Greening western China: A critical view

The dominant narrative in a growing literature about China’s environment conceptualizes a series of recent large-scale ecological construction projects, particularly in western China, as evidence of a teleological graduation into eco-rational modernity, in which environmental improvement and economic growth are intertwined in a virtuous, mutually reinforcing circle. Such ecological modernization narratives take for granted both a crisis of ecological degradation, and the premise that the “greening” of the state will have environmental improvement as its primary outcome. The article reviews recent research on ecological construction projects to protect forests and grasslands in China’s west, which have been identified as major components of China’s ecological modernization goals. It demonstrates the limitations of an ecological modernization framework for analyzing these projects, and argues instead for a critical political ecology analysis, which examines the distributive effects of these projects and employs an analytic of governmentality. Ecological construction is more productively understood as a set of discursive practices that authorize differential interventions through processes of internal territorialization, rework the relationship between different categories of citizens and the state, and produce subjects, whose desires may or may not align with those desired by state institutions.     

Interglacial vegetation succession: A view from southern Europe

Factors influencing interglacial vegetation development in southern Europe are considered in a series of comparisons of the vegetation and climatic signatures of selected periods. Multivariate analysis provides a method for standardizing comparison of interglacial vegetation successions, and insolation values and geological evidence supply information on the climatic character of individual periods. Application of this comparative approach to a long pollen record from northwest Greece presents an opportunity to examine a series of interglacial successions under constant background site characteristics, secure chronostratigraphical positions and minimal differences in species' immigration rates. The record of four interglacial period equivalent to marine oxygen isotopic substages 5e, 7c, 9c and 11c is examined. The comparison shows that the two earliest periods are characterized by similar vegetation development despite differences in climatic regimes. Dependence on initial conditions is one of the emergent aspects of the comparisons, suggesting that the nature of surviving populations during a cold stage may be critical in determining the course of interglacial succession.     

A new view on neotectonics

Conclusion Neotectonics — the discipline examining the youngest history of the Earth in terms of geotectonics — should be complemented by aspects based on other geological sciences (geochemistry, geophysics) as well as geography and geodesy. From the viewpoint of the Earth's history, neotectonics can be regarded as a discipline studying, above all, the Earth's crust and the changes that occurred there in the time span from the Badenian to the Recent. For this reason, the last phase of the Alpine geotectonic stage, which extended from the Oligocene to the base of the Lower Badenian, should be termed pre-neotectonics.     

A view of texture dynamics

Textures in rocks reflect the interactions of driving forces and the mechanisms allowing them to induce change. The driving forces are excess chemical energy induced by changing pressure and temperature, deviatoric stress, and surface energy. The mechanisms whereby they are manifest include diffusion (in grains, fluids and grain boundaries), surface reaction, dislocation creep and nucleation. Emphasis is put on the first two processes in this discussion. Diffusion is frequently important in metamorphic reactions and is the dominant chemical means whereby stress induces shape change (pressure solution). Conversely, surface and interface reaction (and not surface energy anisotropy) control growth and dissolution of euhedral grains. Processes of texture development in turn affect the driving forces, in particular creating new transient forces. Thus a purely chemical driving force induced by, for example, temperature change, can lead to the buildup of stresses whose chemical effect reaches a comparable magnitude. Similarly, surface-reaction controlled growth of grains can give rise to large local surface energies which themselves drive further changes. Detailed grain-scale models are required to describe these phenomena; attempts to 'average' properties such as diffusion or reaction on the scale of many grains can give rise to misleading inferences. Instead, local buffering of species in individual grain boundaries can have a great effect on overall transport properties and texture development. Not only measurements of diffusion and reaction rate parameters, but also consistent qualitative models for texture development are required to characterize these processes.     

Environmentally hazardous industry in South Africa: A spatial view

Akthough issues surrounding the location and relocation of environmentally hazardous industry have attracted international attention, little research has been undertaken in South Africa. The aim is to analyse the geography of dirty industries in South Africa and suggest avenues for future research. The location of environmentally hazardous production in South Africa has not followed the national industrial trend towards polarization reversal.     

Acid-base properties of a goethite surface model: A theoretical view

Density functional theory is used to compute the effect of protonation, deprotonation, and dehydroxylation of different reactive sites of a goethite surface modeled as a cluster containing six iron atoms constructed from a slab model of the (1 1 0) goethite surface. Solvent effects were treated at two different levels: (i) by inclusion of up to six water molecules explicitly into the quantum chemical calculation and (ii) by using additionally a continuum solvation model for the long-range interactions. Systematic studies were made in order to test the limit of the fully hydrated cluster surfaces by a monomolecular water layer. The main finding is that from the three different types of surface hydroxyl groups (hydroxo, μ-hydroxo, and μ₃-hydroxo), the hydroxo group is most active for protonation whereas μ- and μ₃-hydroxo sites undergo deprotonation more easily. Proton affinity constants (pK_a values) were computed from appropriate protonation/deprotonation reactions for all sites investigated and compared to results obtained from the multisite complexation model (MUSIC). The approach used was validated for the consecutive deprotonation reactions of the [Fe(H₂O)₆]³⁺ complex in solution and good agreement between calculated and experimental pK_a values was found. The computed pK_a for all sites of the modeled goethite surface were used in the prediction of the pristine point of zero charge, pH_PPZN. The obtained value of 9.1 fits well with published experimental values of 7.0-9.5.     

Redox State of Tektites from Different Scattering Fields: Evidence from the Data of Electrochemical Study of Intrinsic Oxygen Fugacity

Doklady Earth Sciences - The results of study of the intrinsic oxygen fugacity (fO2) of various types of tektites from the European and Australasian scattering fields (moldavites, indochinites,...     

Prehistoric coastal ecologies: A view from outside Franchthi Cave,Greece

Shackleton and van Andel have raised the question of past human selectivity in the collection of shellfish resources. They reconstruct, for the changing coastlines near Franchthi Cave during the post-glacial transgression, changes in availability of various species of shellfish. The model of availability is compared with the archaeological record of shellfish from the cave. Shackleton and van Andel conclude that selectivity is demonstrated and that this was, in part, “idiosyncratic”. A critical analysis of the model leads to the conclusion that, while the reconstructions of the likely positions of past coastlines may be acceptable, the reconstructions of mollusc availability at various times in the past are highly improbable. Sea-level change is not the only important determinant of past coastal ecology although it will, of course, have an impact on the ways in which coastal ecosystems developed. Other factors (including the physical and chemical properties of the substratum, levels of productivity, and biological interactions), operating at various spatial and chronological scales, cannot be ignored or even subordinated. The shellfish remains from the cave are the only objective evidence of man's exploitation of past coastal resources. Taphonomic analyses of the shells from the site would allow a number of important questions to be addressed, including the reasons for their collection and the possibility of over-exploitation of certain species in the past.     

The southern Rhine graben: A new view of the initial phase

One of the puzzling features of the southern end of the Rhine graben is the Dinkelberg-Tabular Jura block on the eastern shoulder of the graben. It is dissected by a large number of faults, the most notable ones forming a field of narrow little grabens and half-grabens whose bordering faults converge at the level of the Middle Triassic evaporites, which points to décollement at that horizon. The little grabens were traditionally considered to be of Oligocene age, coeval with the main taphrogenesis of the Rhine graben. Two hypotheses were offered for their formation, one ascribing them to extension on the extrados of large basement folds, the other to gravity sliding on paleoslopes. Recent field work uncovered overwhelming evidence for an Eocene age of the little grabens, the time of the initial phase of Rhine graben formation. At that time there were neither large basement folds nor paleoslopes of any significance, and therefore the two hypotheses offered until now do not work. However, the map-view pattern of the field of faults offers a somewhat unusual way out of the dilemma. This pattern is most prominently displayed in the Dinkelberg area north of the Rhine. There a lane of narrow décollement grabens with a mean NNE strike is confined within the NW- striking Dinkelberg graben, which is much wider and rooted in the basement. It is also very shallow, with a subsidence on the order of 100 m. The lane of décollement grabens forms a dextral en-échelon pattern with respect to the Dinkelberg graben, suggesting stretching of the post-evaporite sequence above a basement essentially extended by strike slip. This model, though not as clearly expressed, is also compatible with the data in the rest of the Dinkelberg-Tabular Jura block. It also fits surprisingly well a theoretical model by Withjack and Scheiner (1982) that predicts a dominance of strike-slip in the marginal area of a system consisting of extension superimposed on doming.     

Olympus Mons volcano,Mars: A photogeologic view and new insights

The volcano Olympus Mons is probably the best known extraterrestrial volcano. In the past decade, an unprecedented selection of high-resolution images with a spatial resolution of up to 25?cm/pixel has been collected, and these images now allow detailed morphologic analysis of the entire volcano. The summit comprises a nested caldera with six overlapping collapse pits. There are numerous wrinkle ridges and graben on the caldera floor, and topographic data indicate that the location of these features is controlled by subsidence of the central portion of the floor. Examination of the caldera walls reveals numerous layers interpreted to be lava flows. No clear evidence for eruption sites on the flanks of the volcano exist; rather, many previously identified sources of lava appear to be break-outs from flows up-slope which are controlled by local breaks in slope. The vents for these eruptions were most likely within the summit caldera but have been removed by the set of six large collapse events that have produced the 60?×?80?km diameter caldera, which are collectively called the “Olympus Paterae”. The origin of the basal escarpment surrounding the volcano remains enigmatic, but it is probably related to the origin of the surrounding lobate materials collectively called the Olympus Mons aureole. In places, this escarpment is >5?km high, but the elevation of the back-wall varies from ～1?km to ～8?km relative to the Mars datum. Inspection of kilometer-scale blocks within the aureole indicates that this material is not composed of lava flows, suggesting that the base of Olympus Mons consists of fragmented material comparable to the hyaloclastite material forming the base of Hawaiian volcanoes. Numerous additional features on Olympus Mons are discussed, including two large impact craters near the summit of the volcano, glacial deposits on the lower western flanks, channels and small shields around the base of the volcano, and ridges north of the escarpment which may have formed via the emplacement of dikes into ice-rich materials. Comparison with other Martian volcanoes may also help the analysis of Olympus Mons; the morphology of the basal escarpment of Apollinaris Patera suggests that erosion by wind or water may be restricted to the lowest elevations on Mars. If the basal materials of Olympus Mons are unconsolidated, then Olympus Mons may have been similar to Alba Mons or Tyrrhena Mons during the early phases of volcano growth. Certain basaltic volcanoes on Earth may serve as good analogs for features seen on Olympus Mons; the summit of Masaya volcano, Nicaragua, displays similar features to Olympus Patera at the summit caldera of Olympus Mons.     

Cosmogenic10Be: A critical view on its widespread dominion in geosciences

The radionuclide¹⁰Be (half-life = 1.5my), produced naturally in the Earth’s atmosphere by nuclear interactions of cosmic rays, was sought in ocean sediments in the late fifties, considering its potential usefulness as a radiotracer for dating sediments.¹⁰Be was discovered independently by two groups, one in India and the other in the USA, and used only for dating marine sediments and manganese nodules until the seventies. Subsequently, as a result of a technical advance resulting in the improvement in the sensitivity of measurement of¹⁰Be by about a factor of 10⁶, there was a global rush to measure this nuclide in most materials participating in the physical, chemical and biological processes in the dynamic geosphere. This paper outlines the reasons for this “isotope rush”, and the lessons learned from these studies. I also present my personal views of the special attractive features of this nuclide on the one hand, and on the other, the pitfalls or the wrong message this nuclide could convey!