Biogeochemical prospecting for uranium in Nova Scotia

Ashed twigs of Picea rubens (red spruce) collected over an area of uranium mineralization in central Nova Scotia were analyzed for uranium in the course of biogeochemical prospecting for this element. Uranium levels in background samples were significantly lower than in those collected from areas with mineralization either at depth or on the surface. Scintillometric data were useful only to differentiate background and surface mineralization. Uranium levels in soils showed no correlation whatsoever with mineralization or with radiometry. There was a very high degree of correlation between the scintillometric data and uranium concentrations in ashed twigs and it is considered that twigs of Picea rubens might be successfully used for biogeochemical prospecting for uranium in this area.     

Genesis of the Batinah mélange above the Semail ophiolite,Oman

The Batinah mélange which overlies the late Cretaceous Semail ophiolite in the northern Oman Mountains comprises mostly sedimentary rocks of deep-water facies, alkalic lavas and intrusives, all of continental margin affinities, together with smaller volumes of Semail ophiolitic and metamorphic rocks. Four intergradational textural types of mélange can be recognized. Sheet mélange has large (>1 km) intact sheets either with little intervening matrix or set in other mélange types, and with an organised sheet orientation fabric. Slab mélange is finer textured (>100 m) and more disrupted. Block mélange has smaller (> m) blocks with some matrix and a weak to random block fabric. Clast mélange is matrix-supported rudite with a weak depositional clast fabric. Structural relationships, particularly the absence of tectonic fabrics, the decreasing strength of fragment fabrics with increasing fragmentation, and the abundance of brittle fragmentation, suggest that these mélange types formed by either gravity-driven sedimentary processes or superficial sliding or thrusting of individual rock slabs.In the slab mélange, long sequences can be pieced together, passing up from Upper Triassic mafic sub-marine extrusives and sediments into radiolarian cherts, hemipelagic and redeposited limestones, and terminating in non-calcareous radiolarities with Mn-deposits of early Cretaceous age. Mafic sills are numerous. These sequences can be matched with sub-ophiolite rocks now exposed in fault corridors through the Semail. These sequences become progressively disrupted upwards in the corridors and can be traced continuously into overlying mélange, which then thins away from the corridors.We argue that, during late Cretaceous emplacement over the Arabian margin, active fault corridors split the Semail slab and acted as conduits up which sub-ophiolite rocks were supplied to the ophiolite surface. There the rocks were redisributed by superficial processes.     

Temporal Changes in VOC Discharge to Surface Water from a Fractured Rock Aquifer During Well Installation and Operation, Greenville, South Carolina

Analysis of the vapor in passive vapor samplers retrieved from a streambed in fractured rock terrain implied that volatile organic carbon (VOC) discharge from ground water to surface water substantially increased following installation of a contaminant recovery well using air rotary drilling. The air rotary technique forced air into the aquifer near the stream. The injection produced an upward hydraulic gradient that appears to have transported water and contaminants from deeper parts of the aquifer through fractures into shallow parts of the aquifer. Once in the shallow flow regime, the contamination was transported to the stream, where it discharged during the next several weeks following well installation. After the recovery well was activated and began continuously pumping contaminated ground water to a treatment facility, the VOC concentrations in the stream bottom passive vapor samplers decreased to below detectable concentrations, suggesting that the withdrawal had captured the contaminated ground water that previously had discharged to the stream.     

An assessment of the risk from future eruptions of the Soufriere volcano of St. Vincent,West Indies

The Soufriere volcano is a 1220 m high stratovolcano which occupies the northern part of the island of St. Vincent. It is one of the most active centres of volcanism in the Caribbean and has a record of activity dating back to the Pleistocene. Historic eruptions (since 1718) have caused over 1600 deaths and resulted in damage to property valued in excess of 4.8 million USD. In addition, current development plans for the area point towards increased risk of disastrous consequences from future activity at the volcano.All aspects of risk relevant to the volcano, are discussed, with particular emphasis on the manner in which these are perceived and on the question of acceptable risk. A method is presented for use in risk assessment of volcanic hazard and a number of risk zones are defined for the Soufriere volcano. Numerical estimates of the relative loss expected within each zone are obtained from a consideration of the value of property at risk, its vulnerability to the hazardous volcanic events and the expected spatial impact of volcanic events. Such estimates suggest that the northern-most third of the island is at least ten times more at risk than areas further south. The likelihood of death and destruction is extreme in such high risk areas, while the most feasible method of loss reduction is evacuation before an eruption occurs.Formerly at Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.     

CANADIAN ARCTIC METEORITE SEARCH: 1981

The recovery of several thousand meteorite fragments from Antarctica has led to speculation that accumulations may occur on the Earth's other major ice caps. Meteorites falling over the past 80,000 years on the Devon Island ice cap in the Canadian Arctic may be exposed at the surface near the ice cap margin. From the terrestrial meteorite flux, ice movement rates, and fragmentation factors it is calculated that 12,560 samples of 150 g mass are potentially concentrated in a 65 km² zone along the northwest margin. A search of this region on foot and by helicopter in July, 1981, failed to recover any specimens. Although metre-sized gneissic boulders, plucked from the underlying Precambrian basement, were concentrated in this zone it is postulated that the unseasonal 30 cm snow cover on the ice prohibited the recognition of possible meteorite specimens, which may average only 5 cm in diameter.     

STAMP: spatial–temporal analysis of moving polygons

Research questions regarding temporal change in spatial patterns are increasingly common in geographical analysis. In this research, we explore and extend an approach to the spatial–temporal analysis of polygons that are spatially distinct and experience discrete changes though time. We present five new movement events for describing spatial processes: displacement, convergence, divergence, fragmentation and concentration. Spatial–temporal measures of events for size and direction are presented for two time periods, and multiple time periods. Size change metrics are based on area overlaps and a modified cone-based model is used for calculating polygon directional relationships. Quantitative directional measures are used to develop application specific metrics, such as an estimation of the concentration parameter for a von Mises distribution, and the directional rate of spread. The utility of the STAMP methods are demonstrated by a case study on the spread of a wildfire in northwestern Montana.      

U-Pb-Hf isotopic data from detrital zircons in late Carboniferous and Mid-Late Triassic sandstones,and also Carboniferous granites from the Tauride and Anatolide continental units in S Turkey: implications for Tethyan palaeogeography

ABSTRACT

Zircons from Carboniferous sandstones (three samples) and Mid-Late Triassic sandstones (four samples) from the Tauride and Anatolide continental units were analysed for U-Pb-Hf isotopes. For comparison, zircons were also analysed from Carboniferous granites of the Afyon Zone, Anatolides (three samples). A NE African/Arabian source is inferred for both the Carboniferous sandstones of the Taurides (Alada?) and the Anatolides (Konya Complex). In contrast, the Carboniferous Karaburun Melange is characterised by a NW African provenance. A prominent Devonian population occurs in the Carboniferous Karaburun Melange, characterised by mainly positive ε_Hf(t) values that differ significantly from those of the Devonian granites of the Sakarya continental crustal unit (Pontides). Middle-Late Triassic Tauride sandstones include minor Palaeozoic and Early Mesozoic zircons. In contrast, Devonian and Carboniferous zircons are relatively abundant in Late Triassic sandstones of the Karaburun Peninsula. The Hf isotopic compositions of 25 Carboniferous-aged zircons from three samples of Mid-Late Triassic sandstone and one of Late Carboniferous age (one sample) overlap with the ε_Hf(t) values of Carboniferous arc-type granites in the Anatolides. Taking account of the available U-Pb and Lu-Hf isotopic data from comparative crustal units, the Devonian zircon populations from the melanges in the Karaburun Peninsula and the Konya Complex are inferred to have a westerly source (e.g. granitic rocks of Aegean region or central Europe). A tectonic model is proposed in which Palaeozoic Tethys sutured during the late Carboniferous in the west (Aegean region westwards), leaving an eastward-widening oceanic gulf in which sandstone turbidites accumulated, including Devonian zircons.     

BEEKEEPING AND LOCAL SELF-RELIANCE IN RURAL SOUTHERN AFRICA*

ABSTRACT. Beekeeping has the potential to supplement incomes in rural southern Africa. In light of regional economic constraints, self-reliance strategies that draw on local knowledge and skills take on a renewed importance. We consider the advantages and disadvantages of beekeeping and examine appropriate forms of development support. A short case study from Zimbabwe illustrates these issues.     

Metallogenesis along a fossil oceanic fracture zone: Arakapas fault belt,Troodos Massif,Cyprus

The Arakapas fault belt, southern Troodos Massif, which is interpreted as a fossil oceanic fracture zone, contains a sedimentary and volcanic “fill” including basaltic lava breccias, volcaniclastic sandstones, intercalated Fe-rich mudstones, and minor Cu sulphide mineralisation. The volcaniclastic sedimentary rocks were produced by submarine weathering and gravity redeposition of basalt within the transform zone. In contrast, the Fe-mudstones predominantly originated as chemical precipitates from hydrothermal solutions generated by hydrothermal leaching of basalt by seawater. The rare earth elements, and some trace metals, including Co, Ni, Pb, V and Zr, are thought to have been incorporated from seawater into the ferruginous precipitates. Unusually high Fe/Mn ratios of the Fe-mudstones relative to most modern ocean-ridge sediments may reflect deposition in relatively oxygen-depleted waters on the floor of a major bathymetric depression created by the transform faulting; release of acidic thermal waters would have further suppressed Mn precipitation. Contrary to recent suggestions of metallogenesis along oceanic fracture zones, none of the major Cyprus cupriferous sulphide bodies lie along the fossil Arakapas transform zone.