Can New Zealand's Covenanting Agencies Meet the Challenge of the Biodiversity Strategy?     

MARK BELLINGHAM 《New Zealand geographer》2002,58(1):43-49

In February 2000 the New Zealand Government released its national Biodiversity Strategy with significant emphasis on the role of central and local government, communities and private landowners in achieving biodiversity conservation on public and private land. New Zealand has had provisions in legislation for the protection of biodiversity on private land for more than 70 years. There are now a wide range of of purposes and management flexibility within the nine types of covenants administered by the Department of Conservation (DoC) and the Queen Elizabeth National Trust's (QE II National Trust) Open Space covenants. In addition a small number of territorial local authorities (TLAs) manage private covenanting schemes, the most notable being the Auckland Region by Rodney and Franklin District Councils. Funding appears to be the critical issue for covenanting agencies being able to meet the objectives of the NZ Biodiversity Strategy affecting the ability of agencies to fund survey, administration, fencing, pest management and landowner advice. Unless funding is addressed landowners will be left shouldering most of the burden of conservation management, planning and funding for these areas and the tide may not have turned for biodiversity protection and enhancement on private land.  相似文献   

Pressure, Temperature, and Structural Evolution of West-Central New Hampshire: Hot Thrusts over Cold Basement   总被引：2，自引：0，他引：2  

KOHN  MATTHEW J.; ORANGE  DANIEL L.; SPEAR  FRANK S.; RUMBLE  DOUGLAS  III; HARRISON  T. MARK 《Journal of Petrology》1992,33(3):521-556

Pressure-temperature (P-T) paths have been calculated from pelitesand amphibolites of several major Acadian structures in west-centralNew Hampshire by using both inclusion thermobarometry and differentialthermodynamics (the Gibbs method). P-T paths calculated forrocks exposed in the Orfordville and Bronson Hill anticlinoriaare ‘clockwise’ and show 1–2.5 kb of exhumationwith 30–100 C of heating. Because this type of path ischaracteristic of the lower plate of overthrust terranes, theserocks are interpreted to be (para)autochthonous. P-T paths forrocks exposed in an intervening synclinorium (the Hardscrabblesynclinorium) show isothermal loading of 1–3 kb followedby possible isobaric cooling. This behavior is characteristicof rocks occupying a middle-plate structural position withina multiple thrust package, and so these rocks are interpretedto be allochthonous. The interpretation that the Hardscrabblerocks are allochthonous differs from previous models, but betterexplains the petrologic data and is consistent with the stratigraphicand structural data on which other models have been based. Correlation of the P-T paths with deformational events throughkinematic and textural analysis indicates that during nappestage deformation, the synclinorial rocks were transported westward,and that the anticlinorial and synclinorial rocks were buriedto depths of 25–30 and 20–25 km respectively. Theexhumation with heating recorded by the anticlinorial samplesoccurred during the dome stage of deformation, and differentiallyuplifted the anticlinorial rocks relative to the synclinorialrocks; this differential uplift may have been accommodated throughreactivation of early thrust faults with normal movement sense.P-T paths of the Hardscrabble synclinorium rocks are suggestiveof a relatively elevated initial geothermal gradient for theirpre-nappe source terrane, which is interpreted to have beenbetween the Kearsarge-Central Maine basin and the Bronson Hillparautochthon.  相似文献   

REPLY     

MARK WILKINSON 《Sedimentology》1992,39(3):518-520

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Dacite Genesis via both Slab Melting and Differentiation: Petrogenesis of La Yeguada Volcanic Complex, Panama   总被引：20，自引：2，他引：20  

DEFANT  MARC J.; RICHERSON  PHIL M.; DE BOER  JELLE Z.; STEWART  ROBERT H.; MAURY  REN? C.; BELLON  HERV?; DRUMMOND  MARK S.; FEIGENSON  MARK D.; JACKSON  THOMAS E. 《Journal of Petrology》1991,32(6):1101-1142

La Yeguada volcanioc complex (LYVC) is one of many major volcanoesthat represent the extension of the Central American arc inwestern Panama and that have resulted from current oblique subductionsouth of Panama. There are two major phases of calc-alkalinevolcanic activity at LYVC based on mapping and K-Ar radiometricdates. The first phase began at {small tilde} 13 Ma and ceasedat {small tilde} 7?5 Ma. This sequence, termed the old group,consists of basalts to rhyolites with typical arc mineralogies(OL, CPX, PL, MGT, and OPX). The samples have similar radiogenicSr and Nd values and appear to be related by fractional crystallizationwith assimilation and/or magma mixing involved in the differentiation.The parental basalts were probably derived from the metasomatizedmantle wedge via melting induced by fluids released from thesubducted lithosphere. There was an apparent period of minor volcanic activity from7–5 to 2–5 Ma (only one documented sample from thisperiod). The second phase (<2?5 Ma), termed the young group,consists only of dacites but with very different mineralogies(PL, MGT, AM, BI, with no PX) and geochemistries (e.g., highSr and low Y and HREE) compared with the old-group dacites (andandesites and rhyolites). The dacites cannot be related to theold group by various petrogenetic modeling techniques. Thesehigh-Al dacites have the characteristics of magmas derived fromthe partial melting of the subducted oceanic lithosphere witha hornblende eclogite residuum. This has been substantiatedby geochemical modeling. Samples similar to the young-group dacites in other arcs havebeen termed adakites and arc associated with the subductionof young hot crust which may explain why the slab melts. ThePanama basin has extremely high heat flow values, comparablewith those of the Galapagos ridge system. The change from normalarc volcanism to adakites suggests that the subducted oceaniccrust became hotter as time progressed. The subduction of anoceanic ridge or new ridge development along the Sandra Riftin the Panama basin can explain the change in volcanism withtime but more geophysical data are needed.  相似文献   

The concretions of the Bearreraig Sandstone Formation: geometry and geochemistry   总被引：1，自引：0，他引：1  

MARK WILKINSON 《Sedimentology》1991,38(5):899-912

The sandbodies of the Bearreraig Sandstone Formation (Inner Hebrides, UK) are cemented by two generations of calcite. The first generation, an inhomogeneous ferroan calcite (0.05?3.28 mol% FeCo₃) formed during sulphate reduction (δ¹³C =?24 to ?32%o PDB) in marine porewaters (δ¹⁸O of cement from ?1 to ?4%o PDB) at very shallow burial depths (a few centimetres). These cements are rare but form millimetre-scale clusters of crystals which acted as nuclei to the later, concretionary cements. The second generation of cements are more homogeneous ferroan calcites (mean 1?58% mol% FeCo₃) which evolve to progressively higher Fe/Mg ratios. They are sourced by shell dissolution (δ¹³C of cement from +1 to ?3%o PDB) into meteoric (δ¹⁸O of cement from ?6 to ?10%o PDB) or mixed marine meteoric waters (δ¹⁸O of cement from ?4 to ?6%o SMOW). These were introduced into the formation either during Bathonian times as a freshwater lens, or, subsequent to partial inversion, by confined aquifer flow. Corroded feldspars within the concretions suggest that an interval of at least 8 Ma separated the deposition of the sediments from the onset of concretion growth. Abundant concretions are preferentially developed at certain horizons within the sandbodies, where the early generation of ferroan calcite cements provided nuclei. The latter formed close to the sediment-water interface, the concentration of cement within the sediment being related to sedimentation rate. The relatively high concentrations of the first generation of cement, upon which the concretionary horizons are nucleated, formed during periods of minimal sedimentation.  相似文献   

Rock varnish in the Sonoran Desert: microbiologically mediated accumulation of manganiferous sediments   总被引：3，自引：0，他引：3  

BARTHOLOMEW NAGY  LOIS ANNE NAGY  MARK J. RIGALI  WILLIAM D. JONES  DAVID H. KRINSLEY  NORVAL A. SINCLAIR 《Sedimentology》1991,38(6):1153-1171

Rock varnish occurs in virtually all environments, most commonly in arid and semi-arid climates, including Antarctica. Rock varnish consists of thin layers of intimately mixed aeolian and chemical sediments often showing botryoidal and more rarely stromatolite-like morphologies. Typical rock varnish samples collected at Twin Peak Mountain Park, near Phoenix, Arizona, consist of abundant quartz, with plagioclase, illite and a mixed layer, Fe-clay mineral, probably corrensite. EDS, SEM (BSE) and TEM analyses revealed that the typical Mn, Fe minerals occur as minute particles; some of these particles and other mineral grains are attached to filaments. XRD and electron diffraction showed that the Mn.Fe-bearing particles are poorly crystalline. The filaments, based on morphological criteria, are virtually indistinguishable from fungal filaments. Most filaments are fragments, probably broken by scraping during sample collection. Coccoid and rod-shaped forms, resembling cyanobacteria and other bacteria, respectively, are also present. Unlike definitive minerals, these filaments disintegrated in the concentrated energy of the SEM electron beam at the instrumental and experimental conditions used. In addition, no filamentous, rod-shaped or coccoid forms were observed in samples hydrolysed with 6 N HCl for 24 h at 100°C. Bacteria and fungi in powdered rock varnish were cultured on four media, incubated aerobically in the dark at 25°C. The culture media yielded dense growths of spore-forming bacteria and filamentous fungi. One fungus and two Bacillus isolates oxidized and concentrated manganese. Control experiments revealed that fungi and bacteria are present on and below the surfaces of rock varnish. Free and hydrolysed, peptide/protein-bound amino acids were identified in the rock varnish. Amino acids showed virtually no racemization with the exception of D/L asp = 0.1. Relatively high molecular weight humic matter was also separated from the rock varnish. High-resolution mass spectrometry revealed non-hydrocarbon moieties, similar to a Suwannee River (FL) humic acid standard. Micro-organisms and their original biochemical compounds do not seem to be preserved for long in the accreting varnish layer. The studies showed that the filaments helped to trap mineral particles of rock varnish, and that bacteria and fungi abetted Mn concentration. Some structures in the layers of rock varnish resemble stromatolites and present definitions would allow them to be termed as such.  相似文献   

Wolf Volcano, Galapagos Archipelago: Melting and Magmatic Evolution at the Margins of a Mantle Plume   总被引：1，自引：0，他引：1  

GEIST  DENNIS J.; NAUMANN  TERRY R.; STANDISH  JARED J.; KURZ  MARK D.; HARPP  KAREN S.; WHITE  WILLIAM M.; FORNARI  DANIEL J. 《Journal of Petrology》2005,46(11):2197-2224

Wolf volcano, an active shield volcano on northern Isabela Islandin the Galápagos Archipelago, has undergone two majorstages of caldera collapse, with a phase of partial calderarefilling between. Wolf is a typical Galápagos shieldvolcano, with circumferential vents on the steep upper carapaceand radial vents distributed in diffuse rift zones on the shallower-slopinglower flanks. The radial fissures continue into the submarineenvironment, where they form more tightly focused rift zones.Wolf's magmas are strikingly monotonous: estimated eruptivetemperatures of the majority of lavas span a total of only 22°C.This homogeneity is attributed to buffering of magmas as theyascend through a thick column of olivine gabbroic mush thathas been deposited from a thin, shallow (<2 km deep) subcalderasill that is in a thermochemical steady state. Wolf's lavashave the most depleted isotopic compositions of any historicallyactive intraplate ocean island volcano on the planet and haveisotopic compositions (except for ³He/⁴He) indistinguishablefrom mid-ocean ridge basalt erupted from the GalápagosSpreading Center (GSC) 250–410 km away from the peak ofinfluence of the Galápagos plume. Wolf's lavas are enrichedin incompatible trace elements and have systematic major elementdifferences relative to GSC lavas, however. Wolf's magmas resultfrom lower extents of melting, deeper melt extraction, and agreater influence of garnet compared with GSC magmas, but Wolfand the GSC share the same sources. These melt generation conditionsare attributed to melting in a thermal and mechanical boundarylayer of depleted asthenosphere at the margins of the Galápagosplume. The lower degrees of melting and extraction from deeperlevels result from a thicker lithospheric cap at Wolf than existsat the GSC. KEY WORDS: caldera; Galápagos; mush; partial melting; plume  相似文献   

OPERATION IRAQI FREEDOM: A MILITARY GEOGRAPHICAL PERSPECTIVE*     

EUGENE J. PALKA  FRANCIS A. GALGANO  MARK W. CORSON 《Geographical review》2005,95(3):373-399

ABSTRACT. The war in Iraq has spanned the full spectrum of military operations: intense combat, stability‐and‐support operations, and peacetime activities. Regardless of their nature and relative intensity, military operations are shaped by the characteristics of the military operating environment. Consequently, the scale, tempo, and complexity of any type of military endeavor are linked to the physical and cultural landscapes of the region in which it is conducted. Military geographers use geographical information, tools, and techniques to examine those links. Iraq's operating environment is studied to identify the relevant components of its physical and human geography. This military geographical examination of Iraq tells us a great deal about how the physical and cultural environment have influenced the war, as well as how the complexity of its human landscape continues to affect the postwar rebuilding of the country.  相似文献   

Map and GIS database of glacial landforms and features related to the last British Ice Sheet   总被引：1，自引：0，他引：1  

CHRIS D. CLARK  DAVID J. A. EVANS  ANJANA KHATWA  TOM BRADWELL  COLM J. JORDAN  STUART H. MARSH  WISHART A. MITCHELL  MARK D. BATEMAN 《Boreas: An International Journal of Quaternary Research》2004,33(4):359-375

A review of the academic literature and British Geological Survey mapping is employed to produce a 'Glacial Map', and accompanying geographic information system (GIS) database, of features related to the last (Devensian) British Ice Sheet. The map (1:625 000) is included in a folder and GIS data are freely available by web download (http://www.shef.ac.uk/geography/staff/clark_chris/britice.html). Emphasis is on information that constrains the last ice sheet. The following are included: moraines, eskers, drumlins, meltwater channels, tunnel valleys, trimlines, limit of key glacigenic deposits, glaciolacustrine deposits, ice-dammed lakes, erratic dispersal patterns, shelf-edge fans and the Loch Lomond Readvance limit of the main ice cap. The GIS contains over 20 000 features split into thematic layers (as above). Individual features are attributed such that they can be traced back to their published sources. Given that the published sources of information that underpin this work were derived by piecemeal effort over 150 years, then our main caveat is of data consistency and reliability. It is hoped that this compilation will stimulate greater scrutiny of published data, assist in palaeoglaciological reconstructions and facilitate use of field evidence in numerical ice-sheet modelling. It may also help direct field workers in their future investigations.  相似文献   

Significance of localized pore pressures to the genesis of septarian concretions     

MARK W. HOUNSLOW 《Sedimentology》1997,44(6):1133-1147

The burial-stress and hydrologic conditions existing during concretion formation in mudrocks are evaluated and integrated into a model for the genesis of septarian cracks. Initial concretion cement formation will lower concretion permeability through the filling of pre-existing pore space. During progressive burial, this may lead to increased excess pore pressure, localized within the concretion body causing a reduction of the effective stress. Analysis of the stress conditions and crack morphology suggests that cracks in septarian concretions result from tensional failure (sub-critical crack growth), as a consequence of this localized excess pore pressure. Conditions suitable for crack formation will depend upon the magnitude of the excess pore pressure and the stress corrosion limit of the concretion body. A review of the likely strength of such concretions indicates that cracking could be initiated at depths less than 10 m. A variety of observed crack morphologies can be explained with this model, depending upon the spatial distribution of strength and effective stress in the concretion. Crack orientations mostly reflect stress anisotropy, but are also influenced by directional anisotropy in the crack growth rates. Locally increased pore pressure also likely occurs in non-septarian concretions, but is not sufficient to cause cracking. This enhanced local pressure may assist the crystal surface growth reactions of the carbonate cement. Through this enhancement process, the shape of concretions may be a response to the local anisotropic pore-pressure contours, which reflect the permeability anisotropy of the concretion and surrounding mudrock.  相似文献