Is there a win–win scenario for marine nature conservation? A case study of Lyme Bay,England     

Siân E. Rees  Martin J. Attrill  Melanie C. Austen  Steven C. Mangi  Jo P. Richards  Lynda D. Rodwell 《Ocean & Coastal Management》2010,53(3):135-145

A statutory two hundred and six square kilometre ‘closed area’ in Lyme Bay, South West England entered into force on the 11 July 2008 to protect the reef substrate and the associated biodiversity from the impacts of trawling and dredging with heavy demersal fishing gear. This case study provides an example of how the ecosystem approach has been incorporated into decision making for marine nature conservation and shows that despite sound ecological knowledge of a marine area, the current reliance on traditional neo-classical economic valuations for marine spatial planning can obscure other issues pertinent to the ecosystem approach. With the Government seeking win–win scenarios for stakeholders in the designation of Marine Conservation Zones under the Marine and Coastal Access Act, experience of marine spatial planning in Lyme Bay has revealed that a win–win must be a long-term goal based on a thorough evaluation of the environmental, social and economic values of marine biodiversity.  相似文献   

Proterozoic low-sulfidation epithermal Au-Ag mineralization in the Mallery Lake area, Nunavut, Canada   总被引：2，自引：0，他引：2  

William Turner  Jeremy Richards  Bruce Nesbitt  Karlis Muehlenbachs  John Biczok 《Mineralium Deposita》2001,36(5):442-457

The Mallery Lake area contains pristine examples of ancient precious metal-bearing low-sulfidation epithermal deposits. The deposits are hosted by rhyolitic flows of the Early Proterozoic Pitz Formation, but are themselves apparently of Middle Proterozoic age. Gold mineralization occurs in stockwork quartz veins that cut the rhyolites, and highest gold grades (up to 24 g/t over 30 cm) occur in the Chalcedonic Stockwork Zone. Quartz veining occurs in two main types: barren A veins, characterized by fine- to coarse-grained comb quartz, with fluorite, calcite, and/or adularia; and mineralized B veins, characterized by banded chalcedonic silica and fine-grained quartz, locally intergrown with fine-grained gold or electrum. A third type of quartz vein (C), which crosscuts B veins at one locality, is characterized by microcrystalline quartz intergrown with fine-grained hematite and rare electrum. Fluid inclusions in the veins occur in two distinct assemblages. Assemblage 1 inclusions represent a moderate temperature (Th=150 to 220 °C), low salinity (~1 eq. wt% NaCl, with trace CO₂), locally boiling fluid; this fluid type is found in both A and B veins and is thought to have been responsible for Au-Ag transport and deposition. Assemblage 2 inclusions represent a lower temperature (Th=90 to 150 °C), high salinity calcic brine (23 to 31 wt% CaCl₂-NaCl), which occurs as primary inclusions only in the barren A veins. Assemblage 1 and 2 inclusions occur in alternating quartz growth bands in the A-type veins, where they appear to represent alternating fluxes of dilute fluid and local saline groundwater. No workable primary fluid inclusions were observed in the C veins. The A-vein quartz yields '¹⁸O values from 8.3 to 14.5‰ (average=10.9ǃ.7‰ [1C], n=30), whereas '¹⁸O values for B-vein quartz range from 11.2 to 14.0‰ (average=13.0ǂ.9‰, n=12). Calculated '¹⁸O_H2O values for the dilute mineralizing fluid from B veins range from -2.6 to 0.2‰ (average=-0.8ǂ.9‰, n=12) and are consistent with a dominantly meteoric origin. No values could be calculated for the brine, however, because all A-vein quartz samples contain mixed fluid inclusion populations. However, the fact that A-vein quartz samples extend to lower '¹⁸O values than the B veins suggests that the brine had a lighter isotopic signature relative to the dilute fluid. Hydrogen isotopic ratios of fluid inclusion waters extracted from eleven quartz samples of both vein types range from 'D_FI=-56 to -134‰, but show no particular correlation with vein type. In most respects, the mineralogical and fluid characteristics of the Mallery Lake system are comparable to those of Phanerozoic low-sulfidation deposits, and although the presence of high salinity brines is unusual in such deposits, it is not unknown (e.g., Creede, Colorado). In addition, one of the few other examples of well-preserved, Precambrian, low-sulfidation epithermal deposits, from the Central Pilbara tectonic zone, Australia, contains a similarly bimodal fluid assemblage. The significance of these saline brines is not clear, but from this study we infer that they were not directly involved with Au-Ag transport or deposition.  相似文献   

A Study of Small Magnitude Seismic Events During 1961–1989 on and near the Semipalatinsk Test Site, Kazakhstan     

V.I. Khalturin  T.G. Rautian  P.G. Richards 《Pure and Applied Geophysics》2001,158(1-2):143-171

—?Official Russian sources in 1996 and 1997 have stated that 340 underground nuclear tests (UNTs) were conducted during 1961–1989 at the Semipalatinsk Test Site (STS) in Eastern Kazakhstan. Only 271 of these nuclear tests appear to have been described with well-determined origin time, coordinates and magnitudes in the openly available technical literature. Thus, good open documentation has been lacking for 69 UNTs at STS.¶The main goal of our study was to provide detections, estimates of origin time and location, and magnitudes, for as many of these previously undocumented events as possible. We used data from temporary and permanent seismographic stations in the former USSR at distances from 500?km to about 1500?km from STS. As a result, we have been able to assign magnitude for eight previously located UNTs whose magnitude was not previously known. For 31 UNTs, we have estimated origin time an d assigned magnitude — and for 19 of these 31 we have obtained locations based on seismic signals. Of the remaining 30 poorly documented UNTs, 15 had announced yields that were less than one ton, and 13 occurred simultaneously with another test which was detected. There are only two UNTs, for which the announced yield exceeds one ton and we have been unable to find seismic signals.¶Most of the newly detected and located events were sub-kiloton. Their magnitudes range from 2.7 up to 5.1 (a multi-kiloton event on 1965 Feb. 4 that was often obscured at teleseismic stations by signals from an earthquake swarm in the Aleutians).¶For 17 small UNTs at STS, we compare the locations (with their uncertainties) that we had earlier determined in 1994 from analysis of regional seismic waves, with ground-truth information obtained in 1998. The average error of the seismically-determined locations is only about 5?km. The ground-truth location is almost alw ays within the predicted small uncertainty of the seismically-determined location.¶Seismically-determined yield estimates are in good agreement with the announced total annual yield of nuclear tests, for each year from 1964 to 1989 at Semipalatinsk.¶We also report the origin time, location, and seismic magnitude of 29 chemical explosions and a few earthquakes on or near STS during the years 1961–1989.¶Our new documentation of STS explosions is important for evaluating the detection, location, and identification capabilities of teleseismic and regional arrays and stations; and how these capabilities have changed with time.  相似文献   

Hydrology,hydraulics, and geomorphology of the Bonneville flood by J.E. O'Connor,Geological Society of America,Boulder, Colorado,Special paper no. 274, 1993. No. of pages: VI + 83. ISBN 0–8137–2274–8     

Keith Richards 《地球表面变化过程与地形》1995,20(4):386-386

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Establishing the role of pedogenesis in changing soil hydraulic properties     

S. M. Brooks  K. S. Richards 《地球表面变化过程与地形》1993,18(6):573-578

Chronosequences provide suitable sources for the study of changes in soil hydraulic behaviour as a result of long-term pedogenesis. For a podsol chronosequence in the Scottish Highlands, data are presented to indicate the changes that have occurred over 13000 years in the saturated hydraulic conductivity (K_sat) in each horizon. As the soil profile has evolved into a differentiated sequence of three horizons, the resulting hydrological changes can be both measured and quantified by relating K_sat to textural properties and bulk density. The results are significant for interpretation of changing runoff processes and slope stability.  相似文献   

The significance of rainstorm variations to shallow translational hillslope failure     

S. M. Brooks  K. S. Richards 《地球表面变化过程与地形》1994,19(1):85-94

Landsliding in eastern Scotland results from high-magnitude rainstorms generated under either cyclonic or anticyclonic conditions, particularly during the summer. Data from Aviemore indicated that cyclonic storms produce higher rainfall totals than anticyclonic storms, as well as being of longer duration and lower intensity. The distribution of rain during individual storms also varies with the synoptic conditions under which the storms are produced. These different rainfall characteristics produce different geomorphic responses, which can be investigated in detail using physical based modelling. In this paper, a physically based coupled hydrology–stability model is used to assess the significance of these rainfall characteristics to soil moisture response and slope instability for mature podsols. The results provide evidence that rainstorms of different synoptic origin produce varying hydrological response, involving both the extent and the timing of moisture content change. This affects the depth and timing of slope failure, with anticyclonic storms promoting a large, rapid response in the factor of safety at shallow depths within the soil. Cyclonic storms produce a more gradual response, with the region of probable failure being deeper. Futhermore, each of these storm types is associated with different rainfall distributions, and this is also shown to have a significant effect on the timing and depth of slope instability.  相似文献   

The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada     

J. Potter  B.C. Richards  A.R. Cameron 《International Journal of Coal Geology》1993,24(1-4)

Petrographic analyses were carried out on thin coals and coaly sediments from the Lower Carboniferous Mattson Formation at Clausen Creek and Jackfish Gap-Yohin Ridge in the northern part of the Liard Basin, northern Canada. The composition and optical characteristics indicate that the coals are high-volatile bituminous B, predominantly sapropelic (canneloid) and accumulated subaquatically.The coals are dominantly composed of inertinite-rich and exinite-rich durities with subsidiary inertites and clarodurites; vitrite is minor and liptite is rare. The inertinite-rich microlithotypes are dominated by semifusinite, but micrinite, semimacrinite and ?resino-inertinites are abundant. Sporinite, comprising megaspores, crassispores, tenuispores and miospores, is the dominant liptinite maceral with subsidiary cutinite and minor alginite. Except for pyrite, mineral matter is minimal.Three populations of telocollinite are observed: a low-reflectance variety (I), commonly associated with micrinite (as vitrinertite), displays weak brown fluorescence and a reflectance some 0.4-0.5% lower than type II; type II is non-fluorescing telocollinite, with intermediate reflectance (0.67-0.74% R_om), it occurs as vitrite and is also associated with micrinite; and a higher-reflectance telocollinite (III), having no fluorescence or association with micrinite, has variable reflectance (0.74-0.8% R_om) implying higher oxidation or gelification levels.The abundance of semimacrinite, macrinite and ?resino-inertinites in inertites and durites (I) suggests that much of the peat accumulated subaquatically. Furthermore, fluorescing vitrinite and an abundance of micrinite (derived by oxidation or coalification of bituminite), suggest that the coal accumulated under anaerobic conditions. The predominance of semifusinite in humic laminae and micrinite in sapropelic layers suggests extensive surface or near-surface oxidation of the peat. Oxidised sporinites suggest that they were wind-borne.Depositional environment is interpreted as marginal marine, perhaps in shallow lakes in the middle to upper delta plain. Peat accumulations probably began subaquatically at the oxygen-hydrogen sulphide interface, but periodic subaerial exposure and natural oxidation gave rise to the high inertinite coals. Upper Mattson coals are interbedded with algal laminites and probably accumulated in a lagoonal setting.  相似文献   

Pitchblende and galena ages in the Alligator Rivers region,Northern Territory,Australia   总被引：1，自引：0，他引：1  

J. H. Hills  J. R. Richards 《Mineralium Deposita》1976,11(2):133-154

U-Pb and Pb isotopic studies have been made of pitchblendes and associated galenas from four major deposits in the Alligator Rivers region of the Northern Territory, Australia. These are compared with previously-published data on deposits in the South Alligator Valley and in the Westmoreland area on the Queensland border. In all, four different times of possible mineral formation have been detected (1880 ± m. y., 1700 ± m. y., 800–900 m. y., 400–500 m. y.) Some deposits reveal only one time, others two; no deposit shows evidence for all four. The associated galenas are in general highly radiogenic (206/204 ratios range from 2000 to 29, 000); some can be interpreted as reflecting development in two completely different generations of pitchblende. The clearest evidence for solid-state formation of galena from presently-existing pitchblende is to be found at Nabarlek, where the major time of pitchblende formation (920 m. y.) bears no relationship to any known Rb-Sr or K-Ar age.  相似文献   

Pilbara galenas: Precise isotopic assay of the oldest Australian leads; model ages and growth-curve implications     

J. R. Richards  I. R. Fletcher  J. G. Blockley 《Mineralium Deposita》1981,16(1):7-30

Precise Pb isotopic data are reported for 19 galenas and 2 other minerals from the Archaean Pilbara District of Western Australia. Repeated measurements on the Broken Hill Standard Ore show good agreement with published calibrations from two other laboratories, and an overall 95 percent confidence level within ±0.05 percent per mass unit, whether fractionation correction is by the double-spike procedure or by use of a simple mass-dependent factor. Two stratiform deposits yield the most primitive ratios (²⁰⁶Pb/²⁰⁴Pb=11.89; ²⁰⁷Pb/²⁰⁴Pb=13.69; ²⁰⁸Pb/²⁰⁴Pb=31.79) and model ages in good agreement with the 3.45 Ga age on zircons from volcanics correlatable with the host-rocks. Other minor galena occurrences, with quartz-vein association, appear to be younger, with position along the growth curve surprisingly consistent with the age sequence predicted from field observation. The data also extend the time-range of previously-reported trends in apparent U/Pb of the conceptual Pb source, and reveal new features of the corresponding Th/U systematics: a generally-observable trend in the Archaean of Australia, Southern Africa and West Greenland is that the source Th/U seems significantly higher than is allowed for in any of the current Pb-growth models. In detail, the sample-sample variations in indicated source parameters are in many cases correlatable with the nature of the neighbouring rocks and emphasise that, whereas Pb isotope rations in the galenas of huge deposits may well serve as a convenient sampler of overall trends in the Earth's crust, subeconomic occurrences such as these may reveal valuable information about local variations in U-Th-Pb distribution.  相似文献   

A re-assessment of the Upper Mississippi valley lead isotope data     

J. R. Richards  A. K. Yonk  C. W. Keighin 《Mineralium Deposita》1972,7(3):285-291

Corrections for systematic bias, and a better regression method, are tested on the lead isotope data of Heyl, Delevaux, Zartman and Brock (1966). The new calculations suggest the time of mineralization in the Upper Mississippi zinc-lead district is more likely to lie in the range Mid Devonian (370 my) to Upper Pennsylvanian (280 my) on any reasonable assumption for the age of the basement. It is argued from the isotopic trends that the ore lead in this district was simply derived by radiogenic addition to lead originally derived from rocks of basement age, although the data do not exclude residence in the Lower Paleozoic sediments as an intermediate step. An isotopically different magmatic component is not required. Correlation with the geology suggests that genesis of the deposits probably was related to regional tectonic deformation in Middle to Late Paleozoic time.

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Zusammenfassung Korrekturen systematischer Fehler und eine bessere Regressionsmethode wurden anhand der Blei-Isotopendaten von Heyl, Delevaux, Zartman und Brock (1966) getestet. Diese neuen Berechnungen unter Annahme eines vernünftigen Alters des Grundgebirges zeigen, daß die Zeit der Mineralisation im Oberen Mississippi Zink-Blei Distrikt eher zwischen Mitteldevon (370 Millionen Jahre) und Oberkarbon (280 Millionen Jahre) zu setzen ist. Auf Grund der Verteilung der Isotopenverhältnisse wird auf eine einfache Formierung (durch Addition radioaktiver Zerfallsprodukte zum ursprünglichen Blei im Gestein mit demselben Alter wie das Grundgebirge) des Bleies im Bleierz geschlossen. Die Meßresultate schließen jedoch eine Ablagerung im Unterpaläozoikum als Übergangsstufe nicht aus. Magma mit andern Isotopenverhältnissen wird nicht angenommen. Vergleiche mit der Geologie deuten darauf hin, daß die Bildung der Ablagerungen im Zusammenhang mit tektonischen Deformationen im Mittleren bis Oberen Paläozoikum erfolgte.

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