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41.
This article examines the relationship between place attachment and resistance during participatory planning of the Sengwe Tshipise Wilderness Corridor, located in southeast Zimbabwe, a region that falls within the Great Limpopo Transfrontier Conservation Area. Field research was conducted from July to December 2013 using 69 semistructured interviews, seven focus-group discussions, and analysis of secondary data. By following the dominant narratives articulated by villagers affected by this Corridor, we illustrate the multiple ways in which place attachment becomes part of everyday politics of resistance. Results show that a strong place-based identity is at the center of narratives deployed by villagers displaced by war, conservation, and veterinary fencing restrictions. Through deploying this place-based identity, communities collectively influenced both the spatial extent of the corridor and institutional governance arrangements. This article contributes to debates on the role of community agency in the implementation of transfrontier conservation areas. 相似文献
42.
43.
Tangential-flow ultrafiltration was used to isolate particulate and high-molecular-weight dissolved material from seawater collected at various depths and geographic regions of the Pacific and Atlantic Oceans. Ultrafiltration proved to be a relatively fast and efficient method for the isolation of hundreds of milligrams of material. Optical and electron microscopy of the isolated materials revealed that relatively fragile materials were recovered intact. Depth-weighted results of the size distribution of organic matter in seawater indicated that ˜ 75% of marine organic carbon was low-molecular-weight (LMW) dissolved organic carbon (< 1 nm), ˜ 24% was high-molecular-weight (HMW) dissolved organic carbon (1–100 nm), and ˜ 1% was particulate organic carbon (> 100 nm). The distribution of carbon in surface water was shifted to greater relative abundances of larger size fractions, suggesting a diagenetic sequence from macromolecular material to small refractory molecules. The average C:N ratios of particulate organic matter (POM) and HMW dissolved organic matter (DOM) were 7.7 and 16.7, respectively. Differences in C:N ratios between POM and HMW DOM were large and invariant with depth and geographic region, indicating that the aggregation of HMW DOM to form POM must be of minor significance to overall carbon dynamics. The stable carbon isotope composition (δ13C) of POM averaged −22.7%. in surface water and −25.2%. in subsurface water. Several possible explanations for the observed isotopic shift with depth were explored, but we were unable to discern the cause. The δ13C of HMW DOM samples was relatively constant and averaged −21.7%., indicating a predominantly marine origin for this material. The δ15N values of POM were highly variable (5.8–15.4%.), and the availability of nitrate in surface waters appeared to be the major factor influencing δ15N values in the equatorial Pacific. In the upwelling region nitrate concentrations were relatively high and δ15N values of POM were low, whereas to the north and south of the upwelling nitrate concentrations were low and δ15N values were high. The δ15N values of HMW DOM reflected the same trends observed in the POM fraction and provided the first such evidence for biological cycling of dissolved organic nitrogen (DON). Using the observed δ15N values and an estimate of meridional advection velocity, we estimated a turnover time of 0.3 to 0.5% day−1 for HMW DON. These results suggest a major role for DON in the upper ocean nitrogen cycle. 相似文献
44.
Kristina B. Katsaros Paris W. Vachon W. Timothy Liu Peter G. Black 《Journal of Oceanography》2002,58(1):137-151
This article reviews several microwave instruments employed in research and analysis of tropical cyclones (TCs), typhoons,
and hurricanes. The instruments discussed include scatterometers, microwave radiometers, synthetic aperture radars (SARs),
and rain radar from space. Examples of the particular contribution by one or more of these instruments in analysis of several
storms illustrate the comprehensive new views provided by the SeaWinds scatterometers, the detailed high-resolution wind field
provided by RADARSAT-1 SAR, particularly inside and in the vicinity of hurricane “eyes,” and the presence of secondary flows
in the region between rainbands in TCs. The high spatial resolution of precipitation data from the Tropical Rainfall Measuring
Mission's rain radar, combined with scatterometer or SAR data, give a significant improvement in the details that can be seen
from space, at the surface, and in the precipitating areas of TCs. The microwave instruments provide a penetrating view below
the upper level cirrus clouds.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
45.
The Timbarra Tablelands pluton is an extensive (~550 km2) complexly zoned intrusion forming one of many predominantly monzogranite I‐type plutons, which constitute the Moonbi Supersuite in northern New South Wales, Australia. It comprises an outer rim of Rocky River monzogranite (Zones 1–3), an intermediate zone of Sandy Creek syenogranite (Zones 4A–4C), surrounding a core of Surface Hill syenogranite (Zones 5–7). The suite is calc‐alkaline, high‐K, and varies from mildly metaluminous to weakly peraluminous with increasing fractionation. Average Rb/Sr ratios range from 0.4 in the least evolved very coarse‐grained monzogranite (Zone 3) to 46 in the most evolved very fine‐grained biotite microgranite (Zone 6). Trace‐element modelling indicates that the observed compositional variation could have been produced by crystal fractionation. New bulk rock major‐ and trace‐element data for 71 samples are presented, and indicate that a compositional continuum exists that varies between 63 and 78 wt% SiO2. Importantly, there is no systematic chemical variation with spatial distribution of samples from the core of the pluton to its margin, requiring multiple separate pulses of an evolving magma to explain compositional discontinuities. The pluton is interpreted to have been emplaced at mesozonal levels (~180 ± 60 MPa, 5–10 km depth) and crystallised at temperatures between 620 and 820°C under moderately oxidising conditions (log fO2 = ‐11.5 to ‐19). The association of gold‐molybdenite mineralisation at Timbarra with moderately oxidised I‐type magmas is consistent with fractionation‐redox controls on ore‐element behaviour in magmatic systems in other studies. 相似文献
46.
L. P. Black J. L. Everard M. P. McClenaghan C. R. Calver A. M. Fioretti 《Australian Journal of Earth Sciences》2013,60(7):933-968
Devonian–Carboniferous granites are widespread in Tasmania. In eastern Tasmania, Devonian granites intrude Ordovician–Early Devonian quartz-rich turbidites of the Mathinna Supergroup. The earliest (~400 Ma) I-type granodiorites may be arc-related. Following the Tabberabberan Orogeny (~389 Ma), more felsic and, finally, strongly fractionated I- and S-type granites were emplaced until ~373 Ma. In contrast, western Tasmania granites intrude a more diverse terrane of predominantly marine shelf successions, with depositional ages as old as Late Mesoproterozoic. They are mostly felsic and fractionated I- and S-types emplaced from ~374–351 Ma, possibly in response to post-collisional crustal extension following juxtaposition of the eastern and western Tasmanian terranes. Granites from the two terranes are readily distinguishable by the age spectra of their inherited zircon, which are noticeably similar to those of the detrital zircon from sedimentary successions in their respective terranes. Furthermore, within each terrane, both I and S-types yield similar inheritance patterns. This suggests a pivotal role for the sedimentary successions in the petrogenesis of both types. Western Tasmanian granites are also enriched in ~1600 Ma zircon, which is essentially unrepresented in the exposed supracrustal succession. Subtle differences between the inheritance and detrital age spectra in eastern Tasmania probably relate to unrepresentative sampling of the supracrustal rocks. Nd, Sr and Pb isotopic characteristics of the granites are consistent with their derivation by mixing of magmas derived from the mantle, possibly the lower crust, and from supracrustal rocks. Systematic isotopic trends in some eastern Tasmanian I-types, particularly in the Scottsdale Batholith, correlate well with major and trace element geochemistry and age. The isotopes are inconsistent with simple restite unmixing or crystal fractionation in a closed magma chamber, and indicate progressive contamination by the Mathinna Supergroup, or similar rocks. The isotopic characteristics of late, strongly fractionated granites, although sometimes obscured by hydrothermal alteration, are also consistent with concurrent assimilation-fractional crystallisation processes. Together with the close association of some strongly fractionated I- and S-types, this suggests that such granites were generated directly in the lower crust, and were not derived from unfractionated parental granite magmas. 相似文献
47.
Thomas V. Lowell Katherine Schoenenberger James A. Deddens George H. Denton Colby Smith Jessica Black Chris H. Hendy 《第四纪科学杂志》2005,20(4):313-325
Development of Rhizocarpon growth curve from the Aoraki/Mount Cook area of New Zealand provides a means to assess Little Ice Age glacier behaviour and suggests approaches that have wider application. Employing a sampling strategy based on large populations affords the opportunity to assess which of various metrics (e.g. single largest, average of five largest, mean of an entire population) best characterise Rhizocarpon growth patterns. The 98% quantile from each population fitted with a quadric curve forms a reliable representation of the growth pattern. Since this metric does not depend on the original sample size, comparisons are valid where sample strategy must be adapted to local situations or where the original sample size differs. For the Aoraki/Mount Cook area a surface 100 years old will have a 98% quantile lichen diameter of 34.3 mm, whereas a 200‐year‐old surface will have a lichen diameter of 73.7 mm. In the Southern Alps, constraints from the age range of calibration points, the flattening of the quadric calibration curve and ecological factors limit the useful age range to approximately 250 years. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
48.
Joe Kidston Christian Brümmer T. Andrew Black Kai Morgenstern Zoran Nesic J. Harry McCaughey Alan G. Barr 《Boundary-Layer Meteorology》2010,136(2):193-218
Components of the surface energy balance of a mature boreal jack pine forest and a jack pine clearcut were analysed to determine
the causes of the imbalance that is commonly observed in micrometeorological measurements. At the clearcut site (HJP02), a
significant portion of the imbalance was caused by: (i) the overestimation of net radiation (R
n
) due to the inclusion of the tower in the field of view of the downward facing radiometers, and (ii) the underestimation
of the latent heat flux (λE) due to the damping of high frequency fluctuations in the water vapour mixing ratio by the sample tube of the closed-path
infrared gas analyzer. Loss of low-frequency covariance induced by insufficient averaging time as well as systematic advection
of fluxes away from the eddy-covariance (EC) tower were discounted as significant issues. Spatial and temporal distributions
of the total surface-layer heat flux (T), i.e. the sum of sensible heat flux (H) and λE, were well behaved and differences between the relative magnitudes of the turbulent fluxes for several investigated energy
balance closure (C) classes were observed. Therefore, it can be assumed that micrometeorological processes that affected all turbulent fluxes
similarly did not cause the variation in C. Turbulent fluxes measured at the clearcut site should not be forced to close the energy balance. However, at the mature
forest site (OJP), loss of low-frequency covariance contributed significantly to the systematic imbalance when a 30-min averaging
time was used, but the application of averaging times that were long enough to capture all of the low-frequency covariance
was inadequate to resolve all of the high-frequency covariance. Although we found qualitative similarity between T and the net ecosystem exchange (NEE) of carbon dioxide (CO2), forcing T to closure while retaining the Bowen ratio and applying the same factor to CO2 fluxes (F
C
) cannot be generally recommended since it remains uncertain to what extent long wavelength contributions affect the relationship
between T, F
C
and C. 相似文献
49.
Philippa M. Black 《Contributions to Mineralogy and Petrology》1973,38(3):221-235
A Cretaceous to low-Tertiary sequence of interbedded pelites, cherts, basic and acidic volcanics and calcareous lenses has
been metamorphosed by an Oligocene event. A complete intergradational metamorphic sequence is exposed in the Ouégoa destrict.
The following metamorphic zones have been recognised: — (1) lowest-grade rocks consisting of quartz-sericite phyllites and
pumpellyite metabasalts (2) lawsonite zone, characterized by the association of lawsonite and albite (3) epidote zone, characterised
by epidote-omphacite-sodic hornblendealmandine bearing metabasalts and epidote-albite-almandine-glaucophane bearing metasediments;
calcareous metasediments may also carry omphacite. The epidote and lawsonite zones are separated by a narrow belt of transitional
rocks.
Garnets occur in metasediments throughout the lawsonite zone as rare tiny crystals (<0.03 mm diam.). Garnets first appear
in metabasalts in lawsonite-epidote transitional rocks. Garnets are widespread and abundant in epidote-zone metasediments
and metabasalts.
45 garnets from rocks representative of all lithologies and metamorphic grades have been analysed with an electron-probe microanalyser.
The garnets were consistently zoned. Garnets in lawsonite and low-grade epidote zones show a “bell-type” zoning with cores
enriched in Mn relative to Fe and rims enriched in Fe, Mg and frequently Ca. Garnets from high-grade epidote-zone metapelites
and metabasalts show, in addition, a shallow oscillatory zoning with complimentary variations in Mn and Fe equivalent to 5
mole- % spessartine and almandine. The Fe-for-Mn substitutional zoning, believed to be caused by a diffusion/saturation effect
similar to that of the Rayleigh fractional model (Hollister, 1966), appears to have had superimposed on it the effects of
parent-rock chemistry and metamorphic grade which control in a complex manner the composition of the cores and the rims of
garnets.
Garnets from different rock types and metamorphic grade are compositionally distinct. Garnets from lawsonite-zone rocks, irrespective
of parent-rock chemistry appear to be spessartine. Garnets from epidote-zone metaigneous rocks and most metasediments are
almandine. Garnets from epidote-zone metasediments with bulk-rock compositions which are manganiferous, or have high oxidation
ratios, or both, may be spessartine-rich. Garnets from metabasalts are consistently more pyropic in both core and rim compositions
than garnets from pelitic metasediments; the pyrope content of cores and rims of garnets from equivalent rock types and mineral
assemblages increases with increasing metamorphic grade. Cores of garnets from epidote-zone pelites are richer in grossular
than garnets from lower-grade pelites.
The reaction which brings almandine garnet into Ouégoa district blueschist assemblages simultaneously with the replacement
of lawsonite by epidote involves components of chlorites and sodic amphiboles and can be represented by the following simplified
equation: ferroglaucophane+Fe-rich chlorite+lawsonite → glaucophane+Mg-rich chlorite+epidote+almandine. 相似文献
50.
Tin-bearing granitic rocks of northeast Queensland range in age from Precambrian to Permian. They are high-level granites or adamellites enriched in volatile elements, such as Li, Be, B, and F. Tin contents are significantly higher than those of non-stanniferous granites, but lower than values reported for many tin granites elsewhere. A distribution of tin in which a high proportion of samples have tin contents significantly higher than background values, appears to be a useful criterion of potential tin mineralization. An uneven distribution of tin in the crust (or possibly the upper mantle) would explain the difference in tin contents of granites associated with tin mineralization, compared with granites from areas which do not contain tin deposits.No correlation of granite geochemistry with lead/zinc or copper mineralization was found. In particular, granites associated with such mineralization do not show anomalous abundances of Pb, Zn, or Cu. If mineralization is regarded as an independent by-product of magma generation rather than the result of differentiation processes, then this lack of correlation is explicable. 相似文献