive pour les conditions génétiques des gisements de minéraux, a été examinée quantitativement pour les solutions 0,1–0,2—normales de NaCl. La présentation s'est faite isothermiquement dans le diagramme de concentration-solubilité de NaCl entre la température de chambre et le point d'ébullition des phases mixtes aqueuses.Dans les systèmes ternaires BaSO-NaCl-H₂O et SrSO₄-NaCl-H₂O la solubilité hydrothermique de barytine et de célestine en des solutions 2,0-normales de NaCl est présentée également pour l'espace des courbes limitantes de la région triphase et pour les isochores 0,326–0,6 jusqu'à 600° C et 2000 Bar. Elle est comparée avec les courbes de solubilité de systèmes purement aqueux. Le comportement de dissolution divergeant incongruent des silicates d'alumine à structure stratifiée en treillis est démontré pour le systême KAl₂(OH)₂-AlSi₃O₁₀-H₂O par exemple de la muscovite en déterminant expérimentalement les proportions moléculaires non-stochiométriques SiO₂ K₂O et SiO₂Al₂O₃ dans les solutions saturées pour la domaine d'existence hydrothermique de la muscovite.Importance géologique de la connaissance des dates de solubilité hydrothermique et leur application sur les événements des conséquences hydrothermiques-magmatiques et sur les événements de la métamorphose hydrothermique sont discutées.

---

y 600° 2000 . (CaF₂), ( SO₄), . (SrSO₄) (PbSO₄) - Sio₂-₂.

     

Thermal expansion of Neapolitan Yellow Tuff

Summary In saturated rocks and soils it is possible to define different coefficients of thermal expansion depending on the drainage conditions. This topic is first examined from the theoretical point of view with regard to an ideal isotropic thermo-elastic porous medium. Some special features of the behaviour of natural soils and rocks during thermal expansion tests are subsequently discussed. An experimental evaluation of some of these coefficients is presented in the second part of the paper. The material investigated is a pyroclastic rock, the so-called Neapolitan Yellow Tuff. Thermal expansion coefficient in drairend conditions has been evaluated, when this material is saturated with water. The e pressure increase induced by heating has been measured in undrained tes temperatures investigated range between room temperature up to 225°C.Different types of apparatus have been used and, when possible, a comparison between the results has been proposed. The results obtained in undrained thermal expansion tests are in agreement with theoretical predictions. This research is part of an on-going study of the complex phenomena known as Bradyseism, which is occurring in a volcanic area a few kilometers from Naples (Italy). Some considerations on this phenomenon are drawn in the last paragraph of the paper.List of Symbols _l linear thermal expansion coefficient - _s volumetric thermal expansion coefficient of the solid phase - _ss volumetric drained thermal expansion coefficient of the solid skeleton - _st volumetric drained thermal expansion coefficient that takes into account variations of porosity induced by heating - _t volumetric drained thermal expansion coefficient of the whole system - _u volumetric undrained thermal expansion coefficient of the whole system - _v volumetric thermal expansion coefficient - _w volumetric thermal expansion coefficient of the water - _l ^* volumetric thermal expansion coefficient of the distilled water - Biot's coefficient - _d dry specific gravity - _s specific gravity of the solid phase - _r ^' uniaxial compressive strength - _r ^' yield stress in isotropic compression - B _T parameter relating undrained thermally generated pore pressure with temperature change - d ₀ maximum uplift during Bradyseismic crises - d _f residual uplift during Bradyseismic crises - K _s compressibility modulus of the solid phase - K _ss compressibility modulus of the solid skeleton - K _w compressibility modulus of the water - n porosity - T temperature - T ₀ initial temperature in thermal expansion, tests performed in thermal expansion cell - T _m temperature at which the volume of waterV _Eexpelled from thermal expansion cell. is measured - V volume of the solid skeleton - V _E volume expelled from thermal expansion cell - V ₀ volume of the expansion cell at temperatureT ₀ - V _s volume of the solid phase     

Metamorphic evolution of the palaeozoic series of the Betic Cordilleras (Nevado-Filabride complex,SE Spain) and its relationship with the alpine orogeny

The Palaeozoic rocks of the Veleta nappe (Nevado-Filábride complex, Betic Cordilleras, Southern Spain) consist of graphite-mica schists with oxychlorite — chloritoid — albite — garnet porphyroblasts. Crystal chemistry of the minerals, their phase relations and microfabrics are consistent with a normal prograde metamorphic evolution and a slight retrograde overprint. The basis of the overlying Mulhacén nappe consists also of Palaeozoic graphite-mica schists, but with clear signs of polymetamorphic development. An early low-pressure metamorphism with andalusite and chloritoid is overprinted by high-pressure metamorphism with kyanite and Mg-rich chloritoid. This later development is of Alpine age, which is demonstrated by the metamorphic conditions of Permo-Triassic rocks in the upper part of the Mulhacén nappe, included formation of eclogites, followed by an amphibolite facies overprint. The metamorphism of the Veleta nappe is regarded as pre-Alpine: a possible Alpine overprint did not cause an increase in temperatures. No inverse metamorphic gradient exists between Veleta and Mulhacén nappes, because of the different ages of metamorphism.

---

Zusammenfassung Die paläozoischen Gesteinsserien der Veletadecke im Nevado-Filábride Komplex (Betische Kordillere, Südspanien) bestehen aus Graphitglimmerschiefern mit Oxichlorit — Chloritoid — Albit — Granat — Porphyroblasten. Die Kristallchemie der Minerale, ihre Phasenbeziehungen und Mikrogefüge sind konsistent mit einer normalen prograden Metamorphoseentwicklung und leichter retrograder Überprägung. Die Basis der darüberliegenden Mulhacendecke besteht ebenfalls aus paläozoischen Graphitglimmerschiefern, die jedoch deutliche Anzeichen für polymetamorphe Entwicklung zeigen: Eine frühe Niedrigdruckmetamorphose mit Andalusit und Chloritoid wird überprägt von einer Hochdruckmetamorphose mit Disthen und Mg-reichem Chloritoid. Diese spätere Entwicklung ist, wie die Metamorphosebedingungen der im Hangenden folgenden permotriadischen Gesteine der Mulhacendecke zeigen, frühalpin und schließt Eklogitbildung mit ein, gefolgt von einer amphibolitfaziellen Überprägung. Die Metamorphose der Veletadecke wird als präalpine Metamorphose angesehen: Eine mögliche alpine Überprägung hat keinen Temperaturanstieg verursacht. Zwischen Mulhacendecke und Veletadecke besteht kein inverser Metamorphosegradient, sondern ein Sprung in den Metamorphosealtern.

---

Résumén El Paleozoico del Manto del Veleta (complejo Nevado-Filábride, Cordilleras Béticas, suroeste de España) está formado por micasquistos grafitosos con porfiroblastos de oxicloritas — chloritoide — albita — granate. La cristalquímica de los minerales, sus relaciones de fase y microfábrica son coherentes con una evolución metamórfica progresiva normal y con un ligero retrometamorfismo. La base del suprayacente Manto del Mulhacén está también formado por micasquistos grafitosos paleozoicos, pero muestran signos evidentes de un desarrollo polimetamórfico. El metamorfismo más antiguo tiene unas caracteristicas de baja presión con la formación de andalucita y cloritoide. Estas rocas sufren los efectos de un nuevo proceso metamorfico de edad alpina, lo que puede ser demostrado por comparación con las rocas Permo-Triásicas de la parte superior del Manto del Mulhacén, en las cuales las eclogitas formadas en la primera fase son afectadas por otra en la facies de las anfibolitas. El metamorfismo del Manto del Veleta puede ser probablemente considerado como pre-Alpino: si está afectado por el metamorfismo alpino, éste no ha causado un incremento de temperatura. No existe, por tanto, inversión del gradiente metamórfico entre los Mantos del Veleta y del Mulhacén puesto que la edad del metamorfismo en ambos es diferente.

---

-/ , / . . , , , . , . Mulhacen - , : , , , . , - Mulhacen, , . , - : . , Mulhacen Veleta ; .

     

The global Frasnian-Famennian »Kellwasser Event«

During the UppermostP. gigas conodont zone (P. linguiformis zone) the stepwise Frasnian extinction culminates in the global transgressive-regressive Frasnian-Famennian »Kellwasser event«. Most pelagic organisms of the tropical marine environment are more or less affected by this mass extinction. During the early Upper Devonian extinction rates are clearly related to the deposition of black shales and the storage of a great amount of organic carbon in the (shelf) sediments. Contemporaneous positive excursions of the ¹³C recorded from pelagic limestones of Europe and Australia prove a worldwide change in the CO₂ content of the oceans surface water which is in balance with the atmosphere. If the climate is controlled by the CO₂ content of the atmosphere, a cyclic operation process might have developed with the succession: transgression — high organic production — deposition of organic carbon — lowering of CO₂ in the atmosphere — icehouse effect — polar glaciation — regression — erosion of organic carbon and re-supply of CO₂ to the ocean and atmosphere — greenhouse effect — deglaciation — transgression. During the change from a greenhouse to an icehouse effect an overturn of the anoxic oceans probably was one of the causes for the mass killing of low latitude marine organisms.

---

Zusammenfassung Während der OberstenP. gigas-Zone (=P. linguiformis-Zone) kulminiert das stufenweise Erlöschen der Frasne Organismen im globalen transgressiv-regressiven »Kellwasser-Ereignis«, das die Frasne-Famenne-Grenze markiert. Die meisten Organismengruppen der tropischen Meere werden mehr oder weniger von dem Massensterben betroffen. Während des tiefen Oberdevons sind die Aussterberaten offensichtlich mit der Ablagerung von Schwarzschiefern verknüpft, in denen eine große Menge organischen Kohlenstoffs auf den Schelfen fixiert wird. Gleichzeitige positive Exkursionen der ¹³C-Kurven, die in pelagischen Kalken aus Europa und Australien gemessen wurden, deuten auf eine weltweite Änderung der CO₂-Gehalte des ozeanischen Oberflächenwassers und der Atmosphäre hin.Sollte das Klima vom CO₂ in der Atmosphäre gesteuert werden, könnte sich folgender Autozyklus entwickelt haben: Transgression — hohe organische Produktion — Ablagerung von organischem Kohlenstoff — Erniedrigung des CO₂-Gehaltes in der Atmosphäre — Abkühlung — polare Vereisung-Regression — Erosion und Oxidation von organischem Kohlenstoff — Erhöhung des CO₂-Gehaltes in der Atmosphäre — Treibhauseffekt — Abschmelzen der polaren Vereisung — Transgression. Aufsteigende anoxische Wässer beim Übergang vom Treibhaus- zum »Kühlhauseffekt« dürften eine der Ursachen für das Massensterben tropischer mariner Organismen gewesen sein.

---

Résumé Au cours de la partie supérieure de la zone de conodontes àP. gigas (= zone àP. linguiformis), l'extinction progressive des organismes frasniens a culminé au moment de l'événement de Kellwasser, marqué par une transgression-régression globale à la limite Frasnien-Famennien. La plupart des organismes pélagiques des milieux marins tropicaux ont été affectés à des degrés divers par cette extinction de masse. Pendant le début du Dévonien supérieur, les taux d'extinction sont clairement en relation avec le dépôt de boues noires et le stockage d'une grande quantité de matière organique dans les sédiments de shelf. Simultanément, des variations positives de ¹³C enregistrées dans des calcaires pélagiques d'Europe et d'Australie indiquent un changement modial de la teneur en CO₂ de l'eau de surface des océans et de l'atmosphère.Si on admet que le climat est régi par la teneur en CO₂ de l'atmosphère, le processus cyclique suivant a pu se développer: transgression — forte production organique — dépôt de carbone organique — baisse de la teneur en CO₂ de l'atmosphère — refroidissement — glaciation polaire — régression — érosion et oxydation du carbone organique — élévation de la teneur en CO₂ de l'atmosphère — effet de serre — fusion des glaces polaires — transgression. Lors du passage du stade de l'effet de serre à celui du refroidissement, une remontée des eaux anoxiques océaniques peut être à l'origine de l'extinction de masse des organismes marins tropicaux.

---

, , P. gigas, - Kellwasser, . . , . ¹³ , , ₂ , . ₂ , : — — _opr.- ₂ — — — — — ₂ — - — . » « .

     

Zur Stratigraphie der grobklastischen Fazies im Oxfordium des Wiehengebirges

Zusammenfassung Der Fund vonPeltoceratoides instabiliformis n. sp. in Steinbrüchen am Gehn nordwestlich von Osnabrück (Abb. 3) liefert weitere Kriterien, daß der Wiehengebirgssandstein, dessen stratigraphische Stellung wegen Mangel charakteristischer Fossilien unsicher ist, ins höhere Oxfordium zu stellen ist. Diese grobklastische Fazies vertritt im Wiehengebirge im wesentlichen die für das Wesergebirge typische kalkige Fazies des Korallenooliths. Anschließend wird zu einer neueren paläogeographischen Mitteilung über den Korallenoolith Nordwestdeutschlands kurz Stellung genommen.

---

In quarries at the Gehn NW of Osnabrück, several specimens ofPeltoceratoides instabiliformis n. sp. have been found. This gives further indications to the stratigraphic position of the Wiehengebirgs sandstone — which is uncertain, due to the lack of characteristic fossils — to be of Upper Oxfordian age. In the Wiehengebirge though, this coarse clastic facies substitutes to a large extent the calcareous facies of the Korallenoolith typical for the Wesergebirge.A recent paleogeographic report on the Korallenoolith of NW-Germany is then briefly discussed.

---

Résumé LesPeltoceratoides instabiliformis n. sp. découverts dans des carrières du Gehn au nord-ouest d'Osnabrück fournissent d'autres indices affirmant que le grès du Wiehengebirge dont la position stratigraphique est incertaine faute de fossiles caractéristiques doit être attribué à l'Oxfordien supérieur. Dans le Wiehengebirge, ce faciès clastique à grain grossier remplace dans l'essentiel le faciès calcaire du Korallenoolith typique pour le Wesergebirge.Il suit une brève critique d'une communication paléogéographique récemment parue sur le Korallenoolith du Nord-Ouest de l'Allemagne.

---

. Peltoceratoides instabiliformis n. sp. . . , . - .

---

---

Herrn Professor Dr.Roland Brinkmann zum 70. Geburtstag gewidmet.     

Wegeners „Kontinentverschiebungen“ zu seiner Zeit und heute

Zusammenfassung Ausgangspunkt der Wegenerschen Theorie war der unmittelbare Eindruck von der Kongruenz der atlantischen Küsten. Das eigentliche Fundament bildeten jedoch die Argumente aus Paläontologie, Geophysik, Geologie, Paläoklimatologie und Astrogeodäsie. Wegener war nicht nur der Schöpfer, sondern auch der Propagandist seiner Theorie. Von bleibendem Wert erwiesen sich seine Forderungen: Jede Theorie der Entstehung der Ozeane und Kontinente muß von allen geowissenschaftlichen Disziplinen getragen werden und sie muß sich durch Messungen bestätigen lassen.

---

The starting-point of Wegener's theory was the direct impression of the congruity of the Atlantic coastlines. The fundamental principle, however, is formed by the argumentation of paleontology, geophysics, geology, paleoclimatology and astrogeodesy. Wegener was not only the creator of his theory but he also propagated it. His demands proved to be of lasting value: every theory of the origin of oceans and continents has to be supported by all geosciences and it should be possible to be verified by physical measurements.

---

Resume Le point de départ de la théorie de Wegener fut l'impression immédiate de la concordance des côtes atlantiques. Les bases véritables furent les arguments tirés de la Paléontologie, de la Géophysique, de la Géologie, de la Paléoclimatologie et de l'Astrogéodésie. Wegener fut non pas seulement le créateur de sa théorie, mais encore son propagandiste. Sa démarche reste valable d'une théorie de la genèse des continents et des océans qui soit étayée part toutes les sciences de la terre et verifée par des mesures physiques.

---

. , , , . , . , , .

     

The micro-scale simulation of maturation: outline of a new technique and its potential applications

A micro-analytical technique has been developed for artifically maturing sedimentary organic matter and then quantifying the major components generated during this process in a single analytical step. Such a capability is well-suited for examining the compositional relationships between kerogens and petroleums, determining reaction kinetics and making precursor-product mass balances. According to this technique, simulations are made using sealed glass capillary tubes (heated here for three days at 300 °C, 330 °C and 350 °C). Pyrolysis products are then released directly into a combined thermovaporisation/pyrolysis-GC instrument and the major components of the entire C₁ yto C³⁵ range can be quantified in a single step using gas chromatography. Alkene yields are very low and pyrolysates are oil-like. This is exemplified by the fact that then–C₉–C₁₉ alkane distribution range of simulated whole petroleum chromatograms, from originally immatureGloeocapsamorpha-typz alginite A, resembles that seen in crude oils generated from this same kerogen type in nature. Sealed tube experiments usingBotryococcus type alginite A generated a »high wax« pyrolysate. The relative abundance ofn-alkanes in the C₂–C₃₂ range of many kerogen pyrolysates does not appear to change significantly despite an approximately fifteen-fold difference inn-alkane yield between the 300 °C and 350 °C experiments. Kerogens which are »paraffinic« oil-prone, and whose pyrolysates are very rich inn-alkanes might therefore generate petroleums in nature with a fixed wet gas (C₂-C₄) to oil (C₅+) ratio. Alginite B in a Greenland shale is much more thermally labile than eitherBotryococcus-type alginite A orGloeocapsamorpha-type alginite A. The mass balance capabilities of the technique have been tested using Alum Shale kerogen. Two gas chromatograms were obtained, one for the free compounds generated during simulation, and one for the high temperature pyrolysate of the kerogen residue, for each heating experiment. Precursor-product relationships were qualitatively assessed, and dead carbon formation was quantified in this exercise.

---

Zusammenfassung Eine mikro-analytische Methode zur künstlichen Reifung sedimentärer organischer Substanz konnte entwickelt werden. Dabei werden die Hauptkomponenten, die während des Vorgangs freigesetzt werden, quantitativ erfaßt. Grundlagen dieser Methode sind Simulationen mit kapillaren Glasröhren, nach welchen die Pyrolyse-Produkte direkt in ein kombiniertes Thermovaporation/Pyrolyse-GC Instrument freigesetzt werden. Mit Hilfe der Gas-Chromatographie können in einem einzigen Schritt die Hauptkomponenten der gesamten C₁ bis C₃₅ Spannbreite quantitativ erfaßt werden. Kerogen-Typisierung und Abschätzung des Muttergesteinspotentials werden stark vereinfacht, wenn die Verhältnisse der Vorläufer-Produkte sorgfältig bestimmt und die chemisch-kinetischen Parameter für einzelne Komponenten, Komponentengruppen und/oder Siedepunktbereiche berechnet werden. Diese Anwendung stimmt mit Techniken im Makro-Bereich (z. B. Hydro-Pyrolyse) überein, aber die Vorteile der Annäherung im Mikro-Bereich liegen darin, daß geochemische Informationen schneller und bequemer gewonnen werden können und sehr kleine Probenmengen ausreichen. Ferner kann neben der Möglichkeit der singulären Anwendung die Annäherung im Mikro-Bereich dazu verwendet werden, Proben für detailierte und Labor-intensive Simulationen im Makro-Bereich effizient auszuwählen.

---

Résumé Les auteurs présentent une technique micro-analytique qui comporte la maturation artificielle de la matière organique sédimentaire suivie du dosage des composants majeurs ainsi engendrés. Dans le cadre de ce procédé, on réalise des simulations dans des tubes capillaires en verre, après quoi les produits de la pyrolyse sont libérés directement dans un instrument combiné de thermovaporisation/hydrolyse-GC et les composants majeurs de la lignée complète C₁ à C₃₅ peuvent être dosés en une seule opération de Chromatographie en phase gazeuse. De cette manière, la caractérisation du kérogène et l'estimation du potentiel de la rochemère sont grandement facilitées dans la mesure où les relations des produits précurseurs sont soigneusement établies et où il est possible de calculer les paramètres chimico-cinétiques pour des composants isolés, pour des groupes de composants et/ou les domaines de température où se situent les points d'ébullition. Ces procedures sont en accord avec celles des techniques macroscopiques (p.ex l'hydro-pyrolyse), mais l'avantage de l'approche microanalytique réside dans le fait que les résultats géochimiques sont obtenus plus rapidement et plus aisément et qu'il est possible de traiter de très petits échantillons. Enfin, nonobstant ses avantages propres, l'approche micro-analytique peut être utilisée à la sélection d'échantillons destinés à des simulations détaillées et laborieuses à l'échelle macroscopique.

---

. , . . _{1 35} . - - , / , , - . , .: , , . .

     

A volcanic-carbonate association in the Góry Kaczawskie,Western Sudetes

Amidst metavolcanic rocks and phyllites of the Góry Kaczawskie region occur isolated carbonate bodies known as the Wojcieszów limestones. The bodies enclosed in the metavolcanites show primary (sedimentary) contacts, while those in the phyllites do not have such contacts. The Wojcieszów limestones and metavolcanic rocks form sequences displaying mutual spatial and genetical relations. Submarine volcanic elevations were covered with chemical and biochemical carbonate precipitation, the intensity of which was stimulated and controlled by the volcanic activity.

---

Zusammenfassung Inmitten der metavulkanischen Gesteine und Phyllite von Góry Kaczawskie erscheinen isolierte Karbonatgesteinskörper, die als Wojcieszów-Kalke bekannt sind. Die Karbonatgesteine innerhalb der Metavulkanite zeigen sedimentäre Kontakte, während die in den Phylliten eher tektonisch begrenzt sind. So kann man den Wojcieszów-Kalken und den Metavulkaniten eine räumliche und genetische Beziehung zusprechen. Submarine Erhebungen aus Vulkangesteinen waren mit chemischen und biochemisch gefällten Karbonatserien bedeckt, wobei die vulkanische Aktivität die Karbonatbildung unmittelbar beeinflu\te.

---

Résumé Parmi les métavolcanites et les phyllites de la région du Góry Kaczawskie, il existe des corps carbonatés isolés connus sous le nom de »calcaires de Wojcieszów«. Ceux qui sont inclus dans les métavolcanites présentent des contacts sédimentaires, contrairement à ceux qui sont inclus dans les phyllites, dont les contacts sont tectoniques. Entre les calcaires de Wojcieszów et les roches métavolcaniques, il est donc possible d'établir des relations spatiales et génétiques. Des reliefs volcaniques sous-marins ont été le siège d'une précipitation carbonatée chimique et biochimique dont l'intensité dépendait de l'activité volcanique.

---

, (. 1). , ; . , , , 0 45 NW. . . ; , , . . , . , (. 2). .