Local modification of rock chemistry by deformation

Metabasalts subjected to progressive deformation in large-scale shear zones at Yellowknife display corresponding changes in major element abundances. Deformation, under conditions of greenschist facies metamorphism, has involved grain size reduction from 1200 m to <20 m, depletion of SiO₂ (5%) and Na₂O, together with hydration, and a decrease in specific gravity from 2.97 to 2.80. Chemical redistribution by deformation has been accomplished through a decrease in grain diameter of quartz and albite by intercrystalline diffusive mass transport (pressure solution), with concomitant transfer of material into extension veins. The degree of chemical modification is related to the finite strain. Deformation has involved a redistribution of 7.10¹⁵g of SiO₂ over a volume of about 50km³.The microstructure of an adamellite deformed in a shear zone at higher temperature, under conditions of amphibolite facies metamorphism is indicative of dominant dislocation creep. A low degree of tectonic grain refinement is present. Constant values of major element abundances and specific gravity determined across the shear zone at increasing states of strain imply isochemical and isovolumetric deformation. These results are taken to support the precept that crustal deformation is characterised by a low temperature deformation regime dominated by pressure solution, with local changes of rock chemistry and volume; and a high temperature regime in which strain is accommodated principally by dislocation creep, an isochemical and isovolumetric deformation mechanism.     

A global crisis: Energy in the future

We are beginning to consider the concept of sustainable (renewable) energy when we develop new technologies. Our present technologies are not sustainable. We are living on capital. Given that one hour of sunlight could provide our annual needs for one year, the future must be with solar energy. Geothermal energy sources, using the normal thermal gradient of Earth, are also impressive. There is no sign thatHomo sapiens has the wisdom to use fission energy given the potential abuses of this technology. One thing is certain, if we continue to burn fossil carbon to supply the world's increasing energy demands, the consequences will be devastating for all life.     

Relationships between String Bag Craft Distributions,Language and Geographical Distance in the Upper Sepik and Border Mountains of Papua New Guinea

This paper describes analyses involving patterned string bags collected in the upper Sepik in Papua New Guinea. The Mantel test and correspondence analysis were used to explore whether variability in craft repertoires exhibits any covariance with the region's complex linguistic picture, and if so, whether this relationship is more significant than any spatial autocorrelation the data may exhibit. Bag construction techniques exhibited strong spatial autocorrelation, while for colour patterns the effect was weaker. An effect for language remained for both dependents after statistical control, but colour pattern characteristics had a slightly stronger association with language overall. The weaker spatial autocorrelation for colour pattern variability is argued to be due to higher rates of dissemination facilitated by the visibility of the patterns and their compatibility with a broad range of construction techniques. The effect for language, on the other hand, is argued to have resulted from of a higher rate of inter-settlement migration along a particular stretch of the Sepik where people speak the same language.     

地球科学新的优先考虑的问题：自然科学、工程学、经济学的联合和知识发展的必要性

文章从分析生命支持系统的基本组成着手,指出愈来愈多的人类活动促使大气中ＣＯ２、ＣＨ４、Ｈ２Ｏ、Ｎ２Ｏ…含量不断增加,气候变暖;水资源危机愈加严重;对土壤产出的要求越来越高;地质灾害对人类自身的冲击更加严重;能源和原材料更大程度的短缺;废物的排放量增大及生物变异等新问题和生物种类的新发现。对上述现象的深入研究或解决,均是地球科学优先和急于考虑的问题。而这需要大批高素质,既具自然科学、工程学、经济学,又具管理知识的人才,因而这些优先考虑问题的重中之重是教育。     

Nuclear waste isolation: an urgent international responsibility

The isolation of nuclear wastes for at least thousands of years is an urgent world problem. It is an international problem, for in many nations with such wastes their geology is not suitable for long-term isolation.

A lead geo-question involves which are the best host rocks, with guaranteed long-term low permeability and the best ion-exchange, redox systems for the capture, retention, of the most dangerous nuclides. In general mud rocks on land or the sea floor must be considered.     

An experimental study of algal uptake of U,Ba, V,Co and Ni from dilute solutions

Experiments in which two species of freshwater green algae, Ankistrodesmus sp. and Selenastrum, were cultured in dilute solutions of metals chelated with EDTA reveal massive uptake of U and Ba, but relatively minor uptake of Ni, Co and V. For 2-ppm metal-spiked TBIM culture media at pH 8.1–8.2 and growth durations of 3–21 days at 13–16°C, both species accumulate U and Ba at levels of 1000 to 10,000 ppm by dry weight, representing a concentration factor of up to 5000 times the aqueous metal solute concentration. Uptake was comparable for passage of 100-ml spiked culture media through algal mats over 100 min. For aqueous solute concentrations of 20 ppb Ba, Co, Ni and U the algae adsorbed 3000–4000 ppm U and Ba giving concentration factors up to 200,000. With 40 ppb U, the algae adsorbed 6000 ppm, representing a concentration factor of 150,000. Co and Ni in the algae were present at levels below analytical sensitivity. The Ba aqueous concentration was about equivalent to, and the U concentration 100 times natural marine water abundances. For 2-ppm Co-, Ni- and V-spiked culture media, algal uptake was 40–600 ppm Ni, 17 ppm Co and 12 ppm V, respectively.Given the abundance of algae in both fresh and marine waters, coupled with the known association of plankton with U-rich Black Sea muds, the experimental results may indicate that algae also play a significant role in mediating U and Ba uptake from the hydrosphere. The recorded levels of algal uptake for metals are ～1000 × (U), ～100 × (Ba), ～100 × (Ni), ～20 × (Co), and ～6 × (V), previously reported abundances for “typical” marine plants.     

Development of rodingite in basaltic rocks in serpentinites,East Liguria,Italy

Hydrogrossular replacement of plagioclase in basaltic rocks enclosed in serpentinite, and relationships between hydrogrossular, pumpellyite, vesuvianite are described. Rogingitic rocks are dominated by mixed layer chlorite-smectite, chlorite, pumpellyite, hydrogrossular and vesuvianite. In these rocks pumpellyite attains maximal Mg contents, and chemical analysis shows extreme removal of Na₂O, K₂O, TiO₂ and SiO₂ from the basalts, and increase in the Fe³⁺/Fe²⁺ ratio. Leaching during serpentinization by extremely alkaline solutions dominated by Ca-Mg(OH) may explain removal of components, but the oxidation may suggest that at an earlier stage dykes may have acted as input aquifers.     

Structural states of Mg-cordierite I: Order parameters from synchrotron X-ray and NMR data

The hexagonal to orthorhombic phase transition in synthetic Mg-cordierite has been studied by (i) measuring the spontaneous strain associated with the transition using Synchrotron X-ray powder diffraction and (ii) measuring the degree of Al, Si order in terms of the number of Al-O-Al bonds per formula unit using solid state NMR spectroscopy. This defines the two order parametersQ andQ _od respectively, and their relationship as a function of annealing temperature and time is used to define the structural states of cordierite during the ordering sequence. The formation of modulated hexagonal cordierite within which a high degree of Al, Si order can be attained, results in a strongly non-linear relationship betweenQ andQ _od .The transition from modulated to orthorhombic cordierite is strongly first-order under all temperature conditions studied and involves a large step inQ, whileQ _od changes continuously throughout the ordering sequence with no marked discontinuity at the phase transition. The lattice distortion, traditionally defined in cordierite by the Δ index provides no full information on the degree of Al, Si order in anhydrous Mg-cordierite, and both order parameters must be used to define its structural state. Transmission electron microscopy has been used to study the mechanism of the transformation from hexagonal to modulated to orthorhombic cordierite.