Provenance and depositional environment of Rhenohercynian synorogenic greywackes from the Giessen Nappe,Germany

The Giessen Nappe of the south-eastern Rhenish Massif can be subdivided into a northern group and southern group of Frasnian-?Lower Carboniferous greywackes that differ slightly in their sedimentology, clast petrography, heavy mineral assemblages and bulk geochemistry. Petrographic and geochemical tectonic setting discrimination diagrams indicate that both the northern and the southern Giessen Greywacke groups were derived from a predominantly acidic continental arc source. However, due to the nature of basin development, generation of significant volumes of acidic arc material as a result of southwards directed subduction of Rhenohercynian oceanic crust is considered unlikely. A large part of the arc source may have been contributed by earlier, predominantly acidic, Precambrian terranes together with minor basic igneous and sedimentary components.     

POLAR investigation of the Sun—POLARIS

The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between the magnetism and dynamics of the Sun’s polar regions and the solar cycle.

The localised distribution of U and other incompatible elements in spilitic pillow lavas

The fission track technique was used not only to determine the U distribution, but indirectly, to locate the host minerals of other incompatible elements such as P, Ti, Y, Zr and Nb in spilitic pillow lavas from SW England. The majority of U was introduced early in the alteration process probably due to interaction with sea-water. At a later stage in the process, these elements, some previously considered to be relatively immobile during low-grade alteration, were mobilised and subsequently redeposited in stable secondary phases. The hydrothermal fluid responsible for mobility was rich in CO₂ and H₂O. Carbonate complexes were the most likely mobile species.     

Effects of annealing on deformation textures in galena

Experimental annealing of galena samples with known deformation histories shows that this mineral has the necessary properties to be a valuable source of information about low-grade deformational environments. Annealed galena displays recovery and/or recrystallization features dependent upon the type of texture inherited from the tectonic event, which in turn is closely linked to deformation temperatures.In samples deformed at temperatures less than 200 ° C in the laboratory, later annealing produced subgrains, mosaics of new grains, or rapid grain boundary migration as the annealing temperatures were varied from 200 ° C to 700 ° C. Kink bands maintained characteristic straight simple boundaries inherited from the deformation event. Samples deformed above 300 ° C developed syntectonically recrystallized textures. Kink bands had been converted to elongate grains with complex sutured grain boundaries during deformation, and mosaics of new grains were found in highly deformed regions. These textures were extremely stable through later annealing. Despite our changing annealing temperatures through 500 ° C, we did not produce similar textures from both low and high temperature deformation runs.Examination of polished and etched galena from low-grade tectonic settings may well be worth the effort since galena textures appear to display features indicative of deformational evironments, even after being subjected to considerable post-tectonic thermal perturbations.     

The rain forest and the farmer

The world's tropical rain forests are being cleared at an ever-increasing and alarming rate. If their destruction continues, such forests will virtually disappear over the next half century, with grave consequences to mankind.The major exploirers of the humid tropical forests are timber companies, also crop and livestock farmers. Arguably, the greatest threat come from the many millions of small-scale farmers. If sizeable islands of original rain forest are to be preserved for scientific study and balanced ecological utilization, the rising demands for timber, subsistencee crop and grazing land will need to be satisfied in ways other those currently practised.An overall goal is the integrated development of resources within areas of secondary tropical forest and savanna woodland. If small farmers are to be encouragedto remainin such areas, successful techniques need to be devised to ensure virtually continuous cropping. The strategy of utilizing fast-growing suitable trees as nutrient pumps and for branch mulching is described. The use of appropriate minitaturized equipment and zero tillage is also advocated.It is not intended that these and other measures should provide a permanent blueprint for more intensive small-scale farming in the humid tropics. The penetration of more sophisticated systems subsumed under the Green Revolution should continue. It may be Discovered ultimately that an amalgam of traditional and new practices will best achieve the objective of raising the rural poor of the Third World above the meageress and meanness of their present predicament.