Linking multi-temporal analysis and community consultation to evaluate the response to the impact of Hurricane Stan in coffee areas of Chiapas,Mexico

This paper analyses the responses related to land use of coffee growers in Chiapas, Mexico to the impact of Hurricane Stan (October 2005). A multi-temporal analysis of the effect on land cover was performed through the combination of unsupervised classification of SPOT multispectral images and visual interpretation of panchromatic images (8 months previous to the hurricane, and 2, 14, and 40 months after the hurricane). The information provided by this geographic analysis was interpreted in light of information gathered though household surveys. Although the hurricane wrecked havoc across the region, the main impact in the study area was in the riparian zones where the extent of the loss experienced in terms of coffee harvest and soil was such that, even 14 months after the event, households with land in those areas were struggling to recover. Nevertheless, after 40 months, the zones that had suffered total soil loss began to support soil and vegetation, indicating the possibility of replanting coffee in those areas. Although the hurricane occurred when the coffee sector was particularly fragile as a result of the preceding several years of poor prices, the impact did not trigger extensive land use change. The surveys showed, however, that people are now more informed of the risk of living and farming on the river margins and are now performing soil conservation practices and planting trees to reduce risk.     

Pressure-temperature and evolution of fluid compositions of Al2SiO5-bearing rocks,Mica Creek,B.C., in light of fluid inclusion data and mineral equilibria

Metamorphosed pelitic rocks from Mica Creek, British Columbia contain sillimanite, kyanite with minor fibrolite and andalusite-bearing quartz pods. Mineral equilibria were used to infer peak P-T conditions and fluid compositions in equilibrium with the solid phases. Fluid inclusions in three schist samples appear to be good indicators of conditions affecting those rocks during and after peak metamorphic conditions. In samples from two localities, fluid inclusions from schist and quartz-rich segregations have densities appropriate to the peak metamorphic conditions. The observed compositions for these fluids (low salinity with 12 mole % dissolved CO₂) agree with calculated values of 0.84 to 0.85, based upon paragonite-quartz-albite-Al₂SiO₅ equilibria. The fluids unmixed as the schists were uplifted and cooled; fluid inclusions trapped during this stage outline a solvus in the CO₂-H₂O-NaCl system. A later influx of fluids containing CH₄ and N₂ accompanied formation of andalusite-bearing plagioclaserich segregations. The restricted association of andalusite-bearing pods and low density fluids suggest a localized but pervasive fluid influx during uplift. Preservation of high density fluid inclusions during uplift and erosion, coupled with evidence for unmixing of H₂O- and CO₂-rich fluids on the solvus, provide constraints on the P-T uplift path.     

Lithostratigraphic correlation of Blaini Formation (late Proterozoic,Lesser Himalaya,India) with other late Proterozoic tillite sequences

The Blaini Formation of the Lesser Himalaya has long been considered Permo-Carboniferous in age on simple lithological correlation with Gondwana Tillites in southern India. Rare, and non-repeatable finds of fossils from the type area were thought to confirm this. Recently, Lower Cambrian faunas have been recorded from the overlying Tal and Krol Formations, and possible metazoan trails recorded from the Blaini itself. In addition, the Blaini Formation is, even on a lithostratigraphic comparison, much more like other late Proterozoic glacial sequences. The term Blaini Formation should only be used for rocks of the type area — not for widely scattered glacial deposits which may or may not be correlatable with the type section. The persistent belief in the Paleozoic age of the Blaini (and adjacent formations) has for long retarded unterstanding of Lesser Himalaya stratigraphy and tectonics.

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Zusammenfassung Die Blaini Formation des Niederen Himalaya wurde bisher aufgrund lithologischer Vergleiche mit Gondwana Tilliten aus Süd-Indien in das Permo-Karbon eingestuft. Seltene, nicht wiederholbare Fossilfunde schienen dieses zu bestätigen. Kürzlich wurden Faunen des Unterkambriums in den überlagernden Tal- und Krol-Formationen gefunden sowie vermutliche Metazoanspuren aus der Blaini Formation selbst. Darüberhinaus ist die Blaini Formation sogar über den lithostratigraphischen Vergleich eher mit spätproterozoischen Glazialfolgen zu vergleichen. Der Begriff Blaini Formation sollte nur für die Typlokalität verwendet werden, und nicht für ähnliche Glazialvorkommen in der weiteren Umgebung. Die fortdauernde Annahme des paläozoischen Alters der Blaini- und umgebenden Formationen hat über lange Zeit hinweg das Verständnis für die Stratigraphie und die tektonische Entwicklung des Niederen Himalayas behindert.

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Résumé La formation de Blaini, dans l'Himalaya inférieur, a été jusqu'ici placée dans le Permo-Carbonifère sur la base de ses analogies lithologiques avec les tillites gondwaniennes du Sud de l'Inde. Cette attribution a semblé pouvoir Être confirmée par la découverte de quelques fossiles rares et isolés. Récemment des faunes du Cambrien inférieur ont été identifiées dans les formations surincombantes de Tal et de Krol; dans la formation de Blaini elle-mÊme des traces possibles de métazoaires ont été relevées. De plus, au seul point de vue lithologique, c'est avec les séries glaciaires du ProtérozoÏque supérieur que la formation de Blaini présente le plus de similitude. L'emploi du terme »Formation de Blaini« doit Être restreint à sa localité-type et doit Être évité pour des formations glaciaires d'autres régions, qui peuvent Être d'âges divers. L'âge paléozoÏque, attribué régulièrement jusqu'ici à la formation de Blaini et aux formations adjacentes a constitué un obstacle permanent à une bonne compréhension stratigraphique et tectonique de l'Himalaya inférieur.

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Astronomical Engineering: A Strategy For Modifying Planetary Orbits

The Sun's gradual brightening will seriously compromise the Earth'sbiosphere within 10⁹ years. If Earth's orbit migrates outward,however, the biosphere could remain intact over the entiremain-sequence lifetime of the Sun. In this paper, we explore thefeasibility of engineering such a migration over a long timeperiod. The basic mechanism uses gravitational assists to (in effect)transfer orbital energy from Jupiter to the Earth, and therebyenlarges the orbital radius of Earth. This transfer is accomplishedby a suitable intermediate body, either a Kuiper Belt object or a mainbelt asteroid. The object first encounters Earth during an inward passon its initial highly elliptical orbit of large ( 300 AU)semimajor axis. The encounter transfers energy from the object to theEarth in standard gravity-assist fashion by passing close to theleading limb of the planet. The resulting outbound trajectory of theobject must cross the orbit of Jupiter; with proper timing, theoutbound object encounters Jupiter and picks up the energy it lost toEarth. With small corrections to the trajectory, or additionalplanetary encounters (e.g., with Saturn), the object can repeat thisprocess over many encounters. To maintain its present flux of solarenergy, the Earth must experience roughly one encounter every 6000years (for an object mass of 10²² g). We develop the details ofthis scheme and discuss its ramifications.     

Star formation in NGC 6334 I and I(N)

The northern section of the molecular cloud complex NGC 6334 has been mapped in the CO and CS spectral line emission and in continuum emission at a wavelength of 1300 μm. Our observations highlight the two dominant sources, I and I(N), and a host of weaker sources. NGC 6334 I is associated with a cometary ultracompact H  ii region and a hot, compact core ≤10 arcsec in size. Mid-infrared and CH₃OH observations indicate that it is also associated with at least two protostellar sources, each of which may drive a molecular outflow. For region I we confirm the extreme high-velocity outflow first discovered by Bachiller & Cernicharo and find that it is very energetic with a mechanical luminosity of 390 L_⊙. A dynamical age for the outflow is ∼3000 yr. We also find a weaker outflow originating from the vicinity of NGC 6334 I. In CO and CS this outflow is quite prominent to the north-west, but much less so on the eastern side of I, where there is very little molecular gas. Spectral survey data show a molecular environment at position I which is rich in methanol, methyl formate and dimethyl ether, with lines ranging in energy up to 900 K above the ground state. NGC 6334 I(N) is more dense than I, but cooler, and has none of the high-excitation lines observed toward I. I(N) also has an associated outflow, but it is less energetic than the outflow from I. The fully sampled continuum map shows a network of filaments, voids and cores, many of which are likely to be sites of star formation. A striking feature is a narrow, linear ridge which defines the western boundary. It is unclear if there is a connection between this filament and the many potential sites of star formation, or if the filament existed prior to the star formation activity.