Diagnosis of weathering damage on rock-cut monuments in Petra, Jordan

Studies of many years—combining in situ investigation and laboratory analysis—have provided comprehensive information on weathering damage on the rock-cut monuments in the ancient city of Petra in Jordan. These rock-cut monuments represent outstanding world heritage. Many hundred monuments were carved by the Nabataeans from bedrock about 2000 years ago. The awareness of increasing weathering damage on the monuments has resulted in international efforts towards their preservation. The damage diagnosis has addressed the complex mutual relationships between stone types, stone properties, monument exposure regimes, environmental influences, weathering phenomena, development and extent of weathering damage and weathering progression. The rocks were classified lithostratigraphically and petrographically. Results on weathering forms, weathering profiles and weathering products obtained from monument mapping, in situ measurements and laboratory studies revealed a complex diversity of weathering phemomena with respect to type and intensity. Damage categories and damage indices were used to create a reproducible quantitative rating of weathering damage. Detailed results on weathering forms allowed the characterization and quantification of weathering progression including weathering prognoses. Stone properties and states of weathering damage were jointly considered for the rating of the rocks’ susceptibility to weathering. The systematic evaluation of weathering damage and monument exposure regimes can enhance the assessment of weathering factors and processes.     

Bestimmung sehr kleiner Verteilungskoeffizienten von Cs,Na und Ba zwischen Lösung und KCl-Einkristallen mit Hilfe radioaktiver Isotope

Distribution of Cs, Na, and Ba between great monocrystals of KCl and water solution was investigated. Impurity was either labelled by long-lived radioactive isotopes or was activated after growth of the crystals by neutrons in a nuclear reactor. No influence on partition coefficients was caused by using radioactive tracers, e.g. due to raised inclusion of mother liquor. Between impurity concentrations from 3·10^–4 to 10^–1 in the solution the partition coefficients were nearly constant and about 10^–3 for Na, about 10^–4 for Cs, and <5·10^–5 for Ba in KCl at temperatures of 40° C. If different impurity ions were built in simultaneously, the partition coefficients were independent of composition of solution. In case of Cs in KCl capture of Cs increased with increasing temperature.

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Meinem hoehverehrten Lehrer, Herrn Prof. Dr. W. von Engelhart, danke ieh für die freundliehe Überlassung des interessanten Themas. Für die stete Förderung und die zahlreichen fruehtbaren Diskussionen und Anregungen bin ich ihm und Herrn Dr. H. Puchelt zu großem Dank verpflichtet.Dem Bundesnlinisterium für wissensehaftliehe Forsehung danke ieh ffir die großzügige Unterstützung der Arbeit.Herrn Prof. Dr. W. Seelmann-Eggebert und Herrn Dr. V. Schneider vom Kernforsehungszentrum Karlsruhe und Herrn Dr. Bartel von der Kernforsehungsanlage Jülich danke ich für die Unterstützung bei der Neutronenaktivierung und Herrn Dr. J. Ottemann vom Mineralogischen Instigut der Universität Heidelberg für die Untersuchung mit der Elektronenmikrosonde.     

Paleomagnetic events in the brunhes and Matuyama epochs identified from magnetic profiles reduced to the pole

Eleven oceanic magnetic profiles associated with the paleomagnetic time scale younger than the beginning of the Matuyama epoch (2.43 my) have been reduced to the pole, altered to conform to a 3 cm yr^-1 spreading rate, and then all halves added and averaged to obtain a representative symmetric magnetic profile. This final stacked profile emphasizes the subtle anomalies associated with minor paleomagnetic events and minimizes randomly occurring anomalies. The axial anomaly of the stacked profile shows no evidence of the Laschamp event (centered at 0.025 my); however, a minimum at 0.15 my may correspond to the Blake event. A physical model of the stacked magnetic profile consists of a thin, highly magnetized layer with a 40% magnetization decrease at 10 km from the profile center. Magnetization values were modified from Irving and Talwani and the Blake event included. The stacked profile shows two minor anomalies centered at 1.97 my and 2.17 my. The younger anomaly corresponds with the younger Olduvai event (centered at 1.965 my) on the Cox time scale and the W anomaly (centered at 1.99 my) of Emilia and Heinrichs. The older anomaly lies between the older Olduvai event (2.12 my) of Cox and the X anomaly of Heirtzler, and Emilia and Heinrichs; additional work is required to assess the significance of this older event.This material was presented at the Fall Annual Meeting of the American Geophysical Union, December 8, 1971.     

Performance of the complete travel-time equation of state at simultaneous high pressure and temperature

The complete travel-time equation of state (CT-EOS) is presented by utilizing thermodynamics relations, such as; $$K_T = K_S (1 + \alpha \gamma T)^{ - 1} , \gamma = \frac{{\alpha K_S }}{{\rho C_P }}, \left. {\frac{{\partial C_P }}{{\partial P}}} \right)_T = - \frac{T}{\rho }\left[ {\alpha ^2 + \left. {\frac{{\partial \alpha }}{{\partial T}}} \right)_P } \right], etc.$$ The CT-EOS enables us to analyze ultrasonic experimental data under simultaneous high pressure and high temperature without introducing any assumption, as long as the density, or thermal expansivity, and heat capacity are also available as functions of temperature at zero pressure. The performance of the CT-EOS was examined by using synthesized travel-time data with random noise of 10^?5 and 10^?4 amplitude up to 4 GPa and 1500 K. Those test conditions are to be met with the newly developed GHz interferometry in a gas medium piston cylinder apparatus. The results suggest that the combination of the CT-EOS and accurate experimental data (10^?4 in travel time) can determine thermodynamic and elastic parameters, as well as their derivatives with unprecedented accuracy, yielding second-order pressure derivatives (?² M/?P ²) of the elastic moduli as well as the temperature derivatives of their first-order pressure derivatives ?² M/?P?T). The completeness of the CT-EOS provides an unambiguous criterion to evaluate the compatibility of empirical EOS with experimental data. Furthermore because of this completeness, it offers the possibility of a new and absolute pressure calibration when X-ray (i.e., volume) measurements are made simultaneously with the travel-time measurements.     

Narrow-line dynamics in Seyfert and starburst nuclei

Rotating disks and expanding supershells of ionized gas are supposed to be kinematical components essential for the formation of emission-like profiles from starburst nuclei and the narrow-line regions of Seyfert galaxies. Simple models predict a few typical features of line profiles by which disks may be recognized.A giant supershell is identified SE of the nucleus of the starburst galaxy NGC 253. We suggest that the variously reported outflow cones in Seyfert nuclei are also induced by superbubble dynamics. Observations of NGC 4151 are shown to be consistent with this scenario.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

War and the commons: Assessing the changing politics of violence, access and entitlements in Sri Lanka

There are two antagonistic, but equally influential traditions in the study of the nexus between resource use and violent conflict. One works through a Malthusian frame linking resource scarcity with violence, the other school of thought establishes a nexus between resource abundance and the incentives to use violence for rent monopolisation in a political economy of war or markets of violence. The tacit essentialism inherent in both schools of thought has increasingly come under critical scrutiny by geographers and anthropologists. To escape such essentialism requires a more detailed study of the dynamism of the political economy of (civil) war and its spatial dynamics, the political geographies of violence. In this paper, we study endowments and entitlements of people depending on common-pool or open-access resources in war-affected areas of Sri Lanka. Rural spaces in the war-affected areas became both a strategic retreat for fighters and an important common-pool resource on which a large part of the rural populace depended for their survival. Our research illustrates how the political geographies of war affect access regimes and entitlements to common-pool resources and thereby confine the livelihood opportunities of resource users. These dynamics of the political economy of war cross different scales and go beyond simple place-based struggles, for they are rooted in broader spatial dynamics of warfare creating place-space tensions in the sense that spatial dynamics of military control impinge changing access regimes upon specific places.     

Ductile deformation of garnet in mylonitic gneisses from the Münchberg Massif (Germany)

Mylonitic gneisses from the Münchberg Massif contain single grains (type I) and polycrystalline aggregates (type II) of garnet displaying a distinct elongation parallel to a macroscopic lineation which is interpreted as the result of ductile deformation. Lattice-preferred orientations of quartz (textures) symmetrical to the macroscopic foliation and lineation and the lack of rotational microfabrics indicate that the bulk deformation was pure shear at least during the latest strain increments. Garnet textures measured by EBSD together with microprobe analyses demonstrate that these two structural types of garnet can be related to two different processes of ductile deformation: (1) For the single grains stretching can be attributed to diffusion creep along grain boundary zones (Coble creep). The related mass transfer is indicated by the fact that primary growth zones are cut off at the long faces of the grains while the related strain shadow domains do not show comparable chemical zoning. Pressure solution and precipitation suitable to produce similar structures can be largely ruled out because retrogressive reactions pointing to the presence of free hydrous fluids are missing. (2) For the polycrystalline garnet aggregates consisting of cores grading into fine-grained mantles, dislocation creep and associated rotation recrystallization can be assumed. Continuous lattice rotation from the core to the outer polycrystalline rim allow a determination of the related dominant slip systems which are {100}<010> and equivalent systems according to the cubic lattice symmetry. The same holds for garnets which appear to be completely recrystallized. For this type of fine-grained aggregates an alternative nucleation model is discussed. Due to penetrative dislocation glide in connection with short range diffusion and the resulting lattice rotation, primary growth zones are strongly disturbed.Since for the considered rock unit of the Münchberg Massif peak metamorphic temperatures between 630 and 670 °C can be assumed, this study clearly demonstrates that the inferred processes of ductile garnet deformation can occur not only in HT regimes as often suggested in the literature even if embedded within a matrix of “low-strength” minerals like quartz, feldspars and micas.     

Seismic lamination and anisotropy of the Lower Continental Crust

Seismic lamination in the lower crust associated with marked anisotropy has been observed at various locations. Three of these locations were investigated by specially designed experiments in the near vertical and in the wide-angle range, that is the Urach and the Black Forrest area, both belonging to the Moldanubian, a collapsed Variscan terrane in southern Germany, and in the Donbas Basin, a rift inside the East European (Ukrainian) craton. In these three cases, a firm relationship between lower crust seismic lamination and anisotropy is found. There are more cases of lower-crustal lamination and anisotropy, e.g. from the Basin and Range province (western US) and from central Tibet, not revealed by seismic wide-angle measurements, but by teleseismic receiver function studies with a P–S conversion at the Moho. Other cases of lamination and anisotropy are from exhumed lower crustal rocks in Calabria (southern Italy), and Val Sesia and Val Strona (Ivrea area, Northern Italy). We demonstrate that rocks in the lower continental crust, apart from differing in composition, differ from the upper mantle both in terms of seismic lamination (observed in the near-vertical range) and in the type of anisotropy. Compared to upper mantle rocks exhibiting mainly orthorhombic symmetry, the symmetry of the rocks constituting the lower crust is either axial or orthorhombic and basically a result of preferred crystallographic orientation of major minerals (biotite, muscovite, hornblende). We argue that the generation of seismic lamination and anisotropy in the lower crust is a consequence of the same tectonic process, that is, ductile deformation in a warm and low-viscosity lower crust. This process takes place preferably in areas of extension. Heterogeneous rock units are formed that are generally felsic in composition, but that contain intercalations of mafic intrusions. The latter have acted as heat sources and provide the necessary seismic impedance contrasts. The observed seismic anisotropy is attributed to lattice preferred orientation (LPO) of major minerals, in particular of mica and hornblende, but also of olivine. A transversely isotropic symmetry system, such as expected for sub-horizontal layering, is found in only half of the field studies. Azimuthal anisotropy is encountered in the rest of the cases. This indicates differences in the horizontal components of tectonic strain, which finally give rise to differences in the evolution of the rock fabric.     

A comparison of chironomid biostratigraphy from Lake Vuolep Njakajaure with vegetation, lake-level, and climate changes in Abisko National Park, Sweden

Chironomid remains from the sediment of Lake Vuolep Njakajaure reflect limnological conditions resulting from changing climate and vegetation throughout the Holocene, but do not strictly follow accepted climate trends or the vegetation history based on regional pollen and macrofossil analyses. Chironomid community changes appear to be influenced by organic nutrient input from the surrounding catchment vegetation and lake hydrology, both of which are indirectly responding to some combination of climate change, hypolimnetic oxygen concentration, and changes in basin morphology. The chironomid-based quantitative mean July air-temperature reconstruction differs from other regional quantitative records; this discrepancy is likely related to limnological conditions particular to Lake Vuolep Njakajaure. Comparison of a northern Swedish temperature transfer function and one from western Canada reveals differences in the mean July air-temperature optima of several common taxa, suggesting that the existing conservative estimates of Holocene climate change in northern Sweden may be underestimated due to the limited temperature gradient captured by the Swedish training set.     

Physical properties of ultrahigh-pressure metamorphic rocks from the Sulu terrain, eastern central China: implications for the seismic structure at the Donghai (CCSD) drilling site

About 30 samples representing major lithologies of Sulu ultrahigh-pressure (UHP) metamorphic rocks were collected from surface exposures and exploration wells, and compressional (Vp) and shear wave (Vs) velocities and their directional dependence (anisotropy) were determined over a range of constant confining pressures up to 600 MPa and temperatures ranging from 20 to 600 °C. Samples range in composition from acidic to ultramafic. P- and S-wave velocities measured at 600 MPa vary from 5.08 to 8.64 km/s and 2.34 to 4.93 km/s, respectively. Densities are in the range from 2.60 to 3.68 g/cm³. To make a direct tie between seismic measurements (refraction and reflection) and subsurface lithologies, the experimental velocity data (corresponding to shallow depths) were used to calculate velocity profiles for the different lithologies and profiles of reflection coefficients at possible lithologic interfaces across the projected 5000-m Chinese Continental Scientific Drilling Program (CCSD) crustal segment. Comparison of calculated in situ velocities with respective intrinsic velocities suggests that the in situ velocities at shallow depths are lowered by an increased abundance of open microcracks. The strongly reflective zone beneath the Donghai drill site can be explained by the impedance contrasts between the different lithologies. Contacts between eclogite/peridotite and felsic rocks (gt-gneiss, granitic gneiss), in particular, may give rise to strong seismic reflections. In addition, shear-induced (lattice preferred orientation (LPO)-related) seismic anisotropy can increase reflectivity. For the explanation of the high velocity bodies (>6.4 km/s) around 1000 m and below 3200-m depth, large proportions of eclogite/peridotite (about 40 and 30 vol.%, respectively) are needed.