8,242 research outputs found

    New very high resolution radar studies of the Moon

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    As part of an effort to further understand the geologic utility of radar studies of the terrestrial planets, investigators at the Hawaii Institute of Geophysics are collaborating with NEROC Haystack Observatory, MIT and the Jet Propulsion Laboratory in the analysis of existing 3.8 and 70 cm radar images of the Moon, and in the acquisition of new data for selected lunar targets. The intent is to obtain multi-polarization radar images at resolutions approaching 75 meters (3.8 cm wavelength) and 400 meters (70 cm wavelength) for the Apollo landing sites (thereby exploiting available ground truth) or regions covered by the metric camera and geochemical experiments onboard the command modules of Apollos 15, 16 and 17. These data were collected in both like- and cross-polarizations, and, in the case of the 70 cm data, permit the phase records to be used to assess the scattering properties of the surface. The distribution of surface units on the Moon that show a mismatch between the surface implied by like- and cross-polarized scattering data is being analyzed, based on the scattering models of Evans and Hagfors

    Stratigraphy and development of the Late Miocene-Early Pleistocene Hawke’s Bay forearc basin

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    A Late Miocene-Early Pleistocene mixed carbonate-siliciclastic sedimentary succession about 2 500 m thick in the Hawke’s Bay forearc basin is the focus of a basin analysis. The area under investigation covers 3 500 km2 of western and central Hawke’s Bay. The stratigraphy of Hawke’s Bay Basin is characterised by dramatic vertical and lateral facies changes and significant fluxes of siliciclastic sediment through the Late Miocene and Pliocene. This project aims to better understand the character and origin of the sedimentary succession in the basin. Geological mapping has been undertaken at a scale of 1:25000, with data managed in an ARCINFO geodatabase, following the database model employed in the IGNS QMap programme. Along the western margin of the basin there is progressive southward onlap of late Cenozoic strata on to basement. The oldest units are of Late Miocene (Tongaporutuan) age and the youngest onlap units are of latest Pliocene (Nukumaruan) age. Geological mapping of the basin fill places constraints on the magnitude (about 10 km) and timing (Pleistocene) of most of the offset on the North Island Shear Belt. Lithofacies have been described and interpreted representing fluvial, estuarine, shoreface and inner- to outer-shelf environments. Conglomerate facies are representative of sediment-saturated prograding fluvial braidplains and river deltas. These units are dominated by greywacke gravels and record the erosion of the Kaweka-Ahimanawa Ranges. Sandstone facies typically comprise very well sorted, clean non-cemented units of 10-50 m thickness that accumulated in innershelf environments. Siltstone facies probably accumulated in relatively quiet, middle- to outer-shelf water depths, and comprise well-sorted, firm non-cemented units with occasional tephra interbeds. Limestone facies represent examples of continent-attached cool-water carbonate systems that developed in response to strong tidal currents and a high nutrient flux during the Pliocene. These facies are examples of mixed siliciclastic-bioclastic sedimentary systems. Of these facies the widespread distribution and thickness of sandstone and limestone units present the most potential for hydrocarbon reservoirs. Similarly, the distribution of siltstone and mudstone beds provides adequate seal rocks. Mangapanian limestone facies have already been targeted as potential petroleum reservoirs (e.g. Kereru-1). Geological mapping suggests that potential hydrocarbon reservoir and seal rocks occur extensively in the subsurface

    Systematic lithostratigraphy of the Neogene succession exposed in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand

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    This report presents a systematic lithostratigraphy for the Neogene (Miocene–Recent) sedimentary succession in central parts of Hawke’s Bay Basin in eastern North Island, New Zealand. It has been built up chiefly from strata exposed in outcrop, but petroleum exploration drill hole data have also been incorporated to produce this stratigraphic synthesis. Most of the strata exposed in this part of the basin are of Late Miocene (Tongaporutuan, local New Zealand Stage) to Recent age, and the majority of this report focuses on these starta, with brief description of Middle and Early Miocene formations. A companion PR report (Kamp et al. 2007) contains stratigraphic columns for sections through the Neogene succession described in this report

    Late Miocene – Early Pleistocene paleogeography of the onshore central Hawke’s Bay sector of the forearc basin, eastern North Island, New Zealand, and some implications for hydrocarbon prospectivity

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    The timing of trap formation in relation to the timing of source rock burial and maturation are important considerations in evaluating the hydrocarbon prospectivity of onshore parts of the forearc basin in central Hawke’s Bay. We describe here aspects of the Late Miocene to Early Pleistocene paleogeography for the area based on detailed field mapping and lithofacies analysis, to help constrain petroleum systems evaluations. Key conclusions are: ‱ Most deformation of the forearc basin fill appears to be relatively young (i.e. post-2 Ma). This deformation has occurred after a major phase of Late Miocene to Pliocene sediment accumulation, and is particularly significant along the northwestern and southeastern margins of the basin. ‱ The axis of the forearc basin in central Hawke’s Bay appears to have undergone little structural deformation. Gentle force and reverse faults in the subsurface may be suitable traps. ‱ The most widespread potential reservoir beds are Miocene sandstone beds. ‱ Potential hydrocarbon source rocks are mostly absent from western parts of the basin due to significant Neogene uplift and erosion. They are, however, probably still widely preserved beneath central parts of the basin where uplift and erosion have been much less pronounced. ‱ Miocene structures within the axis of the basin, buried by the Late Miocene to Pleistocene siliciclastic succession, are likely exploration targets. The forearc basin has been substantially inverted along its western side since the latest Pliocene, resulting in erosion of older sediments, including potential source rocks, down to basement in ranges flanking its western side. The stratigraphy along the eastern margin of the forearc basin, and particularly the outcrop pattern of westward-younging Plio-Pleistocene limestones, records the development of faulting and folding associated with the elevation and growth of the inboard part of the accretionary wedge. Parts of the forearc basin succession have become involved in the accretionary wedge, which has migrated westward through time. Uplift of the inboard margin of the accretionary wedge since the latest Miocene helped to cause an interior seaway to develop to the west during the Pliocene. Distinctive coarse-grained bioclastic carbonate sediments of the Te Aute lithofacies were deposited along both margins of the seaway, which was most extensive during the Late Pliocene (Mangapanian). Although significant volumes of siliciclastic sediment were supplied to the basin during the Pliocene, strong tidal currents periodically swept much of these sediments northeastward. Tidal connections existed during the Pliocene into Wanganui Basin in the vicinity of Kuripapango and Manawatu Gorge. By the latest Pliocene (lower Nukumaruan), the interior seaway became closed in the south with uplift of the Mount Bruce block in northern Wairarapa. Potential reservoirs within the map area include both shelf and redeposited sandstone beds in the Miocene to Early Pliocene Tolaga Group. Thick, coarse-grained, variably cemented Plio-Pleistocene limestone lithofacies in the Mangaheia Group are widespread along the margins of the basin, and have been the targets for several past exploration programmes. However, drilling has shown that the attractiveness of the Pliocene limestone facies as reservoir beds is limited because they quickly pass laterally into siliciclastic mudstone away from the margins of the basin

    OSMOREGULATION IN THE PRAWN PALAEMON LONGIROSTRIS (CARIDEA, PALAEMONIDAE)

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    Salinity tolerance, and several aspects of osmoregulation, ionic regulation and permeability were measured for Palaemon longirostris at three temperatures (4, 12 & 20°C). Influence of ontogenetic stage on salinity tolerance and osmoregulation was investigated by testing separately individuals sorted, using carapace length, into 'small' (10-18mm), 'medium' (18-24mm), 'large' (>24mm) and 'ovigerous' (>24mm) size groupings. Effect of seasonal acclimatization on salinity tolerance and osmoregulation was taken into account by comparing responses of summer- with winter-collected prawns. Irrespective of temperature and size, summer Palaemon longirostris were extremely euryhaline and had >90% survival in various salinities from 0.5-34 Âș/oo . For summer prawns, survival in 43 Âș/oo was reduced, particularly at 4°C. Salinity tolerance of winter prawns was generally less than that of summer individuals, this difference being marked at salinity extremes in combination with low temperature. Over the salinity range 0.5-34 Âș/oo , prawns were very efficient hyper-hypo-osmoregulators at each temperature. At 43 Âș/oo, blood osmolalities tended towards the isosmotic, indicating that osmoregulation was breaking down. There was no clear effect of prawn size or season on osmoregulation, however, low temperature appeared to be disruptive. Transfer of prawns from 14 Âș/oo to either 5 Âș/oo or 34 Âș/oo, and from 1 Âș/oo to 34 Âș/oo, resulted in a new steady blood osmolality within 6-12h. Transfer from 34 Âș/oo to 1 Âș/oo , caused blood osmolality to drop significantly within 12h, and a new equilibrium was not reached until 72h. The inorganic ions sodium, chloride, potassium, calcium and magnesium accounted for >94% of total blood osmolality over the salinity range 0.5-34 Âș/oo . There was no consistent effect of temperature on the regulation of these ions

    Tubular carbonate concretions as hydrocarbon migration pathways? Examples from North Island, New Zealand

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    Cold seep carbonate deposits are associated with the development on the sea floor of distinctive chemosyn¬thetic animal communities and carbonate minerali¬sation as a consequence of microbially mediated anaerobic oxidation of methane. Several possible sources of the methane exist, identifiable from the carbon isotope values of the carbonate precipitates. In the modern, seep carbonates can occur on the sea floor above petroleum reservoirs where an important origin can be from ascending thermogenic hydrocar¬bons. The character of geological structures marking the ascent pathways from deep in the subsurface to shallow subsurface levels are poorly understood, but one such structure resulting from focused fluid flow may be tubular carbonate concretions. Several mudrock-dominated Cenozoic (especially Miocene) sedimentary formations in the North Island of New Zealand include carbonate concretions having a wide range of tubular morphologies. The concretions are typically oriented at high angles to bedding, and often have a central conduit that is either empty or filled with late stage cements. Stable isotope analyses (ή13C, ή18O) suggest that the carbonate cements in the concretions precipitated mainly from ascending methane, likely sourced from a mixture of deep thermogenic and shallow biogenic sources. A clear link between the tubular concretions and overlying paleo-sea floor seep-carbonate deposits exists at some sites. We suggest that the tubular carbonate concretions mark the subsurface plumbing network of cold seep systems. When exposed and accessible in outcrop, they afford an opportunity to investigate the geochemical evolution of cold seeps, and possibly also the nature of linkages between subsurface and surface portions of such a system. Seep field development has implications for the characterisation of fluid flow in sedimentary basins, for the global carbon cycle, for exerting a biogeochemical influence on the development of marine communities, and for the evaluation of future hydrocarbon resources, recovery, and drilling and production hazards. These matters remain to be fully assessed within a petroleum systems framework for New Zealand’s Cenozoic sedimentary basins

    Large-scale Advanced Prop-fan (LAP) high speed wind tunnel test report

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    High Speed Wind Tunnel testing of the SR-7L Large Scale Advanced Prop-Fan (LAP) is reported. The LAP is a 2.74 meter (9.0 ft) diameter, 8-bladed tractor type rated for 4475 KW (6000 SHP) at 1698 rpm. It was designated and built by Hamilton Standard under contract to the NASA Lewis Research Center. The LAP employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Testing was conducted in the ONERA S1-MA Atmospheric Wind Tunnel in Modane, France. The test objectives were to confirm that the LAP is free from high speed classical flutter, determine the structural and aerodynamic response to angular inflow, measure blade surface pressures (static and dynamic) and evaluate the aerodynamic performance at various blade angles, rotational speeds and Mach numbers. The measured structural and aerodynamic performance of the LAP correlated well with analytical predictions thereby providing confidence in the computer prediction codes used for the design. There were no signs of classical flutter throughout all phases of the test up to and including the 0.84 maximum Mach number achieved. Steady and unsteady blade surface pressures were successfully measured for a wide range of Mach numbers, inflow angles, rotational speeds and blade angles. No barriers were discovered that would prevent proceeding with the PTA (Prop-Fan Test Assessment) Flight Test Program scheduled for early 1987

    The Role of Communication in Organizational Conflict Management

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    Organizational conflict is a factor affecting all organizations. This study is designed to present an overview of organizational conflict and its causes, conflict management techniques, and communication skills necessary for conflict management. The study begins with the presentation of the definitions of the major terms used throughout the study: conflict, conflict management, organization, and communication. Following these definitions is a discussion of the psychodynamic, field, phase and social exchange theories of conflict. Each theory is discussed in its own right and with respect to its implications for organizational conflict and its management. In addition to a review of theories, the study includes an analysis of the various causes of conflict, focusing on aggression, climate, communication and perception. Other factors affecting these such as interdependence, power and trust are also discussed. The study next shifts to an analysis of what can be done to respond to conflict. To this end, various approaches to conflict including those of Blake and Mouton, Thomas and Pondy, and Robbins are examined. Communication is the most essential element in conflict management, and the final chapter is a discussion of the communication skills necessary for effective conflict management. The primary conclusion drawn is that one can learn to recognize causes of conflict as well as conflict management and communication skills and that conflict management training should become an essential aspect of organizational training programs

    Mangarara Formation: exhumed remnants of a middle Miocene, temperate carbonate, submarine channel-fan system on the eastern margin of Taranaki Basin, New Zealand

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    The middle Miocene Mangarara Formation is a thin (1–60 m), laterally discontinuous unit of moderately to highly calcareous (40–90%) facies of sandy to pure limestone, bioclastic sandstone, and conglomerate that crops out in a few valleys in North Taranaki across the transition from King Country Basin into offshore Taranaki Basin. The unit occurs within hemipelagic (slope) mudstone of Manganui Formation, is stratigraphically associated with redeposited sandstone of Moki Formation, and is overlain by redeposited volcaniclastic sandstone of Mohakatino Formation. The calcareous facies of the Mangarara Formation are interpreted to be mainly mass-emplaced deposits having channelised and sheet-like geometries, sedimentary structures supportive of redeposition, mixed environment fossil associations, and stratigraphic enclosure within bathyal mudrocks and flysch. The carbonate component of the deposits consists mainly of bivalves, larger benthic foraminifers (especially Amphistegina), coralline red algae including rhodoliths (Lithothamnion and Mesophyllum), and bryozoans, a warm-temperate, shallow marine skeletal association. While sediment derivation was partly from an eastern contemporary shelf, the bulk of the skeletal carbonate is inferred to have been sourced from shoal carbonate factories around and upon isolated basement highs (Patea-Tongaporutu High) to the south. The Mangarara sediments were redeposited within slope gullies and broad open submarine channels and lobes in the vicinity of the channel-lobe transition zone of a submarine fan system. Different phases of sediment transport and deposition (lateral-accretion and aggradation stages) are identified in the channel infilling. Dual fan systems likely co-existed, one dominating and predominantly siliciclastic in nature (Moki Formation), and the other infrequent and involving the temperate calcareous deposits of Mangarara Formation. The Mangarara Formation is an outcrop analogue for middle Miocene-age carbonate slope-fan deposits elsewhere in subsurface Taranaki Basin, New Zealand
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