Beaches and dunes of developed coasts: Nordstrom, Karl F. Cambridge University Press, Cambridge, 2000, 338 pages+xiii, 57 figures (b&w photographs and b&w diagrams), 8 tables, UK£45, US$74.95, Hardback, ISBN 0 521 47013 7     

Derek J. McGlashan 《Geomorphology》2001,36(3-4)

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Competitive Exclusion of Sulfate Reduction by Fe(lll)-Reducing Bacteria: A Mechanism for Producing Discrete Zones of High-Iron Ground Water     

Francis H. Chapelle  Derek R. Lovley 《Ground water》1992,30(1):29-36

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The impact of the friction of distance on the early settlement and development of Eyre Peninsula,South Australia     

Derek. L. Smith 《The Australian geographer》1992,23(2):149-163

The cost of overcoming distance has played and continues to play an important role in the evolution of Australia's space‐economy. This paper examines the impact of the ‘friction of distance’, as well as the quality of the resource base, on the settlement and development of Eyre Peninsula in South Australia. A series of maps portraying the spread of pastoralism and then agriculture on Eyre Peninsula reveals clearly the importance of ‘accessibility’ in influencing the pattern and timing of settlement. It was not until well into this century that all the potentially agricultural land in the interior was occupied, for this required the construction of a railway and water pipeline up the centre of the peninsula.  相似文献   

Geochemistry of ice-covered, meromictic Lake A in the Canadian High Arctic     

John A. E. Gibson  Warwick F. Vincent  Patrick Van Hove  Claude Belzile  Xioawa Wang  Derek Muir 《Aquatic Geochemistry》2002,8(2):97-119

The geochemical processes occurring within meromictic Lake A (maxdepth 120 m) on northern Ellesmere Island, Canada, were investigated to determinethe history of the lake and to provide a baseline for future studies. The lake contained seawaterdiluted by freshwater input that had been mixed prior to the lake's isolation from tidalaction. Input of freshwater after isolation of the lake created vertical stratification resultingin the creation of distinct oxic, suboxic and anoxic zones. Dissolved oxygen was present to 13 m,and sulphide beneath 32 m. Manganese and iron cycling dominated the redox chemistrybetween these depths. Total manganese concentrations reached 176 M, higher thanin most other natural stratified lake or marine environments.  相似文献   

天山北部石炭纪埃达克岩-高镁安山岩-富Nb岛弧玄武质岩：对中亚造山带显生宙地壳增生与铜金成矿的意义   总被引：28，自引：30，他引：28  

王强赵振华  许继峰Derek A．WYMAN 熊小林资峰  白正华 《岩石学报》2006,22(1):11-30

新疆天山北部地区存在有石炭纪的埃达克岩-高镁安山岩-富Nb玄武质岩组合，并且其中许多岩石与铜（金）矿床伴生（如达巴特、阿希、土屋-延东、赤湖，等等）。埃达克岩富钠、高Sr但亏损Y与Yb，无明显Eu-正Eu异常以及正Sr异常与Nb、Ti亏损。高镁安山（闪长）岩是本次研究首次报道的，这些岩石无明显Eu-正Eu异常以及Nb、Ti亏损，普遍具有高的MgO和Cr、Ni含量，其中阿希金矿区一些样品类似于日本西南新生代Setouchi弧火山岩带中的赞岐岩类。富Nb玄武质岩富钠贫钾，具有微弱负．正Ba、Nb和Ti异常以及高的Nb／La比值，不同于大多数正常岛弧玄武岩。天山北部地区石炭纪埃达克岩具有高的8Nd（t）（＋3．4-＋9．0）和低的（^87Sr／^86Sr）i（0．7032—0．7043）。富Nb玄武质岩具有变化的εNd（t）（＋3．6-＋11．6）和（^87Sr／^86Sr）；（0．7007—0．7067）。我们的研究表明，天山北部地区石炭纪埃达克岩-高镁安山岩-富Nb玄武质岩组合可能是“埃达克岩交代的岛弧岩浆岩系列”。埃达克岩最有可能由石炭纪北天山洋的年轻洋壳在俯冲过程中熔融形成。另外，俯冲板片产生的熔体以及所释放的少量流体在上升过程中可能交代地幔楔橄榄岩或与其发生反应：一方面，触发地幔楔橄榄岩发生熔融形成富Nb岛弧玄武质岩；另一方面，地幔组分迅速进入到板片熔体中，导致其地幔组分增加，乃至形成高镁安山岩。因此，天山北部地区石炭纪埃达克岩-高镁安山岩-富Nb玄武质岩组合表明：（1）天山北部地区石炭纪可能为岛弧环境而非裂谷环境；（2）天山地区石炭纪的地壳生长可能以侧向增生为主；（3）除了亏损地幔之外，俯冲洋壳的熔融可能也在地壳的生长中发挥了重要的作用；（4）俯冲板片产生的埃达克质岩浆具有高的氧逸度，而其与地幔楔橄榄岩的强烈相互作用将导致地幔中的金属硫化物分解，成矿金属元素进入到岩浆中。这可能是新疆北部铜金矿化与一些埃达克岩、高镁安山（闪长）岩或富Nb岛弧玄武质岩密切共生的基本原因。  相似文献   

Angular resolution of terrestrial laser scanners   总被引：5，自引：0，他引：5  

Derek D.  Lichti  Sonam  Jamtsho 《The Photogrammetric Record》2006,21(114):141-160

Knowledge of a laser scanner's spatial resolution is necessary in order to prevent aliasing and estimate the level of detail that can be resolved from a scanned point cloud. Spatial resolution can be decoupled into range and angular components. The latter is the focus of this paper and is governed primarily by sampling interval and laser beamwidth. However, emphasis is often placed on one of these—typically sampling interval—as an indicator of resolution. Since both affect the resolution of a scanned point cloud, consideration of only one factor independent of the other can lead to a misunderstanding of a system's capabilities. This will be demonstrated to be inappropriate except under very specific conditions. A new, more appropriate resolution measure for laser scanners, the effective instantaneous field of view (EIFOV), is proposed. It is derived by modelling the shift variance of the equal angular increment sampling process, laser beamwidth-induced positional uncertainty and observed angle quantisation with ensemble average modulation transfer functions (AMTFs). Several commercially available terrestrial laser scanner systems are modelled and analysed in terms of their angular resolution capabilities using the EIFOV.  相似文献   

Spectral scaling in Mars topography: effect of craters     

Vladimir Nikora  Derek Goring 《Acta Geophysica》2006,54(1):102-112

Extensive computer simulations aimed at testing a hypothesis that impact craters may explain the scaling behaviour of surface spectra are presented. The simulations show that indeed crater effects alone may explain the spectral scaling of Mars’ topography revealed from MOLA data. The range of the scaling exponents obtained for a wide range of simulation parameters does not exceed the limits observed for Mars. The simulations suggest that the shape of large craters is the key factor leading to the two scaling ranges in the surface spectra. Particular values of the scaling exponents may additionally depend on the depth-diameter relationship and the crater size distribution.  相似文献   

Early Cretaceous adakitic granites in the Northern Dabie Complex, central China: Implications for partial melting and delamination of thickened lower crust   总被引：21，自引：0，他引：21  

Qiang Wang  Derek A. Wyman  Ping Jian  Chaofeng Li  Jinlong Ma 《Geochimica et cosmochimica acta》2007,71(10):2609-2636

To date, few adakitic rocks have been reported in direct association with contemporary intra-continental extensional structures, which has cast doubt on genetic models involving partial melting of the lower crust. This study presents Early Cretaceous (143-129 Ma, new Sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb ages) adakitic granites, which are directly associated with a contemporary metamorphic core complex (i.e., the Northern Dabie Complex in the Dabie area). These granites exhibit relatively high Sr contents, negligible to positive Eu and Sr anomalies, high La/Yb and Sr/Y ratios, but very low Yb and Y contents, similar to subducted oceanic crust-derived adakites. They are also characterized, however, by very low MgO or Mg^# and Ni values, and Nd-Sr isotope compositions (ε_Nd(t) = −14.6 to −19.4 and (⁸⁷Sr/⁸⁶Sr)_i = 0.7067-0.7087) similar to Triassic continent-derived eclogites subducted in the Dabie-Sulu Orogen. Additionally, late granitic dikes in the adakitic intrusions exhibit low Sr contents, clearly negative Eu and Sr anomalies, low La/Yb and Sr/Y ratios, but relatively high Yb and Y contents, similar to 118-105 Ma granites in the Northern Dabie Complex. Based on composition and geochronology data of Neoproterozoic amphibolites and orthogneisses, Triassic high- to ultra-high pressure metamorphic rocks, and Early Cretaceous mafic-ultramafic intrusive rocks, and the constraints provided by experimental melt data for tonalites, metabasaltic rocks and eclogites, we suggest that the adakitic granites were most probably generated by partial melting of thickened amphibole or rutile-bearing eclogitic lower crust as a consequence of Triassic-Middle Jurassic subduction and thrusting. The late dikes probably originated from plagioclase-bearing intermediate granulites. Moreover, we suggest that late Mesozoic delamination or foundering of thickened eclogitic lower crust is also a more plausible mechanism for the petrogenesis of Early Cretaceous mafic-ultramafic intrusive rocks in the Dabie area, and probably involved partial melting of a mixed source comprising eclogitic lower crust that had delaminated or foundered into upper lithospheric or asthenospheric mantle peridotite. Asthenospheric upwelling in response to post-collisional delamination of lithospheric mantle was likely to have provided the heat source for the Cretaceous magmatism.  相似文献   

Erratum to “Rigorous approach to bore-sight self-calibration in airborne laser scanning" [ISPRS Journal of Photogrammetry and Remote Sensing 61 (2006) 47–59]     

Jan Skaloud  Derek Lichti   《ISPRS Journal of Photogrammetry and Remote Sensing》2007,61(6):414-415

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1997 Appreciations     

Derek Sears 《Meteoritics & planetary science》1998,33(1):4-5

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