INSTITUTIONAL OBSTACLES TO SUSTAINABLE DEVELOPMENT IN BALI, INDONESIA

Developing and implementing sustainable development strategies involve overcoming many obstacles. The experience in Bali, Indonesia, illustrates some key institutional challenges which most countries must handle to achieve sustainable development, such as realising cross-sectoral integration, combining top-down and bottom-up planning, and creating credibility for a new policy initiative. Indonesia in general and Bali in particular has, in theory, considerable capability to implement sustainable development. However, as in most countries, effective practice does not always follow from theoretical potential. Strengths and weaknesses related to institutional challenges are identified and assessed, and their general implications are considered. Some key implications are the need to develop sustainable development strategies which reflect the conditions and needs specific to the targetted region, and to address different national and regional perspectives.     

Energy market failure in road transport: Is there scope for ‘no regrets’ greenhouse gas reduction?

The Australian Government policy on reduction of greenhouse gas emissions announced in 1990 includes exploring the scope for immediate, low cost reductions. Such measures can be taken as including ‘no regrets’ policies: those that, in addition to mitigating potential climate change, confer economic gains (including other environmental benefits) which exceed their costs. Some possible ‘no regrets’ opportunities and policies are identified relevant to energy use by the road transport sector over the period to 2020. The MARKALMENSA multi-period linear programming model of the Australian energy sector is used to investigate the cost-effectiveness of these policies.     

World Data Center-A for Paleoclimatology at the NOAA Paleoclimatology Program,Boulder, CO

Conclusion The World Data Center-A for Paleoclimatology, located in the NOAA/NGDC Paleoclimatology Program, is committed to providing the scientific community with easy access to all paleoenvironmental data. Efforts to make archived data readily available include international coordination of data acquisition, management, and distribution, sponsoring workshops and data cooperatives to facilitate the compilation of important data sets, development of a browse and visualization software package (PaleoVu), and dispersal of archived data on magnetic media or over ANONYMOUS FTP/INTERNET. The program publishes a semi-annual newsletter that highlights latest developments and accomplishments in the area of paleoenvironmental data for global change research. Contributions to the newsletter are welcome from researchers describing their efforts to coordinate the free flow of paleoclimate data throughout the international scientific community.For information on the program or to be added to the mailing list contact Mrs Mildred England (phone: 303-497-6227; Fax: 303 497-6513; e-mail: MKE@mail.ngdc.noaa.gov), NOAA National Geophysical Data Center, Paleoclimatology Program/World Data Center-A for Paleoclimatology, 325 Broadway, E/GC Boulder, CO 80303 USA     

The structure, mass and interactions of the hydrothermal plumes at 26°N on the Mid-Atlantic Ridge

Water-column surveys by combined nephelometer/CTD (NCTD) tows contributed to the 1985 discovery of the first black smokers on the Mid-Atlantic Ridge. Subsequent regional water-column mapping has helped define the extent, mass and interactions of the suspended particulate matter phase (SPM) of the hydrothermal plumes emanating from the known and other nearby sources. The results of 29 NCTD cast/tows, covering 25–30 km² of ridge segment, indicate the presence of as many as two additional sources based on SPM concentration gradients and plume-top doming over source areas. Plume doming, documented here for the first time from field observations, conforms strikingly with laboratory experiments and can serve as a marker for source field location. A comparison of the plumes' SPM with potential temperature and salinity distributions indicates close correlation in water-column anomaly patterns for each, confirming modification of the regional potential temperature and salinity structure by hydrothermal plumes, which is expressed by wide separation and sloping of isotherms and isohalines.     

The role of salt in fold-and-thrust belts

The style of deformation in thin-skinned fold-and-thrust belts is critically dependent upon the resistance to sliding along the detachment between the mass of deforming sediments and the underlying rocks. Evaporites can provide an extremely weak horizon within which a basal detachment can form and along which only a relatively small shear traction can be supported. Fold-and-thrust belts that form atop a salt layer, such as the Appalachian Plateau, the Franklin Mountains in northwestern Canada, and the Jura of the Alps, among others, share several readily observable characteristics. As predicted by a simple mechanical model for fold-and-thrust belts, a detachment in salt permits a thrust belt to have an extremely narrow cross-sectional taper. In addition, predicted orientations of the principal stress axes over a salt décollement are consistent with the commonly observed lack of a consistently dominant vergence direction of structures within the thrust belt. Other common attributes of salt-basal thin-skinned deformation include the presence of several widely but regularly spaced folds and abrupt changes in deformational style at the edge of the salt basin.     

The behavior of apatite during crustal anatexis: Equilibrium and kinetic considerations

The solubility and dissolution kinetics of apatite in felsic melts at 850°–1500°C have been examined experimentally by allowing apatite crystals to partially dissolve into apatite-undersaturated melts containing 0–10 wt% water. Analysis of P and Ca gradients in the crystal/melt interfacial region enables determination of both the diffusivities and the saturation levels of these components in the melt. Phosphorus diffusion was identified as the rate-limiting factor in apatite dissolution. Results of four experiments at 8 kbar run in the virtual absence of water yield an activation energy (E) for P diffusion of 143.6 ± 2.8 kcal-mol^?1 and frequency factor (D₀) of 2.23^+2.88_?1.26 × 10⁹cm²-sec^?1. The addition of water causes dramatic and systematic reduction of both E and D₀ such that at 6 wt% H₂O the values are ~25 kcal-mol^?1 and 10^?5 cm²-sec^?1, respectively. At 1300°C, the diffusivity of P increases by a factor of 50 over the first 2% of water added to the melt, but rises by a factor of only two between 2 and 6%, perhaps reflecting the effect of a concentration-dependent mechanism of H₂O solution. Calcium diffusion gradients do not conform well to simple diffusion theory because the release of calcium at the dissolving crystal surface is linked to the transport rate of phosphorus in the melt, which is typically two orders of magnitude slower than Ca. Calcium chemical diffusion rates calculated from the observed gradients are about 50 times slower than calcium tracer diffusion.Apatite solubilities obtained from these experiments, together with previous results, can be described as a function of absolute temperature (T) and melt composition by the expression: In D^apatite/melt_P = [(8400 + ((SiO₂ ? 0.5)2.64 × 10⁴))/T] ? [3.1 + (12.4(SiO₂ ? 0.5))] where SiO₂ is the weight fraction of silica in the melt. This model appears to be valid between 45% and 75% SiO₂, 0 and 10% water, and for the range of pressures expected in the crust.The diffusivity information extracted from the experiments can be directly applied to several problems of geochemical interest, including I) dissolution times for apatite during crustal anatexis, and 2) pileup of P, and consequent local saturation in apatite, at the surfaces of growing major-mineral phases.     

A new solid state diffusion model applied to inverse zoning and diffusion rims in minerals

Any oxide and silicate mineral which is nominally anhydrous but crystallized in the presence of H₂O incorporates traces of H₂O in solid solution. In the case of MgO it can be shown that OH^? pairs convert into H₂+O ₂ ^2? . If the H₂ molecules are lost, the O ₂ ^2? remain in the lattice as excess oxygen stabilized by excess cation vacancies. When the O ₂ ^2? anions decay either thermally or by decompression unbound O^? states (positive holes) are generated which lead to surface charges and subsurface space charge layers. Calculated space charge profiles are presented. O^? concentrations as small as 10–20 ppm suffice to create electric surface fields of the order of 4·10⁷ V·m^?1. The diffusion mechanism which derives from these premises incorporates novel features: the cation diffusion is coupled to the counterdiffusion of unbound and vacancy-bound O^? states. The cation diffusion is predicted to be very fast because first, it is field-enhanced (electrochemically driven) and second, it is not rate-limited by the intrinsic cation vacancy concentration nor by the counter-diffusion of other cations. The model may apply to cases of inverse zoning and diffusion rim formation in minerals under certain P-T conditions.     

Pyroclastic rocks: another manifestation of ultramafic volcanism on Gorgona Island,Colombia

Tertiary ultramafic volcanism on Gorgona Island, Colombia, is manifested not only by komatiite flows, but also by a more voluminous sequence of tuff breccias, which is cut by comagmatic picrite dikes. The ultramafic pyroclastic rocks are chaotic to stratified mixtures of angular to subrounded glassy picritic blocks and a fine grained volcaniclastic matrix that consists primarily of plastically-deformed, glassy globules. The entire deposit is interpreted to have formed by an explosive submarine eruption of phenocryst-laden picritic magma. MgO contents of tuff breccias and picrite dikes range from 21 to 27 wt%. Relative to nearby komatiite flows, these rocks are MgO-rich, and FeO-, TiO₂- and Ni-poor. HREE concentrations are very low (N<0.2), indicating derivation from a more highly depleted mantle source region. Nd isotopic data suggest a cogenetic relationship between the picritic magma that formed the tuff breccia and associated dikes and that which produced the komatiite flows. Nevertheless Pb isotopic data as well as whole rock geochemistry preclude such a connection, either due to olivine fractionation/accumulation or to different degrees of partial melting. These ultramafic rock types crystallized from magmas which most likely were extracted from distinct mantle source regions.